Home

Design of a Wearable Ultrasound System

1. cc ccccecc cece secceeec cece eeaeeeeeeeeeeeeeees 199 Table 35 Internal Audio Cable Assembly nannnnnnnnnnennnnnnnnnnnnnnnnnnnnnnnrnnrneernnnnnnnns 199 Table 36 Internal Battery 1 Cable Assembly annannannannnnonnnnnnnnnnnnnnnnnnnnnnnnnnnennnn 199 Table 37 Internal Battery 2 Cable Assembly annannannannnnnanonnnnnnnnnnnnnnnnnnnnnnnnennnn 200 Table 38 Internal Charger Cable Aesembhy 200 Table 39 Internal CMOS Battery Cable Assembly nnannannnnnnnnnnnnnnnnennnnnnnnnnnnnnnnn 200 Table 40 Internal Fan Power Cable Assembly ccccccceecceeeceeeceeeseeeeeeeeeeseeees 201 Table 41 Internal HDD Cable Assembhy 201 Table 42 Internal IEEE 1394a Auxiliary Power Cable Aesemblv 201 Table 43 Internal IEEE 1394a Cable Assembly cece cece eecceceeeeeaeeeeeeeeeeseeees 202 Table 44 Internal Mouse Cable Asesembhy cess eeaeeeeeeeseeseeess 203 X Table 45 Table 46 Table 47 Table 48 Table 49 Table 50 Table 51 Table 52 Table 53 Table 54 Table 55 Table 56 Table 57 Internal MSM855 CPU Power Cable Aesembhy 203 Internal Power Switch Cable Assembly nannannannnnnnnnnnnnnennnnnnnnnnnnnnnnne 203 Internal Temperature Probe Cable Assembly cccceecceeeeeeeeeeeaes 204 Internal USB Cable Aesemblv 204 Internal VGA Cable Assembhy 204 External VGA Cable Assembly nnannnnnnnnnnnnnnnnnnnnnnnnnnnnnrnnrerrnrrrnrrrnnrnn 206 External Audio Cable Assemblhy 206 External Mous
2. E REN 3 203 Table 47 Internal Temperature Probe Cable Assembly RIIT AN 2004 1x2 pin Shrouded Connector Power Supply Device 1x4 pin Shrouded Connector CPU Special Instructions Replace J26 on the CPU board with a right angle 1x4 pin header Table 49 Internal VGA Cable Assembly Device Pin Signal Pin Device Af Bei 3152 3 Bue C18 Supplied VGA Cable from CPU Cable Kit DDC Clock J15 10 FEMALE SOCKET pl VGA J37 2 2x2 pin Shrouded Connector 9S vk _ J374 Power Supply 204 Appendix Ill External Cable Assemblies Please note that the indicated cable lengths are measured using the exposed cable sheath between connectors as shown in Fig 122 Mi Length _ gt Fig 124 Cable Length Measurement The cable lengths are indicated with a number over another number in parenthesis The top number is in cm while the bottom number is inches Fig 123 shows an example cable length of 25 cm 9 8 in je 9 8 Fig 125 Cable Length Measurement Example The controlling dimension is in cm Whenever a connector pin out is shown for a device the view will always be looking into the connector at the mating face Unless otherwise instructed all connections are made using individual AWG 26 cable 205 Table 50 External VGA Cable Assembly Device Pin Signal Device 1y Ra or OLORON HSYNC 6 7 Ce Coy Goh VSYNC a4 2 03 Wd G VGA Signal
3. 207 Table 55 External Battery 2 Cable Assembly Device 35 1 Special Instructions Bundle 3 wires together for the BAT and BAT signals Device Device FEMALE INLINE CONNECTOR Special Instructions Bundle 4 wires together for each signal The AC adapter must also be modified with the corresponding male inline connector 208 Appendix IV Schematics All components values are correctly specified in Appendix Bill of Materials Where a discrepancy exists the bill of materials should take precedence When modifying the 1394a interface board the following components must be removed to isolate 1394a bus power from the interface board F1 C1 F2 C4 209 Sg Rl UN Teel el as Jo AD AY DIOU Se KEE re Wun wl S TVADHddY ON LIYVAHLNOJ Neoe Ads FG P6ELAASl SN cLLZCAd 06 6 SEP A ddANSHIMOd AG ENEE 2 NOLL de 30 AJH SNOISIASY aek SE Uo Y uid Ad d VICCHA WICH PJ00g ett 211 fr pubo au ou uid eut saulnsg Olaa ofoud ay Dun GEI ns JaMod DI SJI UU0I Uld punod FEET JJJ uo SEI Udg J ng JON Ajqwassyx ant gur ndod 210 Appendix V PCB Layout met gO Or aan fm of estate wee TERTIT DU ii HIEI w EN a BGG iis GHEE mme M e HIT Q4m 6 oe Dei R11 R43 R17 R e d US R33 Fig 127 Top Copper 211 gt il enee oo Ho Gei
4. 181 11 Conclusion and Further Work The goal of this thesis was to produce a wearable ultrasound system for use in clinical trials at MAMC Where possible COTS equipment was used and where required custom design work was performed Included in the custom design work was the development of a power supply and an enclosure to house an embedded computer wireless interface and the power supply There were also several software applications that were written The main piece of software integrated speech recognition data logging power supply monitoring and control and also included an interface to the Terason Ultrasound Application A small server program was written to acquire ultrasound images and make them remotely available in real time to a client application Also another application was written to analyze data stored by the data logger This wearable ultrasound system was developed manufactured and tested in clinical trials The clinical trials occurred over a period of 10 months at MAMC in Tacoma WA It is the third generation in a series of prototypes that evolved from a traditional laptop in a backpack to a completely ruggedized and wearable system It is medical in appearance and was used over a one week period in the deserts of the southwestern United States A total of four prototypes were successfully built Two conference papers were presented One was presented at the American Institute of Ultrasound in Medicine AIUM 20
5. Fig 66 Context Creation Once a context is created the rest of the supporting objects can be created to finish initializing a complete speech recognition system These objects are an audio source feature extractor jump back buffer and the recognizer The audio source object is used to supply speech data to the ASR engine The ASR engine expects 16 bit linear pulse code modulated PCM data sampled at 16 kHz This data is organized into frames containing 384 samples making each frame 768 Bytes in size The data is supplied to the ASR engine by a thread that records incoming audio data into a 16 entry circular buffer where each entry in the buffer 93 contains 32 frames of data Therefore each entry is 24 576 Bytes in size and the entire circular buffer is 393 216 Bytes A circular buffer is a memory model that implements a queue of a predetermined size that can be simultaneously written to by one thread and read from another Each entry written into the buffer is written to a successive position in a circle or ring Data is read from the oldest entry to the current write position This reduces the chance that a sample may be lost if the reader does not remove a sample before another sample is ready to be written This is often the case when a time dependent data stream must be processed by a non real time OS such as Windows The feature extractor object performs basic signal analysis and processing It computes the signal to nois
6. 3 3 2 Enclosure Connectors Each connector used on the WUC is a circular panel mount connector They support as many as 18 conductors per connector Solder cups are used to attach wires to the backside of the connectors The connector is attached to the enclosure by passing through a keyed hole from the rear and then it is secured with a nut on the front The corresponding cord connector which is used by attaching cables to mate with the panel mount connector has a locking ring to ensure that the cables do not come loose unintentionally The panel mount connectors include an integrated gasket to ensure water tightness exceeding Coast Guard specifications CFR 46 Part 110 20 and are also MILSPEC rated for both shock and vibration Each pin can carry a maximum of 6 5 A of current and have a maximum contact resistance of 5m0 This combination of high current carrying capacity and low contact resistance make these connectors well suited for both signaling and power applications The connectors on the embedded computer enclosure are located at both ends of the enclosure This location allows the exiting cables to pass directly into the vest containing the embedded computing platform There is a slight overhang of material beyond the enclosure wall containing the connectors that helps to protect the connected cables from excessive strain The alcove formed by the overhang is detailed in Fig 40 Fig 40 Cable Strain Relief Alcove 49 Th
7. HIGHLIGHT THE BATTERY STATUS INDICATORS AND TIME REMAINING NOTCE TONER 220 Below this are two indicators one for each battery that show the remaining capacity of each battery Finally below the battery indicators is the estimated remaining operating time The time is represented in hours and minutes CUT TO THE OPERATOR S HAND HOLDING THE TRANSDUCER VOICE OVER Issuing a command using speech recognition is a three step process First depress the push to talk button on the transducer OPERATOR PRESSES THE PITE BUTTON VOICE OVER e Say the command then release the button OPERATOR RELEASES THE PEE BUTTON BAUSE CUP TO THE VEDEO DISPLAY SHOWING THE JOOMED DASHBOARD ONLY AS A STATIC IMAGE VOICE OVER Before issuing a command verify that the dashboard says ASR Ready When the push to talk button is depressed the text will change to Listening UPDATE THE SCAT IC IMAGE s VOLCE OVERS Once the system is listening the command can be issued When you are finished speaking the command remember to release the p snsto talk DULL ON UPDATE THE STATIC IMAGE VOICE OVER Once the command has been interpreted the dashboard should again say ASR Ready In addition you should now see the interpretation of the command you just gave SES ECK THE GLAST RECOGNIZED LEX De PAUSE UPDATE THE S lATLC IMAGE TO SHOW A POOR RECOGNITION RESULT VOLCE OVER If the
8. hierarchy is a proper subset of any lower levels and is detailed in Table 12 Table 12 Chomsky Hierarchy Chomsky Hierarchy Grammar Language _ Minimal Automaton Unrestricted Recursively Enumerable Level 1 Context sensitive Context sensitive Linear Bounded automata Context free Context free Pushdown automata Finite automata A minimal automaton is analogous to a minimal computational model A Turing machine describes a computational model equivalent to a modern computer with infinite memory BNF was specifically developed by John Backus and Peter Naur to represent the programming language ALGOL in 1960 41 This was the first use of a grammar to formally define a programming language BNF describes context free languages and is therefore a context free grammar A context free grammar G takes the form of a 4 tuple described by Eq 11 G V 2 P S where V finite set of variables non terminal symbols 11 2 finite set of terminal symbols P finite set of rules S start symbol The sets V and 2 are disjoint V U so no variables may appear in any strings in the language A simple context free grammar in ScanSoft BNF may look like the following 42 start lt Speech gt lt Speech gt lt Drinks gt lt Food gt lt Drinks gt lemonade milkshake orange juice 90 lt Food gt hamburger french fries In this example the start symbol is identified by
9. The shutdown exe process contains a single message loop It uses a separate thread to monitor the state of the three processes that are normally running Once all of these processes have exited the embedded computer is shutdown It was found that directly shutting down the embedded computer while the three processes were running could take over five minutes By waiting until the processes have exited the shutdown process completes in less than thirty seconds It is unknown what causes this slowdown which is manifested by a very slow logout process While the shutdown exe process is running it displays a message reminding the user to shut off the head mounted display The rid exe process is an MFC application that contains a Terason supplied Activex object The Terason ActiveX object is a frame server for the images being displayed by the Ultrasound exe process The image frames are transferred between the Ultrasound exe process and the rid exe process through a shared memory interface which is accessed using the Terason ActiveX object The rid exe process is an MFC application and not a Win32 application because it was found that the Terason ActiveX object could not be used otherwise The Doxygen 53 documentation system was used to document all of the C source code written for the WUC Doxygen works by parsing specially formatted 150 comments in C source and header files to produce documentation in various formats When view
10. The voltage is adjusted by means of a 1 25 V reference voltage provided by a voltage divider The voltage divider is connected to the output voltage to provided feedback to the device for load regulation as shown in Fig 53 Fig 53 Output Voltage Adjustment of Linear Voltage Regulator Eq 8 shows how to determine the output voltage by using two external resistors Note that since l gt gt laps the laps Current can safely be ignored R Vo VREF 0 R 8 1 By assuming HR is connected between the output and the reference terminals and is kept constant at 237 Q an example value in the data sheet we can derive an exact 71 representation for Ro R di Yo 1 9 V REF One peripheral device that requires a regulated voltage other than 5V is the HMD It requires up to 7 W of power at 9 V By substituting into Eq 9 the desired output voltage of 9 V R2 is found to be 1 469 kQ This is rounded to the closest available value of 1 47 KQ in the design At 9 V the linear regulator can supply up to 13 5 W of power which is more than adequate to power the HMD 4 7 SMBus to RS 232 Host Interface The SMBus 81 was originally designed by the Intel Corporation in 1995 It is found in personal computers and utilized for system management communication In a personal computer the SMBus is used for system management by connecting temperature sensors microprocessors memory and other peripherals to an SMBus controller
11. 179 first encounter the device and evokes a wide range of reactions These reactions have ranged from curiosity fashion critiques and ambivalence to confusion and apprehension For some reason many people are initially overly concerned with the weight of the device and simply refuse to believe that it could possibly be comfortable to wear for even a short period of time After finally wearing it however these concerns were quickly allayed Other people immediately set about trying to redesign the vest before even trying it on Some valid feedback has been received on the use of cotton as the vest material This is a poor choice from the standpoint of durability since the cotton can rip easily and may be too warm A nylon material of some sort seems to be the preferred material in the military and was a common comment received from military personnel The head mounted display was a constant source of apprehension for new users when demonstrating the WUC Many people are simply reluctant to wearing it In fact almost everyone upon first encountering the system would only hold up the head mounted display to their eyes to view it Since it is a head mounted display and not a hand held display the viewing experience is sub optimal when used in this manner For the people who could be convinced to use the head mounted display in the manner it was intended feedback was universally positive The voice command system was universally the m
12. 19 Terson 2000 SmartProbe 22 Terason s product called the Terason 2000 is designed to operate using a laptop and their SmartProbe system of ultrasound transducers There are currently nine different ultrasound transducers available to support a wide variety of examinations The ultrasound transducer and front end electronics are a single unit The transducer cannot be detached from the front end electronics The embedded computing platform contains a complete COTS embedded computer manufactured by a company called Advanced Digital Logic It is similar to a laptop class computing device but in an embedded form factor The embedded computing platform also contains a custom designed power supply hard disk drive HDD and an interface for the Terason 2000 called an External DC Module EDCM These parts are all contained in a hermetically sealed enclosure that is further detailed in Section 3 Also included within the embedded computing platform is a wireless interface The uses of this interface and its implementation are discussed in sections 3 and 6 The enclosure that houses the embedded computing platform is custom designed Each of the two rechargeable Li lon batteries is capable of storing up to 95 Watt hours Wh of energy for a total capacity of up to 190 Wh when both batteries are fully charger Each battery can be hot swapped while the WUC is in operation as well as charged within the vest regardless of whether the emb
13. 29 30 EM 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Lippert AT Cool RoadRunner 4 Datasheet February 2006 DIGITAL LOGIC AG Technical User s Manual for MICROSPACE PC 104 plus smartModule 855 MSM855 ver 1 11 2004 IEEE Std 1394 1995 IEEE Standard for a high performance serial bus August 1996 DuPont http heritage dupont com floater fl_delrin floater shtml 2003 DuPont Delrin 100P NC010 2006 BB 04 http Awww ocean server com modules html bbs 2004 DC 023 http Awww ocean server com converters html 2004 DATEL Single Output ULE 20A Models SBS Implementers Forum System Management Bus SMBus Specification Version 2 0 Aug 2000 SBS Implementers Forum Smart Battery System Manager Specification Revision 1 0 Dec 1998 Smart Battery System Implementers Forum SBS IF Smart Battery Charger Specification Revision 1 1 Dec 1998 SBS Implementers Forum Smart Battery Selector Specification Revision 1 1 Dec 1998 SBS Implementers Forum Smart Battery Data Specification Revision 1 1 Dec 1998 Isidor Buchmann Batteries in a Portable World Cadex Electronics Inc May 2001 Inspired Energy Battery Specification Document Number DS129 July 2003 Appnote 751 http Awww maxim ic com appnotes cfm appnote_number 751 2005 Linear Technology LTC1775 High Power
14. 8 1 6 4 DA 2 I l l J I L D 0 1000 2000 2000 4000 5000 6000 rogo 800g 5 Fig 109 Single Smart Battery Discharge Characteristics 157 The total time to discharge a single Smart Battery was 8 600 s 2h 23 m 20s The Smart Battery reported an average power draw of 37 01 W while discharging and provided a total of 88 41 Wh 5 954 Ah of energy These same tests were then repeated but now two Smart Batteries were used The first result shows the relative capacity vs time for two Smart Batteries to be charged by the Smart Battery Charger Both Smart Batteries were discharged into a constant load until the internal protection circuitry disabled the Smart Batteries The Smart Batteries were then connected to the Smart Battery Charger and charged until both Smart Batteries requested that the charging be terminated Each Smart Battery managed to discharge so fully that the reported capacity from each Smart Battery was 0 This can occur when the Smart Battery electronics shutdown to conserver power and require a short charging period to wake up The total time to charge the Smart Batteries was 13 169 s 3 h 39 m 29 s The Smart Batteries reported a total average power consumption of 56 66 W while charging and absorbed a total of 207 28 Wh 13 036 Ah of energy The current limiting is slightly different for charging two Smart Batteries The AC adapter that provides power for charging the Smart Batteries can provide a max
15. The second compartment is used for cooling the sealed compartment It contains two fans and the 802 11b g board Separating the two compartments is an aluminum heatsink that serves two purposes The heatsink as the name implies acts as an efficient conduit for heat transfer between the compartments The cooling performance of the design is detailed in Section 9 3 It also acts as a backbone that all components are attached to Fig 31 shows the three main pieces of the enclosure a Top Enclosure Cover b Enclosure Heatsink c Bottom Enclosure Cover Fig 31 Enclosure Components When a person is wearing the vest the enclosure is oriented such that the person s back is in contact with the curved bottom of the enclosure Due to this orientation the 802 11b g interface is mounted on the heatsink so as to not interfere with the 802 11b g transceiver Mounting the 802 11b g interface within the sealed compartment would have located it between an aluminum plate and the back pf the person wearing the vest This would have resulted in poor radiation of the 802 11b g signals The entire enclosure is milled from two solid pieces of Delrin This material was created by DuPont in 1952 as a general substitute for nonferrous metals 26 such as aluminum tin zinc or brass It is characterized by the manufacturer as lightweight but durable low wear low friction plastic 26 Some selected properties of Delrin are shown in Table 3 4
16. The SMBus is a 2 wire serial bus using a master slave architecture and a maximum data rate of 100 kb s It supports two physical layer types a low power and a high power mode The main difference is in the pull up resistors used and the currents that the bus can be driven with The signaling voltage can be between 2 7 V and 5 5 V allowing a wide range of device to be directly connected The Smart Battery System Manager LTC1 760 has three SMBus connections Two are used for connections to each of the Smart Batteries while the third can be used to connect to a host SMBus It is important to note that the Smart Battery charger does not require a host to operate However providing this connection will allow the host to directly access the data provided by each Smart Battery as well as the smart Charger In this instance the host is the embedded computer Since there is no SMBus interface available on the selected embedded computer an interface was designed using a microcontroller and an RS 232 transceiver The 72 selected microcontroller was from P Cmicro PIC16LF 67 and it integrates a master capable Inter Integrated Circuit CH 40 controller and a UART A UART is hardware device that converts between serial and parallel data accessed from disjoint clock domains This reduced the complexity of the accompanying software since the microcontroller has a hardware peripheral for each bus that was to be interconnected This device was se
17. cart based machines often support multiple transducers although only one 18 transducer can actually be used at any given time Another general limitation is the number of beam formers which directly affects ultrasound image quality Lastly the displays on portable machines may not be as good Most of these differences except for the form factor are rapidly narrowing Portable machines are beginning to offer similar features and image quality as the larger machines They may even offer features not found on their larger cart based brethren For example most of the portable machines are capable of operating on battery power alone for short durations of about an hour or two 1 4 Motivation and Justification The current generation of portable ultrasound machines are designed for use within clinical environments much like the cart based systems that they supplement While this has increased the use of ultrasound procedures and created new applications it is still primarily a tool for use within the clinical environment The clinical environment can best be summarized as an indoor location whether within a building tent or vehicle that is temperature controlled has stable power sources and is protected from the elements It is also the final destination for most patients requiring medical care whether routine or emergency in nature Clinical environments however are only a small subset of the possible locations that ultra
18. e Improve cable management within the vest e Improve head mounted display e Make the embedded computer more medical in appearance e Reshape the embedded computer for a more ergonomic fit when worn by the 26 operator The following sections introduce the individual requirements for the system components that are changes or additions to the second generation WUC 2 3 1 Enclosure Requirements The enclosure was required to fit into the rear pocket of the photographer s vest that was modified to fit the second generation prototype While the overall length and width of the previous enclosure was acceptable 18 3 x 13 2 x 6 5 cm 7 2 x 5 2 x 2 6 in there was a general desire to decrease the height when designing the new enclosure The enclosure also needed to be rugged enough to operate in outdoor environments This need brought forth two major requirements to have an enclosure that could withstand moisture rain foreign particles dirt dust while also providing effective cooling for continuous operation in hot climates as well as use in a Clinical setting Lastly the overall look of the enclosure should be made to be more medical in appearance by having a matte white finish with rounded shapes This also provides a more comfortable form factor when it is worn as part of the vest In an effort to further integrate the design from the second generation WUC the enclosure should be designed to incorporate the
19. entire duration of the test It was expected that the highest measured temperature would be from the sensor on the CPU die as this is the location dissipating the most power This however was not the case Instead the highest temperature was measured on the heatsink followed by the CPU and finally the fan controller on die temperature sensor 167 Each of the temperature sensors is a physically different piece of hardware Both the fan controller and the CPU use on die temperature sensors that were specifically designed for temperature sensing The temperature sensor on the heatsink makes use of an inexpensive transistor that was not designed to be used as a temperature sensor Therefore it may no be as accurate as the other temperature sensors The temperature of 40 C was selected for the test based on the maximum temperature tolerance of the Terason SmartProbe Terason indicated that the SmartProbe had never been tested to determine its maximum temperature tolerance but felt that 40 C was the probable number Based on the above results however it is expected that the WUC with the exception of the ultrasound transducer could safely operate up to 45 C without alteration The lowest operating temperature for the WUC is governed by the Li lon batteries The performance of Li lon batteries degrades significantly as the ambient temperature is reduced The minimum allowable temperature for safe discharge of the Smart Batteries
20. s onboard power supply and drivers to shut down and draw only 1 uA of current when no valid signal is sensed on any receiver inputs In addition to the microcontroller and the Smart Battery charger there is also a fan 13 controller on the SMBus The specifics of the fan controller are discussed in Section Smart Battery SMBus Smart Battery Charger SMBus Smart Battery Each device on an SMBus has a bit address The Smart Battery Charger provides 4 8 Acomplete diagram of the SMBus is shown in Fig 54 Fan Controller Microcontroller Embedded RS 232 Computer Transceiver Fig 54 Power Supply SMBus Block Diagram an SMBus multiplexer to select either Smart Battery for direct communications Table 8 summarizes the SMBus memory map Table 8 SMBus Memory Map NI Address Smart Battery Charger LTC1 760 0x14 0001 010X Smart Battery 0x15 0001 011X Fan Controller ADM1030 Ox5C 0101 110X There are two signals used in the SMBus SMBDAT and SMBCLK Each SMBus device drives each signal using an open collector driver Fig 55 shows a generic SMBus topology that uses mixed supply voltage devices 14 Vop DN Voie 3V SMBus device Fig 55 Generic SMBus Topology 40 SMBCLK SMBDAT All protocols start with the assertion of START condition on the bus The START condition is defined as SMBDAT transitioning from HIGH to LOW while SMBCLK is HIGH After t
21. shows TX when the application is actively transmitting and the other shows RX when the application is receiving An RA indication only means that the application is connected and capable of playing received speech No speech is actually sent until the user signals to do so To transmit speech from the RID client application to the WUC the user holds down the left mouse button anywhere within the window This causes the TX indicator to be displayed while the voice is being actively transmitted Releasing the left mouse 124 button causes the speech transmission to stop Much like the PTT button on the transducer handle which is used for issuing voice commands to the WUC the left mouse button acts as a PTT button for the RID client application If the WUC operator wishes to speak to a connected RID client application speech transmission is enabled through a pop up menu accessed via the Dashboard The WUC operator must right click within the Dashboard to display the pop up menu and select then select the Start Audio option Once the menu item has been selected speech is continuously transmitted to the RID client application Voice commands may still be issued to the WUC in the normal manner but they will also be transmitted simultaneously to the RID client application Voice transmission is stopped by selecting the Stop Audio option in the pop up menu 6 6 Remote Administration The WUC also makes use of
22. symbol is made automatically The particular phrases in the grammar were chosen 91 to maximize phonetic diversity among the phrases to get the highest possible recognition rates The complete listing of the grammar file appears in Appendix VI Speech Recognition Grammar 5 2 Implementation The VoCon 3200 Application Programming Interface is implemented as three separate Dynamic Link Libraries DLL and a single import library These files along with a language model for the particular language being used make up the files supplied by ScanSoft to use the speech recognition system The programmer must also supply a grammar file to be used in building a context that is used by the actual ASR engine There are three distinct phases to a speech recognition application The first phase is to assemble and initialize the various elements that comprise the speech recognition system into the runtime system This is performed during application initialization The runtime system is the actual combination of objects and application code that performs the work while the application is running The work is performed in a separate pop up thread A pop up thread is a thread that is created only when needed performs some work and is then destroyed This is different from a regular thread which is normally present during the entire lifetime of a process The final phase involves freeing any resources used by the runtime system 5 2 1 Speech Recogn
23. 168 0 1 Node IP 192 168 0 2 RTP Data RTP Data UDP 1000 UDP 1000 RTCP e RTCP _ E O Q O c LU _ OI Endpoint Endpoint Endp UDP 1001 UDP 1001 Fig 83 RTP Network Stack In this example there are two network nodes using RIP to transfer data Each network node has a distinct network address An IP address is made up four Bytes and in the example above one node has an IP address of 192 168 0 1 and the other node has an address of 192 168 0 2 The physical layer upon which all data is transferred is 802 11 An RTP session is an association among a set of participants using RIP for communication A session can potentially contain multiple participants such as in the case of audio conferencing Each participant is identified by a unique 32 bit identifier called a Synchronization Source SSRC If a participant is only receiving data it is labeled a receiver while a participant that both sends and receives data is labeled a sender Session control and reporting mechanisms occur using RTCP while the actual transfer of data occurs with RTP data transfer Each RTP data transfer includes a packet header containing the following relevant 112 information e RTP Version e Payload Type e Sequence Number e RIP Timestamp e SSRC Each packet of data transferred by a session participant includes all of the above information The RTP version is the version of the RTP protocol being used The pay
24. E 160 RUS TIO EE 17 18 Example Portable Ultrasound Machines ccccccsecseeeeeseeseeeeeeeeeeeeeees 18 192 Terson 2000 SMAMPlOD ege be panterusanecumoni 22 E Ke LE Te Bella Ce REI 24 21 e Le oe Re EE 24 227 Block BI Teen Reie EE 25 29 FSU ECH Lei WUC EE 30 24 Second Generation Embedded Computer Power Supply and Enclosure 31 29 G 104 PlUS BOard StaCkup 21 EE 34 26 Lippert AT Cool RoadRunner A 231 36 2 Advanced Digital Logic MSM855 GA 36 RL CR E ele EE 39 20 EDON E 39 30 Embedded Computer Enclosure ccccecceccsseceeeeeeeeteeeseeteeeeeeeseseeenaes 40 31 Giele Cf elt lee a EE 41 32 Dimensioned Embedded Computer Enclosure Drawing sensenoen01n11nn 43 33 e COMpPariMeNtS OF EMCIOSUIE EE 44 34 Top Compartment Of E elle 44 35 CPU Board and IEEE 1394a Board Assembly oannannnnnnnnnnnnnnnnnnnnnnnnnnnnn 46 36 Power Supply and HDD Assembly nannannannnnnnnannnnnnnonnnnrnnrnnnnrrnrrnrrnernnnne 47 3 2 TWOINLEMNGIASSEIMDIIGS ee 47 38 EDCM Mounting in Enclosure sereiieirriuneia itai e area 48 39 Complete Internal Assembly of Lower Compartment a annannannennennannnnnn 48 40 Cable Strain Relief Alcove cc cccccccccceeceecsseceeeeeeteeteeeeeeteeeeseteeeeeeseeseeeeess 49 41 Enclosure Connector Model 50 42 Step One of Assembling the Enclosure cccccccccceceseeeeeeeeeeseeeeeeeeeeeaes 51 43 Step Two of Assembling the Endosure nnannennennnnnnnnnnnnnnn
25. Linear Array Microphone Directional Sensitivity The array microphone is not the only microphone that can be used with the WUC The eMagin HMD has a built in microphone that can also be used for speech recognition Testing not performed by this author has proven it to provide comparable speech recognition performance to the array microphone 107 6 Remote Data Facilities In continuing with the desire to have a fully untethered ultrasound device the WUC integrates a wireless data interface that allows for remote administrative access as well as access to any data stored on the device This data includes web pages manuals databases static and real time ultrasound images voice communications and stored ultrasound image clips The data interface as well as most of the protocols used for data transmission is based on open standards to promote the widest interoperability possible The following sections will discuss the various remote data facilities organized according to the Open Systems Interconnection OSI reference network model For reference the OSI model is shown in Fig 82 OSI Model data unit layers Host Layers Media Layers Fig 82 OSI Reference Model 43 6 1 Physical Layer The physical layer as defined in the OSI model represents the physical device and 108 the electrical characteristics of the transmission medium being employed In the case of the WUC the IEEE standard 802 11 44 is used fo
26. MHz Lower frequency transducers provide for deeper tissue penetration but have poorer resolution than higher frequency transducers Fig 14 and Fig 15 each show a similar ultrasound image The image on the left was imaged with a 3 5 MHz transducer while the image on the right was imaged with a 5 MHz transducer 14 Fig 14 3 5 MHz Ultrasound Image 8 Fig 15 5 MHz Ultrasound Image 8 Note the difference in resolution between the images More detail is evident in the 5 MHz image as opposed to the 3 5 MHz image 1 2 Ultrasound Applications Ultrasound imaging is used in a wide variety of diagnostic examinations It is capable of imaging soft tissues as well as bone structures safely and inexpensively Ultrasound is widely used in a variety of medical fields e Cardiology e Urology e OB GYN e Gastroenterology e Nephrology e Vascular e Abdominal e Veterinary Ultrasound transducers are available in a wide variety of configurations Certain high frequency and high resolution transducers are even designed to be used within the body itself These transducers are able to provide high resolution images of 15 structures that would not normally be so well visualized Examples of such probes include transesophageal transvaginal and transrectal probes for imaging structures such as the heart uterus and prostate respectively 1 3 Portable Ultrasound Compared to other imaging modalities such as MRI CAT Scans and X
27. Ray ultrasound is the most portable medical imaging modality However most ultrasound machines are still generally cart based systems that require an installed infrastructure for support Fig 16 shows a typical ultrasound machine found in hospitals and clinics today Fig 16 GE LOGIQ 9 9 To the extent that the machine can be moved within a clinical setting even the largest ultrasound machines are portable to some degree However their large size and weight means that most often it is the patient that is brought to the ultrasound machine Portable ultrasound complements the traditional ultrasound machine by providing nearly the same image quality and features in a small and portable form factor as shown in Fig 17 Fig 17 SonoSite 180 Plus 10 The portable form factor has changed how ultrasound is used in the traditional clinical environment as well as created new applications With a portable ultrasound machine the machine can easily be brought to the patient The reduced size often means greater maneuverability in crowded areas such as in an intensive care unit ICU or a trauma bay Moreover battery operation allows ultrasound examinations to be performed without having to first locate an electrical outlet A single practitioner working out of several offices could carry a single portable ultrasound machine and not have to have an individual ultrasound machine in every office 11 The practitione
