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1. 01 002F 0543 0206 F bo 01 8951 0567 BOLIC 9F BB 01 BCAU 0268 0345 9F bo 01 0604 02580 0622 BF BU 01 8564 0514 8410 BF BS 01 F 0000 00600 BF 90 00 0000 0000 0000 BF 95 00 0000 BA BY EU FB OF 52 BX BY EU FB OF 52 0 40 BBID F B3 01 0640 0545 B20C F bb 01 0978 0569 017A 9F B3 01 BDOF 0269 0344 SF bb 01 0600 0250 022 BF B3 01 8564 Ho14 0410 BF bb 01 0541 0000 00068 BF 93 00 0000 0000 0000 BF 9b 00 0000 BK BY EU FB OF Z BX BY EO FB OF Z 0 3E 001F F B 01 B02F 0545 820A F BE 01 OBRA b6E B1 C 9F Bo 01 0D69 0268 0344 9F BE 01 0b0F 0250 022 BF B 01 Boor Ho14 0410 BF BE 01 0543 0000 0066 BF 96 00 HHAH 0000 0000 BF 9E 00 0000 It is observed that the features of four objects cannot be received so the collection of data stops As other cases the system with the registers set in that way could only work with a distance between LEDs and camera of about 10cm 58 6 Gain1 15 Gain2 31 Distance from the camera 5cm Distance from the camera BX BY EO FB OF 2 B4 BY EU FB OF 52 0074 B16C 7F Bo 81 0700 Ho D 0069 F bb 81 BBBC 05356 8479 9F Bo 81 8716 016F 001F 9F BB 85 000 00068 6000 BF 96 61 0000 OLSE 0222 BF bb 81 5 F 0000 0000 OF 96 H 0000 0589 0444 F bb 00 0644 B4 BY EU FB OF 52 B4 BY EU FB OF 52 08 5 BloH F BS 61 86A4H 05 6 VUGC F BE B1 OAZA dudo 8479 9F bo 81 0729 0163 0011 9F BE Uy GA 0000 8800 BF 98 81 86800 ISE 0221 BF BE 81 0604 0000 6000 BF 95 BE 0000 0589 0446 BF BE 88 0621 B4 BY EU FB OF 2 B4 B
2. 66 Now it is time to get the i and vectors necessary to obtain the k vector and with the three of them get the rotation matrix The i and vectors are just the division between the coordinates of the vector and the s factor and the coordinates of the J vector and the S factor respectively and the k vector is the cross product of these i and vectors i 0 I 0 s1 i 1 I 1 s1 14 i 2 I 2 s1 j 9 3 0 s2 j 1 J 1 s2 15 j 2 J 2 s2 k o i 1 j 2 i 2 j 1 k 1 i 2 j 0 i e 3 2 16 k 2 i 3 1 i 1 j 0 After that following the paper the z coordinate of the translation vector is going to be taken The x and the y coordinates of this vector are the x and y coordinates of the reference object and the z coordinate is obtained dividing the camera focal length by the scale of the projection the parameter s In the PAC7001 camera according to the datasheet the focal length must be 1024 value which is stored in the variable Focal L and to get the z coordinate named as ZO it is done Z0 Focal L s 17 Now new epsilons have to be computed and the vector that contains these new epsilons is called epsiloni Each of the components of the vector is formed from the vectors of the matrix A the vectors of distance of the LEDs with respect to the reference LED LED number 1 Thus the first element of the epsiloni vector is formed from the distance vector of t
3. ESCUELA T CNICA SUPERIOR DE INGENIEROS INDUSTRIALES Y DE TELECOMUNICACI N Titulaci n INGENIERO DE TELECOMUNICACI N T tulo del proyecto HEAD TRACKING SYSTEM WITH LPC1758 Gorka Sanz Cia Luis Serrano Arriezu Pamplona 12 11 2013 Declaration confirm that this thesis is entirely my own work All sources and quotations have been fully acknowledged in the appropriate places with adequate footnotes and citations Quotations have been properly acknowledged and marked with appropriate punctuation The works consulted are listed in the bibliography This paper has not been submitted to another examination panel in the same or a similar form and has not been published declare that the present paper is identical to the version uploaded Wien 22 10 13 Gorka Sanz Cia Place Date Signature Resumen En este trabajo se presenta el diseno de un sistema head tracking que puede ser utilizado como rat n de ordenador para personas con discapacidad El sistema se compone de un microcontrolador LPC1758 integrado en la plataforma eStick2 desarrollada por la FH Technikum Wien adem s de una c mara PAC7001 y un conjunto de 4 LEDs dispuestos en un prisma rectangular El proyecto describe en detalle el proceso de desarrollo del software describiendo los distintos pasos tomados programas secundarios realizados para comprobar el funcionamiento de las distintas conexiones necesarias como USB o UART y los distintos problemas apareci
4. 20cm Distance from the camera 25cm n 0503 025E 6151515 6151515 BY 0249 035 7 6151515 6151515 o 0900 0835 6151515 6151515 It is seen that in one point between 20 and 25cm the camera lost the vision of two of the objects With these values in the Gain1 and Gain2 registers the camera works well between 10 and 20 cm from the set of LEDs 2 Gain1 10 Gain2 15 Distance from the camera 5cm Distance from the camera 10cm The four objects appear in a point close to 10cm of distance from the set of LEDs to the camera 94 Distance from the camera 15cm Distance from the camera 20cm bh BY EO FB OF 52 BK BY EU FB OF SZ W OD 0014 oF BB 01 8829 053F 0161 oF BY 01 892 0615 014b DF BB 01 898F 0240 022A DF B9 01 8370 0238 022C FF BB 01 B42b 0463 0370 FF B9 01 6406 0000 0006 BF 9b 00 0000 0000 0000 BF 99 00 0000 BX BY EO FB OF 52 BX BY EU FB OF Z HO1B 0147 6F BE 01 8941 053D 8162 6F BB 01 084E 0238 022b DF BE 01 B42D 0240 022A DF BB 01 83 9 0516 0420 FF BE 81 842D 0463 B83 C FF BB 01 BABF 0000 0000 BF 9E 00 0000 0000 0006 BF 9b DB HHAH BX BY EO FB OF 52 BX BY EU FB OF S7 HO1C 0146 F Al 01 BISA 033E 0162 oF BE 01 89 06 0237 022b DF Al 81 042D 0240 022A DF BE 01 83 b 0318 0420 FF AL 01 BAIE 0463 03 C0 FF BE 01 B406 0000 0000 BF cl 060 0000 0000 0006 BF 9E 060 8000 The camera starts to fail and just can capture 3 objects at these distances so is not needed to check more The proper distance for
5. There are a lot of devices in the board and each one uses different communication protocols so working with these devices makes us learn how to program these protocols A program to manage the 7 segment display is started and the first thing done is looking at the datasheet of the board to know which pins control the display and which communication protocol is used in it The protocol is the SPI but in the microcontroller the SSP is intended to be used as an alternative for the SPI interface so this is used The pins of the LPC1758 are configured to access to the display activate it following the datasheet and initiate the SSP controller to manage the display Once that this is done a program can be built to make the display do whatever is wanted count from 1 to 9 countdown passing alternative numbers Another program made to practice with the LPC1758 and the interfaces is to set up the USB of the eStick2 One of the micro USBs of the stick is connected to the LPC1343 and the other is controlled by the LPC1758 To activate the USB interface the instructions in the user manual of the LPC1758 have to be followed to introduce the correct commands to the registers The bit PCUSB has to be set to power the USB interface and then the USB clock has to be configured The corresponding pins of the LPC and their modes have to be set to control the USB interface and enable the appropriate interruptions for the objective of the program 25 5 Develo
6. Yim 0 Ycenter 1 1 epsilone 0 Ycenter 0 Yim 1 Ycenter 2 1 epsilon 1 Ycenter 0 6 Yim 2 Ycenter 3 1 epsilone 2 Ycenter 0 After obtaining these image vectors Xim and Yim they have to be multiplied by the matrix B Multiplying B and the vector Xim a vector called is obtained and multiplying B and the vector Yim the result is a vector called J both of them of course with 3 coordinates B Xim J B Yim 7 The way in that these operations are done in the program is the following I e B e e xim 0 B 0 1 Xim 1 B e 2 Xim 2 I 1 B 1 0 Xim e B 1 1 Xim 1 B 1 2 Xim 2 8 I 2 B 2 e xim e B 2 1 Xim 1 B 2 2 Xim 2 J o B e e vim e B e 1 vim 1 B e 2 Yim 2 J 1 B 1 0 vim e B 1 1 Yim 1 B 1 2 Yim 2 9 J 2 B 2 0 Yim 0 B 2 1 Yim 1 B 2 2 Yim 2 Where can be seen how is obtained each term of the vector and J These vectors are necessary to get later the vectors for the rotation matrix and the scale of the projection This scale is s and it is the result of s s2 2 where s and s are s4 I 1 s J J S S So 2 10 So is needed to operate with the and J vector to obtain the s and s factors and finally the scale of the projection s1 I 0 I 0 I 1 I 1 1 2 1 2 s2 J 0 3 0 2 1 2 1 3 2 3 2 11 s1 sqrt s1 s2 sqrt s2 12 S s1 s2 2 13
7. all properly connected to a computer The camera which is attached on the user s head identifies the position of the LED system which is placed on top of the computer screen This information is sent to the microcontroller the created software housed in it estimates the position that the camera Is pointing at and therefore which part of the screen the user is looking at This then translates it into movement of the mouse pointer and sends it to the computer moving the pointer to the estimated point of the screen Up 2 Components of the project 2 1 LPC1758 As it is described in the NXP LPC17xx User Manual that can be found in the appendix A p 3 the LPC17xx is an ARM Cortex M3 based microcontroller for embedded applications featuring a high level of integration and low power consumption The ARM Cortex M3 is a next generation core that offers system enhancements such as improved debug features and a high level of support block integration Continuing with the description of the User Manual the LPC1758 operates at CPU frequencies up to 100MHz The ARM Cortex M3 CPU incorporates a 3 stage pipeline and uses Harvard architecture with separate local instruction and data buses as well as a third bus for peripherals Also includes an internal prefetch unit that supports speculative branching The peripheral complement of the LPC1758 includes up to 512kB of flash memory up to 64kB of data memory Ethernet MAC a USB interface
8. else Quadrant VI Xcenter 3 Xvar Match with LED 4 third distance vector matrix A Ycenter 3 Yvar J J else if Yvar lt 384 Quadrant II Xcenter 2 Xvar Match with LED 3 second distance vector matrix A Ycenter 2 else Quadrant I Xcenter 1 Xvar Match with LED 2 first distance Yvar vector matrix A Ycenter 1 Yvar It is noticed that the first two blocks of data taken from the buffer of the data from the camera have values that are different than the expected even solving the problem of the unset bit That causes a bad assign of objects with LEDs and it have to be solved for their later use in the POSIT algorithm To do that a variable controls the times that the buffer is filled with useful data and the part of LEDs assignations and the POSIT algorithm are not started until this variable is greater than 2 Once that the objects from the camera are matched with the LEDs in the way that is wanted continues with the image vectors There is already described the formula for the image vectors Xim and Yim where each term of the vector depends of the coordinates of 65 the reference object and the coordinates of each of the rest of the object in order as it was described previously To obtain the whole vectors Xim 0 Xcenter 1 1 epsilone 0 Xcenter 0 Xim 1 Xcenter 2 1 epsilonO 1 Xcenter 0 5 Xim 2 Xcenter 3 1 epsilon 2 Xcenter 0
9. 2 MHz 16X 24dB 10 200fps Progressive UART Max Osc 16 Max 1024 768 CSP Table 1 Specifications of the PAC7001 The PAC7001CS can be programmed by setting internal registers via UART and doing that different parameters can be changed such as frame rate exposure control object center resolution UART speed etc Table 2 lists the internal registers of the camera Name Default Allowable Description Register Number 0x00 Gain1 1byte 0x01 0x02 Gain2 1byte Sensor Update Flag LPF 1byte Ny 1byte 0x03 0x04 0x05 IW 2bytes 0x06 IH 2bytes Range 0 15 Sensor Front Gain 0 31 Sensor Global Gain 0 1 1 For Sensor Register Update 110 255 Line per Frame lt LPF Ny Max 1024 Image Width Max 768 Image Height Register Number 0x10 Threshold Mode Power Down Mode Dummy byte number 2 0 Threshold 1 byte Object Assignment Mode Feature Option Enable Flag Tracking Object Number Baud Rate Default Ox7F Allowable Range Ox00 0xFF 1 4 Description Bit7 0 Manual 1 Auto Bit6 0 Bit5 0 Bit4 0 Normal 1 Power down Bit3 1 Bit 2 0 Dummy data in object feature data Object Threshold 0 No Assignment Mode Bit Definition O Disable 1 Enable Bit7 Frame header Bit6 Object aspect ratio Bit5 Object orientation Bit4 Object size Bit3 Object border Y Bit2 Object Border X Bit1 Object center Y BitO Object center X Tracking Obj
10. Enable parity gen 5 4 Parity Select 00 Odd parity 01 Even parity 10 Forced 1 stick parity 11 Forced 0 stick parity 6 Break Control 0 Disable break transm 1 Enable break transm 7 DLAB 0 Disable access to DL 1 Enable access to DL 8 31 Reserved Table 5 Description of the LCR In this case the data character is programed of 8 bits 1 stop bit no parity and setting the DLAB so the value to introduce in the USLCR register is 0x83 and the command used to do it is LPC_UART3 gt LCR 0x83 8 bits no Parity 1 Stop bit DLAB 1 Now the DLL and DLM values have to be selected to have the wanted baud rate The general formula to estimate the baud rate of the UARTS is 30 p 313 UART3baudrate rp MEE DivAddVal 16 x 256 x U3DLM U3DLL x 1 e a 7 41 Where PCLK is the peripheral clock USDLM and USDLL are the baud rate divider registers and DivAddVal and MulVal are the fractional baud rate generator specific parameters In this case the division between these two parameters is 0 because they have not an assigned value the reset value for DivAddVal is O and for MulVal is 1 and so have no impact in the baud rate The PCLK of the UARTS is defined as 4 of the core clock and the baud rate is a chosen value the value of DLM and DLL can be obtained where the DLM is the result of the final division and the DLM is the modulo the integer reminder of this division which is PCLK 16 x 256 x UART3baudrate 1
11. T id La r WHER EF y tsi ET ri CEDE 2 DUOC nae DIT TS d BN zl ud lt Y 4t Figure 18 Hardware connections and mounting 5 2 USB Connection The support required to establish the physical connections is assembled so the programming of the software can be started It begins setting up the USB communication between eStick2 and PC On the Internet there are a lot of programs and libraries that can be used as guide or help to build the needed program Starting with the initialization of the USB following the user manual of the microcontroller LPC1758 first it is needed to set bit PCUSB of the PCONP register which is the bit 31 of this register using the LPC17xx library Then the USB pins and the corresponding modes are selected These modes are as it is shown in the schematic of the eStick2 the USB CONNECT USB UP LED USB VBUS USB D and USB D The USB CONNECT is the function 1 of the pin 2 09 1 in the bit 18 of the PINSEL4 register with the lpc17xx pinsel library The USB UP LED is the function 1 of the pin 1 18 which is the same as set the bit 4 in the PINSELS register the USB VBUS is the function 2 of the pin 1 30 setting the bit 29 of the PINSELS register the USB D and the USB D are both in the PINSEL1 register they are selected setting the bits 26 and 28 respectively USB D is the function 1 of the pin 0 29 and the USB D is the function 1 of the pin 0 30 Here is this part of the program in
12. because the pins of the camera have to be wired to these pins of the stick in the back of the board Looking at the manual of the microcontroller it is noticed that for example the functions of transmitting and receiving for the third of the UARTs are configured in the pins P0 0 and P0 1 respectively so these ports are searched on the pinout of the eStick2 The UARTO 2 or 3 can be used interchangeably for the communication with the camera for this case the UARTS is the chosen option In the pinout of the eStick2 it is seen that the pin P0 0 of the LPC1758 corresponds with the pin 13 from the row X3 of the stick and the pin P0 1 corresponds with the pin 14 from the same row So the pins of the base of the stick and the pins of the base of the camera which agree with the mentioned pins are connected the transmission pin of the camera with the pin 14 of the stick and the reception pin of the camera with the pin 13 of the stick Later when programming the software the register of the pin 13 for UART3 transmission function and the register of pin 14 for UARTS reception mode will be set Now the pins for the power supply and the ground must be localized which are in the first pins of the row X3 and X4 respectively It is made the ground to ground connection with the camera and link the 3 3 volts power supplier of the stick with both the 3 3 volts pin and the reset pin of the camera to keep it on These connections are shown in Figure 18 26
13. chosen pin function in the microcontroller With the other way the bit of the wanted function in the LPC1758 with the PINSEL register is directly set Now it is needed to enable the device controller clocks This is done setting DEV CLK EN and AHB CLK EN bits in the USBCIKCtrl register with this name in the LPC17xx library The DEV CLK EN bit corresponds to the bit 1 in the register and the AHB CLK EN bit to the 4 bit in the register so they are set Once that is done the same bits in the USBCIKSt register has to be checked because it holds the clock availability status and if the clocks are set the software can go ahead with the register access The code to enable the clocks LPC USB USBClIkCtrl 0x1A Dev clock AHB clock enable while LPC USB USBClkSt x1A 0x1A Instead of Ox1A 0x12 could have been put to set the wanted bits but in examples in Internet it is done with Ox1A so that way is followed the rest of the bits apart from the two talked about are reserved and not defined With the while wait until the bits are set 28 At this time a kind of initialization of the registers that control the interruptions it is made clearing them all and without setting any interruption or giving them any priority This registers control the device interruptions and the endpoint interruptions so in both have to make this initialization LPC_USB gt USBDevIntEn 0 LPC_USB gt USBDevIntClr OxFFFFFFFF LPC_
