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VG400 Series User`s Manual

1. VG400 Series User s Manual Crossbew Table 4 VG400 Series Data Packet Format Byte VG M de Scaled Sensor Mode Voltage Mode 0 Header 255 Header 255 Header 255 1 Roll Angle MSB Roll Angular Rate MSB Roll Gyro Voltage MSB 2 Roll Angle LSB Roll Angular Rate LSB Roll Gyro Voltage LSB 3 Pitch Angle MSB Pitch Angular Rate MSB Pitch Gyro Voltage MSB 4 Pitch Angle LSB Pitch Angular Rate LSB Pitch Gyro Voltage LSB 5 Roll Angular Rate MSB Yaw Angular Rate MSB Yaw Gyro Voltage MSB 6 Roll Angular Rate LSB Yaw Angular Rate LSB Yaw Gyro Voltage LSB 7 Pitch Angular Rate MSB X Axis Acceleration MSB X Axis Accel Voltage MSB 8 Pitch Angular Rate LSB X Axis Acceleration LSB X Axis Accel Voltage LSB 9 Yaw Angular Rate MSB Y Axis Acceleration MSB Y Axis Accel Voltage MSB 10 Yaw Angular Rate LSB Y Axis Acceleration LSB Y Axis Accel Voltage LSB 11 X Axis Acceleration MSB Z Axis Acceleration MSB Z Axis Accel Voltage MSB 12 X Axis Acceleration LSB Z Axis Acceleration LSB Z Axis Accel Voltage LSB 13 Y Axis Acceleration MSB Temp Sensor Voltage MSB Temp Sensor Voltage MSB 14 Y Axis Acceleration LSB Temp Sensor Voltage LSB Temp Sensor Voltage LSB 15 Z Axis Acceleration MSB Time MSB Time MSB 16 Z Axis Acceleration LSB Time LSB Time LSB 17 Temp Sensor Voltage MSB Checksum Checksum 18 Temp Sensor Voltage LSB 19 Time
2. 17 3 9 3 Scaled Rate Sensor Voltages cece cee ese cseereeeeeeeeeees 18 3 9 4 Stabilized Pitch and Roll Voltages Angle Mode Only 18 4 VG400 Series Operating Tips eee ee cee eeseeeeceeecesecnaecseecseeeaeeeaes 19 4 1 Mounting the VG400 Series Ll anna eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeees 19 4 2 VG400 Series Start Up Procedure 0 eee eee anna eeeceeeeeeeeeeee 19 5 Appendix A Mechanical Specifications u sssnserer seerne rrererenee 20 5 1 VG400CA Outline Drawing 0 0 eee eeeeeceeeeeceseeeeeeeeeeeseeneeeees 20 Doc 7430 0002 03 Rev B Page i Crossb w VG400 Series User s Manual 5 2 VG400CB Outline Drawing namna nanananananawaaanssnwasnnssnassnans 21 5 3 VG400CC VG400CD VG400MA and VG400MB Outline DDT AWTS ys NAAN AANGAT PA APA n AA 22 6 Appendix B VG400 Series Output Quick Reference uson 23 6 1 Analog Output Conversion u sssesesseerree rese rense ne renerne 23 6 2 Digital Output Conversion u u u ssssesserererrerrerse nerne sener snssnnsnn 23 7 Appendix C VG400 Series Command Quick Reference 24 8 Appendix D VG400MA and VG400MB Addendum aasa 25 9 Appendix E Troubleshooting Tips eee eee anna swnswna suno anas renerne 26 10 Appendix E Warranty and Support Information 28 10 1 Customer SOrvice anna bi KANE KANAN Ann Naia aa 28 10 2 Contact Directory a AGA Baa EEE Lasa aan 28 10 3 Return Procedure a naan era a 28 10 3 Authorization ies
3. 3 9 2 Scaled Accelerometer Voltage Scaled Sensor Mode In scaled mode the DMU will create scaled analog accelerometer voltages on pins 12 14 These analog voltages reflect any calibration or correction the DMU applies to the accelerometer data The analog voltage is created by an internal D A converter using the digital data available to the DSP The data is scaled to the range 4 096 V with 12 bit resolution You do not need to use the calibration data that came with the DMU to use these outputs the DMU is already applying the calibration stored in its EEPROM to the data To find the acceleration in G s use the following conversion accel G GR 1 5 Voud V 4 096 V where accel is the actual acceleration measured V out is the voltage at the analog output and GR is the G range of your sensors The G range is listed Doc 7430 0002 03 Rev B Page 17 Crossb w VG400 Series User s Manual on the calibration sheet For example if your DMU has 2G accelerometers GR is 2 3 9 3 Scaled Rate Sensor Voltages The DMU will output analog voltages representing the rate sensor measurement on pins 8 10 in both scaled sensor mode and angle mode The analog outputs for the angular rate signals are not taken directly from the rate sensors they are created by a D A converter internal to the DMU The output range is 4 096V with 12 bit resolution The analog data will represent the actual measured quantities in engine
4. turns greater than 0 5 sec Normal Mode The tighter turn criteria however is essential for standard operation therefore a transition command has been added that transitions the turn criteria algorithm back to the generic VG400CC or CD Normal mode of 0 5 sec This extra user command switches the Kalman Filter algorithm from Marine to Normal mode The command structure is as follows Command Set into Normal Mode Character s Sent T lt x gt Response t Description The T command sets the unit into Normal mode The argument of the command lt x gt is a single binary byte that the DMU ignores and is part of the legacy code any single byte character can be sent The switch is one way only and cannot be used to reverse the mode back to Marine When the system is powered back on it will default to the Marine mode Doc 7430 0002 03 Rev B Page 25 Crossb w VG400 Series User s Manual 9 Appendix E Troubleshooting Tips Is the supply voltage and connections okay The VG400 needs at least 9V power supply for proper operation Verify that your power supply is regulated and not current limited Ensure that the supply does not fall below 9V or go above 30V Make sure that all the connections are intact Are you providing enough initialization time gt 1 min You need to let the VG400 warm up for at least 60 seconds when first turned on or upon completion of hard iron calibration This allows the Kalman filter to estimate the r