28. TEXT 45 description TEXT 256 tblpackets tstamp DATETIME tstampms SHORT msg SHORT payload LONGBINARY DATETIME tstampms SHORT LONGTEXT tblcputemp pk LONG tblimages tstamp DATETIME patient_name TEXT 255 patient_id TEXT 255 url TEXT 255 tblbattery DATETIME SHORT tstamp tstampms toblwords TEXT 45 LONG bat1_ tte bat2_tte bat1_rc bat2_rc bat1_v bat2_v bat1 i bat2_i SHORT SHORT SHORT SHORT SHORT SHORT SHORT SHORT tstamp DATETIME tstampms SHORT cpu_temp SHORT local_ temp SHORT remote_temp SHORT tblutterance tstamp DATETIME tstampms words end rec confidence abnormal pk SHORT Fig 132 Database Schema LONG SHORT SHORT SHORT LONGBINARY LONGBINARY LONGBINARY LONG 217 tblaudio LONG LONGBINARY Appendix VIII Training Video Scripts WEARABLE ULTRASOUND SYSTEM TUTORIAL OPERATOR NARRATOR INT OPERATOR To STANDING NEAR THE VEST WHICH od Te ON A GHALIR THE BACKS LDE OF THE VEST Io VISIBLE VOICE OVER Hello and welcome to the Wearable Ultrasound System tutorial video This video is a short introduction to the Wearable Ultrasound System and will demonstrate some basic skills required to use the system The same information and much more 1S contained in two manuals that accompany the system The first manual titled Terason User s Guide contains information about using the Terason 2000 ultrasound transdu
29. These patients must often travel great distances for routine care Amore portable ultrasound machine could better service rural populations The current generation of portable ultrasound machines are only portable to the extent that they can only operate for one or two hours on battery power This limits the amount of time that the machine can be operated without returning to a stable power source These machines are also not suited to operation in harsh environments such as in the rain or in a desert They also require a stable work surface to operate them such as a table or chair These limitations limit their suitability outside of the clinical environment The wearable ultrasound system detailed in this thesis addresses these deficiencies to make portable ultrasound suitable to almost any environment 20 2 Wearable Ultrasound This section introduces the wearable ultrasound computer WUC and includes the motivation for performing this work the requirements of such a system and the development history preceding this thesis work 2 1 Introduction to Wearable Ultrasound The WUC as the name implies is a wearable system It has been designed for long term use in harsh environments without the need for installed infrastructure The WUC is worn by the individual performing the examination It is in the form of a vest that contains all the equipment necessary for carrying out completely untethered ultrasound examinations The vest ha
30. be flipped up and down by pressing a plunger above the display Connect the cable and ensure that the display is on before powering on the system Now the system is ready to be powered up The power button is located in the upper right hand corner of the embedded computer located in the back pocket OPERATOR TURNS AROUND ALGCGOWING THE CAMERA TO ZOOM EN O THE BACK POCKET OPERATOR TURNS ON THE EMBEDDED COMPUTER WHEE TURNING BACK AROUND THER CAMERA ZOOMS BACK OUT TO THE FULL SCENE VOICE OVER The system is now coming up After approximately one minute you should be able to see the ultrasound application CUL TO THE VEDEO DLSPCOA T aki SHOWS yao TAC MAGE REPRESENTING A SAMPLE OF WHAT THE USER MAY SEE VOICE OVER Let s now go over the main graphical elements on the screen On the left side of the screen is the image control bar HIGHLIGHT THE IMAGE CONTROL BAR ON CHE o FATIC IMAGE VOICE OVER Ihe image control bar is used to control various aspects of the image It is context sensitive meaning that it will show different controls based on factors such as the current scan mode and whether the image is moving or frozen ADD TT TONATAGY HIGHLIGHT THE TAB CONTRO Lo Ar THR BOTTOM OF IHE IMAGE CONTROL BAR PAUSEs THE VIDEO DISPLAY SHOWS AL EE EMAG HE OF THE DEFAULT APPEICATION STALE VOICEOVER The tab controls at the bottom of the image control bar can be 219 used to access diff
31. contains information about that customer such as their address The goal of designing a schema for a relational database is to not replicate any information This ensures that no space is wasted by having multiple copies of the same data and also ensures error free updates to the database For example if a customer s address is contained in two tables an update to one table and not the other would leave the database in an inconsistent state Every record in a table must also be uniquely identifiable This uniqueness is generally accomplished by designating one of the columns in a table as a primary key Sometimes multiple columns may be combined to create a primary key Using these principles the database schema defined in Appendix VII Database Schema was developed While a full explanation of the design process for relational databases will not be provided the WUC database schema will be detailed The database schema was developed to support statistical analysis of various aspects of the WUC in addition to generic logging These aspects include speech recognition power supply monitoring internal temperatures and errors Additionally the database supports the remote viewing of stored images functionality provided by the web server A set of tables was developed to store information pertinent to each of the aspects noted above The tables use data types defined by MySQL and are detailed in the following tables Table 14 MySQ
32. contains the most information is the Utterance view shown in Fig 98 2 WPI Log Viewer oj x Database Filters View 21 Tue Apr 18 14 08 26 EDT 2006 22 Tue Apr 18 14 08 31 EDT 2006 magenta lt 4056 gt 23 Tue Apr 18 14 08 59 EDT 2006 flame 4094 24 Tue Apr 18 14 09 02 EDT 2006 Listen View SNE 4 Wiew EL Fig 98 Database Analysis Program Utterance View The Utterance view presents a list of the utterances in the database On the left side of each entry is the utterance number in brackets which is the primary key for the table tb Utterance timestamp utterance string and a confidence score in angle brackets On the right side is a bar the represents the duration of the utterance The red portion is proportional to the time between depressing and releasing the PTT button and the green portion is proportional to the processing time used by the ASR engine to generate a recognition result The number above the bar correspond to the duration of these two sequences in ms while the number below the bar is the overall duration of the recognition event Each item in the Utterance view also has a pop up menu From this menu a graph can be displayed that shows the SNR and EL over time for the entire utterance as reported by the feature extractor If the utterance had a poor confidence score it will 142 be highlighted in yellow In this case the actual sound of the utterance was stored in the database and c
33. ee EE 96 WPI Application Cvenvlew 98 PUSHER TO tak CH el RE 99 VS PECCHARECOGNIMOMN Stale S eee E AA 100 Successful Recogntion of live image ccc cecc cece eeeeeeceeeeeeeeeeeseeeeeeeaees 101 Poor Recognition of power doppler ccccccecceecseeceeeeeeseeeeeeseeeeeeeeeees 101 CAO DeCtallS Dialog BOX ee EE 102 View Utterances Dialog Box 103 SOMULGOWNM DIAO BOX EE 105 Shutdown Progress Dialog BOX cccceecceecceecceeeeeeeeeeseeeseeeeeeaeeeseeeaess 105 Sr alent IMfOhmaliOh EE ee BOX EE 106 Patient Information Header 106 Linear Array Micropbone 107 Linear Array Microphone Directional Sensitivity ccccccceeceeeeeeeeees 107 OSI Reference Model A3 108 e ER ING IW ON Le EE 112 BUNS WE Le gee KR EE 119 NOS EMA SW RE 119 AIR RE nie E E svotavoiivolavesqaiaioiadiaioladieloiardvelevadiideleedosteledeavobacbicionsiel 121 ILD WV IEA Client EIERE Ee 121 RID Client Connection Dialog Box 122 EEN 122 Web Server OMG AGG EN 126 Fig 91 User s Guide ON Web Gerver cece eeeeeseeeeeeeeeeseeseeeaeeeaes 126 Fig 92 Saved Images ON Web ener 127 Fig 93 Data Analysis Application Connection Dialog 138 Fig 94 Database Analysis Application Database Menu 139 Fig 95 Database Analysis Application View Menu s nnanonnnnnnnnnnnnnnnnnennnnennnnnnnnnn 140 Fig 96 Database Analysis Application Filters Men 141 tert Dale Filer DIAO EE 141 Fig 98 Database Analysi
34. el ER 78 49 iPOWERSUDDIY PCB DESIGN ee 80 4 10 IEEE 13944 Power SUDDIY EE 82 AANA WISER EE 83 eg E ei e EE 88 5 1 BACK OFOUING WEE 88 Dez JAURES 92 5 2 1 Speech Recognition Initialization ccc ceecceccceeeeeeeeeeeeeeeeeeeeeeneeeaes 92 9 2 2 Speech Recognition Runtime ccccccceccsseceeeceeeceeeeeeceseceeeseeeeeeeaes 95 IV 5 3 SEF INTE Le 99 5 4 Terason Application Integration 103 IF FUSE AON Lei EE 105 O07 SAA VIMIICKO DONG EE 107 6 Remote Data F aCe Senra anda 108 6 1 inte 108 62 ANANSDOM LAY CN eege 109 6 3 Real Time Transport Hrotocol ennari neen E ANE Eh 111 6 4 Real Time Ultrasound Imaging ccccccccceccseeceeeeeeseeeeeeseeeeeeaeeseeeeesees 115 6 5 VOICE COMMUNICALIONS EE 123 60 IREMOLS te un UE de e EE 125 TO E E o e Ae WEE 129 7 1 LOGOO tele WE 129 Ted Loggo Data SOM Genese T ET 131 Lo Daa a E 137 GO System negra UON EE 146 8 1 Hardware Integration 146 8 2 oOlWware Dn e e e Te s s cascisectentevinesienvesdeetwus boson E EEOAE EEEN 149 o9 Ee e lee EE 151 9 Technical SiON Le 153 91 Batey Ee E 153 92 ONV OWINGCHING RE QUIAIOF EE 163 9 3 Embedded Computing Platform Themae 166 JA DSPECCH ee en en WEE 168 Or SPECMOD EE 172 10 Clinical JSage and WC EE 174 NOEL PRO DIGAUOMS EE 175 do Met En te e gene ee EOE E EOE OEEC 175 101 2 Digaster E EE 176 fe ES S Medea Transpo E 177 10 t4 Jee 178 Elo IEN eege 178 10 2 Olut Of Box Experience 179 11 CONGIUS
35. focus five point five focus four invert vertical juliet map charlie quebec romeo smoothing bravo three zero zech fo N S CO CO N D D D D D D D Q Q Q Q Q Q Q oN Ee oN oN Ee Ee Ee De Pl IDN oo oo HH HHH ooo ooo La Fig 118 Utterance Frequency 169 Aouenbei4 a2ugIaun sOUuUeBIOIIN shutdown yes live image b mode cobalt gray freeze image power doppler flame depth two depth five rainbow tan depth four m mode pulsed wave doppler color doppler depth eight depth fifteen two smoothing echo map alpha depth nine save image brightness decrease depth three patient information map echo magenta small size no one sage switch fields eight papa backspace smoothing alpha large size ok sepia brightness increase focus ten map foxtrot depth ten depth twelve charlie full screen map charlie romeo cancel zero depth six x ray contrast increase depth seven contrast decrease smoothing bravo juliet depth twenty one directional power doppler three focus four focus one focus two quebec invert horizontal map delta depth twenty focus five point five five depth nineteen invert vertical focus eight 0004 0002 000 0o00 Fig 119 Average Utterance Confidence 170 0009 u p juo BHeIDAY Most of the utterances occurred during training sessions conducted at MAMC and e
36. from which information about the tissues can be determined A close analogy of this is clapping your hands in an empty room The sound produced by a hand clap is an impulse This impulse is then reflected off the various surfaces in the room until it eventually reaches your ears The reflections probably sound different than the original sound produced by the clap and these differences can be used to interpret characteristics about the room For instance a room with a large open door will sound different than that same room with the door closed While ultrasound uses a directional beam of sound energy and a clap produces an omnidirectional wave of sound energy the underlying principal is the same When applied to sonar where sound energy is transmitted through water the echoes provide a great deal of information about the surrounding environment Radar works similarly although radio waves are used instead of sound waves The use of ultrasound for imaging the human body was first performed in the late 1940 s 1 The technological advances were facilitated by the relative abundance of surplus radar and sonar equipment from World War Il One of the first uses of ultrasound to probe the human body occurred in the early 1950 s 1 Dr Inge Edler 3 and Professor Helmuth Hertz used a commercial reflectoscope to view heart motions The primary purpose of a reflectoscope was to look for flaws in metal welds and was also called a flaw detector
37. full rotational speed of 6000 RPM each fan draws as much as 400 mW for a total of 800 mW A temperature controlled fan controller provided by an Analog Devices ADM1030 was used to vary the fan speed based on the current thermal conditions This allows for reduced power consumption by not always running both fans at full speed During periods of low processor utilization the CPU within the embedded computer can reduce its power consumption dramatically At peak load the CPU consumes as much as 12 96 W of power running at 1 4 GHz and a core voltage of 1 116 V When idle the CPU runs at 600 MHz consuming as little as 2 W of power with a core voltage of 0 988 V Depending on the environmental conditions passive cooling may be all that is required The ADM1030 uses two temperature sensors in conjunction with several registers on the device to determine the proper fan speed One temperature sensor is located within the ADM1030 itself and measures the ambient temperature within the enclosure The remote temperature sensor is located on the heatsink near the 78 CPU and attached with a thermally conductive epoxy This temperature sensor is created by measuring the change in Vse of a general purpose 2N3906 PNP transistor when operated at two different currents This temperature measurement technique is described in Eq 10 Where 10 K Boltzmann s constant q charge on the carrier T temperature in Kelvins N ratio of t
38. in medicine While each has the capability of producing two dimensional 2D images of cross sections of the human body or even three dimensional 3D volumetric images without the need to perform surgery each also has its own unique advantages and disadvantages Different imaging modalities use different methods to produce these images For instance X Rays and Computer Aided Tomography CAT scans use ionizing radiation to penetrate the human body and record the resulting absorption pattern using a detector such as photographic film or by using electronic methods Magnetic Resonance Imaging MRI uses a combination of strong magnetic fields and radio frequency RF energy to produce images Each of these imaging modalities has its own unique sensitivity to different anatomies and tissues found within the human body The suitability of X Ray CAT scans and MRI imaging modalities for portable applications is severely hindered by either the physical size or power requirements of the imaging apparatus Ultrasound is uniquely suited to portable imaging applications due to its low power requirements and its use of sound energy Using sound energy to image the human body is also generally considered safer than using ionizing radiation This thesis involves the adaptation of portable ultrasound into a new wearable form factor A wearable form factor along with other design improvements addresses some of the shortcomings of the current gener
39. is 10 C 9 4 Speech Recognition A critical feature of the logging system described in Section 7 was the capture of information pertaining to speech recognition performance During the clinical trials performed at MAMC which included training sessions and individual first time users 840 utterances were captured The following figures show statistical results for utterances gathered during these sessions Not every possible utterance was used during this testing so only utterances that were used are shown Each chart is sorted in a descending order Fig 118 shows the relative frequency of each utterance while Fig 119 shows the average confidence scores 168 OU tan gray live image flame depth five depth four cobalt shutdown yes depth fifteen freeze image b mode sage rainbow brightness decrease depth eight depth two pulsed wave doppler power doppler color doppler m mode depth three depth twelve magenta map echo save image focus one depth nine focus ten map alpha no patient information backspace brightness increase depth ten small size smoothing echo switch fields two contrast increase depth twenty depth twenty one directional power doppler eight focus two full screen invert horizontal large size map delta map foxtrot ok one papa sepia smoothing alpha x ray cancel charlie contrast decrease depth nineteen depth seven depth six five focus eight
40. much as 5 W of power when the host system is off but the SmartProbe is still connected to 1394a bus power Therefore some modifications to the 1394a interface board were required 82 To reduce the power consumption of the SmartProbe when the system is off an optically coupled relay circuit was introduced This relay circuit is controlled using the parallel port on the host computer and allows 1394a bus power to be switched on and off via software Also the interface board was modified so the 1394a bus voltage would not appear anywhere on the board This was achieved by removing some components on the 1394a interface board to isolate 1394a bus power being supplied by the relay A schematic for the relay appears in Appendix IV Schematics 4 11 User Interface The power supply provides information to the user of the WUC by means of a small window inserted over the Terason application This overlay is called the Dashboard and is made to appear as if it is part of the normal Terason application interface In reality it is a separate window located in the lower right hand corner of the display The window is decorated to blend in with the Terason application It has no title bar or border and uses a similar background and foreground color Fig 62 highlights the location of the Dashboard within the Terason application 83 File Edit View Exam Modes Image Measurement Annotation Tools Help Z xl Exam Abdominal bi size
41. previous example shows the utility of SQL to manipulate and parse data 140 Another feature of the JEventLog program is the ability to add filters to the data being viewed Using the Filters menu a Date filter can be added The Filters menu is shown in Fig 96 0 xl Database Filters View Dm pate Message Payload Mon Ape Te Clear a V CASR_READY D ceart RaDio BUTON UP JS on Apr 17 15 27 39 ED CASR_GAIN 65535 an Apr 1 14 27 39 ED 27 39 ED CASR_CMD ASR_CMD Mon Apr 17 15 27 41 ED YESNO_YES ue Apr 18 13 51 46 EDT ASR_EKIT AcR_READ Y as RE Fig 96 Database Analysis Application Filters Menu Selecting the Date menu item in the Filters menu brings up the dialog box shown in Fig 97 Start Date End Date 01232006 01232006 01 25 2006 01 25 2006 01 26 2006 01 26 2006 Of 0712006 Of 0712006 02 21 2006 02 21 2006 O22 212006 O22 12006 O22 3 2006 O22 3 2006 02 24 2006 O22 4 2006 0309 2006 03092006 moran I morona Z Fig 97 Date Filter Dialog Box The Date filter dialog box contains a list of dates that have log events associated with them in the database By selecting a start and end date only events that occurred within the specified date range will be presented when selecting the 141 various views Again SQL is used to add a filter to the query to only retrieve data within a specific data range Currently only the Date filter has been defined The view that
42. pricing decreases will make this a viable alternative in the very near future In addition to hardware changes the software that currently runs the WUC has reached the limit of its maintainability This is the point where adding new features becomes overly difficult because the original architecture of the software never envisioned some of the features that have become clear choices for implementation in the future Adding features more often than not breaks current features or requires that current features be rewritten 184 some desirable new features include that ability to save a voice annotation along with stored images saving long duration video clips they are currently limited to the last 60 frames by the Terason application and picture archiving and communications systems PACS integration Current ultrasound systems have only very short video clip capabilities 2 6 s and are often augmented with external DVD recorders to store video clips This is not sufficient for all possible situations and the WUC could be modified to store video clips that were limited in duration only by the available storage space on the HDD PACS integration would also be a valuable feature In discussions with emergency department personnel having a portable ultrasound system that automatically disseminates stored images would save valuable time during a trauma and free the practitioner to focus on the patient An additional improvemen
43. prototype devices was being used The facilities ranged from Emergency Departments Vascular Departments simulated Combat Surgical Hospitals CSH tradeshows meeting rooms and medical offices Through all of these collective experiences a great deal was learned about portable ultrasound This section focuses on feedback and observations gathered over this period Portable ultrasound represents the fastest growing segment of the ultrasound market Every major ultrasound vendor is either in the process of or already has released a portable ultrasound product These devices tend to mimic laptops in their general form factor such as the Sonosite MicroMaxx pictured in Fig 120 Fig 120 Sonosite MicroMaxx 55 The MicroMaxx is representative of many other vendors offerings Where a 174 keyboard would normally be found on a laptop is a control panel more akin to what might be found on a full size cart based ultrasound system It contains a familiar set of knobs and sliders to control the ultrasound machine These portable machines also usually have batteries to allow a short period of autonomous operation They can store images and video clips support a number of different transducers and produce good quality images In short they offer excellent value for use in a clinical setting 10 1 Applications There are several applications for portable ultrasound outside of the clinical setting that are uniquely suited to using the WU
44. relates to how closely an utterance matched an entry in the current grammar The confidence score is also dependent on the number of phonemes in the utterance Less phonetically rich utterances the number of phonemes in the utterance will have relatively lower confidence scores since there are fewer phonemes to match Typically the confidence score is used to determine whether a recognition result should be accepted or rejected An acceptance threshold is established where anything lower than the acceptance value is rejected Through laboratory testing and analysis of field trials a confidence score of 3 00 was selected as the acceptance threshold During a recognition event different messages are generated by the ASR engine and must be handled by the application There are three types of messages that are processed recognition result available AGC request and abnormal condition detected Fig 69 shows a complete overview of the application that integrates speech recognition with the Terason application 97 Terason Application COM Automation WPI Application Fig 69 WPI Application Overview When a message indicating that a recognition result is available the application retrieves the result and executes some action based on this result The action may be to display an alphanumeric character on the screen change a parameter pertaining to the current exam or to shut down the machine AGC requests are sent
45. the Smart Battery are calibrated to read 100 when charged to the full rating of the Smart Battery In reality the Smart Battery will always store somewhat less than the rating would suggest This capacity will also degrade over time A calibration cycle can be performed so that the Smart Battery will report a 100 charge when fully charged to whatever the actual maximum capacity is The Smart Battery used in these tests was not calibrated A special charging cycle is required to perform the calibration and while the Smart Battery Charger hardware does support this the interface software does not provide this functionality 154 For Li lon battery chemistries charging occurs at a constant voltage For this model of Smart Battery Inspired Energy NL20204A22 the charging voltage is specified as 16 8 V 50 mV However there is also a 4 A charging current limit This results in a Charging profile that is initially current limited resulting in a lower charging voltage than specified As charging progresses the charging current will drop and the charging voltage will increase to 16 8 V Fig 106 shows the manufacturer s example of the charge characteristics for the Smart Battery Charge Characteristics Constant Current And Constant Voltage Charge Cory 4 2 20 C Voltage Vi Charging Current CmA Ke 1 3 4 5 Charge Time Hrs Fig 106 Manufacturer Single Cell Charge Characteristics 37 The plots are for a single cell w
46. the Smart Batteries However the extra power dissipated by the excessive transient voltages causes the linear regulator components to heat up considerably During charging the components become too hot to touch without Causing injury As charging progresses charging current will slowly decrease The performance of this switching regulator when providing 0 5 A of charging current is shown in Fig 112 161 BAT Charge 0 54 Fig 112 Smart Battery Charger Switching Regulator Providing 0 5 A DC Coupled The mean voltage output is 16 91 V This is within 0 7 of the proper value Fig 113 shows the same setup except that the oscilloscope was set for AC coupling and the Voltage range is much smaller 162 BAT Charge 0 54 AC Coupled I T T CH K BH be co a CH K of fae F Wi oo kA D Ve Fig 113 Smart Battery Charger Switching Regulator Providing 0 5 A AC Coupled The maximum overshoot is 100 0 mV and the maximum undershoot is 81 3 mV This results in an output voltage ripple of 181 3 man As the charging current decreases the performance of the switching regulator improves dramatically These results are markedly better than the results obtained while charging at 3 A 9 2 5 V Switching Regulator The initial switching regulator design was plagued with switching transients that exceeded 700 mV This was caused by a PCB design flaw that inadvertently coupled the switching node to t
47. this report is about The fraction of packets lost indicates the fraction of RTP data transfers that were dropped The total number of lost packets is the cumulative number of lost packets Interarrival jitter is an estimate of the statistical variance of RTP data transfer packet arrival times The timestamp is the wallclock time of the last time a sender report was received from this sender Wallclock time is an absolute time such as might be found on a clock on a wall The relative delay indicates the relative delay since the last time a sender report was received from this sender A sender report is only sent by sender participants and contains the same information as a receiver report but also includes the following information pertaining to the sender e NTP Timestamp e RIP Timestamp e Sender s packet count e Sender s octet count The NTP timestamp defines the current wallclock time according to the sender The RTP timestamp is the same as defined in an RIP data transfer The sender s packet count is the cumulative number of RTP data packets sent by this sender The sender s octet count is the cumulative number of Bytes sent in the payloads of each RTP data packet RTCP is also used by participants to join a session or leave a session Also there are facilities in the RTCP protocol to allow a participant to disseminate information such as the participants name phone number email address geographical 114 location etc RT
48. to enforce charging limits This is an additional safety measure should there be some sort of failure in communication between the charger and the Smart Battery which would normally set the charging limits The battery being charged requires a constant voltage of 16 8 V and maximally draws 4 A during charging Since the maximum charging current of the LTC1760 is 4 A total no charge current limiting is required The data sheet for the LTC1 60 lists the value of the charging voltage limit resistor for setting a limit of 16 8 V as 33 kQ The inductor value is determined from the desired ripple voltage in the inductor The recommended value for the ripple current is 40 of Imax which is 4 A in this case The ripple current from the LTC1 60 datasheet is defined in Eq 3 as Al 2 Von 1 f L Vin Where 3 f switching regulator minimum switching frequency Vin Supply voltage Vout charging voltage 61 The minimum value for the inductor can then be determined by solving for the inductor value in Eq 3 and substituting in a desired ripple current of 1 6 A or 40 of the maximum 4 A charging current e Vp 2 ier glO Dias 4 f AL Viv 255x10 L 24 Therefore the full specification for L is 10 uH 4 A It is also important to minimize the power loss in the inductor by selecting an inductor with the lowest DC resistance DCR possible The specifications for the selected inductor are 15 uH 5 A and 25 mQ T
49. when the feature extractor determines a need to change the input gain The application must retrieve the requested gain and set it before processing any more data Finally several abnormal conditions may be indicated by the ASR engine These include e Signal to noise ratio is too low e Signal is too loud clipped e Signal is too quiet e AGC cannot adjust the gain on the input signal to get it into the proper range 98 These abnormal conditions are logged by the application but are otherwise ignored If the current recognition event results in a successful recognition and an abnormal condition was indicated the confidence score will be negatively impacted Therefore continuing to solely use the confidence score as the criterion to accept or reject a recognition result is still appropriate 5 3 User Interface The speech recognition system has a user interface with two separate aspects The first aspect is a control interface while the second is used to provide user feedback about the current state of the speech recognition system The control interface consists of two pieces The normal means of control is by using the PTT button on the transducer Depressing the PTT button begins the recognition sequence and releasing the PTT button signals the end of an utterance Fig 70 shows the PTT button on a linear array transducer v Fig 70 Push To Talk Button The second piece of the control interface is the right mouse bu
50. written using MFC This separate process called the remote imaging daemon RID is created by the WPI ultrasound application and only interacts with the Terason application to retrieve ultrasound image frames from the shared memory interface A daemon describes a process that provides some sort of service and is not intended to interact with the user All control and setup of the shared memory interface is performed in the WPI ultrasound application to avoid synchronization issues The RID includes a complete RTP server listening for connections on UDP port 1038 Whenever a client application connects to the RID it begins transmitting the ultrasound images to the client as described above The interface to the application is a small dialog box When the RID is running and no client is connected it appears as shown in Fig 86 120 EC WPI Ultrasound Remote Image Server Pie E3 Ready Recenving frames Fig 86 RID Without Client When a client is connected to the RID the RID will display the number of frames per second FPS that are being sent to the client as well as the number of milliseconds it took to compress the entire frame averaged over the last 16 frames Fig 87 shows the RID with a connected client EC WPI Ultrasound Remote Image Server Pie E3 Connected Ava FPS 13 6 Avg Compression Time 54 mg Fig 87 RID With Client Connected In Fig 87 the RID is averaging 13 6 frames transmitted to
51. 0 GB The HDD is from Hitachi and is an Endurastar J4K20 The 44 pin IDE interface supports transfer of data from the HDD at up to 100 MB s and also provides 5 V to power the HDD An industrial HDD was used due to its extended temperature range of 20 to 85 C and its capability to withstand shocks of up to 100 g while operating 3 3 1 5 IEEE 802 11b g Selection The final piece of hardware used by the embedded computer is an IEEE 802 11b g Wi Fi interface 802 11 is a suite of wireless standards with varying physical layer data rates and an approximate range of 100 m This particular interface can operate in either the 802 11b or 802 11g modes Each mode 802 11b or 802 11g is compatible at the physical layer and can interoperate with each other 802 11b provides for physical layer data rates of up to 11 Mb s and 802 119 provides for physical layer data rates of up to 54 Mb s The actual throughput of user data is somewhat less and is realistically 50 or less than the theoretical maximum The 802 11b g interface is provided by way of a Universal Serial Bus USB peripheral USB provides both power and data through a four wire connection Two wires supply 5 V to the device while the other two wires provide full duplex single ended communication at up to 480 Mb s The USB device is normally supplied as a USB key in a plastic housing Within the plastic housing is a board measuring 6 0 x 2 5 x 0 5 cm 2 4 x 1 0 x 0 2 in This board is re
52. 00 was selected to provide a balance between falsely accepting invalid recognition results verse rejecting valid recognition results This threshold is highly subjective and will vary greatly depending on factors such as ambient noise or the accent of the speaker It was constantly adjusted during testing until a good balance was achieved Fig 119 shows the average confidence score for the majority of the possible utterances falling well below this threshold Only six utterances averaged better This poor performance is mainly due to the large number of invalid commands that were issued during clinical trials In laboratory and 171 clinical use by persons properly trained in using the speech recognition system recognition rates were excellent and often exceeded 95 Also the high frequency of tan and gray shown in Fig 118 is due to their relative lack of phonetic diversity When invalid commands were issued the recognition engine tended to return these two utterances for the recognition result with accompanying low confidence scores In addition to issuing invalid commands it was often found that utterances that had poor confidence scores were the result of users pressing the PTT button and not saying anything meant for the WUC Since the logging system recorded utterances with poor confidence scores later analysis showed either invalid commands were being issued or long conversations that were clearly not intended
53. 05KHCT ND 781 SUD50N03 KS MOUSER Jose MOUSER 781 SI4925BDY MOUSER 781 SI6928DQ MOUSER 981 TAJA105K020 DIGI KEY 399 1566 1 ND RECTIFIER DO 204AL 50 V1A D3 D4 MOUSER 512 1N4001 DIODE DO 35 75 V 150 mA D1 D2 DIGI KEY 1N4148MSCT ND PIC 16F767 Microcontroller QFN 28 Header 1x2 4A J33 J34 31 L2 R 71 WSL2010 0 025 BES 12061 mun Je MouseR Samem SR732BLTE1RO0F Department 8 Microchip PIC16LF767 V ML__ DIGI KEY WM6002 ND DIGI KEY WM6804 ND DIGI KEY WM7104 ND DIGI KEY WM4500 ND DIGI KEY WM6403 ND_ DIGI KEY WM6005 ND DIGI KEY WM6602 ND Table 30 Embedded Computer Bill of Materials Description Reference Designator KEE EE Ken EE ME KE KC Kl Quantity Vendor Vendor Part Advanced 80 Digital Logic Advanced Digital Logic 802164 Advanced Digital Logic Ge Advanced Digital Logic a Advanced Digital Logic SE Advanced PC 104 Assembly Kit J1 J24 J26 HDD 8021 IEEE 1394a e Photo Relay o G EE NG E DIGI KEY WM6003 ND z MOUSER 512 FDV303N DIGI KEY P1 0KACT ND DIGI KEY P390ACT ND DIGI KEY WM6004 ND 195 Table 31 Internal Cable Bill of Materials Ge Reference Description Designator Quantity Vendor Vendor Part Crimp Terminal4A 2 DIGIKEY WM2510 ND Terminal Housing 1x24A 0S DIGI KEY WM2800 ND Terminal Housing 1x3 4A 02 DIGI KEY WM2801 ND Terminal Housing 1x4 4A 0 IGEKEY WM2802 ND _ Terminal Hous