14. class request the enable of the NAK interruptions in 45 the incoming transactions the VCOM init and the final connection of the USB with the USBHwConnect function As soon as this part is finished starts the configuration of the camera The first part is initializing the UART connection for the LPC1758 in this case with the UARTS interface to establish communication with the camera The initialization is done with the function UART3_Init and the baud rate is set to 19200 bps which is the default baud rate of the camera Now the connection is realized and the sending of data from the microcontroller to the camera can start As is said in the datasheet the first command is the Check Device command sending the value OxEA This is done with the function UARTS Sendchar and then the camera has to send back to the microcontroller the ACK TrackingV01 as a signal of the start of the camera It is easy to check that the mentioned message is received just every character over the UART3 have to be read with the UARTS Getchar function stored in variables and shown these variables in the hyper terminal with the VCOM putchar function But that cannot be done in the main program only as a prove So to remove the TrackingVO1 message from the receive FIFO queue a loop is made that will not end until the last character of the sentence is read the 1 which is a 49 in ASCII terms UART3_Sendchar xEA h UART3 Getchar while
15. com es Accessed 22 10 2013 ILC NSW ETS Head Pointer online Available http www ilcnsw asn au items 6795 Accessed 22 10 2013 Cult of Mac Accessories for Ipad online Available http www cultofmac com 147506 dutch inventor creates specialized accessories for ipad users with disabilities Accessed 22 10 2013 SL Central NaturalPoint TrackIR online Available http www slcentral com c h r naturalpoint trackir Accessed 22 10 2013 19 27 28 29 30 31 32 33 34 35 36 37 38 39 AbilitiHub Head tracking system online Available http abilityhub com mouse heaatrack htm Accessed 22 10 2013 Methoden den Entwicklungspsychologie online Available http www methoden psychologie de eyetracker 1 html Accessed 22 10 2013 Eyelink Toolbox online Available http cda psych uiuc edu matlab_class Eyelink 20T oolbox 20Home htm Accessed 22 10 2013 LPC17xx User Manual PAC7001CS Datasheet eStick2 schematic online Available https cis technikum wien at documents bel 3 ess semesterplan estick2 estick2_schematic pdf Accessed 22 10 2013 eStick2 pinout online Available https cis technikum wien at documents bel 3 ess semesterplan estick2 estick2_pinning pdf Accessed 22 10 2013 Model Based Object Pose in 25 Lines of Code Daniel F DeMenthon and Larry S Davis AllDatasheets NXP 74LVC595A online Available http html alldat
16. consists in a kind of slipper pointer moving around like a hand mouse and a series of buttons acting as the ones in typical mice including a button for double click or scroll roller There is even a mouse for the toes a small wireless mouse with a clamp which is placed between the big toe and the second toe The pointer is controlled moving this mouse and the left and right click can be done with the big toe and the second toe separately This variety of feet mice is gathered in Figure 13 5 http www oucs ox ac uk enable index xml ID mice Shttp www assistireland ie eng Products Directory Computers Hardware Input Devices Mice and Mouse Alternatives Trackballs BlGTrack Supermouse html 19 Figure 13 Feet mice Source 19 20 21 3 2 4 Special joysticks Joysticks can substitute the mouse and normally less effort is needed to move it always in a smaller area of movement It can be used in a lying position which is something to consider as many patients cannot sit up Another useful type of joystick is the mouth controlled joystick Figure 14 Is an efficient device for those people suffering paralysis below the neck They can control the pointer moving this joystick with the tongue or the mouth even control the clicking Figure 14 Special joysticks Source 22 23 http www yankodesign com 201 0 04 07 flip flop mouse http bilila com foot mouse slipper mouse http www funny potato com computer
17. distance that it can go is around 20 cm which is so close to the screen of the pc and it works in a narrow range of distances of more or less 10cm If the experts are attended they said that the eyes have to be between 40 and 60cm from the screen which is quite far than the distance that the camera can give to us for a proper operation So the position that the user has to take to use the system is not correct and probably the solution will be worse than the problem Apart from that the program does not work well there are parts in the screen were the cursor cannot follow the movement of the camera There are several factors that can affect to that like the mentioned problems to capture the LEDs errors in transmitting or receiving and problems in the code so the program cannot be used well even in a short distance The POSIT algorithm as is described in the Model based object pose in 25 lines of code paper works perfectly integrated in the program of head tracking system The final idea is that is possible to build a head tracking system with some of the components but it will be desirable to select other devices or amend them in order to improve the system and make it helpful and usable by the destination users people with disabilities 72 7 Future lines It was said that the program works well but it is needed more distance between the sensor and the LEDs so the camera or the excitation source of the sensor of the camera can be ch
18. each of his vertex 3 12 cm a rectangle of 4 99x3 74 is obtained This is no compatible with the front square of the set of LEDs which is a square of 11x8 5 However if the same operations are done with an adjacent side of 14 cm which is the 5 cm of distance of the camera to the LEDs plus 9 cm of depth of the prism of LEDs a distance from the center of the rectangle to one vertex of 8 74 is obtained which means that the rectangle is 14x10 5 which is more than the rectangle of LEDs of the back part So these two LEDs of the back part are the objects that the camera captures In the case of 10 cm of distance from the camera to the LEDs the result of the field of view of the camera is a rectangle of 10x7 5 That not fix with the fact of the four objects can be seen when the camera is at a range of 10 cm but it is probably because of the measure is realized from the front of the camera which is approximately at a distance of 1 cm from the sensor plus measurement errors and a wider angle of view For example with this centimeter of more distance all the LEDs can be in the field of view of the camera 61 5 5 POSIT Algorithm The program for seeing the data outputting from the camera has been seen and now the POSIT algorithm is going to be done to work with these data with the objective of moving the mouse pointer according to them The process of develop the POSIT algorithm is well explained by DeMenthon and Davis 34 which paper is collect
19. it is necessary to build functions to send and receive characters over UART3 The register that provides information about the existence or not of data to receive or the possibility of sending a character in the UARTS3 is the U3LSR register The main bits of this register to carry out these purposes are the Receiver Data Ready RDR and the Transmitter Holding 42 Register Empty THRE The RDR bit is the bit O of the USLSR register and is set when the UARTS receiver FIFO is not empty when the U8RBR holds an unread character and it is cleared when the UARTS receiver FIFO is empty The U3RBR register is the top byte of the UART3 Rx FIFO it contains the oldest received byte and can be read via the bus interface but to do it the DLAB must be 0 The THRE bit is the bit 5 of the USLSR register and is set when the U3THR register is empty and clear when USTHR contains valid data the reset value is 1 The USTHR is the top byte of the UART3 Tx FIFO is the newest character in the Tx FIFO and can be written via bus when the DLAB is 0 Writing in the U3THR register causes the data to be stored in the UART3 Tx FIFO Looking what is just described to do the program to send characters over UARTS the THRE bit and the US3THR register are used and for the program to receive data is used the RDR bit and the USRBR register For the receive data program first the RDR bit of the U3LSR register has to be checked until it is set what means the receiver FIFO is
20. the muscular system which translates in bad regulation of complex voluntary movements The affected present a disadvantage in their locomotor system determined by postural limitations displacement coordination and handling The causes can be various hereditary or genetic occurred during pregnancy amniotic for microbial infections by accident or trauma and can be the origin of spinal cord injuries traumatic brain injuries neurological disorders cerebral palsy multiple sclerosis muscular dystrophy and other diseases source of locomotor disabilities Now a review of different tools is going to be done Of devices on the market destined to motor disable people but focusing on those tools dedicated to simplify the access to a computer for these people Currently computers have an important role in our society and not always people with disabilities can make use of them because of their illnesses One of the main fields in assistive technology is to resolve this problem developing accessing gadgets to computers to this kind of users making their lives easier and allowing them to participate in modern society These devices are systems for alternative human computer interaction like special keyboards mice pointers and other advanced tools 13 3 1 Keyboards 3 1 1 Expanded Keyboard It is an adapted USB Keyboard designed with larger keys and high contrast colors This keyboard is removable so the user can rest his hands on it It inc
21. the system it is very important to know how it works For that objective small programs were built using the LPC1758 addressing various functions and utilizing its peripherals to interface with the LPCXpresso Base Board First of all work began with the LPC1343 the other microcontroller integrated in the eStick2 which uses the same language C as the LPC1758 The LPC1343 is an ARM Cortex M3 based microcontroller for embedded applications and has a high level of integration and low power consumption as the LPC1758 Both microcontrollers are quite similar but the LPC1758 has more capacity than the LPC1343 meaning that more different devices can be controlled with the first than with the second microcontroller The LPC1343 manages the dispositive integrated in the eStick2 so with the first built programs the 8 LEDs and the accelerometer of the platform can be controlled To start programing first it is needed to setup an open source tool chain to develop software for the eStick2 so it can be accessible This information is given in the Embedded oystems Software Design page of the FH Technikum Wien web site The first step that has to be taken is the installation of the USB Device Driver and the Download of the CodeSourcery C Compiler for Arm Then the OpenOCD has to be downloaded and installed which combined with the CMARMJTAG debug firmware that has to be attached in the LPC1343 establish the debug message communications between computer and the m
22. the translation vector is composed by the X and the Y coordinate of the reference object which are the Xcenter 0 and Ycenter 0 variables of the program and the ZO coordinate obtained in the described process The rotation matrix is formed by the row vectors i j and k and when the rotation matrix must be perfectly orthonormal these vectors have to be renormalized which is k k k j k x 20 And this is obtained in the program in this way mod sqrt k k k 1 k 1 k 2 k 2 21 krot 0 k 0 mod krot 1 k 1 mod 22 krot 2 k 2 mod jrot 0 krot 1 i 2 krot 2 i 1 jrot 1 krot 2 i 0 krot i 2 23 jrot 2 krot i 1 krot 1 i In this manner i vector is the first row of the rotation matrix jrot vector is the second row and the krot vector the third row of the matrix 68 5 6 Movement of the pointer Once the POSIT algorithm is done and the rotation matrix composed by the three vectors i j and k they have to be translated into movement of the pointer of the mouse depending on where the camera is pointing at When finally that goal is achieved the main objective of this project will be reached built a head tracking system To start with the program there is the same initialization part as the one was in the joystick program because the USB port is going to act as a mouse So it starts with this initialization part of the USB and the different handler
23. this value of the Gain1 and Gain2 is around 10 cm what is not good for the wanted purpose 3 Gain1 10 Gain2 31 Distance from the camera 5cm Distance from the camera 10cm BR BY EO FB OF 52 B4 BY EO FB OF SZ 89059 H11H F BA 81 8631 069 OADE FA 81 60915 0040 443 1F BA 81 87 B 0163 8165 1F A B1 0528 6006 6066 AF 9A Bl BB 0523 8475 AF A ql 85 f 06006 8066 BF 9H H H BOSA 852F BF A B8 863 f b BY EO FB OF Z BR BY EO FB OF Z 8959 H116 F BD 81 8659 0655 BOSC FF AA B1 092C HB5 4E H441 1F BD 61 952 0163 0164 1F HH B1 B53E 6006 AHHH AF 9D B1 0000 0523 8425 HF AA B1 85 F 6006 AHHH BF 9D B8 dB 058 052E BF AA BB 83 B BR BY EO FB OF Z BR BY EO FB OF SZ 8059 0117 F BF 81 8659 0659 B8BBb5F F AD B1 0966 54D 6441 1F BF 01 0857E 0163 6164 1F AD 61 650 00040 AHAA AF SF 81 0000 0523 8475 AF AD B1 668 00040 00068 BF SF H 0000 BOSA 8B52E BF AD 0379 At around 10cm of distance between the camera and the LEDs the features of the four wanted objects are started to be seen in the hyper terminal 99 Distance from the camera 15cm Distance from the camera 20cm BK BY EU FB OF 52 BA BY EU FB OOF SZ 063b 012F 7F A 01 BDI6 0474 026F FE AF 01 BEoo 0175 006D IF A 01 8884 0248 032D LF HF 01 89620 0225 0216 AF A 01 8459 0000 0006 AF SF 01 0000 0000 0006 BF 7 00 HHHQ 0000 0006 BF SF 060 HHAH BA BY EU FB OF SZ BA BY EO FB OF SZ 063F 8132 7F AA 01 BEAD 0476 026F F B2 01 BESO 0173 0109 IF AA 09 HOHA 0249 032D 1F B2 01
24. 0820 0226 0210 AF HH 01 8469 0000 0006 HF 92 01 8880 0000 0006 OF SH 00 HHHQ 0000 00068 BF 92 00 HHAH BK BY EU FB OF 52 BA BY EU FB OF 2 0630 012F F AD 61 BDo1 H4 C 0266 F Bo 01 105E 0179 OLOF 1F AD Oy 8816 0249 0320 1F By 01 082A 0225 0216 HF AD 01 BASE 0000 0006 HF 95 01 8060 0000 00060 OF SD 00 0000 0000 00068 BF 95 00 HHAH The camera starts to fail early and now it is impossible to capture the four needed objects so the collection of data stops As the previous case for Gain1 10 and Gain2 31the distance must be around 10cm 4 Gain1 15 Gain2 0 Distance from the camera 5cm Distance from the camera 10cm BH BY EO FB OF Z BR BY EO FB OF S7 HO gt 5F 8146 F BB B1 8515 062H 88058 oF B8 81 8571 bdo 8453 DF BB 01 8368 020B 0287 DF B8 61 8518 00060 88808 HF 96 81 86860 0528 B43A HF B8 81 851B 00060 0006 BF 980 88 0000 ADAB 0022 BF BS H 837 B4 BV EO FB OF z BA BY EO FB OF S7 B05F 0146 F BS B1 A514 062H 0008 6F BB 81 B57B 0535 8453 DF B3 81 656A H20B 8208 DF BB 81 8512 HHH 6066 AF 93 81 0006 0528 B43H HF BB 81 851D 0000 88808 BF 93 B8 0000 g4B 0522 BF BB 880 86371 BR BY EO FB OF z BA BY EO FB OF 5 A F OLC F B 01 8513 0629 0009 6F BE 81 B57B 0536 8452 DF B B1 5698 020B 0288 DF BE 81 8515 00060 00606 AF 96 81 0000 0528 B43A HF BE 81 851B HHH BABE BF 96 BB 0006 HO4B 0522 BF BE 880 8636F The features of four objects appear in the hyper terminal when the camera is at 10cm from the LEDs Distance from the cam
25. 0x12 DESC STRING By Oy Ey Oy A 0 Bs 0 Ey Oy 0 O D s Oy TE 0 terminator 0 E If the USB device is wanted as interface for a mouse or a joystick the interface field of the descriptor block has to be changed So the function that registers the pointer to the block is USBRegisterDescriptors abDescriptors Following some internet examples now some handlers for requests have to be registered Let s see this registers register HID standard request handler USBRegisterCustomReqHandler HIDHandleStdReg register class request handler USBRegisterRequestHandler REQTYPE TYPE CLASS HandleClassRequest abClassReqData register endpoint USBHwRegisterEPIntHandler INTR IN EP NULL register frame handler USBHwRegisterFrameHandler HandleFrame In the first register HIDHandleStdReq tries to service any HID specific request and the USBRegisterCustomReqHandler function guides the program to it as a callback function The second function registers a callback for HID class request handler with HandlerClassRequest as handler and REQTYPE TYPE CLASS to define the class type With the function USBHwRegisterEPIntHandler and with INTR IN EP the endpoint 8 and 1 are enabled but give a NULL callback function The USBHwRegisterFrameHandler function 34 enables the FRAME interrupt which corresponds with the bit O of the USBDevlntXx registers and this interruption occurs every 1ms lt is used for isochronou
