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GNAV540 User Manual

1. Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields written Page 92 GNAV540 User Manual 7430 0808 01 Rev B MOOG WF Payload Contents Byte Offset Name Format Scaling Units Description 1 fieldO U2 The first field ID written 3 field1 U2 The second field ID written bes ar U2 More field IDs written numFields 2 1 Field U2 The last field ID written Table RF Command Read Fields Command Read Fields RF 0x5246 0x5555 0x5246 1 numFields 2 RF payload CRC U2 gt This command allows the user to read the default power up configuration fields from the EEPROM NumFields is the number of fields to read The field0 field1 etc are the field IDs to read RF may be used to read configuration and calibration fields from the EEPROM If at least one field is successfully read the unit will respond with a read fields response containing the field IDs and data from the successfully read fields If any field is unable to be read the unit will respond with an error response Note that both a read fields and an error response may be received as a result of a read fields command Table 70 RF Payload RF Payload Contents Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields to read 1 fieldO U2 Th
2. 17 Table 6 TL Interface onu E akaa 18 Table 7 IMU Function Advanced Settings rs 26 Table 8 VG Function Advanced Settings miii cr 27 Table 9 AHRS Series Advanced Settings miii nennen nrennnsn ais 29 Table 10 GNAV540 Advanced Settings ennaii aad raain id aaa sete pan inahan 32 Table TT I O CODnDeCLOE oit tette is 35 Table 12 Number Formats matenee M 61 Table EE dee EE 62 Table 14 Message Tale AA 63 Table TS Ping Command ee ae ne 67 Table eent e WE 67 Table 17 Echo Response 2eme 67 Walle EST GP Request unen AD D cee ete en 68 KI Oe Ee rasanan Ra A A A A 68 Table 20 Algorithm Reset Command dinars 68 Table 21 Algorithm Reset Resp AA AN 68 Table 22 Software Reset m 68 Table 23 Software Reset Response miii rs 69 Table Z Calibrate Comm anid p 69 Table 25 WG Payload eeu Rn as 69 Table 26 Magnetic und 69 Table 27 Calibrate WC ACK Response erret ttes ere iS 70 Table 28 WG Payload EC E A iia 70 Table 29 Calibration Completed inn ii 70 Table 30 CC Payload Contents ieu aie detta peii ptm ee lec aie cp aud ida EE 70 Table Saddle 71 Table 32 ID Data a 71 Table 33 ID Payload ERO aan 71 Page 8 GNAV540 User Manual 7430 0808 01 Rev B MOOG Table 34 Version Data PRT unsa atest a cis 71 Table 35 VR Payload Epp A
3. Calibrate Acknowledgement Response Table 27 Calibrate WC ACK Response Calibrate WC 0x5743 0x5555 0x5743 lt WC payload gt lt CRC U2 gt The unit will send this packet in response to a calibrate request if the procedure can be performed or initiated Table 28 WC Payload WC Payload Contents Byte Name Format Scaling Units Description Offset 0 calibrationRequest U2 The requested calibration task Calibration Completed Parameters Response Table 29 Calibration Completed Calibrate Completed CC 0x4343 0x5555 0x4343 lt CC payload gt lt CRC U2 gt The unit sends this packet after a calibration has been completed Currently there is only one message of this type sent after a magnetic calibration has been completed with or without automatic termination and the parameters have been calculated The calibrationRequest field will be 0x000B or 0x000C Table 30 CC Payload Contents CC Payload Contents Byte Name Format Scaling Units Description Offset 0 calibrationRequest U2 The requested calibration task 2 xHardlron I2 2 2 16 G The x hard iron bias 4 yHardIron I2 2 2 16 G They hard iron bias 6 softIronScaleRatio U2 2 2 16 The scaling ratio between the x and y axis Page 70 GNAV540 User Manual 7430 0808 01 Rev B MOOG Error Response Table 31 Error Response Error Response AS