54. 06 annual conference 57 and the other was presented at the American Telemedicine Association ATA 2006 annual conference 58 In the end all but one of the requirements as put forth in Section 2 42 3 was met One of the requirements was that the third generation embedded computing platform be smaller than the previous generation It became evident during the design process that this was going to be difficult to achieve The requirements were then relaxed and only the overall height of the enclosure was reduced Note that the 182 enclosure s height determines how far the enclosure extended outwards from the wearer s back The 2 generation enclosure extended 6 5 cm 2 6 in from the wearer s back It was a metal box so the surface in contact with the wearer s back was flat The 3 generation enclosure was designed to be contoured to fit the wearer s back and has a gentle curve to the bottom of the enclosure Therefore the specified height of 7 6 cm 3 0 in is greater than the actual height of the enclosure which is between 6 0 cm 2 4 in and 7 1 cm 2 8 in Also because it has a curved surface it sits flush with the wearer s back and protrudes a shorter distance than the previous generation s enclosure did The size increase was generally caused by design decisions meant to ruggedize the device The connectors on the enclosure and the strain relief designed into the enclosure s shape add over 7 cm 2 8 in to t
55. 1 Table 3 Properties of Delrin 27 Property Test Method Units Value Yield Stress ISO 527 MPa kpsi 70 10 2 Yield Strain ISO 527 o 235 Strain at Break ISO 527 o 65 50mm min Nominal Strain at Break ISO 527 D 8B Tensile Modulus ISO 527 MPa kpsi 2900 420 Tensile Creep Modulus 1h ISO 899 MPa kpsi 2700 392 1000h 1500 218 Flexural Modulus ISO 178 MPa kpsi 2600 377 poppe Ss ISO 178 MPa kpsi 74 10 7 Melting Temperature ISO 11357 1 3 C F 178 352 Ben Softening Temperature ISO 306 C F 160 320 Surface Resistivity IEC 60093 Volume Resistivity IEC 60093 Dielectric Strength IEC 60243 1 KV MmMm 23 1 0mm Dielectric Constant ISO 1183 kg m g cm 1420 1 42 The final dimensions of the enclosure are 25 7 x 14 0 x 7 6 cm 10 1 x 5 5 x 3 0 in and a dimensioned drawing is shown in Fig 32 42 I I d l A Fig 32 Dimensioned Embedded Computer Enclosure Drawing The final weight of the embedded computing platform which comprises the enclosure along with all of its internal electronics is 1795 g 3 949 Lbs 3 3 1 Internal Arrangement The enclosure is separated internally into two compartments Fig 33 shows a cut section of the enclosure without any internal components 43 Fig 33 Two Compartments of Enclosure The top compartment in Fig 33 contains the two fans and the 802 11b g interface It is open to the environment to allow air to be forc
56. 1 2 Embedded Computer Selection At the time of selecting an embedded computer for the WUC there were only two vendors producing embedded computers with Pentium M CPUs The first board was by a company called Lippert AT The product is called Cool RoadRunner 4 and is pictured in Fig 26 The second board was from a company called Advanced Digital Logic Their product is called MSM855 and is pictured in Fig 27 35 Fig 26 Lippert AT Cool RoadRunner 4 23 Fig 27 Advanced Digital Logic MSM855 24 Each of these boards has an almost identical set of specifications The MSM855 was chosen due to its integrated heatsink aiding in the effective cooling of the CPU Also at the time of final board selection the Cool RoadRunner 4 was not generally available Table 2 summarizes the available CPU options for the MSM855 Table 2 Available CPUs for MSM855 Model Number Architecture L2Cache Clock Speed Bus Speed Maximum Power Celeron M ULV 512KB Lou 400 MHz 512KB 1 0GHz 400 MHz 0 6 1 4 GHz 400 MHz __ 13 0 W 0 6 1 8 GHz 400 MHz 316W The first two options comprising two Celeron processors have less processing power than the previous prototype of the WUC and do not meet the stated requirements Of the two remaining choices the Pentium M LV 738 offers the most performance per Watt and meets the stated requirements Therefore the Pentium M LV 738 was chosen for the design In order to avoid any future lim
57. 14 over finished hole size for component holes This means the annular ring radius of the pad should be at least 005 for vias and a minimum of 0 007 for component holes 0 005 Prototype 0 005 Production default 0 003 Production upon request 1 oz and 2 oz finished copper weight only Minimum finished hole size 0 010 Printed Circuit Board Overall may vary 10 Minimum 0 005 Thickness Minimum finished thickness for 2 layer 0 005 Minimum finished thickness for 4 layers 0 020 Minimum finished thickness for 6 layers 0 031 Minimum finished thickness for 8 layers 0 047 Minimum finished thickness for 10 layers 0 062 Inner Layer Thickness Tolerances do not apply to the inner layers of prototypes Rout Board Outline 0 010 81 Design Rule Description Copper Trace This is the minimum air gap between any two adjacent copper features Trace width Width Spacing is the minimum width of a copper feature usually traces e For trace width spacing we require a minimum of 0 005 for 1 oz finished copper weight on outer layers Premiums are added for trace space specs less than 0 008 For 1 oz finished copper weight inner layers minimum trace width space is 0 005 For 2 oz finished copper weight inner amp outer minimum trace width space is 0 007 For 3 oz finished copper weight inner amp outer minimum trace width space is 0 010 For 4 oz finished copper weight inner amp ou
58. 2005 8 Douglas S Richards http www obgyn ufl edu ultrasound 1 Obtainimage 1Equipment 2frequency html June 2003 9 GE http www gehealthcare com usen ultrasound genimg images img 339 72 500 jpg 10 SonoSite http www sonosite com images stories 180pluscarrying jpqg 11 Renee Dilulio Portable Ultrasound Small Modality Big Impact Imaging Economics July 2006 12 SonoSite http www sonosite com content view 21 77 2006 13 GE Healthcare LOGIQ Book XP 04 9365 Buckinghamshire UK 2004 14 Siemens Medical Solutions USA ACUSON Cypress Cardiovascular System PLUS Portable and complete cardiovascular applications A91US 7 1C A400 Mountain View CA 2006 15 Terason http www terason com products techo asp 2005 16 i O Display Systems http www i glassesstore com patiententertainment html 2006 17 eMagin http www 3dvisor com products php 2006 18 Dalys Sebastian Development of a Field Deployable Voice Controlled Ultrasound Scanner System WPI 2004 19 Carsten Poulsen Design of 277 Generation Wearable Ultrasound System WPI Worcester MA Jul 2004 20 PC 104 Embedded Consortium PC 104 Specification Version 2 5 Nov 2003 21 PC 104 Embedded Consortium PC 104 Plus Specification Version 2 0 Nov 2003 22 PC 104 Embedded Consortium PC 104 Specification Version 1 0 Nov 2003 191 23 24 25 26 27 28
59. 30 V LINEAR REGULATOR D2PAK 3 TO 263 U6 U7 Adjustable 1 2 37 V 1 5A BATTERY CHARGER TSSOP 48 FW Dual Li U1 lon D5 Engineering MOUSER 981 PBRC 3 68B DIGI KEY 913 1040 1 ND MOUSER 912 FDS6912A DIGI KEY 497 1571 1 ND Linear LTC1760CFW Technology fe ee 2 Technology SWITCHING REGULATOR SSOP 16N GN 5 V 10 A RS 232 Transceiver SSOP 16 1 TX 1 RX RECTIFIER 403 3 Schottky 40 V3A D7 RECTIFIER SOD 123 Schottky 30 V 1 A MOSFET SOT 223 P Channel 7 5 A 30 V QS R18 i MAX3221CAE DIGI KEY A E DIGI KEY d 30T10SCT DIGI KEY NDT456PCT ND R18 DIGI KEY P100GCT ND_ DIGI KEY PS51KGCT ND RES 0603 5 1K 1W5 ERO DIGI KEY P13KGCT ND DIGI KEY P20KGCT ND DIGI KEY P1 1KGCT ND DIGI KEY P56KGCT ND 194 SN Reference Description Designator Quantity Vendor Vendor Part RES 0603 10K 1 W 5 i a MOSFET TO 252 N Channel 10 A 30 V Q7 Q8 MOSFET SO 8 Dual P Channel 4 3 A 30 V Q4 Q5 Q6 MOSFET TSSOP 8 Dual N Channel 3 2 A 30 V Q2 Q3 CAP TANTALUM AVX_A 1 uF 20 V C40 C41 CAP TANTALUM KEMET B 4 7 uF 10 V DIGI KEY 399 1801 1 ND CAP TANTALUM KEMET_X 22 uF 35 V 2 30 2 Kl MOUSER 542 2101 V 5 2 5 INDUCTOR TOROID 6 3 uH 10 A DT RES 2010 025 5 W 1 34 R35 MOUSER 71 WSL2010 0 025 1 DIGI KEY P10KGCT ND DIGI KEY PO OGCT ND DIGI KEY P332HCT ND DIGI KEY P1 2GCT ND DIGI KEY P237HCT ND DIGI KEY P1 47KHCT ND DIGI KEY P8 87KHCT ND DIGI KEY P1
60. 45220 EDT 2006 CTerason COM Error 4 Invalid Cor DI x Fig 100 Database Analysis Program ASR Errors View This view is a Summary of the errors that occurred while the WUC was operating These errors may be transient in nature or they may indicate a bug in the software This view is useful in improving the reliability and robustness of the WUC software The final view is the Temperatures view This view displays a table that shows temperatures read from the CPU as well as the two temperatures available from the fan controller The option to save the information into a CSV file is also given In addition another window displays the temperatures as a line plot of degrees Celsius over time as shown in Fig 101 144 5 x i vy 120 140 160 180 200 2270 240 Fig 101 Temperatures View Plot The red line corresponds to the ambient temperature within the enclosure while the green line represents the CPU temperature and the blue line indicates the temperature of the heatsink The presence of a green line without any other lines indicates a loss of communication with the power supply which was a problem with the initial prototypes While only a single database is used at one time for analysis it is also possible to use multiple databases at once The choice of one database at a time was made to facilitate the evaluation of individual clinical trials as well as conveniently separating the performance of one p
61. 57 SMBus Protocols Table 9 SMBus Protocol Mnemonics Mnemonic Definition START condition Read bit value of 1 Write bit value of 0 Acknowledge 0 for ACK 1 for NACK STOP condition Master to Slave Rd P 76 EI Slave to Master Data is transferred on the falling edge of SMBCLK There are further provisions in the specification for arbitration between multiple bus masters collision detection device timeouts and clock stretching to allow slower slaves to successfully communicate with a faster bus master The host communicates with the SMBus master by using a 4 Byte command packet The packet has the following format 7 1 8 8 8 SMBus Address Rd Wr Command Code Data Byte Low Data Byte High Fig 58 Host SMBus Command Packet Regardless of the size of the desired protocol the same command packet format is always used After receiving an entire 4 Byte packet the microcontroller will determine the proper bus cycle to execute based on the SMBus address and the Rd Wr bit Accesses to the fan controller are always Byte sized while accesses to the Smart Battery Charger or a Smart Battery are always Word sized Bit 5 of the SMBus Address bit 6 of the first Byte in the command packet determines the access size by uniquely identifying which device will be accessed This is due to the unique memory map of the SMBus devices on the power supply Once a full command packet has been received the microcontro
62. 69 Fig 119 Average Utterance Confidence ccccccceccceecceeeceeeceeeeeeceeeseeeseeseeeaes 170 Fig 120 Sonosite MicroMaxx ID 174 Fig 121 Bag Based Ultrasound Gvstem 189 Fig 122 Cable Length Measurement 198 Fig 123 Cable Length Measurement Example a nannannnnnanonnnnnnnnnnnnrnrrrnrrnnrnnnnnne 198 Fig 124 Cable Length Measurement 205 Fig 125 Cable Length Measurement Example a nannannennenonnnnnnnnnnnnrnrrrnnrnernennnne 205 FIG 1202 TOP SUKSCNCCM NEE 211 FIGs AZT VOD CODDE ee 211 Fig 128 Layer 2 Copper 212 lk DEE 212 Els TOW BOON ODD Cl mrima aunGaeen ath Gian dth Gavan A 213 Fig 131 Bottom Silkscreen horizontally mirrored Fig 132 Database Gchema Table of Tables Table 1 Component Terminology ccccccceccceeceeeceseceeeceeecueeeeeceueseeeseeeseeeseeeees 25 Table 2 Available CPUs for MSM nn cc ccccccceecceeeceeece cece eeseeseseseeeseeeseeeseeeaes 36 Table 3 Properties of Delrin 27 42 Table 4 Power Requirements for WUC Components s sessssrsersrerrnnrererrersrerrens 57 Table 5 Power Requirements by Regulated voltage 58 Table 6 Characteristics of Commonly Used Rechargeable Batteries 36 63 Table 7 Attributes of Linear and Switching Regulators 381 67 Table 8 SMBus Memory Man 14 Table 9 SMBus Protocol Mnemonics naannannannnnnnnnnnnnnnnnnnnnnnnnnnrnnrnrrrrrnrrnrrnennenne 76 able TOSP CB DESIGN RE 81 Table 11 Speech Recognition E
63. Battery System Manager o Smart Battery Charger o Smart Battery Selector e 5V Switching Regulator e 12V Adjustable Linear Regulator reserved for future use e 9V Adjustable Linear Regulator e SMBus 31 to RS 232 Interface e Automatic Fan Speed Control e Thermal Monitoring local and remote All of these functions were implemented on a four layer PCB measuring 4000x2000 mils 10 16x5 08 cm which is described in Section 4 9 Fig 47 is a block diagram of the power supply indicating the relative areas of each function 56 LOAD 12V 1 5A 9V 1 5A 5V 10A Smart Battery 5V Switching System Regulator RORE Manager apter 24V 4 17A Charger l Li lon Battery 144V6A Li Li lon Battery AANER Li Fan Controller SMBus to RS 232 Host Interface Power Supply PCB 5V Fan RS 232 Fig 47 Block Diagram of Power Supply The main purpose of the power supply is to provide power for all of the devices in the WUC The Smart Battery System Manager provides a combination of battery power and AC adapter power depending on which power sources are currently present to the various voltage regulators This unregulated voltage is called the load voltage Table 4 shows the approximate power requirements for each component in the WUC please note that the WUC supports multiple HMDs but only one at a time can be used Table 4 Power Requirements for WUC Components Component Voltage V Maximum Power W Tolerance Emb
64. C Each of these applications is underserved by the current generation of portable ultrasound equipment The five main applications are in telemedicine disaster relief medical transport rural healthcare and military field use The WUC addresses many of the shortcomings of the current generation of portable ultrasound equipment when it comes to these applications Its main advantages are the ruggedness of the system long battery life wearable display open systems architecture and communications capabilities 10 1 1 Telemedicine Telemedicine is a relatively recent concept that literally means to practice medicine at a distance This can take several forms from a basic video conferencing system to a network enabled medical device The American Telemedicine Association ATA estimates that there were approximately 200 telemedicine networks operating in the United States in 2005 with half of these providing active day to day patient care They are most often used in rural areas to improve the available quality of care The WUC has an on board 802 11b g interface which is a ubiquitous short range 175 wireless communication protocol For ranges up to 100 m this interface can be used as is to provide images both still and moving to a remote viewer For other applications such as specialized long range radio links or satellite communications the 802 11b g interface can be used to connect to a gateway device that could provi
65. CP can also be extended in an application specific manner to send custom information 6 4 Real Time Ultrasound Imaging The WUC has the ability to send real time ultrasound images to a remote viewer using RTP as transport mechanism This section will describe the entire process of acquiring an ultrasound image and displaying it on a remote computer or laptop for viewing The Terason COM interface provides methods for setting up the Terason application as a frame server Access to these image frames is accomplished with a shared memory interface allowing a separate process on the same computer to consume the image frames The frames can be accessed in one of three modes LIO FIFO or LIFO The LIO mode which stands for Last In Out delivers only the last frame to the receiving process This mode has the lowest latency but can result in lost frames FIFO mode which stands for First In First Out improves upon LIO mode by storing frames in a circular buffer This greatly reduces the chances of losing a frame but results in greater latency The final mode LIFO stands for Last In First Out and approximates a fixed size stack This mode also greatly reduces the chances for losing a frame but also has the advantage of low latency However the frames may not always be delivered in order and may need to be sorted by the process consuming the frames produced by the Terason application frame server T
66. Design of a Wearable Ultrasound System by Philip Joseph Cordeiro A Thesis Submitted to the Faculty Of the WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Master of Science in Electrical Engineering by August 2006 Prof Peder C Pedersen Major Advisor SE nM IS Associate Prof R James Duckworth Committee Member Prof David Cyganski Committee Member Abstract Ultrasound imaging is a safe and powerful tool for providing detailed still and moving images of the human body Most of today s ultrasound systems are housed on a movable cart and designed for use within a clinical setting such as in a hospital or doctor s office This configuration hinders its use in locations lacking controlled environments and stable power sources Example locations include ambulances disaster sights war zones and rural medicine A wearable ultrasound system in the form of a vest worn by a sonographer has been developed as a complete solution for performing untethered ultrasound examinations The heart of the system is an enclosure containing an embedded computer running the Windows XP operating system and a custom power supply The power supply integrates a battery charger a switching regulator two linear regulators a variable speed fan controller and a microcontroller providing an interface for monitoring and control to the embedded computer Operation of the system is generally ac
67. GND 7 15 Pin High Density D Sub DDC Data DDC Clock MALE CONNECTOR 8 VGAt Center 2 1 mm id 5 5 mm od 9 V Outside Barrel Plug 17 8 6 9 17 8 6 9 Special Instructions Pins 5 amp 8 are bridged on the D Sub connector D Sub Barrel Plug Table 51 External Audio Cable Assembly Device Line in Signal Tip Rin ER CH EES K Line in GND Collar MALE CONNECTOR Line out Signal Ti Tae 5 3 i 3 5 mm Stereo Jack s mam cor Stereo Jack Stereo Jack USB Special Instructions Pictured USB type B connector is the socket The connector will connect into this socket Tie together the tip and ring on the 3 5 mm stereo audio socket This effectively makes it a mono jack 206 Table 52 External Mouse Cable Assembly Device i Signal i Device L Panel Mount Sealed 4 Common GND Momentary Switch AE CONNECTOR 200 78 Special Instructions Use 2 conductor flex cable attached with hot melt glue to attach the button also attached with hot melt glue on the ultrasound transducer Attach the cable from the connector to the flex cable at the base of the transducer Table 53 External USB Cable Assembly Device i Signal al Device GND USB Type A Receptacle MALE CONNECTOR 10 3 9 Table 54 External Battery 1 Cable Assembly Signal e Device 6 5 4 3 2 1 Molex Connector o 4 Special Instructions Bundle 3 wires together for the BAT and BAT signals
68. ION Tute RG lant VV el 182 FRETCIOCNGCES tege 191 Appendix Bill of Matenals 194 Appendix II Internal Cable Assemblies nnnanonnonnnnonnnnonnnnsnnenrnrerrnrerrrrsrrnrsrerrne 198 Appendix IIl External Cable Assemblies o anonnonnnnennnnonnnnsnnensnrernnrerenrsrrnrsrrerne 205 ADPENdIX IV SCIEMALIGS E 209 EE Ee 211 Appendix VI Speech Recognition Grammar 214 Appendix VII Database Gchema 216 Appendix VIII Training Video Gcrpts 218 Table of Figures Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Tt Sample E ele e Image 2 EE 4 2 Early B Mode Ultrasound Machine 7 6 3 Early B Mode Ultrasound Image 31 6 4 M Mode Ultrasound Image IA T 5 Pulsed Wave Doppler Ultrasound Image A1 8 6 Power Doppler Ultrasound Image L 9 7 Color Doppler Ultrasound Image l 10 8 3D Volume Image Slice xcaccsecercodeacdantdacviagtsaaviag iia guccaddaaesscdscdrcontensriagncaananasuaces 11 9 Rendered 3D Volume Image fo 12 104D Ultrasound Mage k EE 13 11 4 2 MHz Convex Array Transducerli l 14 12 10 5 MHz Linear Array Transducer i 14 13 10 5 MHz Phased Array Transducer i 14 E ee e Be KA Te ef lte IMAGES G EE 15 13 5 MAZ Ultrasound IMAGE T eegne gg 15 167 GE Ee LE e EE 16 Re elle
69. It would transmit ultrasound energy into a metal weld and display the resulting reflections on an oscilloscope Any perturbations in the displayed waveform indicated a flaw in the weld Edler and Hertz adapted one of these devices to produce an A Mode ultrasound machine where the A stands for amplitude A Mode produces an image containing depth information along one axis and the received echo amplitude along another Put another way the A Mode image is the received ultrasound energy after being processed by an envelope detector A sample A Mode image of a stomach wall is shown in Fig 1 A Fig 1 Sample A Mode Image 2 A transducer operating in A Mode consists of a single element transmitting pulses of ultrasound energy into the human body and then receiving and amplifying the return echoes A transducer is a device that converts energy from one form into another Ultrasound transducers convert electrical energy into sound energy The next development in ultrasound was the introduction of B Mode where the B stands for brightness This is an improvement upon A Mode and introduces the 4 concept of a scan line and a scan plane B Mode works by moving the single element transducer along a line or leaving it in one position and rocking it or a combination of the two Each pulse creates a scan line whose brightness is proportional to the amplitude of the returned echo and the depth increases along the line By combi
70. L Numeric Data Types Unsigned Storage Range Size EE Type Signed Range TINYINT 128 to 127 0 to 255 1 Byte unsigned char SMALLINT 32 768 to 32 767 0 to 65 535 2 Bytes unsigned short 132 0 to l l 2 147 483 648 to 2 147 483 647 4 294 967 295 4 Bytes unsigned int Table 15 MySQL Binary Data Types Maximum Range Storage Size C Data Type reece 255 2 T Bytes n 1 Bytes void unsigned long n BLOB 65 GE 1 Bytes n 2 Bytes void unsigned long n MEDIUMBLOB eee 2 1 Bytes n 3 Bytes void g unsigned long n Table 16 MySQL String Data Types Maximum Range Storage Size DY VE a AY of SSE M Characters M 1 Bytes TEXT 65 536 Characters string length 2 Bytes There are additional data types defined by MySQL that are not detailed in the above tables however they are not used Every application defined message that is logged is assigned a timestamp that is accurate to the ms Generic logging uses a single table in the database called tb Packets and is defined in Table 17 Table 17 tblPackets Definition Column Not Se Name Nui Unsigned Data Type Description weng TIMESTAMP Timestamp oooO SMALLINT Millisecond portion of timestamp TINYINT Message identifier Foreign Key payload De TINYBLOB Message payload Any generic messages which are messages that do not undergo any further processing such as PTT BUTTON DOWN are logged into this table The table logs the
71. NYBLOB reported abnormal conditions that may have occurred during this utterance This table stores a multitude of information about each and every recognition event rec confidence snr XT NENE NE NENTS abnormal 134 that occurs The timestamp for each utterance is the time that a recognition results was returned from the ASR engine The words column is a foreign key for table tb Words which contains information about every possible utterance and is detailed in Table 20 Table 20 tblWords Definition Column Not Name Null Unsigned Data Type Description words Vv VARCHAR 45 String defined in the grammar id VW vw INTEGER ID value assigned to the string The words column contains the string for a particular utterance and the id column contains a number assigned to every utterance The id value for a string is the actual value assigned to a particular command The id column cannot be used as a primary key since multiple utterances may have the same id allowing for more than one utterance to correspond to a single command The final table involved in logging ASR specific event is the tb Audio table which is detailed in Table 21 Table 21 tbl Audio Definition Column Not Name Nu Unsigned Data Type Description INTEGER Primary Key Foreign Key audio VW fo MEDIUMBLOB Wave file containing a recorded utterance This is a very simple table whose primary key utterance is also a foreig
72. No RSENSE Current Mode Synchronous Step Down Switching Regulator 2004 Philips Semiconductors The FC Bus Specification Version 2 1 Jan 2000 Thomas A Sudkamp Languages and Machines ac ed Pearson Education Inc Boston 2006 ScanSoft Inc ScanSoft VoCon 3200 Software Development Kit Version 2 0 Developer s Guide Feb 2004 Wikipedia http en wikipedia org wiki OSI model 2006 IEEE IEEE Std 802 11 1999 IEEE SA Standards Board 1999 IEEE IEEE Std 802 11b 1999 IEEE SA Standards Board 1999 192 46 47 48 49 50 51 52 53 54 55 56 57 58 IEEE IEEE Std 802 11g 2003 IEEE SA Standards Board 2003 IETF RFC3550 RTP A Transport Protocol for Real Time Applications 2003 Jean loup Gailly Mark Adler http www zlib net 2005 IETF RFC1950 ZLIB Compressed Data Format Specification version 3 3 1996 IETF RFC1951 DEFLATE Compressed Data Format Specification version 1 3 1996 Virginia Polytechnic Institute and State University Center for Wireless Telecommunications http www cwt vt edu faq gsm htm 2002 IETF RFC3551 http www ietf org rfc rfc3551 txt number 3551 July 2003 Dimitri van Heesch doxygen Manual for version 1 4 2 2004 Jordan Russell http www jrsoftware org isinfo php 2006 http www sonosite com images stories 05 SNO 174 MicroMaxx3 gif http www mamc amedd army mil mamc m
73. SIS SR e Se Ss Oc ele Sie 5 0 OOOO E o QO oo oe Gs Hee Ree a a Si O90 o on 8 0000 en OM ee 20 Fig 128 Layer 2 Copper Fig 129 Layer 3 Copper 212 E rg Power E e 2 5 WP d EE EE Fig 131 Bottom Silkscreen horizontally mirrored 213 Appendix VI Speech Recognition Grammar BNF EM V1 0 lt NATORules gt grammar Terason Grammar zero id 2000 language American English one 1d 2001 Istart lt Terason gt lt NATO gt lt YesNoRules gt two 1d 2002 three 1d 2003 lt Terason gt lt TerasonRules gt four LId 2004 lt SystemRules gt five id 2005 lt NATO gt lt NATORules gt lt SystemRules gt six id 2006 seven 1da 2007 ii lt SystemRules gt eight 1d 2008 Shutdown 1id 1000 niner id 2009 patient information 1d 1003 alpha id 2017 ultrasound rd LO04 gt bravo 110a 2016 Charlie 1d 2019 lt YesNoRules gt delta 1d 2020 yes 1d 1001 echo 1d 2021 go keete Eeer Tid 2022 gorr tad 2023 lt TerasonRules gt hotel 1d 2024 freeze image Iid india 1d 2025 live image id 2 juliet 1d 2026 Small size id 3 kiro had Zor ys medium size id 4 Tima era 2026 large size id 5 mike 1d 2029 depth two Ad november 1d 2030 depth three id 7 oscar iva Z03o1 depth four Tido papa 1d 2032 dep five Sekt gue
74. Section 2 3 1 necessitated a fully custom design An outside vendor DaluM 3D was contracted to assist in the development and manufacturing of the enclosure Using requirements developed by WPI a complete three dimensional 3D model was developed using SolidWorks This model 39 allowed for an interactive and iterative design process that culminated in an initial prototype The 3D modeling process was invaluable in communicating design decisions between DaTuM 3D and WPI and proved to be a powerful collaboration tool An initial prototype was manufactured by DaTuM 3D and tested by WPI The total time between initially meeting with DaTuM 3D and receiving a prototype was four months Over the next three months a new set of requirements was developed using the initial prototype as a basis A second prototype was developed and ultimately accepted as the final design The second prototype took less than two months to design and build Fig 30 shows the final version of the embedded computer enclosure model Fig 30 Embedded Computer Enclosure The enclosure consists of three main pieces along with some mounting hardware There is a top and bottom cover and a heatsink The final enclosure design is segmented into two compartments internally One compartment is hermetically sealed and contains the embedded computer HDD power supply 1394a interface 40 and the EDCM A gasket on the bottom covers helps to seal this compartment
75. Switching Regulator with No Load DC Coupled With no load the switching regulator still performs very well The mean voltage output is 5 07 V This is within 1 4 of the proper value 9 3 Embedded Computing Platform Thermals The thermal performance of the embedded computing platform was tested using a small oven A complete WUC system was placed in the oven and operated in Power Doppler imaging mode while a wireless Remote Desktop session was active The Power Doppler imaging mode combined with an active Remote Desktop session using the 802 11b g link draws the most overall system power 32 W and fully exercises the CPU The oven was set to 40 C 104 F and the temperature was monitored using the temperature sensors provided by the power supply and the CPU Once a steady state was reached the oven door was opened and the system was allowed to continue running at the ambient room temperature of 22 C 104 F The results are shown in Fig 117 166 Temperature Testing at 40 Deg C Ambient S x10 Fig 117 Temperature Testing The maximum ambient temperature that is allowed within the enclosure is 85 C based on manufacturer supplied temperature tolerances The maximum ambient temperature was 66 C The highest temperature 73 C was recorded by the temperature probe attached to the heatsink The location oh this temperature probe places it at the hottest point on the heatsink The system ran without errors for the
76. T Battery 2 Voltage 0 65 535 mV batti SMALLINT Battery 1 Current 32 768 32 767 mA bail v SMALLINT Battery 2 Current 32 768 32 767 mA The internal temperatures were logged into table tb CPUTemp which is detailed in Table 23 Table 23 tblCPUTemp Definition Column Not Name Null Unsigned Data Type Description INTEGER _ Primary Key stamp __ TIMESTAMP SMALLINT Millisecond portion of timestamp TINYINT CPU on die temperature sensor 0 255 C 136 local_ temp yf TINYINT GE Low on die temperature sensor 0 remote temp Y TINYINT Heatsink temperature sensor 0 124 C Any error messages that occurred were logged into the table fb Errors which is detailed in Table 24 Table 24 tblErrors Definition Column Not E Name Null Unsigned Data Type Description wem TIMESTAMP Timestamp o oooO mo 7 xr Errormessagetext SSS The final database table detailed in Table 25 is called tbllmages Table 25 tbllmages Definition Column Not Name Null Unsigned Data Type Description INTEGER Primary Key wem __ TIMESTAMP patient name 1 VARCHAR 255 o name from patient information patient_id ae VARCHAR 255 Patient id from patient information dialog ul VARCHAR 255 URL for web interface This table was used to store information that is presented by the web server when the user wishes to view saved images The w
77. T NUMBER 66 00001 00 SO ces PORTABLE POWER NL20240S 14 4V Lithium lon Battery Fig 50 Inspired Energy NL2024A22 Rechargeable Li lon Battery Since the NL2024A22 is a Smart Battery it implements the Smart Battery interface and requires a Smart Battery Charger to properly charge it It also includes a fuel gauge and protection circuitry to prevent an over charge or over discharge condition Fig 51 shows a block diagram of the battery pack 65 pereerrerteerterrererertierrettiertertiertretietrertecererreccterrecrtertiertert ren d DEE D 3 P MOSFET P MOSFET ei PACK SB FUSE PROTECTION IC CELL STACK TT rock FUEL GAUGE o i a DATA e i THERMOFUSE Si THERMISTOR pa PACK 300 OHMS CURRENT SENSE AEETTETTTETTETEEEOTET TETTE ET FETT AA EE EEEE TETEE E EEEE EEEE E ETE EEE EE EEE EEE EEEE EEEE E EEE E EEEE EE EE EE E EE E EE E EE E EE E e ga r Fig 51 Block Diagram of Smart Battery Pack 37 The three extra signals clock data and thermistor are part of the SMBus interface used by the Smart Battery to communicate with the Smart Battery Charger More details on this interface are provided in Section 4 7 4 5 5V Switching Regulator There are two distinct categories of voltage regulators suitable for providing a lower regulated voltage from a higher unregulated voltage There are linear regulators which regulate the output voltage using an internal network of tra
78. Terason EDCM The printed circuit board PCB for the EDCM is mounted inside the enclosure with the LEMO connector presented externally similar to the other connectors on the enclosure 2 3 2 Enclosure Connector Requirements The sockets are an integral part of maintaining a water tight seal for the enclosure therefore they must create a seal with the enclosure They need to be small 27 enough so as to not add greatly to the overall enclosure dimensions and to allow a separate connector for each external peripheral Also the connectors must be robust enough to endure physical and environmental stresses likely to be encountered with daily use in the field The connectors must be dense enough to fit as many as 8 wires on a single socket where a wire may carry as much as 5 A of current The connectors must also have a locking mechanism to prevent unintended disconnection The impedance of the connector must be compatible with signaling in excess of 400 MHz while attenuating no more than 5 8 dB 1394a physical layer Finally as much as possible each socket should be keyed to prevent the accidental connection of a cable into the wrong socket 2 3 3 Power Supply Requirements The power supply must be capable of powering all the devices incorporated into the system This includes e Embedded Computer e Ultrasound Transducer e Wireless Interface e Head Mounted Display e Microphone The power supply should provide for adjustable
79. USER 502 EN3C5M Battery Connector BAT 2 MOUSER 538 39 01 3063 BatteryConnectorPins OT BAT 10 MOUSER 538 39 00 0041 Cord Connector 2 position Male LCHARGER 1 MOUSER 502 EN3C2M Cord Connector 3 position Male 16 AWG CHARGER 1 MOUSER 502 EN3C3M16 ae Cord Connector 3 position Female 16 CHARGER MOUSER 502 EN3C3F16 Cord Connector 4 position Male MOUSER 502 EN3C4M USB type a receptacle MOUSER 808 KUSBV AS 1 Cord Connector 7 position Female JI MOUSER 502 EN3C7F SWITCH TACT SPST NO 120GF J LEAD DIGI KEY _ 401 1458 1 ND 5 16 inch WOVEN WRAP AROUND TRANSDUCER Tasour ease RDT0312 10 Conductor Cable 100 24 shielded a HE 4 MOUSER 566 9540 100 Table 33 Assembly Bill of Materials Description Quantity Vendor Vendor Part Enclosure Datum3D Fan 40x6 mm 5V 5 5 CFM A W 6000 RPM 26 dBA Allied 997 0064 Electronics Vest L B amp H Photo DOVPL SMART LI ION BATTERY PACK 95Whr 14 4V 6 6Ah BAQ5HC FL Planning Microphone Systems Inc i glasses PC SVGA 1 glasses A502085 196 Description Transducer Terason 2000 Mouse AC Adapter 24VDC DESKTOP 100W Software Licenses 197 Terason as 1 Geeks com BLK FDM G51 USB 1f MOUSER 418 TR100A240 02 fe E Quantity Vendor Vendor Part 1 1 Appendix II Internal Cable Assemblies Please note that the indicated cable lengths are measured using the exposed cable sheath between conne
80. able on line for evaluation participants and was updated based on feedback received from the trials Section 9 provides results from clinical trials as well as other performance metrics Table 1 Summarizes what was designed during this thesis and also introduces the component terminology Table 1 Component Terminology Name Description Design Location PC 104 Plus peripheral providing a 1394a Firewire interface for the Se Embedded Modified 1394a embedded computer Computing COTS Platform USB Peripheral providing a 802 11b g WiFi interface for the Modified Embedded 802 11b g embedded computer COTS Computing Platform AC Adapter A 120 240 V AC 24 V DC converter GE Not Applicable A digital signal processor housed in a small enclosure and connecting mela between the microphone and the embedded computer GaS vee External DC Module that connects between the SmartProbe and the Modified Embedded EDCM 1394a interface Computing COTS Platform Embedded PC 104 Plus form factor embedded computer containing an Intel Modified Embedded Pentium M 738 CPU an Intel 855GME chipset 1 GB of memory and Computing Computer i COTS various other peripherals Platform Embedded The enclosure enclosure connectors and all components contained Computing within WPI Vest Platform The ruggedized container housing the embedded computing platform Embedded WPI with Enclosure electronics Computing Consulting Platform A 2 5 form factor Hard Hi
81. accommodated in the vest Previous vest designs had the cable for the head mounted display and the microphone external to the vest This often resulted in the cables getting caught and interfered with the user s freedom of motion To alleviate this problem the cabling for these components was integrated into the vest The array microphone is located in the mesh area on the upper left portion of the vest It is secured in a mesh pocket and angled towards the wearer s mouth The cable for the microphone is routed internally inside a channel created near the Zipper The cable for the head mounted display is routed inside a channel created in the back of the vest The channel was created in the left side suspender so that the cable exits near the collar An AC adapter is also provided for the WUC The 24 V 4 17 A rated AC adapter was modified by replacing the DC connector with an in line cord connector of the same style used on the enclosure 148 8 2 Software Integration There are several software components that are used to produce the full functionality of the WUC The components are listed in Table 26 Table 26 Software Components Executable Description The wpiultrasound exe rid exe and shutdown exe applications were all written in C The wpiultrasound exe and shutdown exe applications use the Win32 API and run on the Microsoft Windows XP operating system while rid exe uses the Microsoft Foundation Class MFC API an