26. 2 The commands used in the program to find the values for the U3DLM and U3DLL registers and to give these values to these registers are PCLK_UART3 is being set to 1 4 of SystemCoreClock pclk SystemCoreClock 4 Fdiv pclk 16 baudrate Set baud rate LPC_UART3 gt DLM Fdiv 256 LPC_UART3 gt DLL Fdiv 256 Where baudrate is the wanted baud rate for the UART3 communication and is an input variable for the whole program of UARTS initialization Once the baud rate of the UARTS is selected it is needed to enable the UART3 Rx and Tx FIFOs for proper UART operation in transmission and reception This is done in the USFCR register where setting the bit O enable both Rx and Tx FIFOs setting the bit 1 reset the Rx FIFO and setting the bit 2 reset the Tx FIFO So the hexadecimal value 7 is assigned to the register USFCH to enable all and also in the USLCR register the DLAB is disabled to allow enable interruptions but maintaining the rest of the setting bits in the previous access to this register LPC_UART3 gt LCR LPC_UART3 gt FCR 0x03 8 bits no Parity 1 Stop bit DLAB 0x07 Enable and reset TX and RX FIFO With this the program to initialize the UARTS is finished The described functions are collected in one to do the initialization and is in this one where baudrate is an input variable void UART3 Init int baudrate As with this function a communication via UART can be started with a device now
27. 2 So the value 10 2 in hexadecimal is put in the characteristic bits of each pins bits O and 1 for pin PO 0 and 2 and 3 for pin PO 1 in the PINSELO register These bits can be cleared first to ensure the values are correctly written in the register LPC PINCON PINSELO amp x F LPC PINCON PINSELO 0x2 0 TxD3 LPC PINCON PINSELO 0x2 lt lt 2 RxD3 The lines of communication are setting now the format of the data character that passes through them has to be defined This is done in the register USLCR and it is controlled with the LCR command over LPC_UARTS In this register the length of the 40 send receive word can be decided enabled or not the parity and selected the type of it or enabled or not the access to Divisor Latches with the Divisor Latch Access Bit DLAB The Divisor Latch is divided in DLL which is his least significant byte and the DLM which is his most significant byte and the full value is used to divide the PCLK in order to generate the baud rate clock The DLAB must be 1 to access to these DLL and DLM register and select a value for them and must be 0 to enable interruptions and realize other functions The bit description of the LCR is in Table 5 Bit Symbol Value Description 1 0 Word Length Select 00 5 bit character length 01 6 bit character length 10 bit character length 11 8 bit character length 2 Stop Bit Select 0 1 stop bit 1 2 stop bit 3 Parity Enable 0 Disable parity gen 1
28. 8 to 40 as is recommended In the register OxOE the set value is 0 which means there is no assignment mode and for the selection of the objects 46 features to receive the OxOF register is used It is set to 0x93 so the reception of the frame header the object size the object center Y and the object center X is enabled In Table 7 is present the Register OxOF and the meaning of its bits Register OxOF 1Byte Feature Option Enable Flag 0 Disable 1 Enable Bit7 Frame Header Bit6 Object Aspect ratio Bit5 Object Orientation Bit4 object Size Bit3 Object Border Y Bit2 Object Border X Bit1 Object Center Y Bit0 Object Center X Table 7 OxOF register of the camera select the features to receive The register 0x10 determines the number of tracking objects In the case of the Head Tracking System 4 benchmarks are needed 4 points with which calculate the position of the camera with the POSIT algorithm so the value of this register must be 4 Then the 0x16 register is set to O and the Ox1A register to 50 as is recommended for the frame brightness low bound The register Ox1B refers to the Object Area Low Bound OALB where if the camera detected an object but his size is under the defined OLAB the PAC7001 will ignore it and will not output the features of this object If this value is set too large an object will be easily ignored operating at a long distance but if the value is too small less than 3 the accuracy will be los
29. Bit 0 3 Checksum Bytes XOR then Nibbles XOR When it is wanted to end with the outputting of the data it is needed to get out of the Operation mode and go back to the Initial Mode sending the value Ox8E to the camera This Initial mode is the mode in which the registers are configured and is the initial mode of the camera but to activate the camera after power on the value OxEA needs to be sent to check the sensor In Figure 3 it is represented the scheme of this activation of modes Figure 3 Scheme of the modes of the camera up a 11 2 4 Set of LEDs The set of LEDs is the reference that it is going to be taken to move the pointer of the mouse related to the point that the camera is focusing at The camera has to be pointing somewhere inside this set so the program can be able to move the mouse This set is a rectangular prism of 11x8 5x9cm with four infrared LEDs distributed in pairs so that there are two LEDs in the front part and the other two in the back part In the front part there is one LED in the lower left corner and the other in the upper right corner while in the back part the LEDs are in the upper left and the lower right corner The set in Figure 4 can be connected via USB to the computer to act it as power supply of the LEDs and it is also provided with a support to hold it on the screen of the computer Figure 4 Set of LEDs upna 12 3 State of the Art Assistive Technology AT is a term t
30. C PINSEL CFG Type PINSEL InitStruct LPC_PINCON gt PINSEL4 0x1 18 USB CONNECT 2 WAYS TO DO PINSEL InitStruct PortnumzPINSEL PORT 2 PINSEL InitStruct PinnumzPINSEL PIN 9 PINSEL InitStruct Funcnum PINSEL FUNC 1 PINSEL ConfigPin amp PINSEL InitStruct upna 27 LPC PINCON PINSEL3 0x1 4 USB UP LED 2 WAYS TO DO PINSEL InitStruct PortnumzPINSEL PORT 1 PINSEL InitStruct PinnumzPINSEL PIN 18 PINSEL InitStruct FuncnumzPINSEL FUNC 1 PINSEL ConfigPin amp PINSEL InitStruct LPC PINCON PINSEL3 0x10 lt lt 28 USB VBUS 2 WAYS TO DO PINSEL InitStruct PortnumzPINSEL PORT 1 PINSEL InitStruct PinnumzPINSEL PIN 30 PINSEL InitStruct FuncnumzPINSEL FUNC 2 PINSEL ConfigPin amp PINSEL InitStruct LPC_PINCON gt PINSEL1 0x1 26 USB D 2 WAYS TO DO PINSEL InitStruct PortnumzPINSEL PORT 9 PINSEL InitStruct PinnumzPINSEL PIN 29 PINSEL InitStruct FuncnumzPINSEL FUNC 1 PINSEL ConfigPin amp PINSEL InitStruct LPC PINCON PINSEL1 0x1 28 USB D 2 WAYS TO DO PINSEL InitStruct PortnumzPINSEL PORT 9 PINSEL InitStruct PinnumzPINSEL PIN 30 PINSEL InitStruct FuncnumzPINSEL FUNC 1 PINSEL ConfigPin amp PINSEL InitStruct enable PUSB LPC SC PCONP 0x1 31 Note that the pins can be selected in two different ways lt is declared PINSEL InitStruct as a PINSEL CFG type structure to select the port pin and function and then PINSEL ConfigPin is used to set the
31. C7001 and the LEDs to capture 4 objects according to the values of Gain1 and Gain2 With these tests it is seen that the best option for the Gain1 and Gain2 registers of the camera is set the Gain2 register to O and the Gain1 to 10 or 15 That gives a maximum distance between the camera and the set of LEDs a little bit more than 20cm It is observed that in every measure at 5 cm the camera can only capture 2 objects that is because of the field of view The field of view Figure 20 is the part of the world that is visible by the camera and in this case according to the datasheet the field of view is 64 degrees in diagonal FieldO fiev 642 Figure 20 Field of view With this angle two right triangles can be formed one upper and other lower with a horizontal line crossing the angle and dividing it in two angles of 32 degrees Knowing this angle and one of his sides of the right triangle the rest of the sides can be easily obtained Figure 21 60 hyp sin 0 SPP E opp cos P a OPP sin A in e SER Pe adj cos A acl Figure 21 Right triangle and sides There is an angle of 32 degrees and the adjacent side is 5 cm so there is a hypotenuse of 5 89 cm and continuing operating an opposite side of 3 12 cm is obtained So being the field of view a rectangle with 4 3 ratio array elements 128 x 96 in the datasheet and as the angle of view is in diagonal being the distance from the center of the rectangle to
32. FF LE WORD 0x0001 LE WORD 0x0100 Ox01 0x02 0x03 Ox01 ry f7 it i II IT configuration 0x09 DESC CONFIGURATION LE WORD 0x22 Ox01 Ox01 0x00 0x80 0x32 interface 0x09 DESC INTERFACE 0x00 0x00 Ox01 0x03 0x00 0x00 0x00 HID descriptor 0x09 DESC HID HID LE WORD 0x0110 0x00 Ox01 DESC HID REPORT LE WORD sizeof abReportDesc EP descriptor 0x07 DESC ENDPOINT INTR IN EP 0x03 bcdUSB bDeviceClass bDeviceSubClass bDeviceProtocol bMaxPacketSize idVendor idProduct bcdDevice iManufacturer iProduct iSerialNumber bNumConfigurations wTotalLength bNumInterfaces bConfigurationValue iConfiguration bmAttributes bMaxPower bInterfaceNumber bAlternateSetting bNumEndPoints bInterfaceClass bInterfaceSubClass bInterfaceProtocol ilnterface 17 HID bDescriptorType HID bcdHID bCountryCode bNumDescriptors bDescriptorType report bEndpointAddress bmAttributes INT LE WORD MAX PACKET SIZE wMaxPacketSize upna 33 10 bInterval string descriptors 0x04 DESC STRING LE WORD 0x0409 manufacturer string OxOE DESC STRING Ls Oy P Oy C 0 Whe 0 S Oy B 9 product string 0x12 DESC_STRING Fy Oy Fg Oy 0 0 0 90 My 0 E 3 O Es Oy X 96 serial number string
33. Finally two components from the vector krot are taken the first component krot 0 of the vector for the movement in the X axis and the third component krot 2 for the movement in the Y axis These are the components from which the absolute value is taken and multiplied by 127 When the camera is moved from down to up the cursor moves from up to down so is necessary to subtract from 127 the obtained value treating the krot 2 so the movement will be the correct one This way of solve the problem of the movement of the cursor works in one part of the screen but sometimes it does not work for the entire screen Different solutions have been used but none of them have improved the system so the final block for the movement of the pointer of the mouse is the following vax vay sqrt krot krot sqrt krot 2 krot 2 69 MouseInputReport bX vax 127 MouseInputReport bY 127 vay 127 Vax and vay are float variables where the absolute valor of the components of the vector are stored and they are variables that are multiplied by 127 70 6 Summary and Conclusions Once the project is finished some conclusions are obtained from the process of programming and the final obtained program and it s functioning First of all there is an unexplained problem commonly at the time of debug the LPC1758 with the Eclipse program When the eStick2 is connected to the pc and the LPC1758 is tried to be debugged sometimes it did not w
34. Olivia Solon online Available http www wired co uk news archive 201 1 11 29 the eye is the new mouse Accessed 22 10 2013 Silicon Labs Human Interface Device Tutorial online Available http www silabs com Support e20Documents TechnicalDocs AN249 pdf Accessed 22 10 2013 USB Device Class Definition for Human Interface Devices HID online Available http Awww usb org developers devclass docs HID1 11 pdf Accessed 22 10 2013 Rat n Virtual Relativo Controlado con los Movimientos de la Cabeza Pallej Rubi n Teixid Tresanchez Fernandes del Viso Rebate and Palac n online Available http www aipo es articulos 2 37 pdf Accessed 22 10 2013 77 List of Figures Figure T CSICKZ SOUlCE a RU M 6 Figure 2 LPCXpresso BaseBoard Source 2 ocooocccccocccccccncoccnoconcnonannnnnncnonacononanoss 7 Figure 3 Scheme of the modes of the CaMera occcccccnccocnnococnccnnnnonnnncnnnnnonacnnnnnnnnnacnnnnons 11 Fo uredA Seto LEDS 12 Figure 5 Expanded keyboards Source 3 4 o coooocccconcccoccnccocnnococnccncnncnncnnnnnos 14 Figure 6 One handed keyboards Source 5 6 ccooocccooccnccocccooncncononnnoncnnnnoss 15 Figure 7 Ergonomic keyboards Source 7 8 o ccooncnccocccccccnccccnnonocncnnnnnonacnnonons 15 Figure 8 Orbitouch keyboard Source 9 ooccccocccccocccocc
35. USB gt USBDevIntPri 0 LPC_USB gt USBEpIntEn 0 LPC_USB gt USBEpIntClr OxFFFFFFFF LPC_USB gt USBEpIntPri 0 Writing a one to a bit in the Interrupt Enable register USBxxlntEn xx can be for Dev device or for Ep endpoint enables the corresponding bit in USBxxIntSt to generate an interrupt on one of the interruption lines when set Writing a one to a bit in the Interrupt Clear register USBxxIntClr clears the corresponding bit in USBxxlntSt so if an interruption of the type of the clear bit occurs it has no effect in the program The USBxxIntSt is a register where are located the allowed interruptions that are controlled by the USBxxIntEn and USBxxIntClr With the USBxxlntPri the priority of the interruption can be controlled high priority with a 1 and low priority with a O in the bit corresponding to the interruption The endpoint interruptions are 32 equivalent to 16 endpoints with transmission and reception from the bit O with EndpointO RX to the bit 31 with the Endpointi5 TX in the registers which control this kind of interruptions The device interruptions are 10 ERR INT EP RLZED TxENDPKT RxENDPKT CDFULL CCEMPTY DEV STAT EP SLOW EP FAST and FRAME from the bits 9 to O respectively in the registers that control these interruptions These will be later explained Continuing with the initialization only ACK and not NAK from the endpoints can provoke an interrupt This function does that USBHwNakIntEnable 0 In
36. VCOM putchar How to display the data in the hyper terminal can be easily modified and in this case the features are shown separated between them with a space and one object per line so there are rows of objects and columns of features Before the loop of the program is finish the pgGet pointer has to be reinitialized pointing again to the first element of the buffer so the process of filling the buffer and taking the wanted data can be started again 5 4 1 Camera Test Program Obtained Data The program that can communicate with the PAC7001 camera and show in the hyper terminal the data outputting by the camera is built First of all a capture of the data is exposed in Figure 19 with the features of the objects captured by the camera and they are going to be analyzed to understand what they mean Figure 19 Example of data from the camera in the hyper terminal Here there are three blocks of the data sent by the camera represented in the hyper terminal with hexadecimal numbers and distributed in columns of coordinate X BX coordinate Y BY EOB EO Flag Byte FB Object Flag Byte OF and Size SZ of each one of the objects captured by the camera which are every row The BX values must be between O and 1024 in decimal numbers and the BY value between O and 768 lt is noticed that for example 467 in hexadecimal is 1127 in decimal or that 41B is 1051 which are greater than 1024 and 768 respectively This problem is tried to b
37. Y EO FB OF 2 0173 80165 F AD 61 H52b HOLA BUF GF BS 01 05 3 62F 8478 IF AD 81 8577 017C 828C 1F BS 01 84 D 0009 0006 BF 8D 81 0006 Ho1B B43E BF BS 81 0507 0000 0006 BF SD 88 HHHO 0041 852b BF BS 00 0311 bh BY EU Fb OF SZ B4 BY EU FB OF S7 0173 8165 6F BY 81 52H HOLA BSF GF BA 81 0572 Ho2F W478 IF BYU 81 85 9 0170 020C 1F BA 01 B47F 0000 0006 BF 98 61 0006 B51H B 43E BF BA 01 0505 0000 0006 BF 98 66 0006 0041 Bo2b BF BA 00 0311 At a distance of 5cm the camera can only capture 2 objects but when the distance is 10cm the four objects can be captured by the camera Distance of the camera 15cm Distance of the camera 20 cm BA BY EO FB OF Z B4 BY EO FB OF Z 8521 814A 6F B2 81 0533 0506 B20E oF Bo 81 0507 0217 8234 1F B 81 845D 0240 8258 1F Bo 01 8441 B4 6b 0429 BF B2 81 845C 0466 0421 BF Bo 01 0437 8120 84 5 BF B2 88 8452 B1 E 044A BF Bo 00 843D BA BY EO FB OF SZ B4 BY EU FB OF 5 8521 814A GF Bo 81 0933 0506 B20E oF BS B1 Bob 0217 8234 1F Bo 81 Bask 0240 8258 1F BS 01 0442 H46B 0429 BF Bo 81 HAIL 0466 0420 BE bo 01 8435 8120 84 5 BF Bo 00 84535 017E 844A BF bo H 843C BA BY EO FB OF Z B4 BY EO FB OF Z 8521 814A 6F BS B1 80539 0506 8280E GF BA 81 8586 0217 0234 1F bs 61 8460 0240 024 1F BA 01 0440 H46B 0429 BF Es 61 HAIL 8466 0420 BF BA 01 8436 8120 84 5 BF bo H 8452 017E 844H BF BA H 843D In both cases the four objects still appears in the data from the camera show at the hyper terminal 53 Distance from the camera