4. GNAV540 User Manual 7430 0808 01 Rev B Page 83 MOOG Page 84 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 10 Programming Guidelines The advanced commands allow users to programmatically change the GNAV540 settings This section of the manual documents all of the settings and options contained under the Unit Configuration tab within NAV VIEW 2 2 Using these advanced commands the settings of a GNAV540 unit can be modified without NAV VIEW 2 2 Configuration Fields Configuration fields determine various behaviors of the unit that can be modified by the user These include settings like baud rate packet output rate and type algorithm type etc These fields are stored in EEPROM and loaded on power up These fields can be read from the EEPROM using the RF command These fields can be written to the EEPROM affecting the default power up behavior using the WF command The current value of these fields which may be different from the value stored in the EEPROM can also be accessed using the GF command All of these fields can also be modified immediately for the duration of the current power cycle using the SF command The unit will always power up in the configuration stored in the EEPROM Configuration fields can only be set or written with valid data from Table 55 below Table 55 Configuration Fields index Configuration fields Field ID Valid Values Description u 0 1 2 4 5 10 quiet 100Hz 50Hz 25Hz 2
5. GNAV540 Default Coordinate System accels rates MAGS attitude MOOG AHRS Function accels rates nam C mags attitude Correction algorithm Roll pitch heading velocity Accelerometer tilt Magnetometer heading VG Function Attitude propagation 5 SC rates DE heading yaw free Roll pitch heading velocity Accelerometer tilt The GNAV540 Inertial System default coordinate system is shown in Figure 4 below The coordinate system is configurable with either NAV VIEW 2 2 or by sending the appropriate serial commands This section of the manual describes the default coordinate system settings of the unit when it leaves the factory For information about configuring GNAV540 refer to Chapter 7 Configuring GNAV540 with NAV VIEW 2 2 Chapter 6 Viewing and Logging Data with NAV VIEW 2 2 and Chapter 10 Programming Guidelines With the GNAV540 connector facing you and the mounting plate down the axes are defined as shown below Figure 4 GNAV540 Default Coordinate System x X axis from face with connector through the unit Z EE a pitch N 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 SAE right handed coordinate system Acceleration is positive when it is oriented towards the positive side of the coordinate axis For example with a GNAV540 sitting on a level table it will Page 24 GNAV
6. Nav 4 Data Write Fields Request Write Fields Response Set Fields Request Set Fields Response Output Message Output Message Output Message Output Message Output Message Output Message Output Message Input Message Reply Message Input Message Reply Message AHRS NAV AHRS NAV AHRS NAV AHRS NAV NAV NAV NA Page 64 GNAV540 User Manual 7430 0808 01 Rev B MOOG ASCII 2 byte packet Mnemonic type U2 gt 0x5246 0x5246 0x4746 0x4746 payload byte length U1 gt numFields 2 1 numFields 4 1 numFields 2 1 numFields 4 1 Description Read Fields Request Read Fields Response Get Fields Request Get Fields Response Input Message Reply Message Input Message Reply Message Available Functions GNAV540 User Manual 7430 0808 01 Rev B Page 65 MOOG Page 66 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 9 Communicating with the GNAV540 Unit Communication commands are used to verify a unit is present and alive Ping Command Table 15 Ping Command Ping PK 0x504B The ping command has no payload Sending the ping command will cause the unit to send a ping response To facilitate human input from a terminal the length and CRC fields are not required Example 0x5555504B009ef4 or 0x5555504B Ping Response Ping PK 0x504B 0x5555 0x504B lt CRC U2 gt The unit will send this