82. act with the Terason application by sending commands as if the user clicked a button within the application or even replace the graphical user interface GUI entirely The WPI ultrasound application discussed in detail in Chapter 7 uses the Terason COM interface to carry out speech commands An integer value is associated with every recognizable utterance specified by the grammar This integer value is returned as the id portion of a recognition result These integer values are interpreted as commands that are then issued through the Terason COM interface to the Terason application By using an integer value assigned to an utterance and not the utterance itself the actual utterance used to evoke a command can be changed without changing the WPI Ultrasound application It is even possible to have multiple utterances that carry out the same command though this has not been done Not all commands are necessarily meant for the Terason application Some commands are used directly by the WPI ultrasound application An example of this is the shutdown command which is used to shutdown the entire WUC via voice 104 command The shutdown command will display a dialog box shown in Fig 76 asking the user to respond with yes or no to verify that they indeed would like to shut down the WUC WPI Ultrasound wl shutdown the system Fig 76 Shutdown Dialog Box If a no command is issued the dialog bo
83. active Therefore some of the displayed utterances may not be valid 5 4 Terason Application Integration The earlier generations of the WUC interfaced the speech recognition system with the Terason application using keyboard commands This method had several drawbacks prompting a new method to be employed Sending keyboard commands to the Terason application would cause the menus to activate during command execution causing distraction Subsequent Terason application releases 103 often altered the menu structure which would break the interface Also the interface was limited to only sending commands to the Terason application and could not query the Terason application to obtain any information Therefore the interface was rewritten to use a COM Automation interface to interact with and control the Terason application COM stands for Component Object Model and is a mature Microsoft technology that allows COM objects to be exposed by applications for manipulation by other applications A COM object is an instance of a COM class which is registered by the application exposing the class Another program wishing to use an instance of that class can use the Windows registry to locate an instance of that class and use that instance to control the exposing application For instance the Terason application exposes a COM class with methods for every control present in the Terason application Through this interface third parties can inter
84. afety measure These limits were defined by the actual Smart Battery being used in the WUC system described in Section 4 4 Also some filtering capacitors must be properly sized to have a time constant that adequately filters switching noise The reference design parameters that influence these values were not changed so no variation from the reference design was required The LTC1760 will adjust the charging current so as to not overload the DC power source This limit is set by a resistor whose value is determined by Eq 1 _ 1L00mV 1 CL I LIM Through experimental observation it was determined that a DC power source of at least 22 V was required for proper operation of the Smart Battery Charger The closest commercially available AC adapters operate at 24 V The highest power AC adapters available are rated for 100 W or a maximum current rating of 4 17 A 60 Therefore using Eq 1 the value for Ro was determined to be 24 mO This value was rounded up to the standard value of 25 mQ giving a final input current limit of 4 A Since the entire current being drawn from the DC power supply must flow through the current limiting resistor the maximum power dissipation possible is shown in Eq 2 Ror power lim Rey 4 0 025 0 4W 2 The full specification for Rc is therefore 25 mQ 1 0 5 W The rest of the design involves inductor selection for the switching power supply and the selection of two resistors
85. amcinfo htm P C Pedersen P Cordeiro R J Duckworth and T L Szabo Development and testing of wireless wearable ultrasound scanner 2006 AIUM Annual Convention Washington DC March 23 26 2006 R J Duckworth and P C Pedersen Clinical evaluation of wearable ultrasound imaging system 2006 American Telemedicine Association San Diego CA May 2006 193 Appendix I Bill of Materials Table 29 Power Supply Bill of Materials Reference Description Designator Quantity Vendor Vendor Part Devices 3 CAP OS CON SC series 22 uF 30 V C33 C34 C35 C36 oo 30SC22M CAP OS CON SP series 680 uF 6 3 V C37 1 Capacitors 6SP680M Plus et C4 C5 C9 C11 C16 C17 C21 C24 CAP 0603 1 uF 50 V C25 C27 C38 C39 14 DIGI KEY PCC2398CT ND C42 C45 CAP 0603 01 uF 16 V MOUSER 581 0603YC103K CAP 0603 015 uF 25 V DIGI KEY PCC1765CT ND CAP 0603 2200 pF 50V CO IGI KEY 311 1081 1 ND CAP 0603 15uF 25V C20 IGIKEY 399 1290 1 DIGI KEY 490 1570 1 ND MOUSER 581 06035C222K DIGI KEY 311 1073 1 ND DIGI KEY 490 1529 1 ND DIGI KEY 490 1677 1 ND_ DIGI KEY 478 1399 1 ND MOUSER 581 0805ZC104K DIGI KEY 490 1872 1 ND_ DIGI KEY 399 3089 1 ND DIGI KEY 399 3076 1 ND DIGI KEY 490 1860 1 ND MOUSER 581 1210ZG106Z7 DIODE SOD 323 Schottky 30 V 100 mA D6 D8 Ceramic Resonator 3 68 MHz INDUCTOR DR 127 15uH5A MOSFET SOIC 8 Dual N Channel 6 A
86. ameters are called Param and wParam A Windows program contains a main message loop that receives messages and processes them Most of the messages are defined by Windows however some messages may be defined by the application For example when a program initially requests to have its main window displayed a message called WM_CREATE is sent to the program s main message loop One of the additional 32 bit parameters is the memory address pointer of a structure a data type comprising a set of primitive data types that contains information about the new window such as the size and position of the window Windows also provides a mechanism for programs to define their own messages The WUC application defines 35 messages that are used to coordinate between the various elements of the software There is a main message loop that receives all of these messages and takes varying actions depending on the message and the current program state Some of these messages use one of the additional two parameters specifically Param to pass additional information concerning the message This information is referred to as the payload of the message For 129 example when an ASR result is generated by the speech recognition system an application defined message called CASR_RESULT is sent to the main message loop in which one of the additional parameters contains a pointer to a structure that contains information about the recognition result In this i
87. an be replayed using the JEventLog program The next view is the Words view This view just shows a table displaying every utterance string in the grammar and the associated id value Essentially this is table tb Words without the primary key column The next two views shows statistics for the various utterance strings in the grammar The first view is the Word Occurrence view and it is shown in Fig 99 WPI Log Viewer 0 x Database Filters View Words Occurence Frequenc alpha U made Cn ackspace rawo C rightness decrease brightness increase Fig 99 Database Analysis Program Word Occurrence View This view shows the overall occurrence and frequency of each utterance string When selecting this view the user is also presented with the option of saving these results aS a comma separated values CSV file This type of file is easily imported into programs such as Excel or MATLAB for further analysis The other statistical view is Word Confidence This is very similar to the Word Occurrence view but instead shows the average confidence score as generated by the ASR engine for each utterance string It also has the option of saving the results into a CSV file The ASR Errors view is shown in Fig 100 143 2 WPI Log Viewer Database Fillers View Timestarrip Message Tue Apr 18171253 EDT 2006 CTerason COM Error 0x800 r 065A Tue Apr18 1715 05 EDT 2008 CTerason COM Error 0x800 r 06BA wed Apr19 1
88. and assigns personnel responsible for providing maintenance and access to the equipment This problem was eventually solved by identifying the key personnel and personally instructing them on what was required to keep the equipment in good working order The final problem is difficult to address and has manifested itself by low usage of the WUC during clinical trials performed at Army facilities The modern soldier is extremely busy and their performance is constantly evaluated according to certain metrics Their career opportunities and promotion potential are directly related to how well the individual scores in these evaluations This makes finding time to perform research work which could potentially reduce their performance scores difficult and unattractive This becomes a so called chicken and egg problem To allow personnel the time to use new and unproven technologies by granting a relief from their regular duties requires a mandate from the higher echelons And with the already heavy workload commanders are reluctant to use unproven and unfamiliar technologies when familiar and accepted alternatives already exist The WUC brings new capabilities to medical personnel where none currently exists but it must be proven before it can be deployed This circular argument is difficult to reconcile but it is hoped that continued attention and success will eventually overcome these obstacles The wearable form factor though a novel and innova
89. arrival of each message by noting its arrival time the message identifier and the contents of the message payload if there is one 133 The message identifier relates to another table in the database called tb Messages This table relates the message identifier to its mnemonic and description and is detailed in Table 18 Table 18 tbllMessages Definition Column Not Name Null msg Unsigned Data Type Description TINYINT Primary Key related to Windows msg number description WaRCHARS VARCHAR 255 Full description of message The relationship between the two tables is provided by the common msg column The msg column in table tb Packets is a foreign key for the msg column in table to Messages and the msg column in table tb Messages is a primary key uniquely identifying each record in table tb Messages Speech recognition information spans three different tables The primary table is called tb Utterance and is detailed in Table 19 Table 19 tb Utterance Definition Column Not Name Null Unsigned Data Type Description utterance V Y tstamp SE words SMALLINT a time that PTT button was depressed SMALLINT Elapsed time that PTT button was depressed plus processing time to return a recognition result ms SMALLINT Confidence score 0 10 000 BLOB Array of SNR values from ASR engine dB 100 BLOB Array of energy level values from ASR engine dB 100 Structure containing information about any TI
90. as commands for the WUC The conclusion from these results is that speech recognition works well with trained users but does not work well with untrained users The poor results returned from the clinical trials was a direct result of people not reading instructions or watching the training videos and just saying whatever came to mind It could possibly be argued that this means that the system does not work The difficulties are mainly operational in nature and not technical The user interface does still provide access to all of the same commands by using the mouse should that be the user s preference or if they are simply uninterested in learning proper speech recognition commands A further discussion of how this may be approached can be found in Section 11 9 5 Specifications The following specifications were determined by detailed inspection of the manufacturer s specifications for individual items in the embedded computing platform 172 Table 28 WUC Specifications Specification Value Embedded Computing Power Consumption fF O lde SBW Operating Time S O Je Bours Battery SSE EE EEE Battery Charger ti Vibration S Head mounted Display i glasses Weight RS 173 10 Clinical Usage and Value The WUC is a unique university research project in that a prototype was developed and employed by medical professionals in a variety of situations Over a period of nine months at least one and usually more of the four
91. as location user software revision etc A successful test was conducted using UDP multicast to broadcast a message and listen for active systems to reply This method has limitations however and a more robust registry system may better address this need Also the RID client is currently only available for the Windows operating system running on x86 compatible CPUs There are other operating systems including Mac OS X and Solaris and CPU architectures such as PowerPC that may want to use the remote viewing capabilities of the WUC Providing an RID client application that uses the Java virtual machine for its execution environment would make this feature available to a wider audience Finally there is no control protocol for interaction between the RID client application and the WUC An implementation using extensible markup language XML technologies such as simple object access protocol SOAP could potentially provide a framework for a future implementation It is important to note that web technologies while currently popular and becoming very capable place much of the processing burden on the server which in this case would be the embedded computer in the WUC Remote viewing and control features should place as much of the processing burden on the client so as to not reduce the battery life of the WUC or potentially degrade the imaging performance In addition to software improvements for the remote data facilities there are pot
92. ation of off the shelf components met both the space and functionality requirements The entire board was designed and populated in house using available software tools and labor resources The power supply was design using tools from Mentor Graphics The DesignView Expedition tool flow was used The board has a total of four layers three of which are used for signal routing and two of which are used for power planes one layer is split with one half being a power plane and the other half used for signal routing The finished board is made of FR 4 material and finished in a green soldermask with tin plated land pads and a white silkscreen The dimension of the board is 10 16 x 5 08 cm 4000 mils x 2000 mils with an area of 51 62 cm 8 in Appendix V PCB Layout contains shows the complete stackup for the board The finished board is shown in Fig 61 80 E Jee D 02 05 1 Fig 61 Populated Power Supply PCB The design rules were defined by the board house and are summarized in Table 10 Table 10 PCB Design Rules Design Rule Description Inner Layer Clearances A minimum of 0 010 inner layer clearance Copper to Edge of Printed Minimum of 0 010 outer layers and 0 014 for inner layers 0 020 preferred for Circuit Board inner layers For scoring minimum of 015 for outer layers and 020 for inner layers Pad Size Annular Ring Pad size should be at least 0 010 over finished hole size for vias and 0 0
93. ation of portable ultrasound machines The remainder of this thesis presents the design of a wearable untethered ultrasound system The key features of the system are a wearable form factor untethered operation voice activated command and control one handed operation wireless communications and a head mounted display A complete overview of wearable ultrasound is presented in Section 2 The majority of the work this thesis work involved systems integration Wherever possible commercially availably products were used to complete the design However commercial products were not always suited to the unique requirements of producing a wearable ultrasound system and some amount of custom design work was necessary To this end a power supply and enclosure were designed The power supply which is detailed in Section 4 provides power for every device that comprises the wearable ultrasound system It is housed with an ergonomically designed enclosure that is designed to sit comfortably against the back of the person wearing the system In addition to the power supply the enclosure houses an embedded computer which is detailed in Section 3 and a wireless network interface The applications for the wireless network interface are described in Section 6 In addition to the unique hardware that was required to make this thesis a reality several software applications were written The main piece of software provides speech recognition func
94. attery Charger and ATX Power Supply 28 29 While the OceanServer product met most of the functionality requirements the size of the enclosure required to contain it along with the embedded computer was considered too large for portable use Specifically it would have appreciably increased the size of the enclosure relative to previous prototypes while adding minimal extra functionality It also lacked some of the regulated voltages to supply power to certain peripherals under consideration Another option that was considered was the use of a DC DC converter brick These are manufactured by several companies with Datel being one of the most prominent suppliers The bricks use standardized package sizes and pinouts An example of a DC DC converter is shown in Fig 46 Fig 46 1 8 Brick DC DC Converter 30 55 In order to meet the power requirements of the embedded computer the minimum sized brick is a 1 8 brick measuring 5 64 x 2 26 x 0 91 cm 2 22 x 0 89 x 0 36 in This solution is unsuitable because it lacks a battery charger as well as any method of monitoring or control This solution also lacks some of the regulated voltages to supply power to certain peripherals under consideration It soon became clear that in order to meet all of the requirements a custom power supply needed to be designed 4 2 Introduction The power supply for the WUC is an entirely custom design performing the following functions Smart
95. ay the text mage Unavailable 6 5 Voice Communications In addition to real time remote imaging the WUC also supports full duplex voice communications between the WUC operator and the RID client application There are many standards for providing voice communications over IP networks These are collectively referred to as voice over IP VoIP standards However most of these standards deal with replacing the functionality currently provided by the regular public switched telephone network PSTN This functionality includes call setup call teardown billing and call routing Only a small portion of the standards actually addresses the transmission of voice Since the functionality required by the WUC does not include billing call routing or call setup teardown only the voice transmission aspects of the standards were used The VoIP standards include a wide variety of speech codecs for voice transmission Incidentally the transmission protocol of choice is RTP which is the same protocol used to transmit real time ultrasound images The most widely used speech codecs are the family of International Telecommunication Union ITU standards These vary in data rates from 5 3 to 64 kb s However no software could be freely acquired that supports any of these codecs Therefore the second most popular choice the GSM 6 10 codec was used This codec is included with Windows and required no extra software to use 123 The GSM 6 10 c
96. be displayed as positive This information is all acquired from the Smart Battery System Manager The lower portion displays information gathered from the fan controller This includes the temperature sensor read from an on die thermistor the current fan speed and the temperature from the remote temperature sensor In conclusion a complete custom power supply was designed and built In total ten boards were built for use within the embedded computing platform The power supply provides power for the embedded computer as well as every other peripheral in the WUC It integrates a Smart Battery Charger and a host interface provided by a microcontroller and small assembly language program The following three sections discuss the main aspects of the software that was written during this thesis 8 5 Speech Recognition Speech recognition is an important element in making the WUC a portable device It allows for the replacement of a traditional keyboard interface with a more natural voice interface It also frees up one of the sonographer s hands for other tasks such as scanning with the ultrasound transducer interacting with the patient or steadying themselves during transport The speech recognition engine and microphone were selected during prior thesis work 18 and adapted for use with the WUC 5 1 Background There are two major types of speech recognition sometimes called Automated Speech Recognition ASR engines ava
97. bec 1d 2033 Oe pun Saxe E e EEN romeo 1d 2034 depth seven id 1l sierra 1d 2035 depth eight id 12 tango EES EE depth nine id 13 uniform Frat Z2Z03 7 depth ten 1d 14 EE EES depth eleven id 15 depth twelve id 16 whiskey id 2039 x ray id 2040 depth thirteen id 17 yankee 1id 2041 depth fourteen id 18 Zula tt depth fifteen id 19 backspace 1d 2043 depth sixteen 1id 20 vswiten dee erc e 20a depth seventeen id 21 space 1d 2045 depth eighteen id 22 ok trd TOU0U5S depth nineteen id 23 cancel id 1006 depth twenty id 24 depth twenty one id 25 depth twenty two 1id 26 depth twenty three id 27 depth twenty four 1d 28 WLOCUS Zero POLNE sax raz tocus one 1d 30 focus one point three id 3l1 Erres EWO et rr LOCUS TWO Ee Eeer Tid 33 focus two point eight 1da 34 214 TOCuUS three Sek E A focus three point Lave 110136 Pocus four TIa Tocus eege point fave Eet HOCUS five point five faais9 FOCUS six Katau LOCUS Six POINE tive Macca focus seven id 42 focus eight 1d 43 focus eight point five 1d 44 rocus ten KEE focus thirteen Ladc4e focus sixteen 1d 47 focus sixteen point five 1d 48 gray 1d 49 tan id 50 flam
98. bilities of ultrasound where they previously didnt A single practitioner could also use the telemedicine capabilities to receive expert opinions from colleagues in urban centers 10 1 5 Military So far in extensive discussions with both the Army and Air Force the applications with the WUC in the military seem to fall into two distinct categories The first and the source for the funding that developed the WUC is in Army CSHs The second application is for Special Forces use The Army maintains five levels of classification for its CSHs The levels are numbered one through five and increasing numbers bring with them increasing capabilities and levels of care A level one facility is essentially an Army medic in the field while a level five facility is a major trauma center Somewhere in the middle are level two and level three facilities that are generally housed in tents and provide centralized care for entire companies or battalions It is in these facilities where conventional ultrasound machines whether portable or otherwise that the 178 WUC was originally designed for Military equipment must be as rugged as possible to withstand the possible rough handling that it must endure Desert conditions often bring temperatures exceeding 45 C 114 F Equipment must be transported in trucks where it will experience harsh vibrations Power supplies are intermittent Also replacements or spare parts are difficult and time cons
99. ble speech phrases in the grammar file are converted into their phonetic transcription during initialization of the recognition engine The actual phonemes are what is recognized by the recognition engine The conversion from written form to phonetic representation is called phonetic transcription The VoCon 3200 includes a phonetic transcription component however pronunciation of a particular word can vary with geography and language dialects To account for this a word in the grammar file may be spelled using the phonetic alphabet or different pronunciations of the word may be provided This feature allows the grammar file to be fine tuned where appropriate A language can be formally described as a set of strings over an alphabet The alphabet is composed of symbols from the language and a string is a finite sequence of symbols from the alphabet There are two general methods that can be used to fully define a language One method used by the VoCon 3200 is to use a grammar to describe a language Another method uses a computational model that has the minimal complexity required to fully describe a language Languages are classified into a hierarchy according to their complexity Each language classification has a corresponding grammar and equivalent minimal computational model that is required to fully describe the language This hierarchy called the Chomsky hierarchy contains four types of languages Each level in the 89
100. cer The second manual titled WPI Wearable Ultrasound System User s Guide contains information specific to the Wearable Ultrasound System including tutorials We strongly suggest that you go through all of the tutorials before attempting to use the system with patients OPERATOR TS WEARING THE VEST AND POINTING QUT THE VARIOUS COMPONENTS IN THE VEST VOICE OVER Let s begin with an overview of the components in the vest In each of the breast pockets there is a rechargeable battery Each battery can be recharged while still in the vest In the lower right hand pocket is the ultrasound transducer It can be stored in this pocket when not in use Above the ultrasound transducer is a mouse that can be operated with one hand In the back pocket of the vest is the embedded computer The power button is located on the upper right hand side of the embedded computer Sitting in the lower left hand pocket is the head mounted display Finally there 1s a microphone contained in the mesh near the Lett shoulcer Now Let s pur the VESC On and akso snow a different head mounted display OPERATOR PUTS ON LHE VESE 218 VOLCE OVER Ultrasound images are viewed using a head mounted display The next step in putting on the vest is to put on the head mounted display OPERATOR PUTS ON THE HMD CUT TO SHOWING THE HMD BEING FiLLPPED UP CONNECTED TO TIS CABLE AND POWRRED ON AND OFF VOICE OVER The head mounted display may
101. complished through the use of voice commands but it may also be operated using a hand held mouse It is capable of operating for a full day using two batteries contained in the vest In addition the system has the capability to wirelessly share live images with remote viewers in real time while also permitting full duplex voice communication An integrated web server also provides for the wireless retrieval of stored images image loops and other information using a web browser Preface would like to acknowledge the assistance of the Telemedicine and Advanced Technology Research Center TATRC in providing invaluable resources throughout the duration of this research In addition the diligent work and effort provided by the Informatics staff and Army medical professionals at Madigan Army Medical Center MAMC has helped to make this research a success The tutelage and mentoring provided by Professor Peder C Pedersen and Professor R James Duckworth has been fundamental to the success of this work and is greatly appreciated Also the craftsmanship provided by Robert Boisse contributed immensely to the quality and reliability of the final design Table of Contents 1 Late e el ee DEE 1 1 1 WITFaSOUNGHIMaAGING PMET sccciccciceatcestceccseolecsectelcesickel geek enclscseatadensdadienear ye 3 L2 LIMFASOUNG ADDIICANONS EE 15 VS Poran WIA e 1 LEE 16 1 4 Motivation and Justification ccc cecccecceeeeeeseeceeeeeeeeeeees
102. ctors as shown in Fig 122 Mi Length _ gt Fig 122 Cable Length Measurement The cable lengths are indicated with a number over another number in parenthesis The top number is in cm while the bottom number is inches Fig 123 shows an example cable length of 25 cm 9 8 in EK 9 8 Fig 123 Cable Length Measurement Example The controlling dimension is in cm Whenever a connector pin out is shown for a device the view will always be looking into the connector at the mating face Unless otherwise instructed all connections are made using individual AWG 26 cable 198 Table 34 Internal 802 11g Cable Assembly Pin Signal Pin Device DATA 1x4 pin Shrouded Connector DATA CPU je 5 y 9 8 Special Instructions Replace J1 on the CPU board with a right angle 1x4 pin header Remove the USB connector from the 802 11g board Solder wires directly to the pads remembering that they must pass through a small opening in the heatsink that will not accommodate the 1x4 pin shrouded connector Table 35 Internal Audio Cable Assembly Device Pin Signal Pin Device 1x2 pin Shrouded Connector Line in GND Line out Signal J30 19 FEMALE SOCKET Sch Line out GND J30 20 Directly soldered to CPU Power Supply CPU Table 36 Internal Battery 1 Cable Assembly Pin Signal Pin Device J31 3 J31 1 Power Supply J40 3 J40 2 1x3 pin Shrouded Connector Power Supply FEMALE SOCKET S
103. d runs on the Microsoft Windows 2000 operating system Windows XP is the operating system used on the WUC and it is backwards compatible with Windows 2000 applications The Microsoft Visual Studio NET 2003 development environment was used for all C software development In total 21 580 lines of C were written During normal operation the Ultrasound exe wpiultrasound exe and rid exe processes are running The wpiultrasound exe processes is a Win32 application while the rid exe processes is a Microsoft Foundation Class MFC MFC is an alternate API for writing programs for the Windows operating system The dynamic link libraries DLL are required to support the executables and are loaded by the dependent executable when the executable is loaded All of the DLLs with the exception of mfc71 dll support the execution of the wpiultrasound exe process mfc71 dll supports the execution of the rid exe process by providing the 149 MFC API The wpiultrasound exe process is comprised of two message loops each running in its own thread The main message loop processes the Dashboard GUI while another message loop processes speech recognition events All other threads are pop up threads that are created when there is work to be done The use of pop up threads maintains a responsive GUI The ultrasound_client exe process contains a single message loop It uses a separate thread to handle updating the display with newly received images
104. datasheet for the MOSFET The Rps parameter or the on state resistance must be low enough so that Vps does not exceed 300 mV Since the LTC1775 uses the Rps of the MOSFET to determine the current through the inductor the MOSFET should have a maximum Rps given by Eq 6 240mV R 6 DS ON MAX Loge The pr term is used to normalize the equation for the wide variations in Rps that occur with temperature changes Ignoring this term by setting it to 1 yields a maximum Rps of 24 mQ The MOSFET used in the reference design exceeds this requirement with a worst case Rps of 19 mQ The inductor is required to carry all of the output current and must be properly rated to handle the expected 10 A saturation current The actual value of the inductor can be found by reusing Eq 4 and substituting in a desired ripple current of 4 A or 40 of the maximum 10 A current The final equation is shown in Eq 7 69 V Pe 1 ne vl it 7 AI Va JI 135x10 4 24 Therefore the full specification for the inductor is 7 3 uH 10 A It is also important to minimize the power loss in the inductor by selecting an inductor with the lowest DCR possible There are two variations from the reference design that were required to achieve reliable operation These were the disabling of burst mode and a change in the value of the boost capacitor Cp Burst mode is an operational mode whereby both MOSFETs are off for some period of time during the s
105. de where M stands for motion An M Mode image is derived from a B Mode image with a line indicating a region of interest ROI corresponding to a scan line This scan line is displayed versus time in another display showing how the structures along the chosen scan line changes over time This is useful for studying tissues that are in motion such as the heart Fig 4 shows an M Mode image where the scan line is indicated on the upper B Mode image by a dashed line and the lower image is the time verses depth display of the scan line eg Ka ES ech eh es Fig 4 M Mode Ultrasound Image 4 M Mode imaging can also be accomplished with a single element transducer aimed such that the resulting scan line defines the ROI This would result in only the time verses depth being available without an accompanying B Mode image The final set of imaging modes is a family of Doppler imaging modes Doppler imaging takes advantage of the Doppler shift produced when the ultrasound energy encounters a moving structure The movement of this structure will produce a Doppler shift in the frequency of the returned echoes This is the same effect as when a person is standing still and a train goes by while sounding its horn The horn will appear to have a higher pitch when approaching and a lower pitch after it has passed Doppler imaging is mainly used to characterize blood flow in vessels and tissues 7 and presents this info
106. de communications capabilities using these other services 10 1 2 Disaster Relief Disaster relief is perhaps the most promising of the potential applications for the WUC Relief workers must typically work in areas where the public utility infrastructure has been partly or completely disabled There are probably numerous people in need of medical care and efficient triage is difficult The wearable form factor of the WUC is uniquely suited to this application Ultrasound examinations can very quickly detect abdominal bleeding and collapsed lung pneumothorax which are two conditions that will immediately affect the treatment plan for a disaster victim Additionally ultrasound can be used to help in the placement of catheters and central lines making these procedures faster and allowing medical personnel to treat more disaster victims in a shorter time period Also the long battery life of the WUC would allow it to be used in the field for many hours Medical personnel using the WUC would not need to frequently interrupt their work to find a power source to recharge the batteries Also multiple batteries can be carried and hot swapped when needed to continue scanning indefinitely Finally the telemedicine capabilities would be extremely valuable in a disaster zone Medical personnel with less training in ultrasound procedures such as medics could be issued a WUC and have instant access to expert sonographers who could potentially ov
107. dividual assemblies is dictated by the locations of the connectors on each assembly and the internal cable routing requirements They have been optimized to reduce cable lengths and maximize access to cabling locations during manufacture The first assembly consists of the CPU board and IEEE 1394a board stack and is shown in Fig 35 45 Fig 35 CPU Board and IEEE 1394a Board Assembly The integrated heatsink on the CPU board is in direct contact with the aluminum heatsink Thermal grease is used to reduce the thermal resistance between the two heatsinks to promote heat transfer The second assembly consists of the power supply and the HDD The HDD is secured in a bracket that also holds the power supply Fig 36 shows the power supply and HDD assembly 46 Fig 36 Power Supply and HDD Assembly Both of these assemblies are attached to the heatsink by eight standoffs as shown in Fig 37 Fig 37 Two Internal Assemblies The EDCM is held in place within the enclosure by a groove in the bottom cover 47 The end of the EDCM that connects to the Terason 2000 has a retaining nut The EDCM exits the enclosure through an opening and is held in place by this retaining nut Fig 38 shows the mounting of the EDCM within the enclosure Fig 38 EDCM Mounting in Enclosure The complete internal assembly of the lower compartment is shown in Fig 39 Fig 39 Complete Internal Assembly of Lower Compartment 48