5. menu 3 Select the type of display you want under the menu item Windows Graph displays a real time graph of all the DMU data FFT displays a fast fourier transform of the data Navigation shows an artificial horizon display 4 You can log data to a file by entering a data file name You can select the rate at which data is saved to disk 5 If the status indicator says Connected you re ready to go If the status indicator doesn t say connected check the connections between the DMU and the computer check the power check the serial com port assignment on your computer 2 4 Take Measurements Once you have configured GyroView to work with your DMU pick what kind of measurement you wish to see Graph will show you the output you choose as a strip chart type graph of value vs time FFT will show you a real time fast Fourier transform of the output you choose Navigation will show an artificial horizon and the stabilized pitch and roll output of the DMU Page 4 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w Let the DMU warm up for 60 seconds when first turned on This allows the Kalman filter to estimate the rate sensor bias Now you re ready to use the DMU Doc 7430 0002 03 Rev B Page 5 Crossb w VG400 Series User s Manual 3 VG400 Series Details 3 1 VG400 Series Coordinate System The VG400 Series will have a label on one face illustrating the DMU coordinate syst
6. sec extended maneuvers close to the range should be avoided Prolonged rates close to the maximum range may result in larger errors due to scale factor errors on the rate sensors Page 26 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w Do you have heavy EMI interference in the environment Heavy EMI interference can cause a bias shift of the rate sensors and hence continuous drift in calculated angles Before you install the VG400 in the system by closely watching the rate sensor outputs you can test the effect of different potential EMI contributors strobe lights microwave transmitters alternators radio modems controllers etc by actually operating them Move the VG400 to a location where effects of such interferences are within the acceptable accuracy Is the vibration isolation adequate Large amounts of vibration will make the accelerometer readings noisy and thereby may affect the angle calculations In addition if the magnitude of the vibration exceeds the range of the accelerometer the accelerometer output can saturate This can cause errors in the accelerometer output and in turn the estimated angles The VG400 must be installed in a location that is rigid enough to alleviate potential vibration errors induced from normal airframe vibration sources You can use vibration isolators if needed to dampen out the unwanted vibrations Doc 7430 0002 03 Rev B Page 27 Crossb w VG400 Series User s Man
7. MSB 20 Time LSB 21 Checksum 3 7 Timing The maximum VG400 Series data update rate is 75 packets per second In some applications using the DMU s digital output requires a precise understanding of the internal timing of the device The processor internal to the DMU runs in a loop collecting data from the sensors processing the data and then collecting more data The data is reported to the user through a parallel process In continuous mode the system processor activity is repeatable and accurate timing information can be derived based purely on the overall loop rate The unit goes through three processes in one data cycle First the sensors are sampled Second the unit processes the data for output After Doc 7430 0002 03 Rev B Page 15 Crossb w VG400 Series User s Manual processing the data the DMU will make another measurement while presenting the current measurement for output Third the unit actually transfers the data out either over the RS 232 port or onto the analog outputs A time tag is attached to each data packet The time tag is simply the value of a free running counter at the time the A D channels are sampled The clock counts down from 65535 to 0 and a single tick corresponds to 0 79 microseconds The timer rolls over approximately every 50 milliseconds You can use this value to track relative sampling time between data packets and correlate this with external timing 3 8 Temperature S
8. NAKA NANA UNA dass eee teens 28 10 3 2 Identification and Protection eeseeesseeseeeeeeereeeeeneeees 29 10 3 3 Sealing the Container eeceeseeeceeeeeceeeeeeeseceeeeeeneeaes 29 1034 Markie saas snes a Bia nah 29 10 3 5 Return Shipping Address 0 eee pnas eseeeeeeeeeeeeeteeeeeeees 29 104 Warianty aan ANA roser 29 Page ii Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossbe w About this Manual The following annotations have been used to provide additional information 4 NOTE Note provides additional information about the topic M EXAMPLE Examples are given throughout the manual to help the reader understand the terminology IMPORTANT This symbol defines items that have significant meaning to the user 6 WARNING The user should pay particular attention to this symbol It means there is a chance that physical harm could happen to either the person or the equipment The following paragraph heading formatting is used in this manual 1 Heading 1 1 1 Heading 2 1 1 1 Heading 3 Normal Doc 7430 0002 03 Rev B Page iii Crossb w VG400 Series User s Manual Page iv Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 1 Introduction 1 1 The DMU Motion and Attitude Sensing Unit This manual explains the use of the VG400 Series of products The VG400 Series of products are a six axis measurement system designed to measure linear acceleration along three orthogonal axe
9. None Change to polled mode Data packets sent when a G is received by the DMU C None Change to continuous data transmit mode Data packets streamed continuously Packet rate is dependent on operating mode Sending G stops data transmission G Data Get Data Requests a packet of data from the DMU Packet Data format depends on operating mode s ASCII Query DMU serial number Returns serial number as String 32 bit binary number v ASCII Query DMU version ID string Returns ASCII string String b Change Autobaud detection Send b DMU responds B baud rate change baud rate send a DMU will send A when new baud rate is detected Page 24 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 8 Appendix D VG400MA and VG400MB Addendum The VG400MA or MB contain firmware that is based on the VG400CC or CD family of products Its operation and user interface is identical to the VG400 The following information is specific only for the firmware present in the VG400MA and VG400MB The VG400MA and VG400MB employ a unique initialization procedure designed to account for power on while under constant sinusoidal motion such as on the surface of the ocean up to sea states 4 5 To accomplish this the initialization algorithm has been set to start with larger gain authority by monitoring turns that are greater than 5 sec only Marine mode as opposed to the generic VG400CC or CD code that monitors