7. Vertical Gyroscope VG Function The Vertical Gyroscope VG Function provides dynamic roll and pitch measurements in addition to the IMU Function data The dynamic roll and pitch measurements are stabilized by using the accelerometers as a long term gravity reference The VG Function can also output a free integrating yaw angle measurement that is not stabilized by a magnetometer or compass heading At a fixed 100Hz rate the VG Function continuously maintains both the digital IMU data as well as the dynamic roll and pitch data As shown in the software block diagram Figure 2 on page 23 after the Sensor Calibration block the IMU data is passed into an Integration to Orientation block If using external GPS refer to Figure 4 on page 24 The Integration to Orientation block integrates body frame sensed angular rate to orientation at a fixed 100 times per second For improved accuracy and to avoid singularities when dealing with the cosine rotation matrix a quaternion formulation is used in the algorithm to provide attitude propagation Also shown in the software block diagram Figure 2 page 23 the Integration to Orientation block receives drift corrections from the Extended Kalman Filter or Drift Correction Module In general rate sensors and accelerometers suffer from bias drift misalignment errors acceleration errors g sensitivity nonlinearity square terms and scale factor errors The largest error in the orientation propagation
8. MOOG Comments To configure the axis orientation select the desired measurement for each axis NAV VIEW 2 2 then shows the corresponding image of the unit making it easy to visualize the mode of operation Refer to Orientation Field on page 86 for the twenty four possible orientation settings The default setting points the connector AFT The Freely Integrate setting allows a user to turn the unit into a free gyroscope In free gyroscope mode the roll pitch and yaw are computed exclusively from angular rate with no Kalman filter based corrections of roll pitch oryaw When turned on there is no coupling of acceleration based signals into the roll and pitch or magnetometer based signals to the yaw Due to sensor bias the roll pitch and yaw outputs will drift roughly linearly with time For best performance the Freely Integrate mode should be used after the algorithm has initialized This allows the Kalman Filter to estimate the roll and pitch rate sensor bias prior to entering the free gyroscope mode Upon exiting the free gyroscope mode OFF one of two behaviors will occur e If the unit has been in freely integrate mode for less than sixty seconds the algorithm will resume operation at normal gain settings If the unit has been in freely integrate mode for greater than sixty seconds the algorithm will force a reset and reinitialize with high gains automatically The Use Mags setting enables turning on and off the magnetometer
9. This setting defaults to OFF itis recommended to be OFF for NAV Function The stationary yaw lock is only recommended for consideration when the unit is operating with GPS Use GPS ON and WITHOUT magnetometer feedback Use Mags OFF Stationary yaw lock may be appropriate if the user platform is a ground vehicle The Use Mags setting enables turning on and off the magnetometer feedback for yaw heading stabilization The default setting is ON When Use Mags is turned ON the unit uses the magnetic field sensor readings to stabilize the drift in yaw and it slaves the yaw to the compass reading provided from the magnetic field sensor readings When Use Mags is turned OFF the heading yaw angle measurement of the unit will be slaved to the GPS heading if GPS is available otherwise the heading will drift feely The reason for this setting is to give the user an ability to turn off the magnetometer stabilization when severe magnetic distortion may be occurring This setting is desirable when the user vehicle temporarily moves in close proximity to a large ferrous object When the Use Mags switch is turned from OFF to ON the unit will reinitialize the yaw heading angle with the compass reading provided from the magnetic field sensor readings GNAV540 User Manual 7430 0808 01 Rev B Page 33 Setting Restart On Over Range Dynamic Motion Turn Switch Threshold Default Value ON 0 5 deg sec MOOG Comments Th