108. e id 51 sepia id 52 magenta 1id 53 sage 1d 54 rainbow 1id 55 cobalt tase Smoothing lpha bias smoothing bravo Ttia 387 Wsmoothing charlie J10d 59 smoothing delta 1id 60 smoothing echo id 6l persistence zero 1d 62 persistence one 1d 63 persistence two 1d 64 persistence three 1id 65 persistence four 1id 66 persistence five id 67 persistence six 1d 68 persistence seven 1d 69 map alpha id 7 0 map bravo id 71 map Charlie riaz map delta id 73 map echo id 74 map Eeer Tida 75 Eer NorizontalS eet invert vertical id 77 b mode id 78 m mode id 79 pulsed wave doppler id 80 Color doppler id sl directional power doppler pwer doppler 1d 83 save image 1d 84 brightness increase 1d 85 contrast increase id 86 brightness decrease 1d 87 contrast decrease 1d 88 full screen 1d 89 Elek 215 Appendix VII Database Schema The following table shows the data type mappings between MySQL and ODBC Fig 132 shows a graphical representation of the database schema using ODBC data types Table 57 MySQL and ODBC Data Type Mappings MySQL Data Type ODBC Data Type TINYINT SHORT SHORT SMALLINT SHORT INT LONG LONG S TINYBLOB LONGBINARY BLOB MEDIUMBLOB VARCHAR M 216 tblmessages mnemonic
109. e Cable Assembly cccccccceecceeeceeeaeeeeeeeeeeeeeeseeaeeeaes 207 External USB Cable Aessembkv 207 External Battery 1 Cable Assembhy 207 External Battery 2 Cable Assembhy 208 External Charger Cable Assembly c cccceccceecceeeeeeeaeeeeeeeeeeeeeeseeeaes 208 MySQL and ODBC Data Type Mapnpngs 216 xi Table of Abbreviations One Dimensional Two Dimensional Three Dimensional Four Dimensional Three Dimensional plus time Ampere Ampere hours Amplitude Mode Application Programming Interface American Telemedicine Association American Wire Gauge Brightness Mode Computer Aided Tomography Cubic Feet per Minute Centimeter Commercial Off The Shelf Central Processing Unit Combat Surgical Hospital Comma Separated Values Decibel Decibel A weighted DC resistance Driver Development Kit Degrees Celsius Degrees Fahrenheit Field Effect Transistor Dynamic Link Library Direct Current Energy Level External DC Module frames per second foot Acceleration due to gravity 9 8 m s 32 2 ft s gram Giga Byte 1 073 741 824 Bytes Giga Hertz Global System for Mobile communications Hard Disk Drive Head Mounted Display intensive care unit Integrated Drive Electronics Internet Engineering Task Force Inch Internet Protocol xii ODBC OS OSI OZ PACS PCB PCI PCM PSTN PTT RFC RID ROI RPELPC RPM SBS IF SDK SMBus Industry Standard Architecture International Telecommunica
110. e embedded computer must also include an IEEE 1394a interface to support the use of the Terason 2000 2 3 5 Software The software must be capable of utilizing a commercial speech recognition package to control the ultrasound probe Pervasive data logging should be employed to aid in gathering statistical data for off line analysis Also the software is required to allow for the remote viewing of ultrasound images in real time as well as the convenient retrieval of stored ultrasound images 29 2 4 Development History The WUC is the third generation in a series of prototypes each successively smaller more portable and more ruggedized than the last Each prototype used the Terason 2000 for the ultrasound imaging device The Terason 2000 is designed to be used with a laptop computer The first generation system 18 used a standard laptop contained within a backpack The first generation system along with its designer is shown in Fig 23 Fig 23 First Generation WUC The laptop contained an Intel Pentium 4 M processor along with 1 GB of memory This system also had voice command capabilities however it used a different method to interface with the Terason 2000 than is described in Section 5 An HMD was also used to view ultrasound images although it was a monocular design and had a resolution of 640x480 pixels The mouse functionality was provided by a joystick mouse mounted on the transducer Only one of these protot
111. e location of the connectors also allows for adequate internal clearance for cable entry into the solder cups on the connectors Each connector is modeled with two cylindrical regions extending rearwards away from the connector The green region as shown in Fig 41 represents the region of the connector that contains solder cups Fig 41 Enclosure Connector Model The red region encompasses the minimum bend radius of the wire attached to the connector This keep out region was used as a modeling aid to help prevent internal interference with cable routing caused by the internal assemblies One side of the enclosure is dedicated to connectors for the power supply This includes a connector for an AC adapter two rechargeable batteries and a spare The other side has two connections for the Terason 2000 an audio interface head mounted display and a USB port This connector organization creates a single cable for each external peripheral that must interface with the embedded computer platform Each connector is uniquely organized to provide power and signaling to its connected peripheral Also each connector is unique in terms of the number of pins and its gender This prevents accidental attachment of a peripheral cable to an incorrect connector Also each connector is labeled The cable corresponding to that connector also carries the same label 3 3 3 Enclosure Assembly The top and bottom covers are secured by four 5 c
112. e ratio SNR and energy level for each frame of audio data This data is used to make any adjustments to the input gain for the audio data otherwise known as automatic gain control AGC Additionally it can also determine if the frame contains the beginning of speech also known as a voice activity detector VAD or if the frame contains the end of speech indicated as trailing silence A jump back buffer is used by the ASR engine to buffer some amount of the incoming speech samples This is required for situations when the ASR engine detects some characterization about the incoming speech samples and needs to jump back to the beginning of the samples and process it again in some other manner An entire segment of speech comprised of separate frames of audio data is called an utterance A complete utterance in the case of the WUC is a command to be carried out by the WUC The recognizer object does the actual work of creating a recognition result from an utterance A recognition result contains many pieces of information but only three are used by the WUC These three pieces of information are a string representation of the 94 recognized utterance an id value and a confidence score The next section will describe what the id value and confidence score are used for 5 2 2 Speech Recognition Runtime The end result of initializing the speech recognition system is the creation of the runtime system The runtime syste
113. e word Smart has a corresponding SBS IF specification by the same name As shown in Fig 48 a Smart Battery system is designed to accommodate multiple batteries The Smart Battery Selector specification details how the addition and removal of various batteries should be handled simplifying the process of maintaining system power The charger circuit developed for the power supply is designed around a Linear 59 Technology LTC1 60 Smart Battery System Manager which also integrates Smart Battery Charger functionality This chip is capable of charging up to two Smart Batteries from an AC power source while still providing system power The major elements besides the LTC1 60 chip are three power path switches and a switching regulator The power path switches represent the Power Switch functionality described in Fig 48 Each power path switch uses a pair of P channel MOSFETs to diode connect and switch the various power sources to the system power bus A single switching regulator is used to provide the requested charging voltage for both Smart Batteries The charger design is adapted from the reference design provided by Linear Technology All equations in this section were described in the Applications Information section of the datasheet Some component changes were required to adapt the design to the DC power supply used for charging as well as a hardware enforced limit on charging voltage and current as an added s
114. eb page that is presented is derived from this database table The URL column contains a URL that can display a thumbnail preview of the image and contains a hyperlink to the full size image 7 3 Data Analysis Once the logging data has been stored in the relational database it can be analyzed at a later time To facilitate this analysis a program was written using the Java programming language The name of the program is JEventLog It was developed 137 using the Sun NetBeans 5 0 Development environment and the Java 1 5 0 update 6 software development kit SDK The Java programming language is an interpreted language that can run on many different operating systems A Java program is hosted within a virtual machine that is designed to run Java applications on a particular operating system This allows the same program to be run on different operating systems without the need for recompilation and without changes In addition to OS independence the Java language has a rich set of built in APIs to create graphical programs In particular many database vendors include software tools to allow access to their database products from Java programs The particular database vendor chosen for the WUC MySQL also includes this software Before a database can be used a connection to the database server must be established Upon starting the JEventLog program the user is presented with the dialog box shown in Fig 93 2 Event Log x Se
115. ected to the embedded computing platform via custom cable assemblies Each of the cable assemblies in the vest is customized for the component that it supports There is one cable for each component and one pocket for each component The cables are all constructed from a 10 conductor 24 AWG shielded cable The end of the cable that terminates at the embedded computing platform has a single matching cord connector for the panel mount connector on the enclosure The connector on the other end varies widely depending on the component it is designed to connect to Often there are several connectors on a cable For applications requiring the delivery of significant amount of current such as the battery and AC adapter cables multiple conductors are combined to increase the effective gauge of the conductors A full description of all of the cables assemblies is contained in Appendix III External Cable Assemblies The embedded computing enclosure is designed to fit into the back pocket of the vest which was modified to facilitate airflow to cool the embedded computer The bottom of the enclosure is contoured to fit the wearer s back When housed in the back pocket of the vest the cables are free to exit into the vest via two reinforced openings in the back pocket into the internal space Fig 104 shows the location of each component in the vest 147 Fig 104 Vest Component Layout Two components in particular have been specially
116. ed across the heatsink by the two fans Fig 34 shows the top compartment with an arrow indicating the direction of airflow Fig 34 Top Compartment of Enclosure Air is pulled in from the left hand side of the enclosure and exhausted out of the right hand side by two fans Each fan can spin as fast as 6000 RPM and move up to 5 5 CFM of air for a total of 11 CFM Each fan produces no more than 26 dBA of noise for a maximum of 29 dBA resulting in quiet operation 44 The heatsink has fins to increase the surface area for heat transfer It is also shaped so that air must flow through the fans to traverse the heatsink This ensures that the entire 11 CFM of air flows over the heatsink and cannot short circuit around the fans The 802 11b g board is held in place on the heatsink by a small retention bracket A small hole in the heatsink allows the wires for the fans and the 802 11b g board to pass through the otherwise solid heatsink It is located under the retention bracket for the 802 11b g board The lower compartment is organized into two assemblies positioned alongside the EDCM This arrangement creates an overall shape to the enclosure that makes it convenient for its location against a person s back It minimizes the overall height of the enclosure and allows for a gentle curve to be integrated into the lower compartment to fit more comfortably against the lower back of the person wearing the WUC The orientation of the in
117. ed in textual format the documentation is over 200 pages The distributed documentation is in Microsoft Compressed HTML Help that can be viewed using tools provided as part of Windows To facilitate the installation of the software an installer was written using the Inno Setup 54 installer program Inno Setup is a script driven installer that compiles all the required resources into a single executable file The executable includes all of the resources required to install the application along with an installation program The installer installs all the software used by the WUC configures it and additionally installs software and user documentation 8 3 User Integration The WUC is a new technology for most of the people who will use it Wearable computing is not a ubiquitous concept and some extra care was required to introduce people to the system and be able to take full advantage of it in a short period of time To this end a training manual was developed along with an abbreviated version of the Terason Ultrasound System User Guide normally supplied with the Terason application software The sixty nine page training manual is titled WPI Wearable Ultrasound System User s Guide When used in conjunction with the Terason manual it provides all the information a first time user needs to begin using the WUC The manual contains the following sections e Introduction e Quick Start Guide e General Usage Guide e Tuto
118. edded Computer 5 J30 8 5 EECH E DSP Microphone 5 1235 S o SmatProbe Transducer _ 12 30 Op HMD eMagin EB HMD i glasses 19 Fans 802 11b9g 8B Table 5 summarizes the total power required from each power source 57 Table 5 Power Requirements by Regulated Voltage Regulated Power Supply Voltage V Minimum Power Required W In addition to supplying power for the entire WUC system the power supply can also supply information about its current power consumption and thermal conditions via an SMbBus interface This interface can also be used to program certain characteristics of the battery charger and fan controller using the RS 232 host interface The following sections will show the details for the implementation of each of these functions 4 3 Smart Battery System Manager The Smart Battery System Implementers Forum SBS IF has defined a complete system for managing and charging multiple rechargeable batteries A Smart Battery System Manager 32 as defined by the SBS IF consists of a Smart Battery Charger 33 a Smart Battery Selector 34 and Smart Batteries 35 This system derives its intelligence by adding an SMBus 31 interface to a standard rechargeable battery making it a Smart Battery A Smart Battery is a battery that conforms to the Smart Battery Data Specification 35 This specification defines a model that allows a battery to communicate its internal state and characteristics to external devic
119. edded computer is running or not Section 4 discusses the batteries and integrated charging system in further detail In order to view the ultrasound images a head mounted display HMD is worn by the operator There are two displays that can currently be used with the system shown in Fig 20 23 a i glasses 16 b eMagin 17 Fig 20 Head Mounted Displays Each HMD interfaces to the embedded computing platform via a standard video graphics array VGA interface and has a resolution of 800x600 pixels They also each have headphones and one even has a built in microphone An integral part of the voice command system is the microphone that receives the spoken commands The microphone is explained in Section 5 Finally a mouse is also included within the vest The particular mouse being employed is a trackball mouse that can be operated with one hand and does not require a surface for operation The mouse is shown in Fig 21 Fig 21 Trackball Mouse Fig 22 shows an overall block diagram of the WUC containing all of the components introduced above 24 Embedded Computing Platform EDCM Microphone Li lon Battery Li lon Battery AC Adapter SC See e Smart Probe Am Fig 22 Block Diagram of WUC In support of clinical trials being performed at MAMC training materials in the form of manuals and short tutorial videos were also created This material was made avail
120. eeceeeeeeeeesseeaaes 19 Sale Bd E ae RE 21 2 1 Introduction to Wearable Ultrasound ccc ccccccecceeeceeee cesses eeaeeseeeeeenees 21 22 PAV CIOS CIOL eege 22 29 REQUIFEMEIIS TEE 26 2208 lee REJULEMENIS EEN 2 2 3 2 Enclosure Connector Requirements s nsnsenonnenonneronrsrrrrsrrrrsrrrene 2 2363 Power Supply Requirements ccccceccsecceeceecseeteeeeeeeeteeeeeeceeeeeeas 28 2 3 4 Embedded Computer Requirement ccccccscceeeeeceeeeeeseeeeeeeeees 29 ZS SOMWANG EE 29 24 Development TEE 30 3 Embedded Computing Platform cccccccccceccceccseeceeceeeseeeseeeeeeeeeeteeeseeeseeeaes 33 3 1 EMDCAdEC Computersin EE EEE EEO EEN 33 3 1 1 POS otal Gl er Clerrse gustan aint atest at anaeaeacnaw aeataant sia tannantacgentancanntamaneaaes 33 3 1 2 Embedded Computer Selection cccccccecceecceeceeeeeeeeeteeeeeeceeeeeees 35 SN IEEE 1394 e 3 3 1 4 Hard Disk Drive Selection c ccsccecssssssccussurecsecursssccursursesesuususecereas 3 3 45 IEE E802 1 DIG EE Eed 38 22 GR Le Miel e E 38 3 3 Enclosure Uesgn 39 3 3 1 Internal Arrangement EE 43 S et Enclosure e ul el EE 49 3 30 ENGIOSUFEASSOMIDIY sincns esha T T TE TEO TTEA 50 4 Power Supply and Management 54 ed AUSC 11 8 9 D 54 AZ Arou CIOM ett 56 4 3 Smart Battery System Manager 58 AA Li lon Rechargeable Batteries AA 63 4o OV OWNING IREQUIAION EE 66 AG Be eg ROC EI EEN 70 4 7 SMBus to RS 232 Host Interface 72 AS Arabi GON
121. elopment in 3D imaging for ultrasound is 4D imaging 4D imaging brings real time imaging to 3D images This requires the use of a transducer that uses a 2D array of elements in order to acquire 3D volumes in real time The 2D array transducers have many thousands of elements A 4D image is generally viewed by placing a marker within the volume and displaying all three orthogonal planes that intersect at that point in the volume along with a rendering of the volume Fig 10 shows an example 4D ultrasound image AE Healthcare BREAST CYST 4D MI 0 31 Tis 0 0 4D16L JO 09 14 05 02 43 52 PMADM 9 14 1 Welle Breast B Fra 12 0 MHz Gn 45 S A Map D 0 0 DR 72 AQ 100 Q Midi A 60 VR 0 0 Hz Fig 10 4D Ultrasound Image 7 There are a variety of different ultrasound transducers for different exams The transducers can vary in the number of elements contained in the transducer head the shape of the head and the frequency range that the transducer uses for imaging The following figures show the transducer most often employed in medical imaging 13 4C2 10L5 Cured Linear Linear Wklepanmd Vikiehand 126 Ekrgemte 128 Ekments Transducer Transducer Fig 11 4 2 MHz Convex Array Transducer 4 Fig 12 10 5 MHz Linear Array Transducer 4 Phase Ara Viidebarrdl 128 Ek ments Lkaptseusor Fig 13 10 5 MHz Phased Array Transducer 4 Ultrasound transducers for imaging the human body typically operate between 1 and 15
122. enerated using the Microsoft Office FrontPage program More details on the 127 database are presented in Section 7 The last option shown in the navigation menu is Ultrasound Client Clicking this option will begin a download of the RID client application This ensures that only a web browser is ever required to access the full remote functionality of the WUC remote data facilities A final option not pictured in any of the preceding figures is used solely for clinical evaluation The option is called Administrative and is a link to a database dump that must be manually created by a WUC user The database dump is created by running a small script on the WUC and the link is included for ease of use in transferring the actual data off of the WUC 128 7 Logging Logging functionality is an important piece of any large and complex project and the WUC is no exception The prototype evaluations systems were delivered into clinical settings and left to operate without administrative attention for weeks to several months at atime In order to gather meaningful data and statistics about the many facets of the WUC a comprehensive and pervasive logging system was developed 7 1 Logging Method The Windows operating system uses a message passing scheme to communicate events to programs Each message is identified with a 32 bit number and two additional 32 bit parameters whose contents depend on the message The additional par
123. ential improvements to the wireless data interface The wireless data interface is 802 11b g It is designed for communications over distances of less than 100 m This not adequate for situations where it may be impractical to locate an access point within this range However due to the open nature of the embedded 186 computing platform the 802 11b g interface is a standard USB peripheral It can be replaced or augmented with other wireless communications devices These may include cellular network data access such as EVDO for CDMA networks or EDGE for GSM networks For applications requiring greater range or for operation in truly remote areas that are not served by terrestrial wireless networks satellite communication is a possibility Companies such as Globalstar provide satellite based network access using portable phones which could interface with the WUC Based on the lack of initial user success with the speech recognition system it is clear that the learning curve must be further reduced Methods for integrating a speech command reference and addressing the eagerness of first time users should be pursued A more conventional on off indication should also be included There have also been comments made to include indications for HDD activity or network activity as might be found on laptop computers There is a clear need to include an on off indication that can be viewed while wearing the vest or whatever other configuration
124. ep SE ILF Frequency IM ll Depth 17 el cm Focus Gain E ToC For Help press Fi 4C2A E Patient Info oo Image Sorter Abdominal Live Imaging Fig 62 Dashboard Fy Report 26 Apr 2006 ACPA DND 17cm 15 TASR Ready L 76 R 60 4h 59m 16 Hz 26 APR 2006 01 42 02 PM The dashboard contains several pieces of information some of which is explained in later sections The information pertaining to the power supply is contained in the bottom half of the Dashboard and is highlighted in Fig 63 L 71 R 71 Sh 51r Fig 63 Power supply area of the Dashboard The WUC can accommodate up to two batteries Information about the remaining capacity for each battery is displayed separately in the Dashboard The L and the R are intended to show whether the battery is in the left or right breast pocket respectively This information is reported directly from the Smart Battery using the SMBus to RS 232 Host Interface 84 The remaining capacity is indicated through three different display methods The first method is a textual representation of the remaining capacity as a percentage of the total capacity of the battery For example each battery in the WUC has an initial capacity of 95 Wh At 71 approximately 61 Wh of energy remain The second method uses the color of the background to indicate the relative remaining capacity The colored portion of the background will change from green to red as t
125. erent groups of controls For instance the initial default control is the 2D control Selecting the image quality tab will display another group of image controls that provide various image quality settings IHE VIDEO DISPLAY SHOWS A STAFI IMAGE OF THE DEFAULI APPIICATLON STATE RE SELECTING THE IMAGE IsO TAB VOTCE OVER Above the image control bar across the top of the screen is the menu bar HIGHLIGHT THE MENU BAR ON THE STATIC IMAGE VOICE OVER Ihe menu bar provides further controls that are fully explained in the Terason User s Guide included with the system Many of these commands are also implemented as voice commands The Terason User s guide also explains how to interpret the various graphics that overlay the ultrasound image The final graphical element to look at is called the dashboard HIGHLIGHT THE DASHBOARD ON THE SIATIC IMAGE VOICE OVER The dashboard developed by WPI augments the Terason application with information pertaining to speech recognition and system power status SHOW THE ZOOMED DASHBOARD ONLY ON THE STATIC IMAGE VOICEOVER At the top of the dashboard is a line of text that indicates the current status of the speech recognition system HIGHLIGHT THE ASR TEXT IN THE DASHBOARD VOICE OVER Another name for speech recognition is ASR which stands for automated speech recognition The first line of text will always indicate the current status of the speech recognition system
126. ersee multiple medics This could help to further increase the number of medical personnel performing triage during the critical initial phase of a disaster relief effort Also post triage care could be improved by better planning if the 176 ultrasound images were available before the disaster victim arrived for treatment 10 1 3 Medical Transport Medical transport is another interesting application area for portable ultrasound equipment Transportation modes can include ambulances helicopters airplanes and ships In discussions with doctors who practice emergency medicine the utility of ultrasound in urban environment most notably in southern New England during medical transport is in doubt Generally it is best to move the patient to a hospital facility as soon as possible since average transport times are on the order of minutes However Life Flight personnel who transport critical patients via helicopter often must travel to rural areas The medical flight crew rarely has prior knowledge of what facilities they will encounter and having a familiar and reliable ultrasound machine as part of their equipment would be an advantage Patients with pneumothorax need special attention before traveling by air This condition is potentially fatal if not addressed and ultrasound can quickly diagnose its presence It is in rural areas that the WUC becomes a potentially valuable tool for use during medical transport Ambulance trips ca
127. es This allows for a mixture of batteries and battery chemistries to be used in a system and still provide accurate information about each battery This brings along with it several advantages Total system complexity can be reduced by not duplicating functions such as voltage and current measurements Battery energy can be maximized and charging times minimized since the battery can define the best charging scheme for its particular capacity and chemistry Also there is extra added safety with the battery enforcing charging limits on the charger There is also a thermistor in each Smart Battery that provides thermal protection An example Smart Battery system is shown in Fig 48 58 Vcc DC Svstem Unregulated G ss battery Power Ae Supply Switch Note SB A charging powering the system SB B idle AC DC Smart Battery A Smart Battery B ry ry Converter Unregulated SMBus Vbatt SMBus Vbatt Thermistor SMBus Smart Battery System Manager Thermistor Smart Battery Charger VCharge System Host Critical Events Battery Data Status Requests SMBus Fig 48 Example Smart Battery system 32 Each of the elements represented in Fig 48 are implemented in the power supply The key feature of a Smart Battery system is the SMBus that connects all of the major functional components together to bring intelligence to the system Each block in Fig 48 that starts with th
128. esign used to implement the power supply the delay time is 100 ms The implemented design was mostly taken from a reference design provided by Linear Technology Fig 52 shows the reference design used VIN Re 6V TO 22V 19 l LTC1775 SIN VouT EXTVcc VIN To30v 4 SYNC TK SUD50N03 10 RUN SS L1 6uH V Ce Css OUT Re INTVcc FCB 5V 2 2nF 0 1uF 10K 10A ITH D1 MBRS340 L Go 7 680uF 6 3V Cin SANYO 30SC22M Cour SANYO 6SP680M LI MAGENTICS 55380 A2 8 TURNS 15 GAUGE Fig 52 Power Supply Reference Design 39 Switching regulators operate by rapidly switching transistors on or off to manipulate the charge flowing into an inductor A full duty cycle involves turning on the M1 MOSFET then turning off the M1 MOSFET and turning the M2 MOSFET on and then off The period of a full cycle is the switching frequency which sp Zus in this 68 case As the M1 MOSFET turns on current flows into the output capacitor and the load Once a current threshold is reached measured by the Vps of M1 exceeding 300 mV the M1 MOSFET turns off and the M2 MOSFET turns on The cycle will repeat once the switching period has passed By varying the duty cycle a constant voltage is maintained for varying load currents The potential output current is dependent on the MOSFETs and the inductor For the MOSFETs there are two main parameters to be concerned with Rps and Ip The Ip parameter can be read directly from the
129. ethod is an automated method that attempts to analyze incoming speech and select the beginning and end of an utterance To accomplish this the VAD in the feature extractor is used to determine the beginning of speech The end of speech is determined by waiting for the feature extractor to indicate that trailing silence was detected It was found however that trailing silence detection was unreliable in most environments Often ambient noise would fool the feature extractor into thinking that the utterance was continuing when it had already ended This method was soon abandoned in favor of the second method The second method is called push to talk PTT This entails the user to determine when an utterance begins and ends thus bypassing the feature extractor entirely Using this approach the feature extractor is used solely for AGC A recognition event refers to the entire process of beginning an utterance gathering 96 frames of audio data completing the utterance and then processing the entire utterance to create a recognition result The ultimate goal of a recognition event is to obtain a recognition result One piece of information that is returned with each recognition result is a confidence score If the utterance is not pure silence the ASR engine will always return a recognition result whether a correct match for the current grammar is found or not The confidence score can have a value of between 0 and 10 000 and directly
130. he WUC uses LIO mode to acquire ultrasound images for transmission The individual ultrasound images are transferred using RTP to a remote viewer The use of LIO mode for acquiring the images is the most appropriate since the underlying transport protocol can lose packets and no attempt is made to recover the lost packets Since the person viewing the remote images is interested only in the current image attempting to perfectly transfer every image could eventually lead 115 to the displayed image lagging behind the real time image This lagging situation will occur if the time to transmit the frame to the remote viewer is longer than the time it takes for a frame to be produced by the ultrasound system By simply dropping frames that cannot be transmitted in time the remote image remains real time although the frame rate may be reduced in certain situations Each image frame is acquired from the shared memory interface in a device independent bitmap DIB format A DIB image contains a header a color palette and pixel data A DIB image is an indexed color image An indexed color image uses a color palette to describe the color of each individual pixel in the image The images produced by the Terason application contain a color palette with 256 colors Each entry in the color palette is 32 bits in length with 8 bits used for the colors red green and blue for a total of 24 bits The remaining 8 bits are unused By summing the var
131. he capacity decreases from 100 to 11 The third method is the amount of colored area versus the amount of gray area This area is also drawn relative to the remaining capacity of the battery The total capacity of Li lon batteries will slowly diminish over the course of thousands of charge and discharge cycles This translates into less and less total actual capacity for the same displayed remaining capacity The electronics in the Smart Battery constantly monitor the charge going into and out of the battery and uses this to determine the actual capacity of the battery as opposed to the original rated capacity This information along with a two minute average of the current being drawn from the Smart Battery allows for directly predicting the remaining battery time until empty The empty condition as defined by the batteries used in the WUC is indicated when any individual Li lon cell has a voltage of lt 2 9 V The remaining time until empty as reported by each Smart Battery is displayed at the bottom of the Dashboard in hours and minutes The displayed remaining time until empty is determined by averaging the remaining time reported by each Smart Battery This time represents the predicted total remaining runtime of the WUC The Dashboard also displays a warning when any individual Smart Battery is either below 11 remaining capacity or reports a remaining time until empty as less than 21 minutes The warning is displayed by cha
132. he generation of a START condition the bus is considered to be busy A STOP condition is used to signal the end of a bus cycle either by normal or abnormal conditions It is defined as SMBDAT transitioning from LOW to HIGH while SMBCLK is HIGH The bus is considered idle after the generation of a STOP condition SMBDAT SMBCLK 8 so o Soo g p start condition stop condition Fig 56 SMBus START and STOP Conditions 40 Note that the state of SMBDAT between the START and STOP conditions will vary depending on the data being transferred The SMBus defines several bus protocols The four implemented protocols are 19 e Read Byte e Write Byte e Read Word e Write Word Each of these protocols has a slightly different set of bus cycles associated with it and each is summarized in the following tables Note that the number above each bus cycle is the bit length of each protocol segment 1 T 1 1 8 1 1 T 1 1 8 1 1 Slave Address Command Code Slave Address Rd A Data Byte A P a SMBus Read Byte Protocol 1 1 1 7 1 1 8 7 1 1 8 1 1 1 1 S Slave Wr LA Command Ais Slave A Data Byte A Data Byte A Address Code Address Low High b SMBus Read Word Protocol 1 T 1 1 8 1 8 1 1 S Slave Address Command Code A Data Byte A P c SMBus Write Byte Protocol 7 1 1 8 1 8 1 1 1 1 1 Slave Address Command Code Data Byte Low Data Byte High A P d SMBus Write Word Protocol Fig
133. he output A PCB redesign to reduce this coupling along with the addition of two capacitors improved the output voltage ripple to 50 mV The capacitors are of different case sizes and different dielectrics to provide a good ground path for the AC transients The final result was measured using a LeCroy LT342 digital oscilloscope The sampling rate was 500 MS s and no bandwidth limiting was used When connected to a 35 W constant load the performance of the 5 V switching regulator is shown in Fig 114 163 oV supply with 3aVV Load I T T Fig 114 5 V Switching Regulator with 35 W Load DC Coupled The mean voltage output is 5 07 V This is within 1 4 of the proper value Fig 115 shows the same setup except that the oscilloscope was set for AC coupling and the voltage range is much smaller 164 oV Supply 35W load AC Coupled I T T A 3 0 0 2 0 4 0 6 0 8 1 1 2 1 4 1 6 1 8 2 Fig 115 5 V Switching Regulator with 35 W Load AC Coupled From Fig 115 the switching transients can clearly be seen The maximum overshoot is 62 5 mV and the maximum undershoot is 43 8 mV This results in an output voltage ripple of 106 4 man This is well within tolerances for all system components Under very light loads switching regulators often exhibit poor regulation Fig 116 shows the switching regulator with only the oscilloscope probe as a load 165 JV Supply with No Load I I T Fig 116 5 V
134. he overall length of the enclosure The embedded computer chosen for the design has some deficiencies that can only be addressed by moving to a different product The IDE interface has some compatibility issues with certain HDDs It has even rendered several HDDs inoperable The audio circuitry has noticeable noise and the documentation does not correctly describe the pinout The most severe problem has been with the VGA interface The VGA interface is used to provide the image that is displayed on the head mounted display The software driver sometimes fails and leaves the system in an unusable state until it is reinstalled This situation remains unresolved and is serious enough on its own to warrant consideration of another embedded computer To this end preliminary investigation has led to a promising replacement in the form of mezzanine CPU boards in industry standard form factors This is no guarantee that there will not be future driver issues but only this embedded computer has shown this behavior There are several standards for mezzanine CPI boards that can provide the necessary processing power A mezzanine CPU board uses a standardized connector to sit on a carrier board These connectors are standardized and provide a path for a carrier board design to support a selection of different mezzanine CPU 183 boards This has several advantages most notably the removal of the current reliance on a single vendor s products Also newe