10. Response Description Crossb w Request Data G Data Packet G requests a single data packet DMU will respond with a data packet The format of the data packet will change with the measurement mode Raw Scaled or Angle Sending the DMU a G while it is in Continuous Mode will place the DMU in Polled Mode Query DMU Version v ASCII string This queries the DMU firmware and will tell you the DMU type and firmware version The response is an ASCII string that describes the DMU type and firmware version Query Serial Number S Serial Number Packet This queries the DMU for its serial number The DMU will respond with a serial number data packet that consists of a header byte FF the serial number in 4 bytes and a checksum byte The serial number bytes should be interpreted as a 32 bit unsigned integer For example the serial number 9911750 would be sent as the four bytes 00 97 3D C6 Request Auto Baud Rate b This starts the auto baud rate detection process This will allow you to change the DMU baud rate from its default This change will not affect the default settings Doc 7430 0002 03 Rev B Page 13 Crossb w VG400 Series User s Manual 1 Start with communications program and DMU at same baud rate 2 Send b to the DMU The DMU will respond with B 3 Change the baud rate of your communications program 4 Send a to the DMU The DMU will respond with A at the new baud rate when
11. VG400 Series User s Manual Models VG400CA VG400CB VG400CC VG400CD VG400MA VG400MB Revision B February 2007 a Document 7430 0002 03 Crossbgw Crossbow Technology Inc 4145 N First Street San Jose CA 95134 Tel 408 965 3300 Fax 408 324 4840 email info xbow com website www xbow com 6 WARNING This product has been developed by Crossbow exclusively for commercial applications It has not been tested for and Crossbow makes no representation or warranty as to conformance with any military specifications or that the product is appropriate for any military application or end use Additionally any use of this product for nuclear chemical biological weapons or weapons research or for any use in missiles rockets and or UAV s of 300km or greater range or any other activity prohibited by the Export Administration Regulations is expressly prohibited without the written consent of Crossbow and without obtaining appropriate US export license s when required by US law Diversion contrary to U S law is prohibited 2001 2007 Crossbow Technology Inc All rights reserved Information in this document is subject to change without notice Crossbow and SoftSensor are registered trademarks and DMU is a trademark of Crossbow Technology Inc Other product and trade names are trademarks or registered trademarks of their respective holders VG400 Series User s Manual Crossb w Table of Contents I Introduction s
12. a represents the direct voltage output of the sensors The data is 12 bit unsigned The value for each sensor is sent as 2 bytes in the data packet over the serial interface A single data packet can be requested using a serial poll command or the DMU can be set to continuously output data packets to the host The voltage data is scaled as voltage data 5 V 2 where voltage is the voltage measured at the sensor and data is the value of the unsigned 16 bit integer in the data packet Note that although the data is sent as 16 bit integers the data has a resolution of only 12 bits The DMU rate sensor and angle analog outputs are not enabled in this mode Only the linear accelerometer analog outputs on pins 5 7 are enabled because these signals are taken directly from the accelerometers See the Analog Output section for a complete description of the analog outputs 3 4 2 Scaled Sensor Mode In scaled sensor mode the analog sensors are sampled converted to digital data temperature compensated corrected for misalignment and scaled to engineering units The digital data represents the actual value of the quantities measured A calibration table for each sensor is stored in the DMU non volatile memory A single data packet can be requested using a serial poll command or the DMU can be set to continuously output data packets to the host The data is sent as signed 16 bit 2 s complement integers In this mode the DMU operates as
13. a six axis measurement system The scaled sensor analog outputs are enabled in this mode Note that stabilized pitch and roll angles are not available in scaled sensor mode See the Analog Output section for a complete description of the analog outputs To convert the acceleration data into G s use the following conversion accel data GR 1 5 2 Doc 7430 0002 03 Rev B Page 9 Crossbow VG400 Series User s Manual where accel is the actual measured acceleration in G s data is the digital data sent by the DMU and GR is the G Range for your DMU The data is scaled so that 1 G 9 80ms The G range of your DMU is the range of accelerations your DMU will measure For example if your DMU uses a 2 G accelerometer then the G range is 2 To convert the angular rate data into degrees per second use the following conversion rate data AR 1 5 2 where rate is the actual measured angular rate in sec data is the digital data sent by the DMU and AR is the Angular rate Range of the DMU The angular rate range of your DMU is the range of angular rates your DMU will measure For example if your DMU uses 100 s rate sensors then the AR range is 100 The DMU Kalman filter is not enabled in scaled sensor mode Therefore the rate sensor bias will change slightly due to large changes in temperature and time If the unit is changed from angle to scaled mode the last estimated rate sensor bias values are used up