10. e GPS Velocities scaled to a range of 256 256 m s e Altitude scaled to a range of 100 16284 m using a shifted 2 s complement representation e Longitude and latitude scaled to a range of pi pi or 180 deg to 180 deg e GPS heading are scaled to a range of pi pi or 180 deg to 180 deg e The GPS velocity components are directly from GPS measurements No inertial Measurements are involved in its computation Table 52 N3 Payload N3 Payload Contents Byte Name Form Scaling Units Description Offset at 0 rollAngle I2 2 pi 2 16 Radians Roll angle 360 2 16 2 pitchAngle I2 2 pi 2 16 Radians Pitch angle 360 2 16 4 yawAngleTrue I2 2 pi 2 16 Radians Yaw angle true north 360 2 16 6 xRateCorrected I2 7 pi 2 16 rad s X angular rate corrected 1260 2 16 sec 8 yRateCorrected I2 7 pi 2 16 rad s Y angular rate corrected 1260 2 16 sec 10 zRateCorrected I2 7 pi 2 16 rad s Z angular rate corrected 1260 2 16 sec 12 xAccel I2 20 2 16 g X accelerometer 14 yAccel I2 20 2 16 g Y accelerometer 16 zAccel I2 20 2 16 g Z accelerometer 18 nVel I2 512 2 16 m s GPS North velocity GNAV540 User Manual 7430 0808 01 Rev B Page 81 MOOG N3 Payload Contents Byte Name Form Scaling Units Description Offset at 20 eVel I2 512 2 16 m s GPS East velocity 22 dVel I
11. 10 00 3 Filter Y Accel I 10 00 3 Filter Rate Sensor I 15 00 zi Roll Offset E 0 00 Pitch Offset 7 C 0 00 3 Temporary reset after reboot Set Values C Permanent saved after reboot Get All Values Done BIT Configuration enables configuring the logic of individual status flags that affect the masterStatus flag in the master BITstatus field Enabling individual status flags determines which flags are logically OR ed to generate the masterStatus flag This provides the flexibility to listen to the indications that affect specified applications For more information about BIT status fields refer to BIT Status Fields on page 98 Page 56 GNAV540 User Manual 7430 0808 01 Rev B MOOG Viewing Current Configuration To view the current configuration click the Get All Values button The current settings will be displayed in the text fields Under Current Value a box filled with blue color indicates the status field is enabled Refer to Figure 20 Changing Configurations To view the current settings click the Get All Values button To modify Status Field s 1 Checkmark the desired item s under Modify 2 For each Status check or uncheck the item status bit under Enable Disable 3 Select either Temporary or Permanent Temporary The configuration will not be stored in non volatile memory EEPROM The configuration will be applied but the unit will return to the Permanen
12. AddQueue add item in front of queue item holds item to be added to queue queue ptr is pointer to the queue returns 0 if queue is full 1 if successful Kk kk kk kok 22 2 2 kk kk k kok 22 212 22 212 22 2 2 22 212 k k k k 22 k 22 212 22 22 22 212 22 22 22 2 2 22 2 2 2 2 int AddQueue char item QUEUE TYPE queue ptr int retval 0 if queue_ptr gt count gt MAXQUEUE retval else 0 queue is full queue ptr gt count queue ptr gt rear queue ptr gt rear 1 MAXOUEUE queue ptr entry queue ptr gt rear item retval T return retval GNAV540 User Manual Page 117 7430 0808 01 Rev B MOOG PARAR AIR RRA UK AK RR RR 2 2 2 2 2 KA KA 2 2 2 2 2 2 2 2 2 k 2 2 kk kk kk 2 2 2 2 2 2 2 2 2 2 22 2 2 2 2 2 2 2 2 2 ke e ke ek FUNCTION DeleteQeu return an item from the queue ARGUMENTS item will hold item popped from queue queue ptr is pointer to the queue RETURNS returns 0 if queue is empty 1 if successful Kk kk kk kok Ck kk kk KC kk kok kk kk kk kk kk kk kk kk kk k k A 22 k 22 k 22 212 22 2 2 22 22 22 22 22 2 2 2 2 2 2 2073 int DeleteQueue char item QUEUE_TYPE queue_ptr int retval 0 if queue ptr 5count lt 0 retval 0 queue is empty else queue ptr gt count item queue ptr entry queue ptr gt front queue ptr gt front queue