135. he power path multiplexer uses three pairs of P channel MOSFETs connected in series to switch the DC power supply and each Smart Battery in as power sources for the load Each pair of PMOS devices have their sources connected together with one drain connected to a power source and the other drain connected to the load as shown in Fig 49 PWR Input Switch Gate Drive D S S Output Switch Gate Drive D LOAD Fig 49 Power Path Switch 62 This allows the LTC1760 to switch Smart Batteries between charging and powering the load if a DC power supply is present This also allows both Smart Batteries and the DC power supply to power the load simultaneously or to be completely disconnected if a low voltage or over current condition is present 4 4 Li lon Rechargeable Batteries The WUC is designed to operate using any two rechargeable secondary batteries that conform to version 1 1 of the Smart Battery System Manager specification The reasons for using two batteries are twofold First having two batteries doubles the available capacity and second it allows for the hot swapping of batteries By hot swapping a battery that is nearly empty and replacing it with a fully charged battery the system is able to continue operation without interruption There are many different types of rechargeable batteries available Being a wearable system a battery chemistry that minimizes weight and maximizes capacity is the ideal candidate Als
136. he two currents By using the ratio of two currents the device to device variation in Vse can be nullified The registers on the ADM1030 are accessed using the same SMBus used for host communication with the Smart Battery Charger and Smart Batteries In turn the temperatures and fan speed are also available to the host The fans are controlled together as if they were a single fan The fan speed is controlled by pulse width modulation PWM This is a technique to provide different amounts of power to a device by varying the duty cycle of a square wave The amplitude of the square wave is constant and set to the supply voltage of the fans In this case the fans are designed to operate with a 5V supply By running at less than 100 duty cycle the fans can effectively be operated at lower speeds and power levels Fig 59 and Fig 60 show the control loops programmed into the ADM1030 19 Local Temperaiue Sensor Remote Temnperiue Sensor GO PWM Duty Cycle 5 PYM Duty Cycle G i D 50 55 45 50 55 60 55 45 40 45 Deg C Deg C Fig 59 Local Temperature Sensor Control Loop Fig 60 Remote Temperate Sensor Control Loop The control loops are arranged so that the highest duty cycle determined by either control loop is the actual duty cycle used 4 9 Power Supply PCB Design A custom board was designed for the power supply in order to fit all the required functionality into the available space No combin
137. here a wearable system was not the optimal solution This exercise was initiated after receiving feedback about some of the shortcomings of the wearable form factor and should be investigated further Some thoughts have included a version contained in an across the chest backpack or even a fanny pack configuration One final possibility for future work involves the modification of the current embedded computing platform to support a variety of external physiological sensors By utilizing the USB connections found on most embedded computers along with custom hardware to interface to it the embedded computing platform could support an ever wider variety of applications The WUC has the potential to make a positive contribution to the field of ultrasound imaging It opens new applications for portable ultrasound and improves upon the status quo in others Further investment in this research is greatly encouraged 190 References 1 Thomas Szabo Diagnostic Ultrasound Imaging Elsevier Academic Press Burlington MA 2004 2 http Awww aium org aboutAlUM timeline intro asp 3 http Awww ob ultrasound net project japan_brainscan2 jpg 4 Terason Terason Ultrasound System User Guide June 2005 5 GE http Awww logiglibrary com library LOGIQ3 LOGIQ3 001661 jpg 6 GE http Awww logiqlibrary com library LOGIQ9 LOGIQ9 _ 001928 jpg 2004 7 GE http Awww logiqlibrary com library LOGIQ9 LOGIQ9_002140 jpg
138. hout a stable power source To maximize runtime on batteries and to fit within the tight confines of the enclosure a small and efficient power supply was designed 53 4 Power Supply and Management Being a portable and battery powered device the WUC requires comprehensive power management with consideration given to efficient power conversion size and weight This extends beyond various regulated DC voltages and includes other considerations in order to maximize operating life These extensions include a requirement for thermally controlled fans that only run when conditions require it a highly efficient voltage regulator for the embedded computer monitoring and control by the embedded computer to optimize operation an efficient battery charger that allows the embedded computer to operate while batteries are charging and ancillary voltage regulators that can accommodate the power requirements of various peripheral devices This section explores the design and development of the power supply contained within the embedded computing platform 4 1 Justification The first power supply that was considered is a combination battery charger and ATX power supply in the form of a two board PC 104 stack from a company called OceanServer The complete package consisting of two identically sized boards is shown in Fig 45 54 a rH GL Cl Vit Co CU Bea f i wee kiii ut 989 Uu A ETH BET Fig 45 OceanServer B
139. hroughput for 802 11b 6 2 Transport Layer The Transport Layer as defined in the OSI model defines a method for transferring data between two endpoints in a network It sits on top of the Data Link and Network Layer The Data Link layer specifies an addressing and data format scheme for transmitting data between two network nodes and generally includes 109 methods for error detection and correction for the Physical Layer The Data Link layer is part of the 802 11 specifications The Network layer defines an addressing and data format for sending data to a particular network node All of the Transport Layer protocols defined here will use Internet Protocol IP for the Network Layer There are two Transport Layer protocols in use on the WUC The first is called Transmission Control Protocol TCP and the second is called User Datagram Protocol UDP They are often written as TCP IP or UDP IP to indicate that IP is used to locate a particular network node Also both protocols use the concept of a port to locate a specific network endpoint A network endpoint is an actual application running on a network node and a single node can have multiple endpoints Each endpoint may be used with the TCP or UDP protocol to actually transmit user data TCP defines a reliable method of transport that is connection oriented Before data may be transferred a connection must be set up between the two network endpoints When a session is complete th
140. ilable The first type is called speaker dependent This type of ASR engine requires training by individual users before it can be used effectively but has an unrestricted vocabulary The second type is called speaker independent It does not require training by individual users before use but has a restricted vocabulary The different types of ASR engines are Summarized in Table 11 Table 11 Speech Recognition Engine Types ASR Engine Variant Speaker Dependent Vocabulary Speaker Dependent Unrestricted Speaker Independent Restricted The speech engine selected for use in the WUC is speaker independent and provided by a company called ScanSoft The ASR engine is version 2 0 of their VoCon 3200 product It was originally developed by Lernout and Hauspie L amp H for automotive use A speaker independent ASR engine is well suited for use in the WUC where a 88 limited set of commands need to be recognized These commands are defined by a grammar written in a format called ScanSoft BNF form The BNF in ScanSoft BNF stands for Backus Naur Form and is a metasyntax that describes context free grammars This grammar uniquely and unambiguously defines the language that the ASR engine can understand The individual sounds in a language are called phonemes The English language consists of 44 phonemes and each phoneme has a representative symbol Other languages may have more or less The utterances or recogniza
141. ime control protocol RTCP is also defined in RFC3550 As stated in RFC3550 RTP provides end to end network transport functions suitable for applications transmitting real time data such as audio video or simulation data over multicast or unicast network services A custom software stack was written to implement RTP and used to deliver real time ultrasound images and voice communications services The details of the protocol are contained in the specification but the implementation specific details are presented in the remainder of this section RTP makes use of UDP for the actual transfer of data between endpoints Two channels are defined RTP Data Transfer protocol is used to deliver the actual data while Real Time Control protocol RTCP is used as a control channel Each channel is defined as a network endpoint having a sequential port number Port numbers in UDP are defined as unsigned 16 bit data types and therefore have a range of 0 65 535 This means that any network node may have up to 65 536 UDP endpoints When RIP is used one port is used for data transfer and the next sequential port is used for RTCP For example an RTP connection on port 1000 will use port 1000 for RTP data transfer and port 1001 for RTCP Fig 83 shows the RTP network stack as it appears in the WUC Note that the dashed lines represent virtual connections that are made using the underlying protocols for the actual transport 111 Node IP 192
142. imum of 4 17 A of current at 24 V for a maximum power draw of 100 W The Smart Battery Charger was designed to enforce a 4 A limit on the current that can be drawn from the AC adapter With more than one Smart Battery charging the total power that can be consumed exceeds what can be provided by the AC adapter and the charging current is subsequently limited by the Smart Battery Charger After the current limiting portion of the charging cycle has completed the charging voltage reaches 16 8 V 39 mV When two Smart Batteries are charging they must share the available charging current Since both of the Smart Batteries were at similar capacities the available 158 charging current is shared more or less equally between each Smart Battery When compared to charging a single Smart Battery charging two Smart Batteries takes 69 longer and consumes 25 more power while charging The same Smart Batteries were then fully discharged into a constant load As before the load was designed to draw a constant 37 W from the Smart Battery The total time to discharge the Smart Battery was 18 362 s 5h 6m 2s The Smart Batteries reported a total average power draw of 36 46 W while discharging and provided a total of 185 97 Wh 12 346 Ah of energy When compared to discharging a single Smart Battery two Smart Batteries provided 110 more power while requiring only 69 more time to charge The extra power delivered exceeds double what was del
143. ing 1x5 4A 0 IGEKEY WM2803 ND Terminal Housing 2x24A 0 IGEKEY WM2519 ND _ _ Crimp Terminal 7A 4 IGEKEY WM2300 ND _ _ Terminal Housing 1x27A AL DIGI KEY WM2100 ND 12 NPN general purpose small signal transistor TEMP PROBE 1 MOUSER 610 2N3904 Panel Mount Connector 2 position Female CHARGER 1 MOUSER 502 EN3P2F Panel Mount Connector 5 position Female BAT 2 MOUSER 502 EN3P5F Panel Mount Connector 7 position Male MOUSE 1 MOUSER 502 EN3P7M Panel Mount Connector 4 position Female USB 1 MOUSER 502 EN3P4F Panel Mount Connector 6 position Female AUDIO 1 MOUSER 502 EN3P6F Panel Mount Connector 8 position Male VGA MOUSER 502 EN3P8M Ribbon cablew 10pinsocket_ VGA IGEKEY M1AXA 1036J ND Panel Mount Sealed Momentary Pushbutton POWERSWITCH 1 MOUSER 642 IPR3SAD2 IEEE 1394a1m MOUSER 172 1393 Table 32 External Cable Bill of Materials Description EEE Quantity Vendor Vendor Part Designator Cord Connector 6 position Male AUDIO 1 MOUSER 502 EN3COM USB type b connector CF AUDIO MOUSER 154 2010 3 5mm female stereo connector AUDIO 2 MOUSER 161 3300 Cord Connector 8 position Female VGA MOUSER 502 EN3C8F VGA Sockel VGA MOUSER 523 015S AA000 _ VGASocketBackshell EVGA MOUSER 538 DMHE001 VGA CONN POWERPLUG 1 BLACK VGA DIGI KEY SCI051 ND __ Cord Connector 5 position Male BAT 2 MO
144. ious intensities of red green and blue any color can be reproduced The color of each pixel in the image is represented as an index into the color palette Since there are 256 colors each pixel only 8 bits to fully represent its color In order to reduce the time required to transmit an image frame to a remote viewer compression is used to reduce that data that must be transferred Many compression algorithms specifically targeted at video applications make use of the fact that in general individual video frames do not vary much in their content from frame to frame Put another way the video frames are highly correlated For example a scene showing a person talking will probably have a static background that does not change often and does not need to be transmitted with each frame These video compression algorithms take advantage of this and only transmit the differences between frames The initial reference frame is called a key frame and some number of intervening differential frames are encoded for transmission until the coding algorithm decides to send another key frame A popular example of a video compression algorithm using this technique along with others is the MPEG 2 algorithm used on DVDs 116 Unfortunately ultrasound images contain speckle noise that greatly reduces the correlation in image data between frames Also the extreme compression achieved by many video compression algorithms is computationally intensive and pote
145. is connection must be torn down While a session is active TCP ensures that any data sent from one endpoint to another is received properly There are facilities within the protocol to verify that the data was transmitted properly If an error was detected the data is retransmitted UDP differs from TCP in that it is not connection oriented and is not reliable There are no facilities to detect errors in data transmission However UDP does not require a connection to be set up and has less protocol overhead This results in lower latency and higher throughput but at the cost of reliability Each protocol is suited to a particular set of applications TCP is used when reliable delivery is important and the increased latency and reduced throughput can be tolerated On the WUC TCP is used for all data transfers except for real time ultrasound images and voice communications UDP is better suited for applications 110 where lower latency is more important and the occasional dropped packet can be tolerated These applications are often called streaming since a stream of data is sent between endpoints UDP is used to stream real time ultrasound images and for voice communications 6 3 Real Time Transport Protocol The WUC has the ability to transmit live ultrasound images in real time to a single network endpoint using real time transport protocol RTP RIP is defined by the Internet Engineering Task Force IETF in RFC3550 47 real t
146. itations the maximum 1 GB of memory was included 36 with the MSM855 3 1 3 IEEE 1394a Selection An important requirement was the inclusion of an IEEE 1394a FireWire interface in order to support the Terason 2000 The MSM855 does not have a 1394a interface so it was necessary to use an additional board to provide this The IEEE 1394a specification 25 defines a four or six wire serial connection of up to 4 5 m 14 8 ft at a physical layer data rate of 400 Mb s Multiple devices may be connected in a non cyclic bus arrangement Data is transmitted using differential signaling on two twisted pairs of wires creating a full duplex serial connection The six wire version includes two extra wires for providing power and ground A 1394 node may consume up to 1 5 A of current with a supply voltage of 8 40 V The Terason 2000 requires a six wire IEEE 1394a connection providing up to 10 W of power at between 12 V and 30 V To provide this a PC 104 Plus IEEE 1394a board from Ampro having two 1394a ports was used In order to meet the power requirements of the Terason 2000 the Ampro board was provided with power directly from the power supply through an auxiliary header on the board More detail on this is contained in Section 4 10 3 1 4 Hard Disk Drive Selection Storage for the embedded computer is provided by an industrial 2 5 form factor HDD with a 44 pin Integrated Drive Electronics IDE interface and a capacity of 2
147. ithin the Smart Battery pack which are arranged in a 4 series 3 parallel 4S 3P configuration The blue colored plot represents the full charging rate of the battery and shows the characteristic constant current and then constant voltage of a charging cycle Fig 107 shows the charging current and charging voltage vs time for the same test as described in Fig 105 155 Charging Characteristics i i j l i 1000 2000 2000 4000 2000 6000 F000 S Fig 107 Single Smart Battery Charge Characteristics During the current limiting portion of the charging cycle the current is consistently limited to 4 A with the actual value being 3 995 A After the current limiting portion of the charging cycle has completed the charging voltage reaches 16 8 V 15 mV The same Smart Battery was then fully discharged into a constant load The load was designed to draw a constant 37 W from the Smart Battery This power draw represents the observed normal maximum power that the WUC can consistently draw during operation The results are presented in Fig 108 and Fig 109 156 Battery Discharge 100 T j Tt j 1 r T T 90 0 DU 70 oy 60 D 50 Capacity 40 ome 30 Ne 20 7 SC 0 1000 2000 2000 4000 2000 ggg F000 8000 5 Fig 108 Single Smart Battery Relative Charge Capacity vs Time While Discharging Battery Discharge Bue EE E e rasiatnn o cf errr 6 25 a ee SES Bereet 12 10 15 st
148. ition Initialization Several objects are combined together by the programmer to create a complete speech recognition system Most of these objects are supplied by the VoCon 3200 application programming interface API It is up to the programmer using the API to provide audio data to the VoCon 3200 Each object must be created and initialized with a set of parameters to create a complete speech recognition system 92 The first step in creating the speech recognition system is to convert the grammar file using the language model into a form that is usable by the ASR engine This form is called a context To create a context several objects must be combined into a lexicon The lexicon encapsulates the grammar file language model and a grammar to phoneme module The grammar file is created by the programmer to indicate exactly what words or phrases are to be recognized by the ASR engine and how to interpret the recognized results The grammar to phoneme module translates the text in the grammar file into its phonetic representation The language model along with the grammar to phoneme module is used to translate the grammar file into a context that will be run on the ASR engine Fig 66 shows how each of these objects interacts to create a context Lexicon e e e e e re re e e e e re re e e e e e re re e e e re re rs zz Grammar to Banton Grammar Language Phoneme Model
149. ivered by a single Smart Battery because the second Smart Battery probably had a higher capacity than the original Smart Battery used in the original discharge test As Li lon batteries are subjected to multiple charge and discharge cycles they will naturally lose capacity Therefore the second Smart Battery used in the dual Smart Battery tests must have been a newer battery The charging voltage for the Smart Batteries is provided by a switching regulator circuit that is controlled by the Smart Battery Charger A LeCroy LT342 digital oscilloscope was used The sampling rate was 500 MS s and no bandwidth limiting was used The performance of this switching regulator when providing 3 A of charging current as determined by the Smart Battery electronics is shown in Fig 110 159 Fig 110 Smart Battery Charger Switching Regulator Providing 3 A DC Coupled The mean voltage output is 16 74 V This is within 0 4 of the proper value Fig 111 shows the same setup except that the oscilloscope was set for AC coupling and the Voltage range is much smaller 160 BAT Charge 34 AC Coupled I T T Fig 111 Smart Battery Charger Switching Regulator Providing 3 A AC Coupled The maximum overshoot is 493 8 mV and the maximum undershoot is 375 0 mV This results in an output voltage ripple of 868 8 mon While this performance appears to be rather poor it does not appear to decrease the amount of energy that can be stored within
150. lected due to it being the smallest device currently available from Microchip that support a master capable TC controller and a UART While the device is capable of operating with a clock as fast as 20 MHz only a 3 68 MHz clock was used This clock speed results in convenient operation of the UART as well as reduced power consumption while still achieving adequate performance The FC bus has a similar physical layer to the SMBus It is physically compatible with the only major difference being the FC clock rate is reduced from 400 kHz to 100 kHz for SMBus The data link layer however is significantly different The embedded IC controller in the microcontroller is master capable but requires software for controlling the data link layer By providing software to make the I C master act as an SMBus master the FC can be made to act as an SMBus master The microcontroller also integrates an asynchronous UART that is appropriate for use with many serial data protocols RS 232 was chosen due to its availability on the embedded computer and its ubiquity in standard desktop computers The use of this UART in an RS 232 signaling environment requires the use of a transceiver to level shift the incoming 5V signal to 15 V This function was provided by a Maxim RS 232 transceiver MAX3221CAE with auto shutdown This device uses two charge pumped power supplies to provide the 15 V required for RS 232 signaling The auto shutdown feature allows the chip
151. led A charge current of 1000 mAh or 1 C will charge a 1000 mAh battery in slightly more than one hour A 1 C discharge lasts one hour From Table 6 it can easily be seen that Li lon batteries have the highest gravimetric energy density available measured in Wh kg However Li lon batteries also have the most stringent charging requirements and do not tolerate over charging or over discharging The use of a Smart Battery Charger helps to mitigate this issue and provide a safe and reliable power source Based on the requirements in Table 4 and Table 5 a rechargeable battery that maintains at least 12V is required to power the system nspired Energy is the only manufacturer that sells Li lon battery packs commercially The largest capacity battery they carry is nominally rated for 6 6 Ah With a nominal voltage of 14 4 V this capacity can also be expressed as 95 04 Wh With two packs in use the total Capacity is as much as 190 Wh Each battery model NL2024A22 uses a constant voltage charging algorithm and draws a maximum of 4A while charging The battery pack is arranged as a 4 series 3 parallel 4S 3P combination of individual Li lon cells Each individual cell has a nominal voltage of 3 6V and a nominal capacity of 2 2 Ah 7 9 Wh The 64 battery pack weighs 0 647 kg 1 43 Lbs and measures 16 751 x 10 287 x 2 093 cm 6 595 x 4 050 x 0 824 in The NL2024A22 battery is pictured in Fig 50 OceanJerver TECHNOLOGY INC PAR
152. ller will index into a jump table and execute the specified bus protocol Whether reading or writing the microcontroller will always return one or two Bytes back to the host depending on the access size for synchronization purposes If a write protocol was performed the returned data is discarded This synchronization is important in order to avoid issuing a new command while a bus protocol is executing Each command packet is stored on the microcontroller and referenced during the bus operation Sending a new command packet before the previous bus protocol had completed could lead Tf to unexpected behavior and possibly lock up the microcontroller It has been observed that the Windows operating system can occasionally write spurious data out of the serial port To manage this the microcontroller includes a watchdog timer with a timeout of 8 39 s Therefore if the microcontroller locks up it will return to normal operation within 8 39 s The timeout value is specified as a certain number of periods of a local 31 25 kHz oscillator In this instance the multiple is 262 144 or 2x101 The timeout value is long enough to not interrupt normal execution but short enough to reset the microcontroller within a reasonable time period 4 8 Fan Controller The embedded computer uses a pair of fans to provide active cooling Each fan is a 40x6 mm box fan capable of pushing 5 5 CFM of air per fan for a total of 11 CFM of air flow Also at the
153. load type identifies what sort of data is in the packet such as video or audio data The sequence number is incremented by 1 for every packet that is sent allowing for the identification of dropped or out of order packets The RIP timestamp is used to indicate the sampling instance of the data within the packet The SSRC uniquely indicates the participant that sent this packet RTCP is used for periodically reporting statistical data to all of the session participants gathering information on session participants session initiation and session tear down The statistical data takes the form of sender or receiver reports depending on the type of participant and is periodically sent by every participant in the session This primary purpose of this statistical data is to inform session participants about the quality of the data distribution This can be used to diagnose network problems provide for congestion and flow control algorithms or as input to adaptive encoding algorithms A receiver report sent by receiver participants contains the following information for each sender that the receiver has received data from e Sender SSRC e Fraction of packets lost e Total number of lost packets 113 e Interarrival jitter e Timestamp relating to the last sender report receiver from this sender e Relative delay since receiving the last sender report receiver from this sender The sender SSRC uniquely identifies which sender in this session
154. lsewhere Of the 135 possible utterances only 74 or 54 8 were actually used There is a sharp drop in confidence scores following the color doppler command This is most likely due to the training session scenario Most training session began with a demonstration by someone familiar with the speech recognition system issuing the same series of commands These commands appear in Fig 119 grouped together and have the highest confidence scores Following this demonstration training attendees were then given manuals and instructed to perform the tutorials However this advice was never followed Training attendees would instead begin issuing voice commands without knowing what the proper commands were It is important to note that a confidence score is relative It is directly related to the phonetic diversity of an utterance For a given grammar confidence scores may improve or degrade with different microphones However changing the grammar will also affect the confidence scores The various parameters that control the operation of the speech recognition system must be tuned for each implementation The speech recognition engine will always return a value and the confidence score is used to accept or reject the result Through laboratory testing a minimum confidence value of 3 00 was set for the acceptance threshold Recognition results that were returned with a confidence score of 3 700 or lower were rejected The value of 3
155. m 2 in Allen head screws Each 50 screw passes through conduits in the bottom cover and is seated in threads that are part of the top cover When ready for assembly all of the components are attached to the heatsink All of the connectors for the enclosure are also wired to their respective cable assembly This heatsink assembly is then placed into the bottom cover by first angling the end with the fans so that the edge of the heatsink is in contact with the edge of the bottom cover The other end remains away from the bottom cover while each of the connectors is fed through the bottom cover and retained with a nut Fig 42 shows this first step in assembling the enclosure Lem O Fig 42 Step One of Assembling the Enclosure Once one set of connectors has been inserted the heatsink assembly can be seated in the bottom cover Before being fully seated the connectors on the other side of the enclosure must be fed through the bottom cover and retained with a nut Fig 43 51 shows the results of completing the second step of assembling the enclosure Fig 43 Step Two of Assembling the Enclosure Finally the top cover can be placed over the heatsink and the four screws tightened to firmly clamp the top and bottom covers together A picture of the final enclosure along with the WUC itself is shown in Fig 44 Fig 44 Enclosure 52 A key feature of the WUC is its ability to operate for extended periods wit
156. m exists for the duration of the application and performs the actual work of speech recognition The combination of context feature extractor and recognizer is called the ASR engine The ASR engine along with the audio source and a jump back buffer comprise a complete speech recognition system Fig 67 shows a representation of the speech recognition system during runtime ASR Engine Context Feature Extractor Jump Back Audio Source Buffer Recognizer Fig 67 Speech Recognition System Runtime Each of these components is provided by the VoCon 3200 The audio source is used by the VoCon 3200 to receive audio samples from the application The jump back buffer is shown with vertical lines to represent a line of samples waiting for processing by the ASR engine 95 The audio source is supplied with frames of audio data by the application A separate set of threads within the application are used to supply this data to the audio source These threads exchange frames of audio data with the pop up thread that contains the speech recognition system by using a circular buffer Fig 68 shows how speech data is buffered in a circular buffer for consumption by the ASR engine Circular Buffer Speech Recognition system Audio Threads Fig 68 Circular Buffer There are two main methods used to determine what portion of incoming audio data should be submitted to the ASR engine for recognition The first m
157. may be produced The inclusion of other indicators however may be unnecessary distractions The embedded computing platform does not look like a computer even though it is and adding indications that do not clearly contribute to its operation as an ultrasound device should be avoided One of the more challenging aspects of this project was working extensively with military personnel The culture is very different from either corporate or academic environments The medical personnel are every bit as talented and qualified as their civilian counterparts but the work environment can be very different There were three main facts of military life that while initially viewed as obstacles eventually contributed to producing a better system The biggest challenge was personnel turnover With the current political situation many people involved in clinical trials were often deployed soon after receiving 187 training on the system This was addressed by making the manuals for the WUC available on the Army intranet and obtaining an Army email address to facilitate Communications The second challenge was providing physical access to the WUC during clinical trials MAMC is a major trauma center that receives approximately 821 000 56 outpatient visits per year It was important that physical security be provided to prevent misplacement or theft of evaluation systems It took several visits to fully understand how the Army tracks equipment
158. moved from the plastic housing and mounted within the enclosure Details on the placement within the enclosure are provided in Section 3 2 3 2 EDCM Integration The Terason 2000 is connected to a host computer via IEEE 1394a through an EDCM The EDCM is a power supply that produces several voltages required by the Terason 2000 and also passes through the 1394a connection to the Terason 2000 It is normally supplied in a plastic housing that has two connectors on either end One connector receives an IEEE 1394a cable and the other connects to the Terason 2000 The EDCM measures 14 8 x 3 8 x 2 7 cm 5 8 x 1 5 x 1 1 in and weighs 95 g 0 20 Lbs Within the plastic housing is a small PCB measuring 14 2 x 3 1 x 1 8 cm 5 6 x 1 2 x 0 7 ml and weighing 45 g 0 10 Lbs Fig 28 and Fig 29 show the EDCM 38 enclosure and the EDCM PCB 3 terason External DC Module em system 10 2009 05 02 1604 my ey Pa pe DDR LA E ki EA Pe f gt no Cay DS WT EN ee ae ee oe Fig 28 EDCM Enclosure Fig 29 EDCM PCB The EDCM is removed from its plastic housing prior to being placed within the enclosure due to space constraints The reasoning is that having a plastic housing within the enclosure would be redundant 3 3 Enclosure Design One of the key features of the WUC is the enclosure housing the embedded computer and the EDCM The unique requirements of the embedded computer enclosure as described in
159. n key for the utterance column in table tb Utterance The audio column contains complete WAVE file recordings of utterances that had poor confidence scores This allows for later review by listening to utterances with low confidence scores to determine what may have caused the poor performance 135 It would also have been correct to include audio column in the tb Utterances table However the frequency of needing to store this data was expected to be low Also a record that has blank fields still requires some data in the blank fields to indicate that they are blank Having a mostly empty column in a table justified moving the data to a separate table The next two tables are used for periodically logging the current status of the power supply and the internal temperatures of the WUC This data was logged once every minute into two separate tables The battery information was logged into table tblBattery and is detailed in Table 22 Table 22 tbiBattery Definition Column Not Name Null Unsigned Data Type Description INTEGER Primary Key stamp __ TIMESTAMP SMALLINT Millisecond portion of timestamp bat1 tte Sf By SMALLINT Battery 1 estimated minutes until empty 0 65 535 min bat2_tte wi wi SMALLINT Battery 2 estimated minutes until empty 0 65 535 min bat1_rc TINY INT Battery 1 relative charge 0 100 TINYINT Battery 2 relative charge 0 100 SMALLINT Battery 1 Voltage 0 65 535 mV SMALLIN
160. n often take over an hour This allows for plenty of time to perform more advanced procedures on patients while on route When combined with telemedicine ultrasound could be used to better assess the patient and prepare for their arrival The long battery life ruggedness and communications capabilities make the WUC a good fit for use in medical transport The WUC could easily operate for several trips without needing to be recharged Additionally the flexibility of the communications system should allow it to be adapted to the various telemedicine systems that may be encountered 177 10 1 4 Rural Healthcare Rural healthcare is a term encompassing the unique circumstances that the healthcare industry faces in rural areas According to the U S Census Bureau in the year 2000 59 million people or 21 of the population lived in rural America The lower population density often means that medical facilities are smaller and less equipped The medical staff generally fulfills multiple roles and transport to these facilities may take an hour or more There are often no specialists available and more complicated or critical medical issues must be addressed at nearby urban centers Again it is the portability and long battery life that makes the WUC well suited for rural healthcare applications Medical personnel who must travel to see patients or work in facilities lacking adequate backup power could have access to the diagnostic capa