14. a successful detection of the new baud rate is completed 3 6 Data Packet Format In general the digital data representing each measurement is sent as a 16 bit number two bytes The data is sent MSB first then LSB In voltage mode the data is sent as unsigned integers to represent the range O SV In scaled and angle mode the data generally represents a quantity that can be positive or negative These numbers are sent as a 16 bit signed integer in 2 s complement format The data is sent as two bytes MSB first then LSB In scaled and angle mode the timer information and temperature sensor voltage are sent as unsigned integers The order of data sent will depend on the selected operating mode of the VG400 Series Each data packet will begin with a header byte 255 and end with a checksum The checksum is calculated in the following manner 1 Sum all packet contents except header and checksum 2 Divide the sum by 256 3 The remainder should equal the checksum 4 NOTE The header byte OxFF will likely not be the only OxFF byte in the data packet You must count the bytes received at your serial port and use the checksum to ensure you are in sync with the data sent by the DMU This is especially critical when using the continuous data packet output mode Table 4 shows the data packet format for each mode Page 14 Doc 7430 0002 03 Rev B
15. ate sensor biases The VG400 needs to be held stationary during this initialization process Any rate inputs during this process may cause a constant offset on the rate sensors and in turn a drift in calculated angles The VG400MA and VG400MB however can initialize under sea states up to 4 5 Is the VG400 mounting orientation okay The Pitch angle corresponding to 90 degree orientation are singularity points for the Kalman filter algorithm and you should not let the unit sit in this position for extended periods of time As a result the angles start drifting if you stay at these singularities for long time The longer you keep the unit in a singularity position the longer it will take for the unit to stabilize upon recovery Are you exceeding the range of rate sensors causing the outputs to over range Whenever the maximum range of the rate sensors is exceeded the Kalman filter goes into re initialization mode and saturates the outputs When recovered from this over ranged condition the VG400 resets itself and needs to be steady and level The recovery time may vary from 30 60 second depending on the nature of the preceding maneuvers It is recommended that whenever the rate sensors are over ranged the system is brought back to level and held still for at least 60 seconds before doing any further testing Do you have extended maneuvers close to the maximum range of rate sensors Although the VG400 is rated to operate at 100 or 200 deg
16. avity then rotations around the center of gravity will cause the DMU accelerometers to measure an acceleration proportional to the product of the angular rate squared and the distance between the DMU and the CG The DMU will measure rotations around the axes of its sensors The DMU sensors are aligned with the DMU case The sides of the DMU case are used as reference surfaces for aligning the DMU sensor axes with your system You should align the DMU case as closely as possible with the axes you define in your system Errors in alignment will contribute directly to errors in measured acceleration and rotation relative to your system axes The DMU should be isolated from vibration if possible Vibration will make the accelerometer readings noisy and can therefore affect the angle calculations In addition if the magnitude of the vibration exceeds the range of the accelerometer the accelerometer output can saturate This can cause errors in the accelerometer output The DMU case is not weatherproof You should protect the DMU from moisture and dust M EXAMPLE 4 2 VG400 Series Start Up Procedure As an example look at how the DMU might be used on an airplane Assume DMU is mounted on a small twin prop plane and will be used to record the plane s attitude during flight Flights will be 2 6 hours long The DMU is mounted near the CG of the plane and is connected to a laptop serial port during flight 1 Turn on power to the DMU and let it war
17. ch as the list of information provided to request the RMA number Place the equipment in the original shipping container s making sure there is adequate packing around all sides of the equipment If the original shipping containers were discarded use heavy boxes with adequate padding and protection 10 3 3 Sealing the Container Seal the shipping container s with heavy tape or metal bands strong enough to handle the weight of the equipment and the container 10 3 4 Marking Please write the words FRAGILE DELICATE INSTRUMENT in several places on the outside of the shipping container s In all correspondence please refer to the equipment by the model number the serial number and the RMA number 10 3 5 Return Shipping Address Use the following address for all returned products Crossbow Technology Inc 4145 N First Street San Jose CA 95134 Attn RMA Number XXXXXX 10 4 Warranty The Crossbow product warranty is one year from date of shipment Doc 7430 0002 03 Rev B Page 29 Crossb w Crossbow Technology Inc 4145 N First Street San Jose CA 95134 Phone 408 965 3300 Fax 408 324 4840 Email info xbow com Website www xbow com
18. e x axis roll right The angles are defined as standard Euler angles using a 3 2 1 system To rotate from the body frame to an earth level frame roll first then pitch and then yaw 3 2 Connections The VG400CA has a female DB 15 connector where as VG400CB VG400CC VG400CD VG400MA and VG400MB have a male DB 15 connector The signals are as shown in Table 1 All analog outputs are fully buffered and are designed to interface directly to data acquisition equipment See Analog Output for details Page 6 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossbaw 15 Pin D Connector Socket Pinout Female 15 Pin D Connector Socket Pinout Male N 0 0 0 0 amp o se no 0 se 10 se Table 1 VG400 Series Connector Pin Out Pin Signal 1 RS 232 Transmit Data 2 RS 232 Receive Data 3 Positive Power Input Vcc 4 Ground 5 X axis accelerometer Analog voltage 6 Y axis accelerometer Analog voltage 7 Z axis accelerometer Analog voltage 8 Roll rate analog voltage 9 Pitch rate analog voltage 10 Yaw rate analog voltage 11 NC factory use only 12 Roll analog voltage X axis scaled analog voltage 13 Pitch analog voltage Y axis magnetometer scaled analog voltage 14 Unused Z axis scaled analog voltage 15 NC factory use only Notes 1 The accelerometer ana