38. Y EU FB OF 52 0074 B16A 7F BB 81 0664 0577 006B F AB 81 BAST BOJA 84 7H 9F BB 81 8 59 0165 0011 9F AB 85 0009 0000 8800 BF 9B 81 0000 ISE 8221 BF AB 81 05 6 00068 6000 BF 96 H 0000 0585 0446 OF HB BB GIF The wanted reception in the hyper terminal of four objects starts with a distance around 10cm between camera and LEDs Distance from the camera 15cm Distance from the camera 20cm BK BY EU FB OF SZ BX BY EU FB OF SZ 0 3E 001F F B 01 002F 0543 0206 F bo 81 8951 0567 B1 C 9F BO 01 C4 0268 0345 9F bo 801 OBA 0250 022 BF BY 01 8564 0514 0418 BF bo 81 U5JF 0000 8880 OF 98 80 0000 0000 0000 BF 95 00 0000 b BY EO FB OF 2 BX BY EO FB OF S7 0740 BOLD F 63 01 0040 0545 0200 FF BB 81 8978 0569 B817H 9F B3 81 0DOF 0269 8344 9F BB 81 0600 0250 022 BF BS 01 8564 0514 0410 BF BB 81 0541 0000 0000 BF 93 00 0006 0000 00060 BF 9b 00 0000 ba BY EU FB OF Se BX BY EU FB OF se 0 3E 001F F b 01 002F 0540 820A F BE 81 BAAS b6E 6170 9F Bo 81 BD69 0268 0344 9F BE 01 BBUF 02580 8252 BF Bo 81 56F 0514 8418 BF BE 81 0543 0000 88800 OF 96 00 0000 0000 8888 BF 9E 80 0000 It is seen that like in other cases at these distances the reception of four objects starts to fail The distance between the PAC7001 and the LEDs with this configuration cannot be more than 10cm In Table 9 all the results of the measurements are collected 59 Range of distances between PAC7001 and LEDs to captures 4 objects Table 9 Distances between PA
39. a loop that finish when reach this obtained number from O adding 1 each iteration void Delay int secs int i while i lt secs 1000 i So with this function a time is given to the camera to process the information putting it just after every UART3_sendchar function Once all the commands required to set a register are sent to finish with the CameraSet function the Rx FIFO queue is read with the UARTS Getchar function where must be the ACK message generated by the camera to clear this queue and thus completed the function Here is the complete CameraSet function void CameraSet char RegNum char RegValH char RegValL int f UART3 Sendchar 0x18 Delay 30 UART3 Sendchar RegNum Delay 300 if RegValH 0 UART3 Sendchar RegValH Delay 300 UART3 Sendchar RegValL Delay 300 f UART3 Getchar UART3 Getchar f Finally the function to set the registers of the camera is completed so this process can start but first the previous initialization has to be done The program that is going to be done now is to configure the camera and check if it works showing the received data from the camera in the hyper terminal as the treated characters are shown in the USB program for exchange data So the same process for initialize the program is used with the USBlnit the pointer to the descriptor of the USB device the register of the handlers for the endpoints frame interruptions and
40. anged In the SET of LEDs one possible solution is to put together more than one LED to simulate only one of the objects needed for the POSIT algorithm A bunch of LEDs can be put in the positions of the set where now there is only one LED to try to increase the power of it so the camera can capture it at a farther distance than the actual one Another type of infrared light transmitter can be selected too directive and with more power but provably they will be more expensive than the LEDs In the case of the camera the different registers have been changed and the best ones are selected Changing the LEDs the camera probably works better but also can be tried the actual disposition of the system with a different camera of the PAC7001 With the code it can be studied to be improved as well as the POSIT algorithm which can be optimized There are different possibilities of doing the main program too The translation of the matrix obtained in the POSIT algorithm into the movement of the pointer of the mouse can also be optimized and done in a different way 73 Bibliography 1 eStick2 online Available https cis technikum wien at documents bel 3 ess semesterplan estick2 estick2 html Accessed 22 10 2013 2 Embedded Artist Xpresso Base Board online Available http www embeddedartists com products Ipcxpresso xpr base php Accessed 22 10 2013 3 Ciapat expanded keyboard online Available http www ciapat org es ca
41. ase Set Address Device DO Write 1 byte Configure Device Device D8 Write 1 byte Set Mode Device F3 Write 1 byte Read Current Device F5 Read 1 or 2 bytes Frame Number Read Test Device FD Write 1 byte Register Set Device Status Device FE Write 1 byte Get Device Status Device FE Read 1 byte Get Error Code Device FF Read 1 byte Read Error Status Device FB Read 1 byte Select Endpoint Endpoint xx xx same as the Read 1 byte endpoint optional Select Endpoint Endpoint xx 40 xx Read 1 byte Clear Interrupt Set Endpoint Endpoint xx 40 xx Write 1 byte Status Clear Buffer Selected Endpoint F2 Read 1 byte optional Validate Buffer Selected Endpoint FA None Table 3 SIE commands 30 They will be explained when it is needed The USBCmdData contains the read data from a command when there is Read on the CMD PHASE When a command is write in the USBCmdCode the CCEMPTY bit of the USBDEvintSt register bit 4 changes to a O because the reset value is 1 and means that the USBCmdCode is empty and when the USBCmabData register has data to read it is full the CDFULL bit of the USBDevintSt register bit 5 is set The operation mode for these commands is first clear CDFULL and CCEMPTY bits with USBDevintClr register Then in the USBCmdCode register put the wanted command code in the CMD CODE and the sequence 0x05 Command in the CMD PHASE field and wait until USBCmdCode is empty again with a 1 in the corresponding CCEMPTY bi
42. asheet com html pdf 344789 NXP 74LVC595APW 378 6 74LVC595APW html Accessed 22 10 2013 NXP 74HC4052 74HCT4052 online Available http www nxp com documents data_sheet 74HC_HCT4052 pdf Accessed 22 10 2013 LPCXpresso Base Board online Available http laboratorios fi uba ar Ise curso intensivo practicas laboratorio LPCXpresso _ Base Board revB pdf Accessed 22 10 2013 Adafruit PL2303HX Edition USB to Serial Brifge Controller Product Datasheet online Available http www adafruit com datasheets PL2303HX pdf Accessed 22 10 2013 NXP LPC zone online Available http www nxp com techzones microcontrollers techzone news html Accessed 22 10 2013 76 40 41 42 43 44 45 46 47 48 PJRC Teensy online Available http www pjrc com teensy gcc html Accessed 22 10 2013 Keil Forum online Available http www keil com forum 16845 Accessed 22 10 2013 Code Red RDB1768_usbstack online Available http support code red tech com CodeRedWiki RDB1768ExampleProjects action AttachFile amp do view amp tar get RDB1768 usbstack zip Accessed 22 10 2013 AsTeRICS Project online Available http www asterics eu Accessed 22 10 2013 University of Washington AccesIT Assistive Technology online Available http www washington edu accessit articles 109 Accessed 22 10 2013 Wired co Low cost eye tracking system developed to control computer mice by
43. ask of Oxff Finally it is obtained the command sent by the joystick in a one byte variable The order of the bits from this variable from the bit O to the bit 4 are joystick right joystick left joystick down joystick up and select joystick so depending on which of these bits are set the movement of the joystick is known and so the movement that the pointer has to do The described function is 36 void JoystickRead int pi JoystickState int i up idn il ir i sel int i State i sel LPC GPIO2 FIOPIN 0 amp 1 r LPC GPIO2 FIOPIN 1 8 1 up LPC GPIO2 FIOPIN 2 amp 1 l LPC GPIO2 FIOPIN 3 8 1 _dn LPC GPIO2 FIOPIN 4 amp 1 i l i i i State i sel 4 i up 3 i dn 2 i 1 1 i_r i State i State Oxff pi JoystickState i State In the variable appears pi JoystickState In this case the name of the variable is JoystickState the state of the joystick where it is moved to To know which of this is it is compared with a series of defined parameters Each of these parameters correspond with a state of the joystick so that the JOYSTICK CLICK parameter has the value 0x10 the JOYSTICK UP parameter has 0x08 and so on so it is easy to see which of these parameters has the same value the same bit set as the variable i JoystickState Once the state of the joystick is identified the correct movement in the X axis or in the Y axis t
44. cococcnnnoncnononononacnonnnnnnoncnonnnos 16 Figure 9 On Screen keyboards Source 10 11 oooncccoonnccoccnccncncconcnconcnnnnncnnnnoos 17 Figure 10 Different types of keyboards Source 12 13 14 18 Figure 11 Ergonomic mice and joysticks Source 15 16 sssessssess 18 Figure 12 Trackballs Source 17 18 oooccococcnccocnnococococonnnconnnonononnncnononononacnnnnons 19 Figure 13 Feet mice Source 19 2O0 21 ooooccococnnncccncoccnncoccncconnnonaconononononcnonnnos 20 Figure 14 Special joysticks Source 22 23 oooocccooncccoccccconcnonocncononnnncncononnnnacnnonons 20 Figure 15 Headpointers and mouthsticks Source 24 25 sss 21 Figure 16 Head tracking devices Source 26 27 ooocccconcccccnncconnnccocncononoconcnnnnons 22 Figure 17 Eye tracking systems Source 28 29 ococoncccconcccoccncconnnocococonnnncnncnnnnnos 23 Figure 18 Hardware connections and mounting ooccooccncncnnncnnncnnncnnncnnnonanonanonanonanenanenanos 27 Figure 19 Example of data from the camera in the hyper terminal 51 Figure 20 Field of view ccccsecccsecccececuccceeeceucecueeseeceusessueesueecsueesseessueeseueeseeessuseseeesaas 60 Figure 21 Right triangle and sides cccccccseccceeeeeeeeceeeeceeeeeeeeseuee
45. cted and set with the proper value Once the setting of the register is finalized the sensor has to be switched to Operation mode by sending the Ox8D value to the camera to start the output of the objects features These outputs features depend on the OxOF register but the normal outputs it is first the header and then the list of the features of the objects The header which is of 4 bytes is OxFF 0x00 gt OxFF gt OxFF And the normal selected features and their order is Flag Byte 1 byte Object Flag Byte 1 byte X High Byte X Low Byte Y High Byte Y Low Byte EOB 1 byte 10 This scheme is repeated with the features of each object If the sensor is programed for detecting only one object the same scheme will be repeated four times but if the sensor can detect 4 different objects there will be four different schemes preceded by the header Below are the means or the values that have to be received in each bit of the parameters Flag Byte Object Flag Byte and EOB lt Flag Byte Object Flag Byte gt Bit 7 always 1 gt Bit 5 6 Condition gt Bit7 0 0 Invalid Object is not found gt Bit 4 6 Reserved 1 Trace gt Trace is O gt Bit 2 3 2 Reserved 0 Circle object 3 Reserved 1 Bar Object Bit 0 4 Frame Number 2 Circle hole Object 3 Bar hole Object Bit 1 Reserved BitO 0 Finish 1 Not Finish EOB gt Bit7 0 Bit 4 6 Object Number gt
46. d to initialize the VCOM port which is initialize the transmission FIFO and the reception FIFO initialize his pointers This is done with the function VCOM init and all the FIFO instructions are located in the library serial fifo When it is switched on the USB bus is connected with the function USBHwConnect TRUE After that a loop is started with the getting of characters from the computer keyboard and then the put back of the character on the USB bus which can be the same character or this one treated For the getting of characters there is the function VCOM getchar which takes the characters in order from the Rx FIFO queue This FIFO is filled by the Bulkln handler with the characters pulsed in the keyboard The VCOM getchar function returns to the main program the first character of the FIFO queue and advanced the FIFO pointer to the next character all of these aided by the program fifo get from the library serial fifo After calling this VCOM getchar function and store the obtained character in a variable this treated character is needed to be put back to the computer to show it This is done with the function VCOM putchar where the character to show is an input variable Inside the function with the fifo put order the character is put in the Tx FIFO queue to send it to the endpoint and advance in the Tx FIFO pointer to continuing filling the queue In this case the treatment that is applied to the received character is adding 1 t
47. dos as como el protocolo de activaci n de la c mara Se ofrecen tambi n los distintos resultados de las mediciones realizadas para el sistema head tracking y conclusiones al respecto de esas mediciones En conclusi n en este trabajo se analizan las limitaciones de la configuraci n seleccionada y se cuestiona su idoneidad para la funci n deseada Abstract The intention is to create a program that controls a head tracking system for disabled people The system is composed by a PAC7001 camera the LPC1758 microcontroller integrated in to the eStick2 platform and a set of infrared LEDs To attain this objective UART and USB connections are used and the POSIT algorithm also has a relevant role in the final achievement of the software In this paper the process of doing the software of the head tracking system and the different programs built to finally obtain this software are described These programs are used to understand how the USB or the UART connection worked to check how the pointer of the mouse is moved or to see the data captured by the PAC7001 camera and how these data had to be treated The different problems that appeared during the programming are described how they have been solved and also the final result Finally it is discovered that it was no possible to build a program that worked properly with the components used and some advices for future improvements are given Keywords Head tracking system PAC7001 LPC1758 Table
48. e byte of interface number has to be changed to 0x01 because now the mouse function is needed and the byte of interface protocol must be 0x02 because it corresponds to Mouse protocol After changing that the initialization of the USB stack is the same as well as the function to register the pointer to the device descriptor the function to register the HID standard request handler the one for the class request handler and the function that registers the endpoints A report descriptor of the data is added when the USB is used as an interface for a mouse and it is used in the handler of standard request This report is generated by a HID descriptor tool program which can generate descriptors for other purposes or protocols Another function that has to be changed is the handler of the frame interruptions to provide a real mouse reports This handler is the responsible of the movement of the cursor in the computer It is needed to introduce a different data to the endpoint buffer computer from the one it previously had This data is the displacement of the mouse along the X axis the Y axis and the press button of the 35 mouse These are defined as a structure called HIDDMouselnputReport and the variables are bmButtons bX and bY The final structure of the definition is typedef struct unsigned char bmButtons Bitmap state of three mouse buttons signed char bX Pointer displacement along the X axis signed char bY Pointe
49. e solved 91 discovering the reason of this behavior of the values for BX and BY and a sweep is done with a light from the beginning to the end of both X and Y axis of the field of view of the camera to see the variation of the X and Y coordinates Finally is figured out that the most representative bit of the low byte of X and Y is always set to 0 never change and it is not taken into account in the final values of X and Y so there are some jumps that have to be fixed later in the program for a proper operation That is the reason of this high values for the X and Y coordinates in this capture In the Flag Byte field FB is represented the number of frame and if the object is found if the camera can capture the correspond object The bit 7 is always 1 the 6 and 5 represent the capture of the objet 01 or not 00 and the rest of bits represent the frame number It is seen that all the objects of the same frame have the same FB byte and the following frames have not continue the progression of numbers because during the treatment of data or because one frame is not completely in the buffer frames are lost in the middle With the Object Flag the shape of the object can be known and if the frame is finished or not The bit 7 is always O and bits 3 and 2 represent the shape of the object 00 means circle object 01 bar object 10 circle hole object and 11 bar hole object In this case there are circle objects The last bit represent if t
50. ect Number System clock 27MHz 0 27M 1407 19200bps 1 27M 256 2 27M 16 3 27M 703 38400bps 4 2 M 469 57600bps 5 27M 234 115200bps 6 27M 117 230400bps 7 27M 59 460800bps 8 27M 29 921600bps Register Name Default Allowable Description Number Range 0x16 SRC 0 Skip Report Count Aspect 0x00 OxFF Bit 7 4 Orientation Threshold Ratio Bit 3 0 Reserve Ox1A YLB 50 0 255 Frame Brightness Low Bound 0x1E Np_H 0 0 3 PXCLK SYSCLK 2Np Np Np_H Np_L 3 255 PXCLK SYSCLK 2Np Np Np_H Np_L Table 2 Registers of the PAC7001 Gain1 is analog front gain Gain2 is global gain is preferable increase Gain1 first for better SNR The Gain equation is G1 16 Gain1 6 Gaini 0 15 G2 10 gain2 8 Gain2 0 31 Total Gain dB 20logG1 20logG2 The Exposure Line is equal to LPF 1 Ny and the Exposure time equation is 187 LPF 1 Ny 2 Np SystemClock Frame per second fps is SystemClock 187 LPF 1 2 Np Then the IW value must be 128 integral for example 128 256 and IH must be 96 integral as 96 192 and the IW IH ratio must be 4 3 About the OLAB if the camera detected an object but his size is under OLAB defined then PAC7001 will ignore this object and will not output its features o0 these are the registers that have to be configured in the sensor to make it work as it is wanted but to write in this register first it is needed to send the value 0x10 to set them and then the register number can be sele