161. ndpass hypotheses 50 VAD trailing silence 200 ms Extra event detection Enabled Far Close talk microphone Far talk Initial beam width 2500 AGC 3284 Word penalty 100 Firstpass approximations 500 Fig 74 ASR Details Dialog Box This dialog box contains a detailed display showing the current state of the speech recognition engine and accepts no user input It is updated whenever any speech recognition event occurs The upper left portion of the dialog box indicates the current state of the speech recognition system The upper right portion will display any results that are returned after processing user speech Below this is an area that can display various warning and error messages that may be generated by the speech recognition system Below this are two progress bars that show in real time the currently reported values for the SNR and the energy level both in Decibels dB parameters currently in use by the speech recognition system An exact description At the bottom of the dialog box are two lists showing the exact of each parameter and its possible values is contained in the manual for the speech recognition system 102 In addition to displaying the current state of the recognition system the user can also display a dialog box containing all utterances for all grammars Fig 75 View Utterances Dialog Box The view utterances dialog box always displays all of the possible utterances regardless of which grammar is
162. nds for deleting a character and moving between fields in a dialog box are also implemented Fig 78 shows the dialog box used to enter patient information Patient Information Patient Name PC Patent ID 0123456789 Date 11 16 2005 Fig 78 Patient Information Dialog Box This dialog box can easily be extended to include other data This data is used in two separate places The first place is as a header at the top of any saved ultrasound images or video clips as shown in Fig 79 de dem Ee O Dec 2O045 Abdominal 01 28 57 PM Fig 79 Patient Information Header The second place that the patient information is used is for remote viewing of saved images This is further detailed in Section 6 106 5 6 Array Microphone One of the most important elements of a speech recognition system is the microphone The WUC makes use of a four element linear array microphone connected to a digital signal processor DSP contained in a small box The DSP implements algorithms to make the microphone more sensitive along the long axis When in use the microphone is pointed in the direction of the users mouth This helps to reject directional noise sources such as other people talking which could interfere with the accuracy of the voice recognition system The array microphone is shown in Fig 80 while Fig 81 shows the directional sensitivity of the array microphone Fig 80 Linear Array Microphone Fig 81
163. ng Platform The embedded computing platform is the centerpiece of the WUC All of the system peripherals are connected to the embedded computer The embedded computer consists of the following e 1394a Interface e 802 11b g Interface e Embedded Computer e EDCM e HDD e Power Supply Each of these items is enclosed within a custom designed enclosure forming a complete embedded computing platform 3 1 Embedded Computer There are several commercially available form factors for embedded computers that support the necessary processing power required by the WUC To further explain a Pentium M class CPU having a maximum clock speed of greater than 1 1 GHz Of these the PC 104 form factor is the smallest and most mechanically robust form factor 3 1 1 PC 104 Standards The PC 104 standard is maintained by the PC 104 Embedded Consortium There are three variations of the standard that are distinguished by the expansion busses that they support The original PC 104 standard 20 released in March of 1992 defines the Industry Standard Architecture ISA bus for connecting peripheral boards to the system A later update to the specification called PC 104 Plus 21 33 added the Peripheral Component Interconnect PCI bus in addition to the ISA bus The latest addition to PC 104 in November of 2003 is the definition of a PCI only form factor called PC 104 22 Each of the various standards are mechanically identical and to s
164. ngine Types cccccccceccceeeseeeseeeeeeeeeeseeeseeeaeeeaes 88 Table 12 Chomsky e HE ten EE 90 Table 13 WUC Application Defined Meseages 130 Table 14 MySQL Numeric Data TYPES cronan ea ara AORE ARORO ENE 132 Table 15 MySQL Binary Data Tvpes esse eeseeeseeeeeeseeeseeeas 133 Table 16 MySQL String Data fvpes 133 Table 17 tblPackets Definition cccccccceccseeceeeceeeceeeeeeseeeseeeseeesaeeaeeeeeeseeeseeegs 133 Table 18 toliMessages Rtl UL EE 134 Table 19 TOM Me real Ge RTE ln e EE 134 Table Oe ele EN RI ln le EE 135 able 21 1OIAUGIO DOTMIMION EE 135 lable 22 1olBattery BE Lade EE 136 Table 23 1DICPU TEMP DENNOM EEN 136 Table 24 tblErrors Definition cc ccc cccccecc eee eeeceeeseeeseeeseeeseeeeeeseeeseeeseeeaeeseeseeees 137 Table 25 oll mages RE On e BEE 137 iFable 26 Sofware GOMPONECINS EE 149 Table 27 gt Manno dee 152 Table 2S WUC SPeCiiGallOnS EE 173 Table 29 Power Supply Bill of Materials ccc cccccccsecceeeceeeceeeeeeeeeeeeeeseeseees 194 Table 30 Embedded Computer Bill of Materials ccc ccc ccc cecseeeeeseeeeeeeeeeeeeees 195 Table 31 Internal Cable Bill of Materals ccc ccccsecceeeceeeseeeeeeeseeeeeeeeeeseeees 196 Table 32 External Cable Bill of Materials 0 0 0 0 ccccccseccseeceeeseeeseeeeeeeeeeeeeeseeess 196 Table 33 Assembly Bill of Materials 0c cecccccceccceeeceeseeeseeeseeeeeeeeesaeeseeesaeees 196 Table 34 Internal 802 11g Cable ASSEMDI
165. nging the battery indicator to a blinking yellow black box with the text LOW displayed in a reverse color The indicator will reverse colors every second 85 ASR Ready ASR Ready R 11 R 11 Oh 21m Oh 21m Fig 64 Low Battery Warning Indicator In addition to displaying a warning for each individual Smart Battery a warning will also be displayed if the total remaining time is less than 21 minutes This is displayed by changing the color of the remaining time indication to yellow Further information about the status of the power supply is also provided by a dialog box This dialog box among others is accessible via a pop up menu The pop up menu is displayed by clicking with the right mouse button on the Dashboard Selecting the Power Supply option will display the Power Supply dialog box shown in Fig 65 Power Supply 22 461 W xX Battery 1 Battery 2 15 217V 2 17 ILEI7Y 245 0 687A 63 Fig 65 Power Supply Dialog Box The power supply dialog box displays all of the remaining information that is routinely gathered using the SMBus to RS 232 Host Interface When the dialog box is displayed the information it contains is updated every 10 seconds For each Smart Battery voltage current remaining time until empty and relative capacity are displayed The current is displayed as negative when it is flowing out of the battery 86 If the battery was recharging the value would
166. ning multiple scan lines where each scan line is a one dimensional 1D image a scan plane is created A scan plane is a complete 2D image created from multiple scan lines Early B Mode machines had arms attached to the transducer so that the position and orientation of the transducer was known in order to place the scan line in the appropriate position on a display A long exposure photograph or a storage scope was used to display the final scan plane 1 This procedure was similar to having your portrait taken during the early years of photography The subject could not move during the procedure as the individual scan lines were acquired Fig 2 shows an early ultrasound machine Note the transducer attached to an armature Fig 3 shows a B Mode image created by rocking the transducer while keeping it in the same location a i gi E KA Zei TRANSDUCER 2 25 Mc Fig 3 Early B Mode Ultrasound Image 3 Fig 2 Early B Mode Ultrasound Machine 2 In the 1970 s manually sweeping the transducer either by hand or mechanically was replaced by incorporating a linear array of elements in the transducer in order to electronically steer the beam These phased array transducers use multiple elements to steer the beam and sweep the scan plane in real time The imaging modes described in the following paragraphs all use phased array transducers to acquire real time 2D images Another mode of ultrasound imaging is called M Mo
167. nnector Power Supply J35 1 IEEE 1398 Power 1394a Board ie SD ea OOO 1 7 Special Instructions The two pins that are used in the 2x2 shrouded connector are diagonally across from each other 201 Table 43 Internal IEEE 1394a Cable Assembly Pin Signal Pin Device 1 IEEE 1394a Power J61 O2 GND J62 1 2 TPB Jos o4 TPB TC J 6 6e me 4 t K Aga Pin 1394a Cable Shield Shield J6 Shield J30 BAe 1394a Board 5 5 Special Instructions TEST the 1394a board before performing any of these instructions Cut the cable in half Remove J6 from the 1394a board Solder the bare wire end of the cable to the pads on the board where J6 was Device Aloin E e p 202 Table 44 Internal Mouse Cable Assembly Device Pin Signal Pin Device 1x4 pin Shrouded Connector CPU BI RADIO LJ728 2x2 pin Shrouded Connector TT CPU MALE SOCKET Common GND J7 22 Special Instructions Replace J24 on the CPU board with a right angle 1x4 pin header Please indicate a pin 1 on J7 on the CPU board that corresponds to pin 1 on the 2x2 pin shrouded connector Table 45 Internal MSM855 CPU Power Cable Assembly Device i i i Device Soldered directly to CPU blade connectors Power Supply Table 46 Internal Power Switch Cable Assembly Device Pin Signal Pin Device Main Switch J16 1 WE a E 1x2 pin Shrouded Connector Gemen A J16 2 CPU Momentary Switch
168. nsistors and generally have few pins and there are also switching regulators which generally control external circuitry to provide a regulated voltage While both classes of regulators perform the same function each has different attributes as summarized in Table 7 66 Table 7 Attributes of Linear and Switching Regulators 38 Linear Switching Only steps down input voltage must be greater Steps up steps down or inverts than output Low to medium but actual battery life depends Efficiency on load current and battery voltage over time high EE if Viv Vour difference is small switch mode quiescent current is usually higher High if average load and or input output voltage difference are high levels below 10W Medium to high which usually requires inductor LOW iiis REECH digde and ter caps in addition to the ICs for high ow value bypass capacitors WE power circuits add external FETs larger if heatsink is needed levels for which linear requires a heat sink Low Low no ripple low noise better noise rejection In the case of the power supply an unregulated 12 24 V input voltage depending on whether the system is powered from a 24 V AC adapter or the Li lon batteries in varying states of discharge must be regulated to 5 V Since the regulated voltage is not more than 42 of the input voltage a switching regulator will provide superior efficiency Also a switching regulator often provides better load regula
169. nstance the recognition result is the payload for the CASR_ RESULT message At the entry point into the main messaging loop every message that is defined by the application is first passed to a logger This piece of software logs every message into a persistent data store In the case of the WUC the persistent data store is a relational database Each message is parsed and stored into the database for later retrieval and analysis The 32 bit number that defines each message is given a mnemonic which is a short string that is interpreted synonymously with 32 bit number Table 13 contains a list of every application defined message Table 13 WUC Application Defined Messages Mnemonic Description CASR_ERROR ASR error lParam gt error message CASR_READY ASR engine is ready ASR parameters IParam gt EE CASR_PARAMS_PAYLOAD CASR REJECT AOR utterance had poor confidence score IParam gt wave_buffer CASR_GAIN ASR requested a new gain IParam gt new gain ASR abnormal condition lParam gt abd Sacchi CASR_ABNORMAL_PAYLOAD CASR_DONE ASR done CASR_EXIT ASR exited PTT BUTTON DOWN Push to talk button down 130 YESNO_YES YESNO_ NO Yes No dialog no CPU Temperature sensor measurement IParam gt ERR TEMPERATURES Updated battery status measurement is available IParam gt BATTERY_STATUS EXCEPTION An exception was thrown RADIO BUTTON DOWN Radio button down RADIO BUTTON UP Radio button u
170. ntially unsuitable for resource constrained systems Therefore a generic and readily available data compression algorithm is employed to compress the ultrasound image frames The freely available compression library zlib 48 was used for lossless data compression zlib implements IETF standard RFC1950 49 for compression and the IETF standard RFC1951 50 for decompression It is important to use lossless data compression to avoid degrading the ultrasound image and possibly leading to diagnosis errors The actual compression and decompression routines are implemented in assembly for the highest speed possible In order to recover the original data from its compressed representation the entire compressed representation must be available RIP is not a reliable transmission method so it is expected that some packets will be lost If the entire image was compressed as a whole and segmented into packets for transmission then the loss of a single packet would corrupt the entire image and the receiving computer would be unable to reconstruct the image Therefore the image is split into a number of tiles whose maximum compressed size will fit into a single RTP data packet The WUC uses a resolution of 800x600 pixels for the ultrasound images This limit is bounded by the maximum resolution that can be displayed using the head mounted display By observation this image can be compressed to a size of no greater than 14 kB The lower limit for
171. o in order to derive the required system voltages a battery exceeding 12 V was required Table 6 contains an overview of various rechargeable battery chemistry characteristics Table 6 Characteristics of Commonly Used Rechargeable Batteries 36 Lead Se Li ion Reusable KA SEN Acid SEH polymer Alkaline Gravimetric Energy Se Density Wh kg 45 80 60 120 30 50 110 160 100 130 80 initial Internal Resistance 100 to 200 to lt 100 150 to 200 to 200 to includes peripheral 200 300 12V 2000 circuits in mW 6V pack 6V pack pack 7 2V pack 7 2V pack 6V pack Cycle Life to 80 of 15002 300 to 200 to 500 to 300 to 50 initial capacity 500 300 1000 500 to 50 Fast Charge Time 1h typical 8 16h 2 3h Overcharge low high low moderate Tolerance Self discharge Month room 20 30 5 10 10 0 3 temperature wen EE 1 25V 1 25V 2V 3 6V 3 6V 1 5V nominal Load Current peak 20C best result 5 gt 2C gt 2C 0 5C or 1C or 1C or lower lower lower Teniv ra kie 40 to E to E to E to a 0 to aie ony 60 C 60 E 60 E 60 E 60 a 65 C Maintenance 30 to 60 to 3 to 6 sere ae aie Requirement 60 days 90 days months q q q Operating SEN 50 60 25 100 100 5 US reference ETI 7 2V oe ae lad ae Cost e e 0 04 04 0 12 0 10 0 14 0 29 0 10 0 50 1950 1990 1970 1991 1999 1992 since The C rate is a unit by which charge and discharge currents are sca
172. odec is commonly used in GSM cellular telephone networks This type of cellular telephone network uses TDMA methods for transmission of voice and data on any one of 125 possible channels frequencies 51 The bandwidth of a standard GSM channel is 22 8 kb s The GSM codec uses a Regular Pulse Excited Linear Predictive Coder RPELPC algorithm to encode speech This method encodes the differences between the current speech samples and the previous speech samples It also includes a long term predictor to estimate speech samples that may be lost during transmission This allows for the loss of several speech packets in a row before voice quality degrades This makes the GSM codec well suited for packet based communications on bandwidth constrained networks RFC 3551 52 provides a profile for transporting GSM encoded speech using RTP GSM encodes speech into 20 ms frames of 260 bits 32 5 Bytes in length RFC 3551 describes a method of packing each of these frames into a 33 Byte packet for transmission This results in an effective data rate of 13 2 kb s for the encoded speech The RIP header for each packet is 12 Bytes resulting in a protocol overhead of 4 8 kb s Therefore the total data rate is 18 kb s When the RID client application is connected to the WUC a voice connection is automatically established along with the real time imaging stream There are two indicators in the bottom of the window showing the RID client application One
173. of the patient information dialog To enter patient information mode use the command patient EE ENEE ISSUE THE COMMAND PATIENT INFORMATION VOICE OVER A dialog box will be displayed showing the current patient information To enter information the NATO phonetic alphabet is used Let s start by entering some initials ILSSUE THE COMMANDS PAPA JULIET CHARLIE VOICE OVER Please note that each letter is a separate recognition event Now use the command switch fields to move EO the Patrent ER line ISSUE THE COMMAND SWITCH FIELDS VOICE OVER Notice that the Patient ID field is now highlighted Now enter some numbers again using the NATO phonetic alphabet ISSUE THE COMMANDS ZERO ONE TWO NINER VOICE OVERS OK now suppose a mistake was made You can always erase the last character by using the command backspace ISSUE THE COMMAND BACKSPACE VOICE OVER When you have finished entering the patient information issue the command OK to accept the information or cancel to reject the information ISSUE THE COMMAND OK 223 VOICE OVER You should now be able to see the patient information at the top of the screen This concludes the patient information EES tah END 224
174. ome extent interoperable The degree of interoperability is determined by the availability of either the ISA or PCI bus as necessary for the interconnection of selected peripherals All PC 104 board variants are designed to be stacked one on top of each other The mechanical design is such that the bus is passed from one board to another Fig 25 shows how different PC 104 P us boards can be stacked Fig 25 PC 104 Plus Board Stackup 21 In the example given in Fig 25 each of the four boards has an ISA bus while two of the boards have a PCI bus and an ISA bus The embedded computer contains both ISA and PCI busses on the underside of the PC 104 Plus board These busses are used to stack a 1394a peripheral board below the embedded computer The 1394a 34 board discussed in Section 3 1 3 has connectors for both the ISA and PCI busses but only uses the PCI bus A PC 104 Plus board measures 9 589 x 9 017 cm 8 775 x 3 550 in for a total board area of 86 464 cm 13 401 in The max component height on the top side of the board is 0 876 cm 0 345 in and on the bottom side of the board is 0 483 cm 0 190 cm The top side bus connectors are 1 105 cm 0 435 in tall The bottom side connectors are 1 118 cm 0 440 in tall Notice that there are four through holes with one on each corner of the board Each board is secured with standoffs to the next board ensuring a strong mechanical connection between boards 3
175. ons PTT Down ASR Ready Listening Processing Fig 71 Speech Recognition States 100 Fig 72 and Fig 73 show the upper area of the Dashboard after two separate recognition events Fig 72 shows a successful recognition of live image while Fig 73 shows a poor recognition of power doppler Ak Ready ASR Ready live Image Fig 72 Successful Recogntion of live image Fig 73 Poor Recognition of power doppler Note that the poor recognition event is displayed in yellow This is because the confidence score reported by the ASR engine is below 3 700 In this instance the command is not carried out and the user must repeat the command The secondary mechanism for providing user feedback about the speech recognition engine is a dialog box accessible via a pop up menu The pop up menu is displayed by clicking with the right mouse button on the Dashboard Selecting the ASR Details option will display the ASR details dialog box shown in Fig 74 101 ASR Details Utterance Words Confidence Idle SNR dB Energy Level dB Recognition Engine Feature Extractor Parameter Value Parameter Value Trailing silence mode Stop Voice activity detector VAD Enabled Trailing silence time 1500 ms Trailing silence mode Stop Accuracy 7000 VAD sensitivity 90 Garbage 60 VAD threshold 35 00 dB Maximum N Best results 3 VAD leadin 100 ms Secondpass Enabled VAD buffer 300 ms Seco
176. ost challenging feature of the system for first time users Unsurprisingly not a single person took the time to understand the operation of the speech recognition system before attempting to operate it It is also by far the single feature that most differentiates the WUC from other ultrasound systems While there are some high end ultrasound machines that also have the ability to be controlled with voice commands few sonographers seem inclined to use it Most people seemed to instinctively want to use the mouse to control the system rather than use the voice commands It is unknown why this is so and no one was asked why they behaved this way It may be that they have had negative experiences in the past with speech recognition or that the mouse is simply so familiar that it is more comfortable 180 Finally many people commented that they would like to have a light that indicates that the system is on It was erroneously assumed that being able to look into the head mounted would be an adequate indication of the system s status However the reluctance to wearing the head mounted display served to undermine this assumption The WUC complements the current generation of portable ultrasound products by extending their reach into application areas that they were previously unsuited for The rugged nature of the device long battery life and telemedicine capabilities make the WUC well suited for operation outside of the clinical environment
177. p An ultrasound image was saved lParam gt US IMAGE SAVED US IMAGE PATIENTINFO_ EXIT Patient Info dialog exited PATIENTINFO_SAVEDLAST MESSAGE Patient information was saved BAT STATUS The messages described above are generated in different parts of the application but are all sent to the main message loop They are all first logged and then processed according to the message type and any additional information that the message may carry 7 2 Logging Data Store The WUC uses a relational database to store information gathered during usage The choice of a relational database was made to take advantage of the search and data analysis capabilities they offer This will be further discussed in Section 7 3 A relational database consists of a set of tables Each table has a set of columns of a predefined data type The data types are generally specific to the particular database being used Information is stored in rows in the tables of the database Each row is called a record and contains fields that correspond to the column definitions for a table The entire definition of tables and columns is called a schema For the WUC the open source database MySQL was used The database is made relational by storing information in certain columns that 131 correspond to the same column in other tables For instance a customer ID in one table containing orders placed at a store may correspond to an entry in another table that
178. pecial Instructions Use AWG 18 cable for BAT and BAT signals Ensure that all pins are connected on the J31 connector on the power supply 199 Table 37 Internal Battery 2 Cable Assembly Signal Pin Device J32 3 J321 Power Supply PA J32 2 Special Instructions Use AWG 18 cable for BAT and BAT signals Ensure that all pins are connected on the J32 connector on the power supply Signal Pin Device 1 J41 1 T 2 GND J41 2 POETS FEMALE SOCKET 14 2 5 6 Special Instructions Use AWG 18 cable for all signals Also indicate a pin 1 on the connector used to attach to the power supply Table 39 Internal CMOS Battery Cable Assembly Device Pin Signal Pin Device 3 6 V Lithium Battery e 2 Directly soldered to CPU e a K 2 7 Special Instructions Weld nickel tabs onto the battery to have a surface that solder will adhere to Attach the battery in place to the heatsink using a small piece of Velcro The battery should be placed between the power Supply and the heatsink near L1 on the power supply 200 Table 40 Internal Fan Power Cable Assembly Device 2x2 pin Shrouded Connector Power Supply Table 41 Internal HDD Cable geg Device Pin Signal Pin Device et A gg am 20 JLE Instructions Fold a cable as shown Table 42 Internal IEEE 1394a Auxiliary Power Cable Assembly Device Pin Signal Pin Device 1x2 pin Shrouded Connector J35 2 IEEE 1394aPower 2x2 pin Shrouded Co
179. r CPU technologies are already available on these mezzanine CPU boards than on the currently used PC 104 Plus form factor Some of these newer CPU technologies provide equivalent processing power while consuming less energy Others provide significantly more processing power and may allow new applications to become possible A carrier mezzanine CPU board may also carry other benefits This combination could potentially result in a smaller overall design Only the necessary components could be included reducing the potential for hardware failure Also the inclusion of specialized coprocessors such as an FPGA or DSP may be easier The non volatile storage currently in the form of a HDD could also be mounted on the carrier board Additionally connectors may also be mounted on the carrier board which would reduce manufacturing and assembly costs by taking advantage of the automation techniques used in PCB manufacturing While no problems have been encountered in the form of HDD failures in the field it remains the most sensitive Component in the embedded computing platform Besides the fans it is the only other moving part and is especially susceptible to vibration A solid state storage device such as flash memory has several advantages It would generally consume significantly less power provide faster performance when reading or writing data is smaller and is highly vibration resistant Storage capacity has been steadily increasing and
180. r also benefits by having a single familiar ultrasound 17 machine that can travel from site to site instead of potentially encountering different ultrasound machines with differing capabilities and image quality This greater access to ultrasound has led to its increased usage for procedures such as the placement of lines and catheters These routine procedures can be performed faster and more safely with the assistance of ultrasound 11 The portable ultrasound market became a reality in 1999 with the introduction of the SonoSite 180 product from SonoSite 12 Since then numerous other manufacturers have released or are planning to release portable ultrasound products Portable ultrasound differs from conventional ultrasound in several ways The main difference is in the actual form factor of the devices Traditional ultrasound machines are typically cart based systems that take on a variety of sizes and shapes Portable ultrasound systems are also available in a variety of shapes and sizes however the laptop style form factor is the most prevalent Some example portable ultrasound machines are shown in Fig 18 GH i sl En i P 4i ita a GE LOGIQ Book XP 13 b ACUSON Cypress 14 c Terason Echo 15 Fig 18 Example Portable Ultrasound Machines Compared to cart based systems portable machines often support fewer types of transducers Also only a single transducer can be attached at one time whereas
181. r the physical layer There are several variants within this standard identified with letters which indicate which variant is being used Specifically the 802 11b and 802 119 variants are available on the WUC IEEE 802 11b 45 and IEEE 802 11g 46 are often written as 802 11b g to indicate their inherent interoperability Each standard operates in the same Industrial Scientific and Medical ISM frequency band of 2 4 GHz The band limits in North America are 2 402 GHz to 2 480 GHz Within this band as defined in North America are 11 channels allowing for multiple networks to operate in geographically overlapping areas by using frequency division multiplexing Within each channel network nodes access the medium using time division multiple access TDMA methods and transmit data in timeslots The 802 11b standard defines a maximum physical layer data rate of 11 Mb s However due to protocol overhead the actual throughput for application data will be somewhat less and will vary depending on the number of nodes and the condition of the transmission channel The 802 11g standard enhances the 802 11b standard with a higher physical data rate of 54 Mb s This is accomplished by using a different modulation standard for the application data being transferred but is otherwise similar to the 802 11b specification It will also have a throughput that is somewhat less than the maximum rate due to the same reasons that affect the maximum data t
182. rennnrnnrnnnnnnnne gt 52 AA lee orrn E A E SEN 52 Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig OceanServer Battery Charger and ATX Power Supply 28 29 55 41 8 Brick DC DG Converter 30 BEE 59 Block Diagram ol Power SUDDIY ieireniio n E 57 Example Smart Battery system 321 59 POWE PANS e pariera eE AEE land yanaienantuamunadueuoaadwaeda 62 Inspired Energy NL2024A22 Rechargeable Li lon Battery 0 8 65 Block Diagram of Smart Battery Pack 37 66 Power Supply Reference Design 301 68 Output Voltage Adjustment of Linear Voltage Heogulator 71 Power Supply SMBus Block Diagram annannannnnnennnnnnnnnnnnnnnnnrrnrernnnnnnnnnne 14 Generic SMBus Topology AO 15 SMBus START and STOP Conditions OI 75 SONI SHI POLO O Stats tacos cad epadnnsaroudnins onan E EEE E E 76 Host SMBus Command Hacket EEN 77 Local Temperature Sensor Control Loop 80 Remote Temperate Sensor Control Loop 80 Populated Power Supply HCH 81 DWASNDOd Curve turn wan nA 84 Power supply area of the Dashboard nnnnonnanonnennnnennnnsnrnrsrrernnrerrnrerrnne 84 LOW Battery Warming EE Ee 86 eer ai Dialog BOX EE 86 Ee alt Xb C FEAT OM E 93 Speech Recognition System Huntme 95
183. rials e Administrative Guide 151 e Specifications In addition to the manuals a CD containing three training videos was produced The training videos were produced using a digital video camera and later transferred to a computer for editing The final videos are in the Windows Media Player 9 format The audio format is the same as a CD two channels of 16 bit samples with a sampling rate of 44 1 kHz and the video format is the same as the broadcast standard used in North America NTSC 720 x 480 pixels with a frame rate of 29 97 fps Each video is encoded for a data rate of 2 083 kb s The training videos are described in Table 27 Table 27 Training Videos Running Video Time Size Synopsis A complete introduction to the Introductory Tutorial 63 584 578 Bytes components of the WUC use the patient information system Selected examples from the tutorials Voice Command Tutorial 9m07s 37 600 988 Bytes contained in the WPI Wearable Ultrasound System User s Guide The full scripts for the Introductory Tutorial and the Patient Information Tutorial videos are contained in Appendix VIII Training Video Scripts 152 9 Technical Performance The following sections describe the performance of the completed system beginning with the Smart Battery Charger and followed by the thermal performance power supply and the speech recognition system A complete system specification is also included 9 1 Ba
184. rmation using several methods The first modes called Pulsed Wave Doppler takes advantage of the Doppler shift to present the information audibly The ultrasound user can actually hear blood flow in a vessel and can plot the blood velocity over time Fig 5 shows an example of a Pulsed Wave Doppler image of the carotid artery The ROI is indicated by the equal sign intersecting the long line and the lower image shows the time verses blood velocity Freq 2 5 MHz PREF 3 00 kHz WF 150 Hz Angle 42 SY size 1 0 mm oY dep 2 6 cm Invert Mi _ k Fig 5 Pulsed Wave Doppler Ultrasound Image 4 Power Doppler mode can be used to show the relative density of blood Fig 6 shows the jugular artery with the ROI indicated by the parallelogram Fig 6 Power Doppler Ultrasound Image 4 Finally Color Doppler imaging can be used to quantitatively determine blood velocity and direction Fig 7 shows an example image of the carotid artery which has a ROI indicated by the parallelogram with blood flowing down 6 93ecemis Fig 7 Color Doppler Ultrasound Image 4 Some machines may even have the ability to mix some of the aforementioned scan modes into hybrid displays For example Pulsed Wave Doppler can be combined with Color Doppler and displayed simultaneously A relatively recent development in ultrasound imaging is the use of three dimensional 3D ultrasound 3D ultrasound involve
185. rototype from another Section 9 will use the contents of all of the databases generated during clinical trials to shows the overall performance of the WUC 145 8 System Integration All of the preceding chapters focused on the individual system components that comprise the WUC This chapter deals with the interactions between each of the components as well as other activities related to improving user interaction with the WUC 8 1 Hardware Integration The key piece of hardware that makes the WUC wearable is the vest The vest is an off the shelf photographer s vest called PhoTOGS from a company called Domke It must be at least a large in size to ensure that the vest pockets are large enough to accommodate everything This is especially important for the batteries The vest is shown in Fig 102 and Fig 103 Fig 102 Vest Front pide h ach In addition to housing all of the system components the vest also contains all of the cables that interconnect the components To this end the vest was modified by a local tailor to include openings and channels in the vest for cable routing 146 The vest is a two layer design with one piece of fabric forming the outside shell and another piece of fabric forming the inner lining Between these two pieces is a space that also contains all of the pockets in the vest The vest was modified to place reinforced holes in the pockets that contain system components All of these components are conn
186. rs View eme Mon Apr 1715 27 21 mi a Mon Apr 17 15 27 21 Tree Co Mon Apr 1715 27 39 Words BASS Mon Apr 17 15 27 39 Word Occurence shutdown 1000 on Apr 17 15 27 41 es 001 Mon Apr 17 15 27 41 i aes Mon Apri 1s 27 41 ASR Errors 4001974 60347507 25 Mon Apr 17 15 27 41 Temperatures i EE Tue Apr 18 13 51 46 EDT LA REALT EE ie Tue Apr 1 13 51 47 EDT RADIO BUTTON Up DS Tue Apr 18 13 53 59 EDT PTT DUTTON DOWN 222 EE Tue Apr 18 13 54 27 EDT PTTBUTTON DOWN SS Tue Apris 13 54 30 EDT PTTBUTTON UP PTTLBUTTON_DOWN Tue Apr 18 13 54 39 EDT PTT_BUTTON_UP E Tue Apr 18 13 54 40 EDT CASR_CMD Tue Apr 18 13 55 13 EDT PTTBUTTON DOWN Tusani 13 56 14 EDT PTTBUTTON UE TI EE Tue Aprig 13 56 55 EDT PTTBUTTON DOWN a Tue Apr 18 13 56 56 EDT PTTIBUTTON UP Fig 95 Database Analysis Application View Menu The Packets view shows the interpreted contents of the tb Packets table in the database For the messages that contain a payload the payload is parsed and displayed in a user readable manner For instance the CASR_CMD message has a payload that is the id value of a command to be executed The Packets view uses the contents of the tb Words table to display the utterance string that led to that command Databases are manipulated using a language called structured query language SQL The JEventLog program uses SQL to define queries that retrieve or update information stored in the database The
187. rver Host EEGEN Username root Password Fig 93 Data Analysis Application Connection Dialog Databases use username password authentication mechanism Different users can be assigned different privileges restricting what they can read or change Upon logging in a database on the database server must be selected Fig 94 shows the JEventLog program after a successful login 138 i WPI Log Viewer EI m x uktrasound0001_ 10042006 ultrasound0001 122927005 ultrasound0007 04102006 ultrasound0d002_ 122927005 ultrasound0003_01252006 ultrasound0d003_02092006 ultrasound0004 01252006 ultrasoundaMb 27042006 Connected Please select a database from the Database menu Fig 94 Database Analysis Application Database Menu All of the menus are unavailable except for the Database menu Using this menu a particular database can be selected In this instance there are eight separate databases on this particular server Specifically each of these databases is a snapshot from a WUC prototype after it was received in from a clinical trial Once the user has logged in and selected a database there are seven views that can be selected for the database Each view focuses on a particular set of data and presents it in a conveniently readable manner Fig 95 shows the default view that is presented after a database is selected This figure also shows the View menu items 139 S WPI Log Viewer Database Filte