19. elerometers GR 2 RR is the rate range of the rate sensors For example if your DMU has 100 s rate sensors RR 100 6 1 Analog Output Conversion Accelerometer Use sensitivity offset from calibration sheet Output is raw sensor voltage Pin 5 X axis accelerometer raw Pin6 Y axis accelerometer raw Pin7 Z axis accelerometer raw Accelerometer Scaled Mode Accel G Vout V GR 1 5 4 096 Pin 12 X axis accelerometer Pin 13 Y axis accelerometer Pin 14 Z axis accelerometer 6 2 Digital Output Conversion Rate Sensor Rate s Vout V RR 1 5 4 096 Pin8 Roll rate sensor Pin9 Pitch rate sensor Pin 10 Yaw rate sensor Roll Pitch Angle Mode Angle Vout V FA 4 096 Pin 12 Roll Angle FA 180 Pin 13 Pitch Angle FA 90 Data is sent as 16 bit signed integer for all but Temperature Temperature sensor data is sent as unsigned integer Acceleration Accel G data GR 1 5 2 Rate Rate s data RR 1 5 2 Roll Pitch Angle Mode Angle data 180 27 Temperature Temperature C data 5 4096 1 375 44 44 Doc 7430 0002 03 Rev B Page 23 Crossb w VG400 Series User s Manual 7 Appendix C VG400 Series Command Quick Reference Command Response Description ASCII R H Ping Pings DMU to verify communications r R Change to Voltage Mode c C Change to Scaled Sensor Mode a A Change to Angle Mode VG Mode P
20. em With the connector facing you and the mounting plate down the axes are defined as X axis from face with connector through the DMU Y axis along the face with connector from left to right Z axis along the face with the connector from top to bottom The axes form an orthogonal right handed coordinate system An acceleration is positive when it is oriented towards the positive side of the coordinate axis For example with the DMU sitting on a level table it will measure zero g along the x and y axes and 1 g along the z axis Gravitational acceleration is directed downward and this is defined as positive for the DMU z axis The angular rate sensors are aligned with these same axes The rate sensors measure angular rotation rate around a given axis The rate measurements are labeled by the appropriate axis The direction of a positive rotation is defined by the right hand rule With the thumb of your right hand pointing along the axis in a positive direction your fingers curl around in the positive rotation direction For example if the DMU is sitting on a level surface and you rotate it clockwise on that surface this will be a positive rotation around the z axis The x and y axis rate sensors would measure zero angular rates and the z axis sensor would measure a positive angular rate Pitch is defined positive for a positive rotation around the y axis pitch up Roll is defined as positive for a positive rotation around th
21. ensor The DMU has an onboard temperature sensor The temperature sensor is used to monitor the internal temperature of the DMU to allow for temperature calibration of the sensors The temperature sensor is specified to be within 2 accurate over the DMU operating temperature range The DMU reads and outputs the temperature sensor voltage with 12 bit precision The DMU will output the temperature sensor voltage in the digital data packet scaled as follows V temp V data 5 4096 where data is the 16 bit unsigned integer sent as the temperature information in the data packet The DMU uses two full bytes to express the data but it is really scaled to 12 bits Calculate the temperature with the following calibration T C 44 4 CC V Viemp V 1 375 V where Viemp is the temperature sensor voltage sent in the DMU data packet The DMU temperature sensor is internal to the DMU and is not intended to measure the ambient temperature The internal temperature of the DMU may be as much as 15 C higher than the ambient temperature 3 9 Analog Output The DMU provides six fully conditioned analog outputs in scaled mode three accelerometer voltages and three rate sensor voltages In angle mode the scaled accelerometer voltages are replaced with the pitch and roll analog voltages In all modes the raw accelerometer sensor output is also available The analog signals can be connected directly to an A D or other data acquisition d
22. ering units not the actual voltage at the sensor output To convert the analog output to a sensor value use the following relation rate AR 1 5 Vou V 4 096 V where rate is the actual measured rate in units s AR is the angular rate range of your sensor and Vout is the measured voltage at the analog output For example if your DMU has a 100 s rate sensor and the analog output for that sensor is 1 50 V the value of the measurement is 100 s 1 5 1 50 4 096 54 9 Vs 3 9 4 Stabilized Pitch and Roll Voltages Angle Mode Only In angle mode the DMU outputs the stabilized pitch and roll angle analog voltages on pins 12 and 13 The analog pitch and roll outputs are created by the DMU internal D A The voltage output will be in the range 4 096 V with 12 bit resolution The output is scaled so that full scale is 180 for roll and 90 for pitch To convert the voltage to an actual angle use the following conversion angle FA Vou V 4 096 V where angle is the actual pitch or roll angle in degrees and Vout is the analog pitch or roll voltage measured FA is 180 for roll FA is 90 for pitch Page 18 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 4 VG400 Series Operating Tips 4 1 Mounting the VG400 Series The DMU should be mounted as close to the center of gravity CG of your system as possible This will minimize any lever effect If it is not mounted at the center of gr