13. GNAV540 User Manual 7430 0808 01 Rev B Page 115 MOOG Pop queue ptr numToPop if Size queue ptr lt 0 header was not found return 0 make sure we can read through minimum length packet if Size queue_ptr lt 7 return 0 get data length 5th byte of packet dataLength peekByte queue_ptr 4 make sure we can read through entire packet if Size queue ptr 7 dataLength return 0 check CRC myCRC calcCRC queue ptr 2 dataLength 3 packetCRC peekWord queue ptr dataLength 5 if myCRC packetCRC bad CRC on packet remove the bad packet from the queue and return Pop queue ptr dataLength 7 return 0 fill out result of parsing in structure result gt packet type peekWord queue ptr 2 result gt length peekByte queue_ptr 4 result gt crc packetCRC for counter 0 counter lt result gt length counter result gt data counter peekByte queue ptr 5 tcounter Pop queue ptr dataLength 7 return 1 KKK KA K k K K k k RRA RRA RR RR RAR RRA RRA ARA RRA kok kok AK A kok A kk ke ke ke ke T ke k ke e e KK FUNCTION calcCRC calculates a 2 byte CRC on serial data using ki CRC CCITT 16 bit standard maintained by the ITU International Telecommunications Union Page 116 GNAV540 User Manual 7430 0808 01 Rev B MOOG ARGUMENTS R
14. Leveling roll and pitch alignment is data that must be manually entered the offset of the set magnetometer related to the axes of the system in which it is installed Roll Offset Pitch Offset 1 Ensure the unit is configured to use the external magnetometer Refer to Advanced on 0 00 0 00 page 56 2 Under External Mag Leveling Alignment enter the Roll Offset and Pitch Offset in the data fields and then click the Set button NOTE The features of the secondary leveling interface are not available Refer to Figure 24 To save the values in the EEPROM click the Apply button Refer to Figure 25 on page 60 The new configuration settings will be saved and immediately implemented GNAV540 User Manual Page 59 7430 0808 01 Rev B MOOG Figure 24 External Magnetometer Alignment Dialog Rotational Alignment zu 1 Ensure the unit is configured to use the X Hard Iron Offset Y Hard Iron Offset Soft Iron Ratio Soft Iron Angle E L 0 0000 0 00000 external magnetometer Refer to Advanced on eco uus noong page 56 External Mag 4 00 2 Ensure the leveling alignment of the Instructions magnetometer has been configured Leveling e Click Start for the desired test ext mag leveling or ext mag align then Alignment page 59 E immediately connect to external mag turn switch to ON 3 Click Configuration and then select Magnetometer Alignment from the dro
15. Master BIT and Status Nav Data Packet 1 Table 49 N1 Data Packet Nav Data N1 0x4E31 0x5555 0x4E31 lt N1 payload gt lt CRC U2 gt This packet contains navigation data and selected sensor data scaled in most cases to a signed 2416 2 s complement number Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angles scaled to a range of pi pi or 180 deg to 180 deg e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Temperature scaled to a range of 100 100 C e Velocities scaled to a range of 256 256 m s e Altitude scaled to a range of 100 16284 m using a shifted 2 s complement representation e Longitude and latitude scaled to a range of pi pi or 180 deg to 180 deg GNAV540 User Manual Page 79 7430 0808 01 Rev B MOOG Table 50 N1 Payload N1 Payload Contents Byte Name Format Scaling Units Description Offset 0 rollAngle I2 2 pi 2 16 Radians Roll angle 360 2 16 5 2 pitchAngle I2 2 pi 2 16 Radians Pitch angle 360 2 16 4 yawAngleTrue I2 2 pi 2 16 Radians Yaw angle true north 360 2 16 6 xRateCorrected I2 7 pi 2 16 rad s X angular rate corrected 1260 2 16 sec 8 yRateCorrected I2 7 pi 2 16 rad