188. s Program Utterance View 142 Fig 99 Database Analysis Program Word Occurrence View 143 Fig 100 Database Analysis Program ASR Errors View 144 Fig 101 Temperatures View lot 145 Ste Maer e e Camere Serene Rete een eum ane aT eee em ne ee oo 146 le Oe LOS PRES th oso en ee ne ee een ee E een ere 146 Fig 104 Vest Component Layout 148 Fig 105 Single Smart Battery Relative Charge Capacity vs Time While Charging Eeer 154 Fig 106 Manufacturer Single Cell Charge Characherstcel 155 Fig 107 Single Smart Battery Charge Charachertsice 156 Fig 108 Single Smart Battery Relative Charge Capacity vs Time While Discharging SE 157 Fig 109 Single Smart Battery Discharge Characherstce 157 Fig 110 Smart Battery Charger Switching Regulator Providing 3 A DC Coupled E E E T E eEEeEEEE 160 Fig 111 Smart Battery Charger Switching Regulator Providing 3 A AC Coupled AE EPERE EEEE E ENEE acces ETE E EERTE E RT T EATE E ET 161 Fig 112 Smart Battery Charger Switching Regulator Providing 0 5 A DC Coupled EE 162 Fig 113 Smart Battery Charger Switching Regulator Providing 0 5 A AC Coupled EE 163 Fig 114 5 V Switching Regulator with 35 W Load DC CGoupled k 164 Fig 115 5 V Switching Regulator with 35 W Load AC Coupledt 165 Fig 116 5 V Switching Regulator with No Load DC Coupled ees 166 Fig 117 Temperature Testing ccccccccceccecceeceeeceeeeeeeeeeeeseeseeeeeeseeeeeeseeseesaeeaees 167 Bids 116 E een Une 1
189. s been modified to provide conduits for cables to interconnect the various components The WUC is intended to operate for a full day approximately 8 hours on battery power alone It includes wireless data communications to allow for remote viewing of ultrasound images up to 100 meters wirelessly and for voice communications This system is intended to be used anywhere that a portable and rugged ultrasound system can contribute to the quality of care Some examples of its uses are e Rural Medicine e Emergency Room e Disaster Response e Medical Transport e Military Triage One of the most unique features is the ability to control the ultrasound scanning system using voice commands This frees one hand of the ultrasound operator to support the patient or stabilize themselves during transport 21 2 2 Architecture The major components housed in various compartments and pockets within the vest are e Ultrasound Transducer e Embedded Computing Platform e Two Li lon rechargeable batteries e Head mounted display e Microphone e Mouse The ultrasound transducer along with its front end electronics is a commercial off the shelf COTS device from Terason a medical ultrasound company The combination of ultrasound transducer and front end electronics is called a SmartProbe by Terason A phased array transducer SmartProbe is pictured in Fig 19 G Ci 7 terason system 128 F 24 G d mee bw b a D S Fig
190. s creating three dimensional volumes from the individual scan planes produced in traditional ultrasound imaging This volume information can then be presented as a surface or volume rendering To do this a similar method to creating 2D images from a single element transducer is employed A traditional transducer containing a linear array of elements is swept over the area to be imaged An off line reconstruction is performed to create a 3D volume from the individual scan planes acquired over the imaged area 3D imaging creates new methods and applications for using ultrasound Once a 3D volume is acquired it can be viewed from any angle by slicing into it This allows for the creation of 2D images from viewpoints not previously attainable with ultrasound Before the introduction of 3D ultrasound imaging ultrasound images could only be obtained from planes perpendicular to the skin With a 3D volume available image planes can now have any orientation Additionally the 3D volume can also be rendered into a 3D object which can then be rotated for viewing from any angle Fig 8 shows an example 3D volume image with a plane cut into the volume Fig 8 3D Volume Image 5 11 Fig 9 shows a rendered 3D volume GACE Medical Systems LOGIQ 9 DEMO MI 0 22 Tic 0 0 4D3C L Z9 10 03 04 1 26 11 PM ADM 11111Demol9 Sen SE S A 2 3 Map C 0 0 DR 78 AO 100 H Mid A 45 VR 0 0 Hz Fig 9 Rendered 3D Volume Image 6 The latest dev
191. sk Hrive Embedded HDD COTS Computing Platform HMD Head Mounted Display COTS Li lon Battery Rechargeable 14 4 V 6 6 Ah Li lon battery COTS GrianProbe Terason 2000 SmartProbe containing a transducer and front end COTS Vest electronics 4 element array microphone COTS Hand held trackball mouse COTS PCB containing various power supplies battery charger Embedded Power Supply microcontroller and fan controller WPI Computing Platform USB peripheral connector for the embedded computer S Embedded Modified USB Computing COTS Platform WUC Wearable Ultrasound Computer refers to the vest and all components WPI Not Applicable contained within 2 3 Requirements The requirements for the WUC were developed from experience building prior generation devices and the desire to add important new features The second generation prototype was also a wearable system housed within a vest 19 A development history is included in Section 2 4 The following is a list of overall design goals for improvements to the second generation device e Reduce the size of the embedded computer e Increase the run time on batteries e Integrate wireless communications into the embedded computer e Integrate the Terason 2000 power supply EDCM into the enclosure e Create robust packaging capable of withstanding outdoor environments e Implement real time remote viewing of ultrasound images e Increase the performance and reliability of voice commands
192. sound procedures could be employed Pre hospital care defined as any medical procedures that occur before reaching a clinical setting is becoming more of a focus within the healthcare community The golden hour defined as the first hour after an injury has occurred is often toted as the most critical time period in which to successfully treat injury The golden hour most often occurs in the per hospital setting Ultrasound is useful in the detection and treatment of critical care injuries in the pre 19 hospital setting Some examples include detecting the presence of bleeding within the abdomen or a pneumothorax condition collapsed lung Both of these conditions would immediately change the course of treatment in the pre hospital setting In particular the availability of ultrasound within the golden hour can help in performing procedures such as central line placement or observation of certain characteristics of the heart Routine medical care can also benefit from the availability of ultrasound outside of the clinical environment In certain situations it may be better for the patient or simply more economical to bring ultrasound imaging to the patient For example certain high risk pregnancies requiring regular ultrasound examinations could be performed outside of the clinical environment such as at home Also remote locations such as rural settings may not be located near facilities that possess ultrasound equipment
193. speech recognition system had trouble recognizing the command it will be displayed in yellow Don t worry the command will still be executed Please refer to the included WPI Wearable Ultrasound System User s Guide for a complete 221 listing of the available commands When you are finished scanning two voice commands should be issued to power off the system The first command is shutdown This has to be followed by yes to initiate the shutdown sequence OPERATOR ISSUES COMMANDS VOICE OVER Once the shutdown commands have been issued you can take off the vest Whenever the vest is not in operation it should be plugged in to ensure that the batteries are always fully charged OPERATOR REMOVES THE VEGI AND PLACES LT ON A CHALR WITH THE BACKo LDE VISIBLE VOICE OVER The charging cable is located in the back pocket of the vest Remove it and plug it into the AC adapter as illustrated AQOM IN TO THE BACK POCKET Ao THE OPERATOR PULLS OUT THE CHARGER CABLE OPERATOR SHOWS THE CHARGER CABLE BEING PLUGGED LNTO THE AC ADAPTER VOICEOVER Thank you for your attention and this concludes the introductory training video For further help the WPI Wearable Ultrasound System User s Guide includes contact EENEG BEND 222 WEARABLE ULTRASOUND SYSTEM PATIENT INFORMATION TUTORIAL NARRATOR SCREEN VOTER OVER Welcome to the patient information tutorial This tutorial will cover the use
194. t to the software architecture would be the integration of the RID process into the main application Inter process communication has proven to be tedious and error prone also multiple threads are more efficiently handled by the operating system than multiple processes Late in the project the source code to the Terason software that prevented running the RID in the same process became available This enabled a test to be performed whereby the remote imaging software was moved into the main program The results were encouraging mainly from a performance point of view The application loaded noticeably quicker and the issue with a slow system shutdown also disappeared The RID also has room for improvement The entire RTP protocol stack was implemented but none of the information regarding link congestion and latency is used to improve the overall frame rate of the transmitted real time images This is an important feature of RTP and future revisions to the RID should take advantage of this 185 The RID client application has some shortcomings as well Currently the IP address of the WUC that the program should connect to needs to be known a priori This requirement creates extra network administration work and adds a level of complexity that may confuse RID users A mechanism should be developed that allows for the discovery of systems that are available for remote viewing and provides more information about the system being viewed such
195. ted in an off screen buffer The sequence number of this message is noted and used to determine where the subsequent image tiles should be placed in the image Each subsequently received image tile is the uncompressed and placed into the image Finally when another RTP message containing a new DIB header and color palette is received completed image is displayed on the screen The process then starts anew with another blank image created in an off screen buffer This method of displaying an image on the screen while creating the next image to be displayed off of the screen is called a buffer backed GUI and is shown in Fig 84 118 Current Image New Image U 25 gv 2 o O D d _ Fc gs o amp OC OO Oo gt N a gt 9 o 2 E 7 o D CG c rab ebe gt j e e Loo 5 Qa o O O 2 D y 2 DOE o H o Oo NDF Q E 0 V o oO O kk gine gt D 2 Zz Oo A D Ke e ew S E doa ZS o S y 2 O o o ZS So o e OW oe D KL DO bk Cc ag S eal 5 O O c E T E d Oo gt s O O i O 6 z 5 Kan S saog FE O o O OC j Zoe e V e 2 O E i H c 7 o O l e SE SC S fo g E e Le SS ae rE C ji So FO i Oo og SS S ii lt d DO d S 2 Cc e e a 2 S P S S go ZS E o Co c O oS 30 3 Q 2s 8 Bw a LG E a 5 Sf QV tten ION IS WI b Ultrasound Image wi
196. ter minimum trace width space is 0 012 Trace Width Air Gap The greater of 20 or 0 002 Soldermask Swell This is the expansion of mask relief over pad area Our minimum is 0 005 over pad dimension or 0 0025 each side Advanced Circuits will modify files to meet the minimum dimension Slot Width Minimum 0 031 in width Tab Rout Spacing Please allow 0 100 spacing between your individual PCBs for tab rout spacing When scoring there should be no spacing between boards silkscreen Legend 0 008 minimum line width In general the manufacturer s suggested layout guidelines were followed for each individual integrated circuit The addition of two capacitors to the output of the 5 V switching regulator was required to limit the coupling of the switching noise to other parts of the board This also reduced the switching noise present on the 5 V output 4 10 IEEE 1394a Power Supply The typical bus power used on IEEE 1394a links is 12 V In the case of the WUC only the Terason SmartProbe is being supplied with 1394a bus power The SmartProbe has an input voltage range of between 12 and 30 V Using this range the SmartProbe can be directly powered from either the Smart Batteries or the AC adapter This results in a range of voltages between 12 and 24 V appearing for 1394a bus power However the 1394a interface board cannot withstand 1394a bus voltage in excess of 22 V Also it has been observed that the SmartProbe will draw as
197. th Lost Tile 119 Lost Image Tile Ultrasound Image Fig 85 rigina a O There are several ways to write applications for Windows and each approach uses a different programming model and API The WPI ultrasound applicat using the lowest level API called Win32 This was chosen because it offers the lowest overhead and fewer resource requirements than other APIs In fact many of the other APIs are written using Win32 and are attempts at making writing programs for Windows simpler and faster for the programmer However this ease of use brings a penalty by requiring more memory resources and sometimes slower execution and reliability None of which is desirable in an embedded computing system The API to access the shared memory interface containing the ultrasound images is only provided by Terason as an ActiveX object An ActiveX object is a special type of COM object that must be run within a container In this instance a container is a software construct that provides certain services to software designed to run within the container Containers for ActiveX objects are only available using technologies other than the Win32 API Terason uses the Microsoft Foundation Class MFC API to implement the majority of their software as well as to write the ActiveX object used to access the shared memory interface Therefore a separate process was required to implement the server portion of the real time ultrasound imaging and it was
198. that are currently stored on the WUC An example display showing three stored images is shown in Fig 92 WPI Wearable Ultrasound Computer Mozilla Firefox loj x De Edt View Go Bookmarks Tools Help ei gt E FA 2 http 192 168 1 200 sl Go ict Time Patient Image click for a larger Information view Ee EN E wl Bi 4 iad pa 5 16 2005 d ps 11 16 2005 yg 865 Ee Peas 12 10 47 PM The University of Science and Teci logy 11 16 2005 12 11 05 PM Images Ultrasound Client 11 16 2005 12 11 11 PM Fig 92 Saved Images on Web Server The saved images are displayed in ascending order according to the time that the image was saved The first column in the table shows the time that the image was saved The second column would display any patient information that may have been stored with the image In the previous example there is no patient information associated with any of the images The third column shows a thumbnail view of the saved image By clicking on any of the thumbnail images a full size version of the image is displayed in the right frame If there are more images available than can be displayed in a single frame the frame will become scrollable The table is created using an auto generated VBScript VBScript is a scripting language that the Microsoft web server uses to generate dynamic content In this case the content is gathered from a database on the WUC The script was g
199. the start directive and is represented as lt Speech gt All variables or non terminal symbols are enclosed in angle brackets lt gt All grammar rules end in a and a means that any of the following variables or terminal symbols can be substituted Using the above example and the definition of a context free grammar we can see the following sets defined V lt Speech gt lt Drinks gt lt Food gt 2 English alphabet U English phonetic alphabet P lt Speech gt lt Drinks gt lt Food gt lt Drinks gt lemonade milkshake orange juice lt Food gt hamburger french fries S lt Speech gt To see how the grammar G describes a language a derivation can be performed to produce a string in the language A derivation starts with the start symbol S and continues substituting variables with terminal symbols and variables according to the rules of the grammar until a string consisting of only terminal symbols is produced For example lt Speech gt gt lt Drink gt gt milkshake Therefore milkshake is part of the language described by the grammar G The grammar used in the WUC is extremely simple and only contains six rules There are also three possible start symbols that must be selected before any recognition can take place This is done to limit the number of strings in the language to improve recognition accuracy The selection of the appropriate start
200. the client with an average compression time of 54 ms for an entire image frame The RID client software for viewing real time images is a very simple program When it is first run the user is presented with a small dialog box requesting the IP address of the WUC system to connect to The dialog box contains a list of any prior successful connections to make selection of a connection target more convenient Fig 88 shows the RID client connection dialog box 121 Fig 88 RID Client Connection Dialog Box Once pressing the connect button the user is presented with the main window for the RID client application as shown in Fig 89 22 May 2006 Arterial 1 e he Ee ESSE E r LI de Ur ee ee TEE Ce di Be een EE e e m r i ee a Fig 89 RID Client Application The window displays the current stream of ultrasound images from the WUC Below the image is a status bar control that displays three items The leftmost indication is 122 the number of FPS that are being displayed by the application The next two fields to the right are used for indications relating to voice transmission which is further covered in the next section The RID client will always display a main window whether it was able to connect to a running instance of a RID or not If no image data is available either because a connection was made to the wrong address or if the WUC is currently not acquiring ultrasound images the window will displ
201. the compressed image sizes is unknown The default maximum size for a UDP packet in Windows is 1280 Bytes The RTP data transfer header is 12 Bytes long leaving a maximum payload size of 1268 Bytes When using UDP it is important to not send messages that exceed the maximum allowable size or they will be most likely be dropped at some point along the transmission path 117 To address the limitations in packet size the 14 kB image is split into 16 separate tiles These tiles are then individually compressed to create 16 RIP packets of a small enough size that they can be transmitted over UDP The DIB header and color palette are less than 1 kB but they are also compressed to shorten transmission time and transmitted together in a single RTP message In total 17 RTP messages are transmitted for each ultrasound image frame Because each message has been compressed independent of any of the other messages the loss of any number of RTP packets does not corrupt any of the other RTP packets that carry the data for the image The RIP message that is sent contains the compressed DIB header and color palette followed by 16 RTP messages containing the compressed image tiles The receiving computer simply needs to acquire the 17 messages and reconstruct the sent image This process begins whenever a new RIP message containing the DIB header and color palette arrives at the receiver Upon arrival a new blank image containing all black pixels is crea
202. the web server that is supplied as part of Windows The web site hosted on the WUC can be used to e View the User s Guide e Retrieve stored images e Download the RID client application e Retrieve logs The home page for the WUC is shown in Fig 90 125 WPI Wearable Ultrasound Computer Mozilla Firefox letz De Edit View Go Bookmarks Tools Help G s B 1D htte192 168 1 200 The University of Science and Technology And Life User s Guide Images Ultrasound Client Fig 90 Web Server Home Page The web pages are organized as two separate frames In the left frame is a navigation menu that does not change Selecting options in the navigation menu displays different content in the right frame For example selecting User s Guide in the navigation menu will bring up the User s Guide as shown in Fig 91 WPI Wearable Ultrasound Computer Mozilla Firefox E _ O xj File Edit View Go Bookmarks Tools Help a ad gt 3 3 IS A B http 192 168 1 200 A o Adobe Reader 7 0 A le ex e cs qe Sica J2 gt ore e n n a The University of a a Science and Technology And Life Lee User s Guide Images Ultrasound Client WPI Wearable Ultrasound Computer User s Guide R Attachments Say ez AO o a Hp 7 Fig 91 User s Guide on Web Server 126 Selecting the Images option will display a table containing all of the images
203. tion Union kilo Byte 1 024 Bytes kilo bits per second kilogram kilo Hertz Level 2 Pound Pounds milli Ampere Madigan Army Medical Center minute meter Motion Mode Mega Byte 1 048 576 Bytes Mega Bytes per second Mega bits per second Mega Hertz micro 10 millimeter milli Ohm Magnetic Resonance Imaging micro Farad microsecond millisecond milli Volt nanometer Open Database Connectivity Ohm Operating System Open Systems Interconnection Ounce 1 16 Lb Picture Archiving and Communication System Printed Circuit Board Peripheral Component Interconnect Pulse Code Modulation Public Switched Telephone Network Push To Talk Request For Comment IETF standards document Remote Imaging Daemon Region Of Interest Regular Pulse Excited Linear Predictive Coder Revolutions Per Minute Smart Battery System Implementer s Forum Software Development Kit system Management Bus xiii SNR SOAP SQL TCP TDMA UART UDP USB VGA VoIP Wh WUC XML Signal to Noise Ratio Simple Object Access Protocol structured Query Language Transmission Control Protocol Time Division Multiple Access Universal Asynchronous Receiver Transmitter User Datagram Protocol Universal Serial Bus Volt Video Graphics Array Voice over Internet Protocol Watt Watt hours Wearable Ultrasound Computer Extensible Markup Language XIV 1 Introduction Currently there are several major imaging technologies used
204. tion when current requirements change dramatically Modern CPUs can quickly draw several Amperes of current when switching from a power conservation mode to a more active mode In light of the amount of power being drawn from the regulated 5 V supply gt 43 W from Table 5 and the nature of the load rapidly changing current requirements the efficiency gains offered by using a switching regulator over a linear regulator justify the added complexity The 5 V power supply is a switching regulator designed around a Linear Technology LTC1775 controller chip This chip is a synchronous step down switching regulator operating at 150 kHz that when used with the appropriate components provides up to 20 A of current at 5 V or 100 W It can respond to severe load changes in hundreds of micro seconds and is gt 90 efficient throughout the loads that the system will present The input voltage to the switching regulator can be as high as 30 V although it is expected that a range of 12 24 V will be present The performance of the final design is presented in Section 9 2 67 The LTC1775 has a soft start feature that enables the output current to ramp up which reduces the inrush current to the load An external capacitor is charged by an internal 3 uA current source As the voltage on this capacitor increases the output current limit is increased This relationship is given in Eq 5 ls CneLAY uF Css 5 In the case of the reference d
205. tionality which is detailed in Section 5 Additionally this software also provides much of the remote services functionality which is described in Section 6 Finally it provides for extensive data logging capabilities as described in Section 7 In addition to the hardware and software that was developed there were also training materials provided to first time users of the system This training material includes both written manuals and short videos This material is discussed in Section 8 Section 9 details he technical performance of both the hardware and software that was designed for the system and Section 10 discusses the clinical applications for 2 the system as well as the conclusions that were drawn from clinical testing A primary goal of this thesis research was to provide units for clinical evaluation at Madigan Army Medical Center MAMC in Tacoma WA To this end a total of four complete systems were built and tested in the Vascular and Emergency departments in the hospital Section 11 presents an evaluation of the performance of the system in a real clinical setting as well as some valuable lessons that were learned during the trials 1 1 Ultrasound Imaging Primer Ultrasound works by emitting impulses of sound energy into the human body This impulse travels as a thin beam through the body and is reflected at tissue interfaces By detecting the echoes from the original sound wave an image can be reconstructed
206. tive approach allowing new applications for ultrasound imaging is not necessarily the best choice for all 188 circumstances Ultrasound examinations are often performed for short periods of time usually lasting less than ten minutes Other than sonographers whose primary job responsibility is performing ultrasound examinations most portable ultrasound users will then switch to another task They may not require the use of ultrasound for some time and will probably want to take off the vest Constantly donning and removing the vest is inconvenient Military personnel also often wear load bearing vests These are rip stop nylon vests with various compartments for supplies such as food ammunition firearms and ballistics protection Wearing the WUC over this vest is not feasible Finally there is the size issue to take into account People come in many different shapes and sizes and having a piece of equipment that may only be efficiently used by a subset of the potential audience limits its adoption To address this issue one of the prototype embedded computing platforms was placed into a small medical bag along with the rest of the WUC hardware and is shown in Fig 121 Fig 121 Bag Based Ultrasound System 189 This exercise had two benefits First it showed that adaptability of the underlying WUC components to different environments and even form factors And second allowed for the system to be utilized in applications w
207. ttery Charger The battery charger is the most complex circuit on the power supply PCB The design went through several iterations and two PCBs until satisfactory performance was achieved A full description of the battery charger can be found in Section 4 3 The first result shows the relative capacity vs time for a single Smart Battery to be charged by the Smart Battery Charger The Smart Battery was discharged into a constant load until the internal protection circuitry disabled the Smart Battery The Smart Battery was then connected to the Smart Battery Charger and charged until the Smart Battery requested that the charging be terminated The results were obtained by querying the electronics in the Smart Battery and are presented in Fig 105 153 Battery Charge Capacity i in CH l i i j l i 0 1000 2000 2000 4000 2000 6000 F000 S Fig 105 Single Smart Battery Relative Charge Capacity vs Time While Charging The total time to charge the Smart Battery was 7 803 s 2 h 10 m 3 s The Smart Battery reported an average power consumption of 45 32 W while charging and absorbed a total of 98 25 Wh 6 032 Ah of energy Some of the energy absorbed by the battery is dissipated as heat during the charging process The same is true during discharge so not all of the energy used to charge the battery is available for use In Fig 105 the Smart Battery only reaches relative charge of 94 This is because the electronics within
208. tton It performs the same functions as the PTT button when the mouse pointer is over the Dashboard 99 User feedback is provided through two mechanisms The first and primary interface is the Dashboard The upper area of the Dashboard contains two lines of text The first line of text indicates one of four possible states for the speech recognition engine by displaying a corresponding notification message The notification message can be one of the following e Initializing e ASR Ready e Listening e Processing Any text that is followed by an ellipsis indicates an ongoing operation Each notification message indicates the current state of the speech recognition system The start state for the speech recognition system displays the text Initializing This state will transition to ASR Ready once the speech recognition system has been fully initialized The operator is then ready to issue commands The PTT button is used to enter the Listening state where the speech recognition system is actively processing user speech By releasing the PTT button the speech recognition system begins processing the acquired speech and the notification message Processing is displayed Once speech processing is complete a command is issued and the speech recognition system returns to the ASR Ready state Fig 71 shows a graphical representation of the speech recognition system state machine and its transiti
209. uming to obtain The WUC was designed to operate reliably under these severe conditions as shown in Table 28 The wearable form factor allows the Army surgeon to move about untethered and work without restriction The long battery life allows the WUC to operate when power is not available The Army is also quickly moving towards using more sophisticated patient management systems that are more and more electronic rather that paper based The communications flexibility and COTS hardware employed in the WUC will make adapting it to the changing patient management system both fast and cost effective The same features of the WUC that make it suitable for use in a CSH also make it suited for Special Forces operations For these applications the small size is also a key feature Weight and size restrictions severely limit the equipment that Special Forces members can utilize The wide variety of diagnostics procedures that can be performed or assisted by ultrasound makes it a potentially valuable addition 10 2 Out of Box Experience The WUC is a new concept in medical imaging in that it is significantly different from what a traditional ultrasound machine whether portable or not looks and operates like The three most often observed aspects that confronted first time users of the system are the wearable form factor head mounted display and the voice commands The wearable form factor of the WUC is a new concept for many people when they
210. voltage outputs to support various devices that may be added in the future A battery charger that is capable of charging two Li lon batteries simultaneously while the system is in operation should be included Moreover the system should also be capable of seamlessly switching between battery power and external power without interruption of power to the power supply The power supply should also include a fan controller This is to reduce power 28 consumption by not running the fans at full power all the time The speed should be thermally controlled by a temperature sensor Lastly the power supply should provide the embedded computer with an interface to monitor the status of the batteries fan speeds and temperatures 2 3 4 Embedded Computer Requirements The Terason software can only be run on an x86 compatible CPU under Windows XP Therefore the CPU must be capable of executing the x86 instruction set Also the minimum performance of the CPU must exceed that of a 600 MHz Pentium Ill as required by Terason The original CPU used in the second generation WUC was a 1 1 GHz Pentium M CPU model 713 This was found to be minimally acceptable for running the envisioned software and therefore a CPU with greater performance should be used Besides the CPU requirements a small and standardized form factor is required to minimize the overall enclosure size reduce system cost and ensure adequate availability of parts Th
211. witching cycle This is meant to provide better efficiency during low current operation where the capacitor charge can supply the load current Burst mode is slower to respond to abrupt load changes as are often found in modern microprocessors Starving a microprocessor of required current can result in latch up of the internal transistors and lead to unreliable operation Therefore this operational mode was disabled Another change that was required was a modification to the value of the boost capacitor Cg This capacitor provides the gate drive voltage for the M1 MOSFET It is charged through the Schottky diode Dg from an internal voltage regulator when the M2 MOSFET is conducting When the M1 MOSFET is conducting the boost capacitor floats between the gate and the source of M1 The reference value of 33 UF was found to be too low to carry enough charge for driving the gate long enough This value was doubled to 66uF 4 6 Linear Regulators In order to have various peripheral devices integrated into the system several other regulated voltages are required To fulfill this need two adjustable linear voltage regulators have also been included 70 Each regulator is capable of providing up to 1 5 A of current at output voltages ranging from 1 2 37 V with a maximum dropout voltage of 2 V The same unregulated 12 24 V input voltage used to power the 5 V switching regulator is also used to provide power to each of the linear regulators
212. x will be destroyed and imaging can continue If a yes command is issued another dialog box shown in Fig 77 will be displayed iol xi Preparing to shutdown WW Fig 77 Shutdown Progress Dialog Box The dialog box has a progress bar at the bottom that will indicate the progress of shutting down the WUC as it progresses This dialog box was implemented because there is a fairly long delay of up to 10 seconds before the Terason application disappears from the screen 5 5 Patient Information The speech recognition system is also used to enter patient information Since there is no keyboard a system was developed to enter alphanumeric information using the NATO phonetic alphabet A phonetic alphabet uses strings to represent letters 105 and sometimes numbers For example the letter a is represented as alpha and the letter fr is represented as romeo The numbers zero through eight are represented with their normal English names but nine is represented as nine A complete listing of the NATO phonetic alphabet appears in the listing of the grammar file in Appendix VI Speech Recognition Grammar A phonetic alphabet is used to improve recognition accuracy by providing greater phonetic diversity for each letter This data is used to associate metadata about a patient with captured ultrasound images or clips Currently only the patient s name patient id and current date are saved Rudimentary comma
213. ypes was 30 produced The second generation system 19 replaced the laptop with an embedded computer in a non standard 3 5 form factor This form factor defines a 14 5 x 10 2 cm 5 7 x 4 in board with an unspecified height It contained a 1 1 GHz Pentium M and 1 GB or memory This was housed along with a COTS power supply with a custom designed metal enclosure measuring 18 3 x 13 2 x 6 5 cm 7 2 x 5 2 x 2 6 in The embedded computer and it associated enclosure are shown in Fig 24 Fig 24 Second Generation Embedded Computer Power Supply and Enclosure This generation also marked the first use of a vest to house the system It also made use of two rechargeable Li lon batteries as a power source The batteries were charged by removing them from the vest and using an external charger The software was identical to the software used in the first generation Two of these prototypes were produced Neither of these systems was weather proof to any extent Each of these systems 31 was wearable and untethered but neither was capable of operating in harsh environments The third generation device which is the focus of this thesis was explicitly designed to be ruggedized This means that the system would be impervious to foreign particles dust or moisture and be capable of operating in moderately high temperatures for extended periods To this end a new embedded computing platform was developed 32 3 Embedded Computi

Design of a Wearable Ultrasound System

Contents

Download Pdf Manuals

Related Search

Related Contents