51. ed in the appendix B and this explanation is followed to build the POSIT program The part of the main program which contains the POSIT algorithm has to start after the ProcessData function after the obtaining and orderly storage of the data from the buffer There are 6 different steps described in the mentioned study of the POSIT the first of them is the preliminary step which consists in writing a matrix composed by the vectors that connect a reference point with the rest of the points In this case there are four points four objects that the camera can capture and output their features and these objects correspond with the four LEDs in the set of LEDs So what it is done is select one of these LEDs as reference point and measure the distance with the rest of the LEDs in this manner a matrix with dimension 3x3 is obtained where each row is the vector of this distance from the reference point to each one of the rest of LEDs The set of LEDs is according with the coordinate system of the camera a rectangular prism of 11x8 5x9 cm with the distribution of the LEDs appearing in Figure 22 3 lt O T a gt N MN NE UN Frontal Part Y Figure 22 Set of LEDs and the position of them The red spots are the places of the LEDs and the LED 1 is selected as the reference point so the distance vector to the LED 2 is 11 8 5 0 the vector to the LED 3 is 11 0 9 and the vector to the LED 4 is 0 8 5 9 and the rows of the
52. era 15cm Distance from the camera 20cm Now at these distances is still seeing in the hyper terminal the features of the four LEDs captured by the camera Distance from the camera 25cm BA BY In a distance between 20 and 25cm the receiving of the features of two of the objects stops so the measure stops too In this case of configuration of the Gain1 and Gain2 registers a valid range is obtained from 10 to a bit more than 20cm 97 5 Gain1 15 Gain2 15 Distance from the camera 5cm Distance from the camera 10cm bh BY EU FB OF SZ BX BY EO FB OF 52 0074 0160 7F bo 81 8 88 5 D 0069 F bb 61 BBC 0338 0479 9F b 81 8 16 lo F 001F 9F bb 85 BBBE 0000 0006 BF 96 81 8888 OLSE 8222 BF bb 81 H5 F 0000 00060 BF 96 88 HAHA 0009 B444 BF bb BH644 bh BY EO FB OF SZ BX BY EU FB OF SZ 0075 B16A FF BS 81 B64H 05 50 BBOU F BE 81 BAJA 0536 84 9 9F bo 81 8 29 0163 0011 9F BE 85 BB8H 0000 0006 BF 98 81 HHHH OISE 0221 BF BE 81 86804 0000 0006 BF 9S 88 HHHH 0009 0446 F BE 88 8621 bh BY EU Fb OF SZ BX BY EO FB OF 52 0074 B16H FF bb 81 8664 0577 BYOB F HB B1 BASL BOJA 04 7H 9F bb 81 8 59 0165 0011 9F AB By HB889 0000 0006 BF 9b 81 8888 OISE 8221 BF A 81 85 6 0000 00060 BF 9b 68 HAHA Hobs B446 BF HB B6lF It is seen again that the reception of four objects starts at a distance of 10cm Distance from the camera 15cm Distance from the camera 20cm BA BY EU FB OF SZ BX BY EU FB OF SZ 073E BB1F F B
53. es 26 AP 26 USBCOM ON astas een ee ee ee EER 27 USD OE UM I OY SN eos tree cists ene ease AERIS MM EMEN UEM SE MIS 35 USB Program Send Receive CharacterS ccccccccseeeecseeeeeeeeeceeeeeaeeeeseneenseeeesees 38 UART GOS CHO aise eed NOE ENDE HE 40 5 4 Camera configuration and COMMUNICA ION ccoocccccccnccncnncncnnonannnnnnnnnnannnnnnnnnnnnnos 44 5 4 1 Camera Test Program Obtained Data c oonccconcnccnnnnconcnncnnnnonncnnonnnnonncnnonanonnncnnnns 51 5 5 ji AEAEE AAE 62 5 6 Movement OF the POINTE ssssisuidsutasm tuendi si S opt i Doa d R EE 69 6 Summary and Conclusions esssssssssssssessseeee nennen nennen nena nnns nnn nn 71 7 mU AIRE mm 73 0 n eee ee ee ae eee ee eee eee E ee E ee ee ee ee 74 LSU Ol e I PRETI I Tm 78 EE e TUTTI 79 A LPC17xx Microcontrollers User Manual cccceccccseeeeeeeeeeeeeeeseeeeseeeeeseeeesseeeseeesaeeeess 80 By aT PAM aspects appetat patna yess amm dt mud Medus DEN TM IR NE 81 1 Objective of the project The aim of this project is to build a low cost head tracking system and mainly to make a program to govern that system with the best possible efficiency and capability to control the mouse pointer of the compute It must be appropriate for people with motion disabilities especially for those with spinal damage The scheme of the head tracking is composed of a microcontroller a camera and a small simple system of four infrared LEDs forming a rectangular prism
54. found in the market as the ones in Figure 11 so the user can select the comfortable model that reduce or solve his pain Figure 11 Ergonomic mice and joysticks Source 15 16 Shttp www demotix com news 1758185 foot keyboard unveiled gajah mada university disabled users all media http www coroflot com erikcampbell optical keyboard keyset 1 gt http walyou com jellyfish keyboard keyset 19 http www computer posture co uk Tennis Elbow 1 http www fentek ind com zero tension mouse htm3t UiCtZH8rj9M 18 3 2 2 Trackballs Another device working as a mouse is the trackball It consists in moving a ball instead of the whole dispositive of a mouse to move the pointer Normally it has separated buttons to avoid unintentional pressing and make clicks like a normal mouse The roll of the ball can be done with a hand or just with one finger That reduces the movement of hand and arm to control the pointer and makes it perfect for people with wrist problems or similar ailments Two types of trackballs are shown in Figure 12 Figure 12 Trackballs Source 17 18 3 2 3 Feet mice There are also mice that can be moved with our feet They are much appropriated and specially designed for people with disabilities of the upper limbs There are different types of feet handled mice in the market most of them based in two pedals system controlling the pointer with one and the clicking with the other A different model
55. ful later The same scheme as the used to do the joystick program is followed with the same initialization of the USB stack Then comes the USBRegisterDescriptor function to set a pointer to the descriptor block of the USB device In this case the descriptor of the USB device is different from the descriptor of the joystick program because the USB is not an interface for a mouse protocol is only a bridge to exchange data So instead of define the mouse protocol is needed to define which endpoints are used to send the data and which to receive it There are a lot of examples in the Internet of these types of descriptors and in this case it is used the endpoint O TX for the transmission of data via USB BULK OUT EP and endpoints 1Rx and O Rx for the reception of data BULK IN EP Once there is an instruction to register a pointer to the descriptor continue with the function that calls the function to handle the USB class request USBRegisterRequestHandler is the function that calls the handler of the USB class request and this handler is HandleClassRequest After that is needed to continue with the endpoints handlers which are registered with the function USBHwhRegisterEPIntHandler Three different handlers have to be registered for different endpoints the endpoint for the notifications as in the joystick program INT EN EP 0x81 with null handler the endpoint for the outgoing data BULK OUT EP selecting BulkOut as handler which controls
56. h 49 h UART3 Getchar When the ACK from the PAC7001 is received the program can continue with the set of the registers described in the section about the camera As it was said previously with the CameraSet function the number of the register has to be introduced as an input variable as well as the value wanted to be introduced on the register The configuration of the registers starts with the Gaini and Gain2 and first they are set to 10 and O respectively Then come the LPF and the Ny registers which are programmed with the values 118 and 1 as recommend the datasheet After that the register Ox1E Np H is set to O and the register Ox1F Np L to 3 The datasheet said that the register 0x02 must be set to 1 for sensor register update after the registers 0x00 0x01 0x03 0x04 Ox1E or Ox1F have changed and these registers are which have just been configured so now the register 0x02 is put to 1 The registers IW and IH have two value bytes and they are set to the maximum value permitted 1024 for the IW register which is 0x04 for the high byte and 0x00 for the low and 768 for the IH register 0x03 for the high byte and 0x00 for the low one and they meet the requirement of IW IH 4 3 Continuing with the registers and following the datasheet the value 0x88 is introduced to the register 0x07 to put the threshold mode in automatic and set it without dummy data and the Threshold register is set which value register is 0x0
57. hat covers lots of fields related to the use of technology in the common life of people with disabilities to make it easier to perform functions that otherwise could be difficult or impossible AT includes assistive adaptive and rehabilitative technology and even the process used in selecting locating and using them AT technology can include mobility devices as wheelchairs walkers or mobility scooter as well as hardware software and peripherals that assist people with disabilities in accessing computers or different kinds of automated dispositive All this things promote greater independence to the users for example people who are blind may use software that read texts on a screen with a computer generated voice those who have low vision can enlarge the content of a screen using a special software deaf people may use a text telephone or users with speaking problems can employ devices that speak for them introducing a text via keyboard But this research is focused on disabled people with mobility problems because the system is addressed to this kind of disability These people have permanent or transitory difficulties moving their body difficulties that can affect from one specific part of their body to a total paralysis It can be caused by problems with the tone or the power of the muscles or problems with mental functions that control sequencing complex movements the usual functioning of the central nervous system and the articular system or
58. he LED2 the second element of the vector from the distance vector of the LED3 and the third element from the distance vector is formed from the distance vector of the LED4 To complete the obtaining of the epsilon1 each of these vectors have to be multiplied by the k vector and the result divided by the ZO coordinate previously obtained Finally the wanted vector is achieved That is how it is done in the program epsilon1 0 1 Ze A e e k e A e 1 k 1 A e 2 k 2 epsiloni 1 1 ze A 1 k A 1 1 k 1 A 1 2 k 2 18 epsilon1 2 1 Ze A 2 0 k 0 A 2 1 k 1 A 2 2 k 2 At this moment epsilonO and epsilon1 vectors are in the program Now the epsilonO is subtracted to the epsilon1 term by term and done the absolute value of the subtraction to check if the final results of each operation are greater or not than an error value previously defined 67 lepsilont i epsilonO i lt Error 19 The selected value for this error is 0 1 and if the results of the subtractions are greater than the error value the epsilon1 vector becomes the new epsilonO vector Thus the process is repeated to obtain a new epsilon1 vector from the estimation of the Xim and Yim vectors to the comparison step with the error value until each subtracts between terms of the epsilons are lower than the error value When that occurs the translation vector and the rotation matrix can be built As it was said previously
59. he frame is finish 1 says not and O says yes and as is seen in the first 3 objects is represented that the frame is not finish and the last one has a O in their last bit which means the frame is finished The rest of bits are reserved Now this data will be seen changing the registers of Gain 1 and Gain 2 which are previously set to 10 and O respectively to test which combination is better in matter of distance of the camera from the set of LEDs and better reception of the four objects To do these checking the camera is placed at a height of 7 5cm 4 cm displaced from one side of the set of LEDs and pointing to this set so the camera is put more or less focusing at the center of the triangular prism that form the set The measure starts with the camera at 5 cm from the front side of the prism and it will be distanced 5 cm by 5 cm searching to receive all the objects and finished when it cannot be possible The maximum value for the Gain 1 is 15 and for Gain 2 is 31 The comparisons start with the pair Gain1 10 Gain2 0 the recommended value in the datasheet and then these values will be varied 92 1 Gain1 10 Gain2 0 Distance of the camera 5 cm Distance of the camera 10 cm bh BY EU FB OF SZ B4 BY EU FB OF 2 0173 8165 6F AA 81 525 HOLA SE GF Bo 81 05 5 62F W478 1F AA 81 Bo 0170 6260 IF Bo 01 04 7D 0000 00606 BF SA 61 0006 HO1B BAJE BF Bo 01 0507 0000 0000 BF SA A 8868 0042 852b BF Bo 00 0312 bh BY EU FB OF SZ BX B
60. he upper body Two ergonomic keyboards are collected in Figure 7 Figure 7 Ergonomic keyboards Source 7 8 http www tested com tech 280 alternative keyboard layouts why are you still using qwerty http carlygoogles blogspot com es 201 1 02 has anyone invented one handed keyboard html http ounae com maltron keyboard http www enablemart com catalogsearch result q alternative keyboards upna 15 diem EAT gt S f Y p H 297 One different ergonomic keyboard it is the Orbitouch keyboard in Figure 8 It consists of two special joysticks with eight positions On the right joystick there are five letters numbers or symbols in each position each character with one color and on the left joystick there are the five colors So when it is wanted to select a character the joystick of the left hand is moved to the color of the character and the joystick of the right and to the position where the character is Figure 8 Orbitouch keyboard Source 9 3 1 4 On screen keyboard They are virtual keyboards on the computer which can be controlled by the common mouse or by a special adapted mouse Most of them have words or phrases that are predicted while typing and can stock new words and register the frequency of usage of the words Some of the software of these virtual keyboards give the option to select the position of the characters in the keyboards which make them more accessible to the users There are
61. icrocontroller After that the CRC tool has to be copied in the appropriate folder following the given indications and then it only remains to install an environment to work in C in this case the Eclipse CDT Eclipse CDT is a fully functional C and C Integrated Development Environment and is the tool used to create the programs to control first the eStick2 and the Xpresso Base Board and them the head tracking system The instructions are followed to install the Eclipse program and to how to set up a project and to configure the preferences of this project Once this has been done the different programs can be written After making the programs a few steps have to be done to compile and prove them As soon as all these orders are completed the user can started with the programs and building knowledge of how the C language the eclipse program the eStick2 and the microcontroller work The first program made is one to control the LEDs of the eStick2 Controlling the configuration of the inputs and outputs from determined pins of the microcontroller the LEDs can be set on or off and can be changed of color from green to red So functions that run LEDs in various ways are created setting on them alternating colors with different delays of time between setting on and off one or various LEDs Then the accelerometer 24 which is integrated in the eStick2 can be used to make a new program where depending on the position of the eStick2 diffe
62. ject j FlagByte tmp object j ObFgBy tmp object j BX tmp lt lt 8 object j BX tmp object j BY tmp lt lt 8 object j BY tmp object j Size tmp lt lt 8 object j Size tmp object j EOB tmp Now the characteristics of the objects are correctly localized and stored if the user wants to see them just have to show them in the hyper terminal with the function VCOM_putchar but have to treat the stored data The data containing in the variables in each element of the Data array are represented in decimal code and it needed to be translated into hexadecimal code to a better presentation and interpretation of the information To do this the TreatData function is used with the byte of data to treat as input variable In the function first the bits from 7 to 4 of the byte are taken and transformed into hexadecimal value and then the same is done with the bits from 3 to O of the byte The process is the following void TreatData unsigned char x unsigned char b x gt gt 4 VCOM putchar b b lt 10 0 A 10 b x amp 15 VCOM putchar b b lt 10 0 A 10 50 With this method if the numbers are bigger than 9 which are letters in hexadecimal code the corresponding letter is shown in the hyper terminal with the ASCII code This function is applied to every byte of data that is wanted to be shown with the