23. evice without further buffering The input impedance of any data acquisition device should be greater than 10 kQ for DAC outputs Page 16 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w and relatively higher impedance for raw analog outputs The circuit diagram for the raw accelerometer outputs Pin 5 6 and 7 is shown below co Accel LE Pin 5 6 7 Output gt 1 uF HHH The DMU must be set to scaled sensor mode or angle mode to enable the scaled analog signals 3 9 1 Raw Accelerometer Voltage The analog outputs from the accelerometers are taken directly from the sensor through a buffer They are raw in the sense that they do not represent a calculated or calibrated value The user needs the zero bias point and scale factor given on the DMU calibration sheet to turn the analog voltage into an acceleration measurement To find the acceleration in G s use the following conversion accel G Vout V bias V sensitivity G V where accel is the actual acceleration measured Vout is the voltage at the analog output bias is the zero G bias voltage and sensitivity is the scale factor in the units G volts For example if the x axis of your accelerometer has a zero G bias of 2 512 V a sensitivity of 1 01 G V and you measure 2 632 V at the analog output the actual acceleration is 2 632 V 2 512 V 1 01 G V 0 121 G The raw accelerometer voltages will always be available on pins 5 7
24. g on the accelerometers when the DMU is moved This Page 10 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w makes the DMU very accurate in dynamic maneuvers Unlike other Crossbow DMU systems the user does not need to set an erection rate The VG400 Series outputs the stabilized pitch and roll angles in the digital data packet in angle mode To convert the digital data to angle use the following relation angle data SCALE 2 where angle is the actual angle in degrees either pitch or roll data is the signed integer data output in the data packet and SCALE is a constant SCALE 180 for roll and for pitch 3 5 Commands The VG400 Series have a simple command structure You send a command consisting of one or two bytes to the DMU over the RS 232 interface and the DMU will execute the command 4 NOTE The DMU commands are case sensitive Gyro View formulates the proper command structures and sends them over the RS 232 interface You can use Gyro View to verify that the DMU is functioning correctly GyroView does not use any commands that are not listed here 4 NOTE Certain combinations of characters not listed here can cause the unit to enter a factory diagnostic mode While this mode is designed to be very difficult to enter accidentally it is recommended that the following command set be adhered to for proper operation 3 5 1 Command List Command Ping Character s Sent R Response H Descript
25. ion Pings DMU to verify communications Command Voltage Mode Character s Sent T Response R Doc 7430 0002 03 Rev B Page 11 Crossb w Description Command Character s Sent Response Description Command Character s Sent Response Description Command Character s Sent Response Description Command Character s Sent Response Description VG400 Series User s Manual Changes measurement type to Voltage Mode DMU outputs raw sensor voltage in the data packet Scaled Mode Cc C Changes measurement type to Scaled Mode DMU outputs measurements in scaled engineering units Angle Mode a A Changes measurement type to Angle VG Mode DMU calculates stabilized pitch and roll Also outputs sensor measurements in scaled engineering units Polled Mode P none Changes data output mode to Polled Mode DMU will output a single data packet when it receives a G command Continuous Mode C Data Packets Changes data output mode to Continuous Mode DMU will immediately start to output data packets in continuous mode Data rate will depend on the measurement type the DMU is implementing Raw Scaled or Angle Sending a G will return DMU to Polled Mode Page 12 Doc 7430 0002 03 Rev B VG400 Series User s Manual Command Character s Sent Response Description Command Character s Sent Response Description Command Character s Sent Response Description Command Character s Sent
26. ist of vibrating silicon structures that utilize the Coriolis force to output angular rate independently of acceleration The three MEMS accelerometers are surface micro machined silicon devices that use differential capacitance to sense acceleration Solid state MEMS sensors make the VG400 Series responsive and reliable The DMU Kalman filter algorithm tracks bias changes in the rate sensors in real time and corrects the rate sensor output This allows the VG400 Series to use the equivalent of a very low erection rate when compared to traditional vertical gyro systems The VG400 Series does this automatically and no user configuration or intervention is required at power up Doc 7430 0002 03 Rev B Page 1 Crossb w VG400 Series User s Manual 1 2 Package Contents In addition to your DMU sensor product you should have e 1CD with GyroView Software GyroView will allow you to immediately view the outputs of the DMU on a PC running Microsoft Windows You can also download this software from Crossbow s web site at http www xbow com e 1 Digital Signal Cable This links the DMU directly to a serial port Only the transmit receive power and ground channels are used The analog outputs are not connected e 1 DMU Calibration Sheet The Digital Calibration Sheets contains the custom offset and sensitivity information for your DMU The calibration sheet is not needed for normal operation as the DMU has an internal EEPROM to store