63. le 1 and inside this loop all the treatments that the data need are done from the collection of them from the camera to the final display of them in the hyper terminal The first step is filling the previously mentioned buffer through the pbPut pointer The first value output from the camera is assigned to the pointer with the function UART3_Getchar so that in the first position of the buffer that value is stores and then the pointer is advanced one position to point to the next position of the buffer This process is done continuously until the buffer is empty whose size is 64 so it stop when pbPut reach the position 64 of the buffer When it happens pbPut has to be initialized to the first position of the buffer and start working with the data from the buffer At the time to work with the buffer the beginning of the group of data that forms the features of the four objects has to be identified It is easy to think that now it starts at the first position of the buffer but it is necessary to deal with cases in general where the buffer can start to store the data from the middle of the group of data from the features of the third object for example The header is the key Searching the header in the buffer the group of data will be found in 48 order first the features of the first object then the features of the second of the third and finally of the fourth object so the header has to be localized It is know that the header is com
64. ludes mouse buttons that can handle the pointer and make clicks as a conventional mouse It is a keyboard created for people with motor problems or reduced visibility Two different types of these keyboards are exposed in Figure 5 1 2 3 4 55 ie 38 B8 Figure 5 Expanded keyboards Source 3 4 3 1 2 One handed keyboard This kind of keyboards like the ones in Figure 6 is designed to be handled with one hand even some of them with only two fingers They have the keys distributed in an accessible way to be able to reach them easily with one hand They can also have only a few keys less than a normal keyboard and it is necessary to enter key combinations to write with them There are keyboards for both hands or some of them can be programmable to select the hand to use It is optimum to people with reduced mobility in one of the upper extremities http www ciapat org es catalogo_producto teclado expandido http www geekets com 2009 02 upna 7 Figure 6 One handed keyboards Source 5 6 3 1 3 Ergonomic Keyboards They have special form and distribution of the keys to facilitate the insertion of data as they adapt to the shape of our hands It reduces wrist movement and the movement of arms neck and shoulders The disposition of the letters can be changed to decrease the movement of the fingers They are available for left right or both hands They are also useful for people with problems or pains in t
65. mice html Shttp www turningpointtechnology com Sx AltMice asp http jansapansa blogspot com es upna Do 3 2 5 Headpointers and mouthsticks There are other tools that are less advanced that allow people with disabilities to make use of computers These are the headpointers and mouthsticks consisting in a stick held by the head or the mouth used to type move the mouse or touch the screen One example of each of these tools is exposed in Figure 15 Figure 15 Headpointers and mouthsticks Source 24 25 3 3 Tracking systems Following other techniques of interaction with computers are described based on the tracking of the user focusing on head and eye tracking 3 3 1 Head tracking Head tracking technology consists of a device transmitting a signal from on top of the computer monitor or the laptop and tracking a reflector placed on the user s head or on special glasses Acting as a mouse with a head tracking system a person can control the cursor movement with the movement of his head Turning the head left or right up or down the pointer follows that movement on the screen There are also head tracking systems in the opposite way with reflectors placed on the screen and the transmitting gadget on the head of the users The gadget and the reflectors can be replaced by infrared detector camera and infrared lights acting as positional signals and it works as the previous describe system Two different devices are prese
66. mouse s pointer This camera is normally integrated in special glasses or other devices attached to the head which also can have included another camera pointing to the screen to take into account the position of the head relative to it and coordinate this with the eye camera Some examples of eye tracking systems are gathered in Figure 17 http www sIcentral com c h r naturalpoint trackir Shttp abilityhub com mouse headtrack htm 22 Figure 17 Eye tracking systems Source 28 29 This system could be used for people who have spinal cord injuries as well as those with late stage Parkinson muscular dystrophy and multiple sclerosis The eyes are directly connected to the brain stem so their movement is not affected by spinal cord injuries As in the case of head tracking system the mouse click function can be controlled by a blink system much more easily since there is already a camera pointing to the eye An also with one on screen keyboard tool this systems is much more complete http www methoden psychologie de eyetracker_1 html http cda psych uiuc edu matlab_class Eyelink 20Toolbox 20Home htm upna 23 4 Preliminary Work The implemented low cost head tracking system consist of a LPC1758 integrated in the eStick2 a PAC7001 camera and a set of LEDs All of them are needed to be controlled to make them work as it is required and this role falls in the microcontroller Since the microcontroller is the main part of
67. mpany http www nxp com documents user manual UM 10360 pdf 80 B POSIT Algorithm This appendix contains the direction to the paper of Daniel f DeMenthon and Larry S Davis Model Based Object Pose in 25 Lines of Code which is followed to obtain the pose of the camera with respect to the LEDs and translate it into movement of the mouse http citeseerx ist psu edu viewdoc download jsessionid2347E01840E649BCOFCB8E22D FB228873 doi 10 1 1 65 306 amp rep rep1 amp type pdf upna Universsdad P blica de Navarra Nafarroako Unibertsitate Publikos Todos los derechos reservados Eskubide guztiak erresalbatu dira 82
68. mum packet size for the endpoint When this is done wait for setting the EP RLZED bit in the USBDevintSt register which means that the endpoint is correctly done and then clear it This is done with the function USBHwEPRealize idx endpoint n2 wMaxPacketSize and then the endpoint is enabled with the function USBHwEPEnable idx TRUE which uses the Set Endpoint Status command to write in the wanted endpoint to enable it Both functions are gathered in the function USBHwEPConfig and to set the wanted endpoints the order to put in the program is USBHwEPConfig 0x00 MAX PACKET SIZEO0 USBHwEPConfig 0x80 MAX PACKET SIZEO0 Following the examples to finish this initialization of the USB a function of the usb control library is needed to be used to register a callback for the handlers of the interruptions This function is USBRegisterRequestHandler REQTYPE TYPE STANDARD USBHandleStandardRequest abStdReqData 32 Now the initialize of the USB is finished but more things have to be done to establish the connection First a pointer to a descriptor block has to be registered This block contains all descriptors for the device In internet there are a lot of examples of descriptor of USB devices and in this case it is needed a USB connection so the device descriptor used is static const U8 abDescriptors Device descriptor 0x12 DESC_DEVICE LE WORD 0x0110 0x00 0x00 0x00 MAX PACKET SIZEO LE WORD OXxFF
69. nd which to the others following the order shown in the cube image For doing that it is know that the object center coordinate resolution of the camera is max 1024 768 which means that the maximum value of the coordinates for X is 1024 and for Y 768 with a range between 0 and these numbers So the center of the system the point which is in the middle of the set is the point 512 384 and the coordinates for X and Y for each object captured by the camera are referred to this center The camera always must be pointing inside the cube of LEDs so the central point of the coordinate system must be placed somewhere between the four LEDs In this manner a LED is placed in each one of the quadrants of the coordinate system Figure 23 so it will be easy to identify the quadrant and the correspondent LED 63 Quadrant ll X gt 512 Quadrant X gt 512 Y lt 384 Y gt 384 512 384 Y Quadrant lll X lt 512 Quadrant IV X lt 512 Y lt 384 Y gt 384 Figure 23 Quadrants in the camera s reference system and the LEDs on it As it is shown in the picture to identify the LED 1 the reference object it is needed to find the object outputting from the camera which features BX and BY match with the condition described for the Quadrant lll and select this object as reference The same search for the LED 2 in the Quadrant the LED 3 in the Quadrant Ill and the LED 4 in the Quadrant IV to maintain the order of vectors following for the mat
70. not empty and there is something to read When this is the case the receiver character has to be read from the USRBR and stored in a variable to use it as output of this program to receive The name of this function is UARTS3 Getchar char UART3 Getchar i int c while LPC UART3 LSR LSR RDR 0 c LPC_UART3 gt RBR return c i For the transmission program the bit THRE has to be checked until it is set what means the USTHR register is empty so the Tx FIFO is empty to receive data to send When this bit is set the character wanted to send over the UARTS can be written in the US3THR This character is an input variable of this sending program in this case named c The name of the program is UART3_Sendchar void UART3 Sendchar int c while LPC_UART3 gt LSR amp LSR_THRE 0 LPC_UART3 gt THR c J With the function for the initialization of the UART3 and these two functions to send and receive characters via UART3 a program can be built to communicate with the PAC7001 camera These last functions are needed to first configure the camera sending the parameters for the camera registers and second to receive the information from what the camera can see 43 5 4 Camera configuration and communication Now start with the camera the configuration and the communication between it and the LPC1758 For knowing how to work with the PAC7001 the datasheet of it is followed To configure the camera in
71. nt CCEMTY In these three functions the field bCmd is for the wanted command code in byte and the bData field is for the byte data to write in the selected command The last is the one used in the function USBHwNakIntEnable 0 to use the Set Mode command as it has been shown before After this preparation process of the USB pins and interruptions encompassed in the UsBHwInit function of the usbhw_lpc library it is the turn of the interrupt handlers With the function USBHwRegisterDevIntHandler HandleUsbReset of the usbhw_lpc library the DEV STAT interruption can be enabled which corresponds with the bit 3 in the USBDevintXx registers This interruption occurs when USB bus is reset USB suspends change or when connect change event happens Now following some internet examples the same of enabling the device interruption is done but with the endpoints interruptions USBHwRegisterEPIntHandler 0x00 USBHandleControlTransfer USBHwRegisterEPIntHandler 0x80 USBHandleControlTransfer With these functions the endpoints interruptions for the EPO and the EP8 are enabled as well as the EP SLOW interruption which is the slow endpoint interruption for endpoints with no priority and established UsBHandleControlTransfer as a handler on endpoint transfers Once this is done the endpoints have to be enabled and configured Configure an endpoint means to realize it to reserve a buffer space for the endpoint and to establish a maxi
72. nted in Figure 16 http www ilensw asn au items 6795 http www cultofmac com 147506 dutch inventor creates specialized accessories for ipad users with disabilities 27 28 Figure 16 Head tracking devices Source 26 27 To the mouse click function there are different possibilities depending on which head tracking device is used With some systems peripherals buttons can be added to act as the common mice buttons others can interpret that if the cursor is stationed on an icon during a predefined time it means that the user wants to click here or making another assigned mouse function It can be combined with blink systems that recognize the blinks of the user and translate them in mouse buttons functions depending on how it has been configured It is really interesting to combine this head tracking system with the on screen keyboards previously described so the user can both control the cursor of the mouse and write only moving his head 3 3 2 Eye tracking Eye tracking systems work similar as the head tracking system Eye tracking is the process of measuring the point of gaze where the user is looking or the movement of the eyes related to the position of the head To use this technology to help disabled people to interact with computers the system consists of a camera pointing to the user s eye and a software that translates the movement of the eye or the place of the screen where it is looking at into movement of the
73. o the cursor is needed to be sent As it was said before this movement is controlled by the variables of the HIDDMouselnputReport structure a value to these variables is given depending on the state of the joystick The X axis is the horizontal axis and the Y is the vertical axis and the movement of the cursor for each movement of the joystick is 10 units positives when moved right and down and negatives when moved left and up The comparison with the parameters and the corresponding send of movement orders are in a loop together with the USB interrupt handler to call them continuously One of these blocks of comparison and send movement orders for the UP state of the joystick is if i JoystickState amp JOYSTICK UP MouseInputReport bY 10 MouseInputReport bX 0 MouselInputReport bmButtons 0 So finally the program is done It is needed to integrate the eStick2 in the XPresso Base Board make relevant connections and at the end the pointer of the mouse can be moved with the joystick of the Board It is concluded that the USB connection works and the instructions for the mouse too and they will be needed for the main program of the head tracking system 37 5 2 2 USB Program Send Receive characters Now another program for the USB communication is done to receive characters via USB from the keyboard of the computer and to send these characters back to the computer and show them in the screen something that will be help
74. o his value so if the a button of the keyboard is pushed the program will send back a b Put the VCOM putchar function in an IF loop where the program gets in if the variable is not EOF while 1 c VCOM getchar if c EOF VCOM putchar c INCREMENT ECHO BY J J To see the characters back in the computer a hyper terminal is used In some Windows systems the hyper terminal is not included so a free version can be downloaded as Hyper Terminal Private Edition For the proper functioning of the hyper terminal and the detection of the USB cable from the USB device of the LPC1758 in the eStick2 to the computer when it is required Windows has to be directed to a special file which is found in examples in internet usbser inf With this file Windows creates an extra COMX port for the mentioned connection that can be opened in the hyper terminal To see the treated characters that are sent back from the program as well as the typed characters is necessary to configure the hyper terminal The hyper terminal should be set to append line 39 feeds to incoming line ends and to echo typed characters locally so the typed characters can be compared with the treated ones and check that the program works 5 3 UART Connection Once the USB connection is done is turn of the UART connection As it was done with the USB the manual of the LPC1758 is followed to establish the connection It is needed to remember that the phy
75. of Contents 2 1 2 2 2 3 2 4 3 1 3 1 1 3 1 2 3 1 3 3 1 4 3 1 5 3 2 3 2 1 3 2 2 3 2 3 3 2 4 3 2 5 3 3 3 3 1 3 3 2 9 1 9 2 9 2 1 9 2 2 5 3 ODC IVE OFC ONG CC enee E E E E EA 5 Components of the Proje ct cccccsecccseccccsececeececeeeeceusesseeeeseueessueesseeesseeesseeesees 6 A O a 6 LPOXPRHESSO Base Boadas E 7 gien iEuu cec m 7 SEO TLEDS aaa eee E eee ee ee ee eee 12 State ol ME 3 13 KODO OS ETE 14 Expanded ING OO AN MNT RR REEL 14 ORS Hae Ky OC AC MN E D OO TT 14 Ergonomic KeyboardS ssesssesssssssseseese nennen nennen nnne nnn nnne nna nnne nnns 15 On screen keyboard seessssessssssssesssesee nennen nnn nnns nsn nnns nnn nn 16 TINS Ty CS P 17 NANG SAG VOW SUNG EIE TOT 18 Ergonomic mice and joysticks oocccccccocnccocnconnnnncnconcnnnnnonncncnnnononnnnncnnnnnnnnnnonors 18 e A 19 guis 19 Special OVSUCAS asii 20 Headpointers and mouthsticks ococccccoccccncnconcnnncnccncnnnanonnnnonanononnnnncnnnanonnnnonons 21 WAC IS SUIS serere hese cctools atatum ameet du acond 21 Head CACHING EETA E E A TT AE TT 21 EVO MAGO EE T 22 CIN WY OU ERE 24 Development of the Head Tracking System cccecccseeeseeeeceeeeseeeseeeeseeesaeeesee