27. its calibration data However this information is useful when developing your own software to correctly scale the output data Save this page e 1 DMU User s Manual This contains helpful hints on programming installation valuable digital interface information including data packet formats and conversion factors Page 2 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 2 Quick Start 2 1 GyroView Software Crossbow includes GyroView software to allow you to use the DMU right out of the box and the evaluation is straightforward Install the GyroView software connect the DMU to your serial port apply power to your unit and start taking measurements 2 1 1 GyroView Computer Requirements The following are minimum capabilities that your computer should have to run Gyro View successfully e CPU Pentium class e RAM Memory 32MB minimum 64MB recommended e Hard Drive Free Memory 15MB e Operating System Windows 95 98 Me NT4 2000 2 1 2 Install GyroView To install GyroView in your computer 1 Insert the CD Support Tools in the CD ROM drive 2 Find the GyroView folder Double click on the setup file 3 Follow the setup wizard instructions You will install GyroView and a LabVIEW Runtime Engine You will need both these applications If you have any problems or questions you may contact Crossbow directly 2 2 Connections The DMU is shipped with a cable to connect the DMU to a PC COM port 1 Con
28. log voltage outputs are the raw sensor output These outputs are taken from the output of the accelerometers 2 The rate sensor analog voltage outputs are scaled to represent s These outputs are created by a D A converter 3 Actual output depends on DMU measurement mode The pitch and roll analog outputs are scaled to represent degrees The accelerometer analog outputs are scaled to represent G s These outputs are created by a D A converter Doc 7430 0002 03 Rev B Page 7 Crossb w The serial interface connection is standard RS 232 On a standard DB 25 VG400 Series User s Manual COM port connector make the connections per Table 2 Table 2 DB 25 COM Port Connections COM Port Connector DMU Connector Pin Signal Pin Signal 2 TxD 2 RxD 3 RxD 1 TxD 7 GND 4 GND Note Pin 4 on the DMU is data ground as well as power ground On a standard DB 9 COM port connector make the connections per Table 3 Table 3 DB 9 COM Port Connections COM Port Connector DMU Connector Pin Signal Pin Signal 2 RxD 1 TxD 3 TxD 2 RxD 5 GND 4 GND Note Pin 4 on the DMU is data ground as well as power ground Power is applied to the DMU on pins 3 and 4 Pin 4 is ground Pin 3 should have 9 30 VDC unregulated at 200 mA If you are using the cable supplied with the DMU the power supply wires are broken out of the cable at the DB 9 connector The
29. m up 5 10 minutes Power can be on to all electronics but the engines should be off 2 Start the engines 3 Start data collection Proceed with flight Doc 7430 0002 03 Rev B Page 19 Crossb w VG400 Series User s Manual 5 Appendix A Mechanical Specifications 5 1 VG400CA Outline Drawing a 3 00 in gt X 7 62 cm roll 4 HDX Connector side View Y 3 20 in pitch 8 13 cm Zz yaw Z T 0 10in oy 0 25cm 4 le 3 75 in gt 9 53 cm 0 25in Y K 0 64 cm 8 BN HDX Top View x 3 00 in 7 62 cm Y diam 0 19in 0 48 cm a HA 0 19in 48cm H ke Page 20 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 5 2 VG400CB Outline Drawing 3 00 in x 7 62 cm Connector side View roll pith 3 3 in 8 38 cm 1 24 in Z 3 15 cm 3 00 in 7 62 cm diam 019in 0 48 cm 019in o4scm 4 Fe Doc 7430 0002 03 Rev B Page 21 Crossb w VG400 Series User s Manual 5 3 VG400CC VG400CD VG400MA and VG400MB Outline Drawing 3 00 in x 7 62 cm roll Connector side View pitch Z 0 19in L 0 48 cm F 3 75 in 9 53 cm 0 25in L 3 00 in 7 62 cm diam 019in 0 48 cm 019in 048 cm k Page 22 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 6 Appendix B VG400 Series Output Quick Reference GR is the G range of the accelerometers For example if your DMU has 2 G acc
30. mosso eenean aea Es BREAK ANG 1 1 1 The DMU Motion and Attitude Sensing Unit 1 1 2 Package Contents aT NIN eek i ihian 2 2 Qwck Star ma inahin laba KU Anhn haa ahahaha 3 2 1 Gyro VIEW SOftWate AA sens ER EET ER 3 2 1 1 GyroView Computer Requirements cc eee eee eee eee 3 2 1 2 Install Gyro ViCW uccse nenene 3 2 2 Connors so rese one nerne 3 2 3 Setup GYLOVICW aanak ANAN baba Kiana bang 4 24 Take Meas re mentse nan ANNA KGG aE 4 3 VG400 Series Detalls Llana pano ceseeceneesncessee seen seesseessecnsesneecnee sees 6 3 1 VG400 Series Coordinate System eeeeseceseceecsseeneeenes 6 3 2 CONMECHONS as GANA AU NIGERIAN ANAN 6 3 3 Ina pah baban mna pia kana nahanap kA Ana 8 3 4 Measurement Modes aman annn anas swna san waaawnanwsanasannssnssas anas sassans 9 3 4 1 Voltage MODE a UA Naman NINANG AD 9 3 4 2 Scaled Sensor Mode ce eseecseceescensenssensesnsesseessersees sees 9 3 4 3 Angle MOE ss pasasaan asses dakul nina 10 3 5 Commands ANN ible ne heh ee 11 3 5 1 Command List cuisine cline Gh eee 11 3 6 Data Packet Format eceeceeceseeesceeecesecesecssecseecneesaeeeseeeeeees 14 3 7 TING 7 0a NGA REE SEER ESSEN SE lh Wa Nein mia den Aas 15 3 8 LEMpPerature SCMSOL ssicsisss cscesiesussdsienvepusvescdpuendeossuevebspedsesbosvaeens 16 39 Analog Output sirenerne em e aieea snes 16 3 9 1 Raw Accelerometer Voltage u sssenseeersrr rene rrrnsnnnee 17 3 9 2 Scaled Accelerometer Voltage Scaled Sensor Mode
31. nect the 15 pin end of the digital signal cable to the port on the DMU 2 Connect the 9 pin end of the cable to the serial port of your computer 3 The additional black and red wires on the cable supply power to the DMU Match red to power and black to ground The input voltage can range from 9 30 VDC at 200 mA See the specifications for your unit 6 WARNING Do not reverse the power leads Applying the wrong power to the DMU Doc 7430 0002 03 Rev B Page 3 Crossb w VG400 Series User s Manual can damage the unit Crossbow is not responsible for resulting damage to the unit 4 NOTE The analog outputs from the DMU are unconnected in this cable IMPORTANT The Crossbow Inertial Systems have an EMI filtered connector The issue with grounding EMI shield is very important because the EMI filter capacitively couples the signals together if it is left floating The solution is to provide a good ground for the DMU connector shell This can be accomplished by soldering a wire between ground pin Pin 4 and the cable metal part that contacts the DMU connector eg backshell 2 3 Setup GyroView With the DMU connected to your PC serial port and powered open the GyroView software 1 GyroView should automatically detect the DMU and display the serial number and firmware version if it is connected 2 If GyroView does not connect check that you have the correct COM port selected You find this under the DMU
32. on entering scaled mode 3 4 3 Angle Mode In angle mode the DMU acts as a vertical gyro and outputs the stabilized pitch and roll angles along with the angular rate and acceleration information The angular rate and acceleration values are calculated as described in the scaled sensor mode The DMU Kalman filter operates in angle mode to track the rate sensor bias and calculate the stabilized pitch and roll angles The DMU analog outputs are enabled in this mode including stabilized pitch roll and yaw angles See the Analog Output section for a detailed description of the analog outputs In angle mode the DMU uses the angular rate sensors to integrate over your rotational motion and find the actual pitch and roll angles The DMU uses the accelerometers to correct for the drift in the rate sensors This is the modern equivalent of an analog vertical gyro that used a plumb bob in a feedback loop to keep the gyro axis stabilized to vertical The DMU takes advantage of the rate gyros sensitivity to quick motions to maintain an accurate orientation when accelerations would otherwise throw off the accelerometers measurement of the DMU orientation relative to gravity The DMU uses the accelerometers to provide long term stability to keep the rate gyro drift in check The VG400 Series of products use a sophisticated Kalman filter algorithm to track the bias in the rate sensors This allows the DMU to use a very low effective weightin
33. red wire is connected to VCC the black wire is connected to the power supply ground DO NOT REVERSE THE POWER LEADS The analog outputs are unconnected in the cable Crossbow supplies The analog outputs are fully buffered and conditioned and can be connected directly into an A D The analog outputs require a data acquisition device with an input impedance of 10kQ or greater for DAC outputs and relatively higher impedance for raw analog outputs 3 3 Interface The serial interface is standard RS 232 38400 baud 8 data bits 1 start bit 1 stop bit no parity and no flow control Crossbow will supply DMU communication software examples written in C and LabVIEW Source code for the DMU serial interface can be obtained via the web at http www xbow com Support downloads htm Page 8 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 3 4 Measurement Modes The VG400 Series of products are designed to operate as a vertical gyro You can also use it as a six axis sensor module The VG400 Series can be set to operate in one of three modes voltage mode scaled sensor mode or angle VG mode The measurement mode selects the information that is sent in the data packet over the RS 232 interface See the Data Packet Format section for the actual structure of the data packet in each mode 3 4 1 Voltage Mode In voltage mode the analog sensors are sampled and converted to digital data with 1 mV resolution The digital dat
34. s and rotation rates around three orthogonal axes The VG400 Series uses three accelerometers and three angular rate sensors to make a complete measurement of the dynamics of your system In addition the VG400 Series firmware includes an advanced Kalman filter algorithm to track the rate sensor biases in real time and to calculate absolute angle The VG400 Series is designed to provide stabilized pitch and roll in dynamic environments The VG400 Series is the solid state equivalent of a vertical gyro artificial horizon display This unit is designed specifically to operate under standard airborne conditions and other moderately dynamic environments The DMU series units are low power fast turn on reliable and accurate solutions for a wide variety of stabilization and measurement applications All DMU products have both an analog output and an RS 232 serial link Data may be requested via the serial link as a single polled measurement or may be streamed continuously The analog outputs are fully conditioned and may be connected directly to an analog data acquisition device The Crossbow DMUs employ onboard digital processing to compensate for deterministic error sources within the unit and to compute attitude information The DMUs accomplish these tasks with an analog to digital converter and a high performance Digital Signal Processor All six of the VG400 Series sensor elements are micro machined devices The three angular rate sensors cons
35. ual 10 Appendix E Warranty and Support Information 10 1 Customer Service As a Crossbow Technology customer you have access to product support services which include e Single point return service e Web based support service e Same day troubleshooting assistance e Worldwide Crossbow representation e Onsite and factory training available e Preventative maintenance and repair programs e Installation assistance available 10 2 Contact Directory United States Phone 1 408 965 3300 8 AM to 5 PM PST Fax 1 408 324 4840 24 hours Email techsupport xbow com Non U S refer to website www xbow com 10 3 Return Procedure 10 3 1 Authorization Before returning any equipment please contact Crossbow to obtain a Returned Material Authorization number RMA Be ready to provide the following information when requesting a RMA e Name e Address e Telephone Fax Email e Equipment Model Number e Equipment Serial Number e Installation Date e Failure Date e Fault Description e Will it connect to Gyro View Page 28 Doc 7430 0002 03 Rev B VG400 Series User s Manual Crossb w 10 3 2 Identification and Protection If the equipment is to be shipped to Crossbow for service or repair please attach a tag TO THE EQUIPMENT as well as the shipping container s identifying the owner Also indicate the service or repair required the problems encountered and other information considered valuable to the service facility su

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