76. ork and it is necessary to plug and unplug until it worked or simply is needed to switch off the computer and start it again That problem slows down a lot the programming of the software because it cost a lot to connect with the debugger to check the code It will be important to discover the origin of this problem to avoid it in the future The part of the USB connection was not so difficult and can be easily done following the user manual of the LPC1758 The manual always is a very good help and it had to be followed during all the programming Previous programs are done to know how the connection worked and finally adapt them to the program that wanted to build So it was good to take previous little steps before facing the main problem Most of the problems came with the programming of the camera The first datasheet was not complete to configure well the camera or ranges that each registers can be set so the first configuration that could be done was not so good Finally with the second datasheet there was a better idea about how to set the registers and doing different test it is concluded that the Gain1 and Gain2 registers of the camera have to be set to 15 and O respectively But then came the part of data reception from the camera where strange things with the value of the X and Y coordinates of the objects are discovered They supposed to be between O and 1024 the X coordinates and between O and 768 the Y but sometimes higher values ap
77. ot of devices which can be used to make different programs for the microcontroller that is wanted to be integrated in the board So it is possible to get started with experiments and with the operation of a microcontroller Different standards of communication can be learnt to manage and use this board and it is the way used in the study to start working with the LPC1343 and the LPC1 758 Figure 2 LPCXpresso BaseBoard Source 2 2 3 PAC7001 camera The camera used for the head tracking systems is a PAC7001CS from the PixArt Imaging Inc Company According to the datasheet it is an object tracking sensor MOT sensor a motion tracing application specific integrated circuit ASIC with high quality CMOS image sensor DSP and UART protocol This sensor can track up to four objects http www embeddedartists com products lIpcxpresso xpr_base php upna 7 smartly with sub pixel accuracy and output the objects features like center coordinates or the object size These output features of the objects can be transferred to an external processor in this case to the LPC1758 microcontroller through UART interface The specifications of the sensor are in the datasheet and are exhibited in Tablet Specification Power Supply Array Elements Optical Format Pixel Size System Clock PGA Gain Frame Rate Scan Mode Output Interface UART Baud Rate Object center coordinate resolution Package Values Sn 128 x 96 1 10 11um x 11um
78. peared A sweep is done with a light to discover what happened and finally the problem with the 8 bit of the variable is figured out and it is solved before starting with the POSIT algorithm Another problem that appeared is that the first and second blocks of data taken from the camera had strange values that confused the process that relate each object captured by the camera with each of the LEDs in the set so this process and the POSIT algorithm are started after two buffer filling The implementation of the POSIT algorithm was easily done following the instructions in the paper of DeMenthon and Davis and then the movement of the mouse is done with the obtained k vector from the POSIT The movement of the cursor cannot be done properly in the entire screen The causes can be the problems with the reception by the camera of the four LEDs and their later treatment the obtaining of erroneous data possible errors in the sending of the data from the camera to the LPC or the implementation of the movement code As conclusion can be said that with these components the head tracking system cannot work well for the wanted objective The LPC1758 is fast enough to receive the data from the camera process it and send the mouse s pointer movement to the computer in a short time but the problems come with the set of LEDs and the camera 71 As it was seen in the realized tests with different gains and distances between the set and the camera the longest
79. pment of the Head Tracking System Beginning with the program that manages the head tracking system the first problem that had to be solved is the connection between the LPC1758 integrated in the eStick2 the PC and the camera The connection with the PC had to be done via USB with the mini USB port of the eStick2 controlled by the LPC1758 and one USB port of the PC and the camera requiring connection via UART The USB connection can be easily done with a standard mini USB to USB cable as the ones used for smartphones but for the UART connection a system to connect the camera to the eStick2 had to be made 5 1 Hardware Taking the camera out of its box one can see that it has six pins It is necessary to look what they are for and connect them to the correct pins of the LPC1758 microcontroller through the pins of the eStick2 On one side of the row of pins of the camera there is a picture of a square This pin corresponds with the 3 3 volts supply and from this side to the other the pins are for UART transmission UART reception reset oscillator and the ground in that order Once the pins are identified the corresponding pins in the eStick2 have to be localized and linked to the first To make better connections a support with a holed board is built so the necessary bases to hold the camera and the eStick2 in the board are soldered on to it Once the bases are added to the board the correct pins of the eStick2 must be carefully identified
80. posed by four bytes which are OxFF 0x00 OxFF and OxFF in that order so this succession of bytes has to be found to localize the features of the four objects in order For doing that a variable is declared and equated to the pbGet pointer to go with it across the buffer which contains the data from the camera in search of the header In a While loop this variable is compared with 255 the decimal value of OxFF the variable pointer is advanced the new value is compared with 0 from 0x00 advanced it again compared with 255 and so on until these four values are found followed and then is when the loop is left Once the header is located as the program is for general cases the buffer has to be checked to see if all the wanted information with the data from the four objects is on it The size of the buffer is 64 and each object has 9 bytes of information with the header are 40 bytes that must be together The pbGet pointer is pointing to the first byte of the header after the search of the succession so the current position of the pointer plus 40 is compared with the 64 bytes of size of the buffer to check that everything is in the buffer Now that is sure that the features of the objects are all followed and together in the buffer starts their identification recognition of what type of feature is In the datasheet is shown the order in which the camera output the information of each object and it is collected in Table 8 Received Byte
81. r ACK Check Device OxEA Tracking VO1 Set Register 0x10 Register Number 0x10 Register Value Read Register 0x11 Register Number Register Value High Byte First Switch to Operation 0x8D 0x8D Mode Table 6 Set camera modes As it is shown to set a register first 0x10 has to be sent to the camera following by another message with the number of the register wanted to be set and then another message with the value wanted to be introduced in the selected register Notice that the camera generates an ACK with every command it receives Looking at the system to setting a register a function is made to do it directly CameraSet char RegNum char RegValH char RegValL where RegNum is the number of the register to set RegValH is the high byte value for those registers that have two value bytes and RegValL is the low value for these registers or the unique value for those register with only one byte value In the function the first step is send a 0x10 to the camera to indicate that a register is going 44 to be set and then continuing with the sending of the RegNum RegValH and RegValL values with the UARTS sendchar function to select the registers and the proper values But the camera needs a time to process the information and the messages cannot be sent one after the other without waiting a little so the function Delay int secs is used The field secs is for a number which is multiplied by 1000 and then the function entered in
82. r displacement along the Y axis attribute packed HIDDMouseInputReport Once the structure is defined it is necessary to initialize it and it is done with the function HIDDMouseInputReport_Initialize HIDDMouseInputReport report where report is the name given to the structure in this case MouselnputReport This function equals to O the three variables of the structure so they are initialized The variables that control the cursor movement are prepared but remain the joystick controls Looking at the pinout of the eStick2 it is seen that the joystick is controlled by the pins 2 0 2 1 2 2 2 3 and 2 4 in the corresponding function GPIO Port Here in Table 4 is the list of the controls Press Joystick GPIO Port 2 0 Joystick Right GPIO Port 2 1 Joystick Up GPIO Port 2 2 Joystick Left GPIO Port 2 3 Joystick Down GPIO Port 2 4 Table 4 Functions for the joystick program Now that it is known which pins control the joystick a function to check is made in the FIOPIN register of the port 2 the bits corresponding with these pins The current state of digital pins can be read from the FIOPIN register so if the joystick is moved to the right the bit 1 of the FIOPIN register of the port 2 is set and if it is moved to the left the bit 3 of this register is set The bits from O to 4 in the FIOPIN register are checked and then put them in order in one byte invert this byte and pass it with an AND operator through a m
83. rent LEDs will set on o0 with these programs the registers of the pins and their configuration are known which is an important thing prior to establish a communication with the peripherals devices The libraries are beginning to be used how to call them and use them for example the LPC13xx library and inside it how to work with the GPIO exploring the possibilities it gives us Once the functioning of the LPC1343 is known and the elements integrated in the eStick2 controlled by the microcontroller are used the work with the LPC1758 can be started where the programs will be more extensive and complete The LPC1758 is integrated in the eStick2 but it does not control the rest of integrated devices in the platform however it is connected to the pins of the stick The eStick2 can be combined with the Xpresso Base Board so that the LPC1758 can manage the board and the elements that are contained in it In order to start using the LPC1758 putting the stick in the Xpresso Base Board and programing in Eclipse a series of instructions have to be followed to run these programs To be able to use and debug an application running on the LPC 1758 the LPC1343 has to be configured as a remote debugger Once the debug has been flashed on the LPC1343 and the instructions to configure the Eclipse are followed the programs can be written and tried The LPCXpresso Base Board gives an extensive field testing and different communication standards can be tested
84. rix A Now there is a problem with the data received as the X and Y coordinates of the different objects as it was described previously The most significant value of the low byte of X and Y does not change it is always 0 and it must not be taken into account to store the value of the coordinates So it is needed to skip it and put together the two resulting parts of both X and Y variables the part of the left of the bit and the part of the right This is done with the following commands obtaining the wanted and correct values in the variables Xvar and Yvar U16 Xvar 0 Yvar 0 a 0 b a Data cont BX amp 127 b Data cont BX gt gt 1 Xvar b a a Data cont BY amp 127 b Data cont BY gt gt 1 Yvar b a Finally values for the coordinates that will be in the expected ranges are obtained from O to 1024 for X coordinate and from O to 768 for the Y coordinate Once the data is 64 treated it can be compared to place the objects in the different quadrants and estimate which LED is the studied for cont cont 4 cont U16 Xvar 0 Yvar 0 a 0 b a Data cont BX amp 127 b Data cont BX gt gt 1 Xvar b a a Data cont BY amp 127 b Data cont BY gt gt 1 Yvar b a while Xvar 0 Yvar 0 if Xvar lt 512 if Yvar lt 384 Quadrant III Xcenter Xvar Match with LED 1 reference LED Ycenter 0 Yvar
85. s and continues with the UART3 initialization and the code described for the configuration of the camera and the collect and store of data from the camera After that comes the POSIT algorithm as it is described in the previous point and when the rotation matrix is obtained it is used to move the mouse First of all it is important to understand how the mouse works In the descriptor the movement of the mouse is changed from relative to absolute because it is wanted to move the pointer where the user is looking at in the set extrapolated it to the screen After that the structure MouselnputReport is used like in the joystick program to check how the pointer moves along the screen Finally it is realized that with the present descriptor the pointer moves in the screen from O to 127 in the X axis and from O to 127 in the Y axis with both Os in the upper left corner To move the pointer different proves are done with the vectors of the rotation matrix All the components of the matrix have a range between 1 and 1 so they can be negative and the maximum absolute valor is 1 Different pairs of components of the same vectors are tried to move the pointer one for the X axis of the pointer and one for the Y axis To translate these components into coordinates it is needed to obtain the absolute value of the component and multiply it by 127 to get a coordinate according to the ones used in the movement of the mouse as have been seen previously
86. s from the camera in order of arrival Flag Byte Object Flag Byte X High Byte X Low Byte Y High Byte Y Low Byte Size High Byte Size Low Byte EOB Table 8 Order of arrival of bytes from the camera As the sequence of arrival is known the data is going to be identified and stored as it is needed To do that there is the ProcessData function In this function the mentioned Data array and the pbGet pointer are introduced as input variables where as it was said pbGet is pointing to the first byte of the localized header in the buffer Inside the function the first step is to remove the bytes of the header and advance along the buffer until the pointer is on the first byte of information of the first object In this moment a loop is started to take every feature of each object and put it in the Data array each object in one of the elements of the array and every type of characteristics in their corresponding variables of 49 the structures in each element of the array So the loop goes from 1 to 4 going through the elements of the Data array and following the order of arrival storing the features in the correct variable and advancing through the buffer The complete ProcessData function is the following void ProcessData obj object unsigned char buffer unsigned char tmp tmp buffer head 0 tmp head 1 tmp head 2 tmp head 3 tmp for j20 j 4 j ob
87. s packet transfers and the function gives the HandleFrame as callback function too Once the handlers are prepared the USB has to be connected This is done with the function USBHwConnect TRUE so that with TRUE a 0 is written in the connect bit bit 0 of the Set Device Status command It means that the CONNECT pin go high so the connection with the USB Bus is done When the connection is established and all is prepared a loop is built to call the USB interrupt handler continuously while 1 USBHwISR The USBHwISR function which is the USB interrupt handler is included in the usbhw_lpc library With all of this the program of the USB connection is finished The describe functions developed are in the different libraries such as usbstdreq usbinit usbhw lpc or usbcontrol and the handlers are described in the actual USB connect program 5 2 1 USB Program Joystick To check that the USB connection works properly a program is built that will help later in the aim of moving the pointer of the mouse with the PAC7001 camera respect to the set of LEDs A mouse joystick is going to be configured with the joystick of the LPCXpresso Base Board managed by the LPC1758 and connected to the computer via USB The previous USB program is used but it must be adapted to act as a mouse attending to the movement of the Board joystick One of the changes is in the descriptor of the USB device is in the interface field of the descriptor th
88. saeesseeeseueesueesaneesseesaes 61 Figure 22 Set of LEDs and the position of them cccooccccccncoccccncnconcnnonnnoncncnaconnnncnnrnnnanonos 62 Figure 23 Quadrants in the camera s reference system and the LEDs on it 64 78 List of Tables Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Specifications of the PAC7001 occcoccnccccnccccnnccncnccnnnnonnnnononnnonnnnonnnnnnnnnnnnnnnnonaninonons 8 Rea Isis On TIC PACTO mm 10 SIE CONAN AS ricino iaaaienanaeanasaed 30 Functions for the joystick program c ccccseecceeeeceeeeseeeseuceceeeeaeeeseueeseesauseseeesees 36 Description of the LCR seessssssssssseeeneeennnn nennen nnnm nnne nnne nnne nnns 41 OC Kel IM Op O NETTO OTT 44 OxOF register of the camera select the features to receive 47 Order of arrival of bytes from the camera cccoocncccccnccncnnccncnonncnnnnnnnonacnnnnnnnnnncnnnnnns 49 Distances between PAC7001 and the LEDs to capture 4 objects according to the values of Gain1 and Gaiin2 2 2 2 cece cccccccccccccccccecececcccacccececeaeceucuceneaeaeaceteceauauseeueneavansesneneanas 60 79 A LPC17xx Microcontrollers User Manual This appendix contains the direction for the LPC17xx User Manual which is followed during all the programming of the LPC1758 and the development of the head tracking system The User Manual can be localized in the website of the NXP Co
89. sical links are done with the UARTS pins so it is necessary to configure the UART3 registers to set up well the connection First the bit PCUARTS in the register PCONP has to be set up to turn on power to UART3 This bit is the number 25 of the register and it is saved in the parameter PCUART3 POWERON so power on is done with the instruction LPC SC PCONP PCUART3 POWERON Then the peripheral clock for the UART3 is needed to be selected which is in the PCLKSEL1 register The corresponding bits for the PCLK UARTS3 are the bits 18 and 19 of this register and depend on the values of these bits the clock is set in one way or another with respect to the core clock CCLK So that a 00 means the PCLK is equal to CCLK 4 a 01 means PCLK CCLK a 10 PCLK CCLK 2 and 11 PCLK CCLK 8 In this case the clock is set to a of the core clock so first clean the PCLK UARTS bits of the PCLKSEL1 register and let them with a 00 value LPC SC PCLKSEL1 amp PCLK_UART3_MASK LPC_SC gt PCLKSEL1 0 lt lt PCLK UART3 Now the UARTS pins have to be selected in the correct function setting them in the PINSEL register The pin who controls the UARTS transmission is the P0 0 and the one for the UARTS reception is the PO 1 so both are in the lower half of the Port 0 that means this functions are controlled by the PINSELO register In both cases the wanted function to operate the pins as UARTS transmission and reception respectively is the function
90. side this function void USBHwNakIntEnable U8 bIntBits USBHwCmdWrite CMD DEV SET MODE bIntBits What it does is write the value blntBits 0 in this case in the command Set Mode CMD DEV SET MODE OxF3 of the SIE The SIE is the Serial Interface Engine and it handles the transfer of data between the endpoint buffers in EP RAM and the USB bus so it controls what is read from and is written in the endpoints buffers The functions of this 29 block include synchronization pattern recognition parallel serial conversion bit stuffing de stuffing CRC checking generation PID verification generation address recognition and handshake evaluation generation These commands as the Set Mode are used to access to the registers and functions of the SIE and consist on a command code followed by optional data bytes Two registers are used for this access USBCmdCode and USBCmabData The USBCmdCode register is divided in CMD PHASE from bit 8 to 15 and CMD CODE or CMD WDATA from bit 16 to 23 In the CMD PHASE there are 3 possibilities e Write with the value OxO1 e Read with the value 0x02 e Command with the value 0x05 If in the CMD PHASE field there is Read or Command then the field name is CMD CODE and it contains the code for the command and if there is Write the field is CMD WDATA and it contains the command write data The SIE commands are collected in Table 3 Command name Recipient Code Hex Data Ph
91. t online Available http www coroflot com erikcampbell optical keyboard keyset Accessed 22 10 2013 Walyou jellyfish keyboard online Available http walyou com jellyfish keyboard keyset Accessed 22 10 2013 Computer Posture Ergonomic vertical mouse online Available http www computer posture co uk Tennis Elbow Accessed 22 10 2013 Fentek Zero Tension ergonomic mouse online Available http www fentek ind com zero tension mouse htmzt UICtZH8rj9M Accessed 22 10 2013 University of Oxford iT Services Facilities for Users with Disabilities trackball online Available http www oucs ox ac uk enable index xml ID2mice Accessed 22 10 2013 Assist Ireland BIGTrack Supermouse online Available http www assistireland ie eng Products Directory Computers Hardware Input Dev ices Mice and Mouse Alternatives Trackballs BlGTrack Supermouse html Accessed 22 10 2013 Yanko Design Flip Flop Mouse online Available http www yankodesign com 2010 04 07 flip flop mouse Accessed 22 10 2013 Bilipro foot mouse online Available http bilila com foot mouse slipper mouse Accessed 22 10 2013 Computer mice online Available http www funny potato com computer mice html Accessed 22 10 2013 Turning Point Technology Alternative Mice online Available http www turningpointtechnology com Sx AltMice asp Accessed 22 10 2013 Jaanika Aas online Available http jansapansa blogspot
92. t it captures The process which corresponds with the Initial mode and the configuration of the camera registers is ended now starts the Operation mode part with the collection of data from the objects the adequate treatment of them and their shown in the hyper terminal First two pointers are declared pointing to a buffer one of these pointers is pbGet and the other pbPut In this buffer the collected data from the camera will be stored with the pbPut pointer go over the buffer and saving the data coming from the camera on it and the pbGet pointer taking this data to showing it in the hyper terminal Apart from these pointers a structure is declared to store the features of the detected objects when they have been selected and identified from the buffer This structure contains all the types of features that the camera could send of each object As the camera will send information of four different objects four of these structures are needed which will be saved in an array of four elements called Data The structure is typedef struct U16 BX U16 BY U16 Size U8 FlagByte U8 ObFgBy U8 EOB obj These components of the structures in each one of the four elements of the array Data have to be initialized This is just put their values equal to 0 and this is done with the function Datalnit putting the Data array as input of the function After this is done an infinite loop is started with the instruction whi
93. t of USBDevintSt This part always must be done and when this is accomplished clear CCEMPTY again If the purpose is read the same command code has to be put as well as the sequence 0x02 Read in the CMD PHASE field Then wait until the bit 5 of USBDevintSt CDFULL is set that means there is data to read in the USBCmdData register clear the CDFULL and save the data from USBCmdData wherever is wanted If the purpose is to write put in the CMD WDATA field the wanted data to write and in the CMD PHASE the sequence 0x01 Write Then wait until CCEMPTY is set in USBDevintSt and clear it There are some functions in the libraries to do what is described here static void USBHwCmd U8 bCmd clear CDFULL CCEMTY LPC_USB gt USBDevIntClr CDFULL CCEMTY write command code LPC USB USBCmdCode 0x00000500 bCmd lt lt 16 Wait4DevInt CCEMTY j This function manages the first part described the common for write and read with the wanted command selection The following is the function for the read mode static U8 USBHwCmdRead U8 bCmd write command code USBHwCmd bCmd get data LPC USB USBCmdCode 0x00000200 bCmd 16 Wait4DevInt CDFULL return LPC USB USBCmdData And this is the function for the write mode static void USBHwCmdWrite U8 bCmd U16 bData write command code USBHwCmd bCmd write command data LPC USB USBCmdCode 0ex00000100 bData lt lt 16 Wait4DevI
94. t when interpolating higher coordinate resolution 1024x768 and the noise will be easily came in The suggested value in the datasheet is 3 so this value is the used one Finally the registers setting is finished but once this was done and the entire program was completed nothing is received from the camera there were not features of the objects in the hyper terminal That was because of the baud rate At first the baud rate was very low to configure the registers of the camera but to the outputting of the features of four objects and the collecting of them by the LPC1758 a higher baud rate is needed So afterwards setting the register Ox1B the register 0x11 has to be set because this register controls the baud rate After several tests with different baud rates finally is prove that the best value for it is 115200bps which corresponds with the value 5 of the register 0x11 so this value is introduced to the register For the proper operation of the connection between camera and microcontroller the UART3 of the LPC1758 has to be re initialized but with the new baud rate value Once the baud rate is set correctly the camera has to be changed from the Initial mode to de Operation mode to start with the output of the objects features To do this with the function UARTS3 Sendchar the value Ox8D is sent to 47 the camera In this mode the registers cannot be changed and the camera starts to produce the features of the objects tha
95. talogo_producto teclado expandido Accessed 22 10 2013 4 Geekets big keys keyboard online Available http www geekets com 2009 02 Accessed 22 10 2013 5 Tested Alternative keyboards online Available http www tested com tech 280 alternative keyboard layouts why are you still using qwerty Accessed 22 10 2013 6 Carly Googles One handed keyboard online Available http carlygoogles blogspot com es 201 1 02 has anyone invented one handed keyboard html Accessed 22 10 2013 7 Ounae Maltron keyboard online Available http ounae com maltron keyboard Accessed 22 10 2013 8 Enable mart alternative keyboards online Available http www enablemart com catalogsearch result q alternative keyboards Accessed 22 10 2013 9 Orbitouch online Available http orbitouch com Accessed 22 10 2013 10 X Safe bit virtual keyboards online Available http www safebit net screenshots safebit disk encryption software screenshot virtual keyboard html Accessed 22 10 2013 11 Aureo soft see and type online Available http www aureosoft com see and type html Accessed 22 10 2013 12 X Demotix foot keyboard online Available http www demotix com news 1 758185 foot keyboard unveiled gajah mada university disabled users all media Accessed 22 10 2013 74 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Coroflo
96. that can be configured as either Host Device or OTG 8 channel general purpose DMA controller 4 UARTs 2 CAN channels 2 SSP controllers SPI interface 2 I C bus interfaces 2 input plus 2 output I S bus interface 6 channel 12 bit ADC 10 bit DAC motor control PWN Quadrature Encoder interface 4 general purpose timers 6 output general purpose PWN ultra low power Real Time Clock RTC with separate battery supply and up to 52 general purpose l O pins In the case of the used system the LPC1758 is integrated in the eStick2 The eStick2 presented in Figure 1 is a low cost powerful embedded computing platform and has been developed in the context of the MA23 funded project Embedded Platforms at the FH Technikum Wien Figure 1 eStick2 Source 1 http www nxp com documents user manual UM10360 pdf https cis technikum wien at documents bel 3 ess semesterplan estick2 estick2 htm The eStick2 provides a compatible interface to the LPCXPRESSO Base Board from Embedded Artist Power is supplied to the eStick2 board via a standard micro USB cable as used by almost all smartphones nowadays 2 2 LPCXPRESSO Base Board The LPCXpresso Base Board is a useful tool when prototyping work is needed or to learn more about a certain microcontroller It works with the LPCXpresso boards and with the mbed module and it is also compatible with the eStick2 used in this research The LPCXpresso Base Board it is shown in Figure 2 and contains a l
97. the FIFO get the data from it write this data into an intermediate buffer to send it later to an endpoint and control the NAK interruptions For the endpoint of the incoming data BULK IN DATA Bulkln is selected as handler which controls the getting data from an intermediate buffer This buffer has data from the endpoint which transmits and the handler put the data into a FIFO The form to register a handler for an endpoint is USBHwRegisterEPIntHandler U8 bEP TFnEPIntHandler pfnHandler Where bEP is the field for the number of the endpoint and pfnHandler is the pointer to the handler The endpoints handler functions are USBHwRegisterEPIntHandler INT IN EP NULL USBHwRegisterEPIntHandler BULK OUT EP BulkOut USBHwRegisterEPIntHandler BULK IN EP BulkIn Now is turn of the frame handler Select USBFrameHandler with the USBHwRegisterFrameHandler which points at this handler as frame handler After that the interruptions have to be activated when both successful and NAK transactions occurs in an input endpoint This is done setting the bit 5 in the Set Mode command and this is done with the function 38 USBHwNakIntEnable U8 bIntBits Where bintBits is the byte wanted to be written or the bits wanted to be set in the SET MODE command With USBHwNaklntEnable INACK Bl where INACK Bl is 1 5 0x20 the bit 5 is set and these desired interruptions are activated Once the interruptions are enabled it is neede
98. the wanted way a series of commands are sent in a specific order but first of all the mode of the camera has to be changed When the camera is power on it starts in an Initial mode as a default mode The first thing that has to be done is send the command Check device which is done sending the hexadecimal value OxEA With this command the chip of the camera starts is a kind of password for it Then all the wanted registers can be set up or read but for this a combination of instructions has to be followed After the work with the registers is done the camera has to be switched to the Operation mode sending the data Ox8D to the camera Once the PAC7001 has entered this mode it starts to output the objects features it sends determined characteristics of the object that capture to the microcontroller In this case send means that the microcontroller takes this information from the camera with the previously described function UARTS getchar To get out of this Operation mode and the output of data from the camera Ox8E is sent to the PAC7001 and it will go back to the Initial mode The sending of data from the microcontroller to the camera is done with the function UARTS3 sendchar to work with the registers Now in Table 6 the described process to access to the modes of the camera is presented and the instructions that have to be followed to set or read the registers of the PAC7001 Command Order Command Content Senso
99. two on screen keyboards in Figure 9 Virtual Keyboard WII tLe JILL LJ Lee J Pup M EL Cus Js Gs JE EEG JEJE OG JC em nnb Ct JO EN eo OOO j Cancel http orbitouch com 16 Esku Figure 9 On Screen keyboards Source 10 11 3 1 5 Other types There are lots of other types of keyboards Figure 10 so useful to people with disabilities There are keyboards to handle with feet for those who cannot use their hands They are larger than the common keyboards to reach each key without problems of space There are also keyboards which do not look like keyboards They have only a few keys and can be handled with one hand and the combination of these keys can generate the characters of a usual keyboard They are suitable for people with problems moving their arms shoulders or with back problems http www safebit net screenshots safebit disk encryption software screenshot virtual keyboard html http www aureosoft com see and type html upna m vados atu dil Figure 10 Different types of keyboards Source 12 13 14 3 2 Mice and joysticks 3 2 1 Ergonomic mice and joysticks The normal design of mice and joysticks can be harmful for people with joint problems or other similar diseases Therefore there are lots of different forms and models for these devices making them suitable for the people with these ailments A large variety of ergonomic mice can be
100. wanted matrix the A matrix are 62 11 85 0 A 11 0 9 0 65 9 Once the A matrix is formed his pseudoinverse matrix has to be taken the B matrix The pseudoinverse matrix equation is A A A A B 3 The result of that operation is 1 1 1 22 22 22 1 1 1 B4 2 o ao 17 17 17 1 1 1 18 18 18 Once we have the two matrixes the epsilonO has to be initialized as it is said in the paper There are 3 epsilonO as vectors in the A matrix and they have to be equalized to 0 at the beginning of the loop of the POSIT algorithm When this is done first both the image vector x and image vector y have to be computed with 3 coordinates one for each one of the objects that there are excluding the reference object The name for these vectors in this case is Xim and Yim and the form of the coordinates that make them is Xim X 1 epsilonO Xo Yim Y 1 epsilonO Yo 4 Where Xo and Y are the BX and BY features of the reference object and X and Y the same features of the rest of the object with i 1 2 3 corresponding with LED 2 LED 3 and LED 4 respectively But in this point there is a problem because is not known to which of the four LEDs correspond the features sending by the camera as the first object the same happened with the second third and fourth object So before starting with the image vectors the data has to be identified which of the objects outputting by the camera refers to the reference LED a

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