16. Offset 0 BITstatus U2 Master BIT and Status Field 2 hardwareBIT U2 Hardware BIT Field 4 hardwarePowerBIT U2 Hardware Power BIT Field 6 hardwareEnvironmentalBIT U2 Hardware Environmental BIT Field 8 comBIT U2 communication BIT Field 10 comSerialABIT U2 Communication Serial A BIT Field 12 comSerialBBIT U2 Communication Serial B Page 72 GNAV540 User Manual 7430 0808 01 Rev B MOOG T2 Payload Contents Byte Name Format Scaling Units Description Offset BIT Field 14 comSerialCBIT U2 Communication Serial C BIT Field 16 softwareBIT U2 Software BIT Field 16 softwareAlgorithmBIT U2 Software Algorithm BIT Field 20 softwareDataBIT U2 Software Data BIT Field 22 hardwareStatus U2 Hardware Status Field 24 comStatus U2 Communication Status Field 26 softwareStatus U2 Software Status Field 28 sensorStatus U2 Sensor Status Field Output Packets Polled or Continuous Scaled Sensor Data Packet 0 Table 37 SO Data Packet Scaled Sensor Data SO 0x5330 0x5555 0x5330 S0 payload CRC U2 gt This packet contains scaled sensor data The scaled sensor data is fixed point 2 bytes per sensor MSB first for 13 sensors in the following order accels x y z gyros x y z mags x y z temps x y z board Data involving angular measurements
17. where the unit rapidly estimates the gyroscope bias and uses the accelerometer feedback heavily This setting is recommended when the source of over range is likely to be sustained and potentially much greater than the rate sensor operating limit Large and sustained angular rate over ranges result in unrecoverable errors in roll and pitch outputs An unrecoverable error indicates the EKF cannot stabilize the resulting roll and pitch reading Ifthe over ranges are expected to be of short duration 1 sec and a modest percentage over the maximum operating range it is recommended that the restart on over range setting be turned off Handling an inertial rate sensor over range is controlled with the restartOnOverRange switch e If restartOnOverRange is off the system will flag the overRange status flag and continue to operate through it If restartOnOverRange is on the system will flag a masterFail error during an over range condition and continue to operate with this flag until a quasi static condition is met to allow for an algorithm restart The quasi static condition required is that the absolute value of each low pass filtered rate sensor falls below 3 deg sec to begin initialization The system will then attempt a normal algorithm start The default setting is ON Turning off the dynamic motion setting results in a higher gain state that uses the accelerometer feedback heavily During periods of time when there is known low dynamic accele
18. 0 Ux 1 Uy 2 Uz 3 N A Y Axis Sign 0 positive 1 negative Y Axis d 0 Uy 1 Uz 2 Ux 3 N A 0 positive 1 negative 0 Uz 1 Ux 2 Uy 3 N A Reserved N A There are 24 possible orientation configurations Setting Writing the field to anything else generates a NAK and has no effect Table 57 Orientation Field Values Orientation Field Value X Axis 0x0000 0x0009 0x0023 0x002A 0x0041 0x0048 0x0062 0x006B 0x0085 0x008C 0x0092 GNAV540 User Manual Page 87 7430 0808 01 Rev B Orientation Field Value X Axis 0x009B Uy 0x00C4 Uz 0x00CD 0x00D3 0x00DA 0x0111 0x0118 0x0124 0x012D 0x0150 0x0159 0x0165 0x016C MOOG An example of orientation field value 0x12D is shown in the figure below Figure 27 Orientation Field Z Uy User Behavior Switches This field allows on the fly user interaction with aspects of the algorithm Table 58 Behavior Aspects Algorithm Aspect Bits Values Free Integrate 0 0 use feedback to stabilize the algorithm 1 6DOF inertial integration without stabilized feedback Page 88 GNAV540 User Manual 7430 0808 01 Rev B MOOG Algorithm Aspect Bits Values Use Mags 0 Do not use mags to stabilize heading heading will run open loop or be stabilized by GPS track 1 Use mags to stabilize heading Use GPS 0 Do not use GPS to stabilize the system 1 Use GPS when available Stationary Yaw Lock
19. 0 Do not lock yaw when GPS speed is near zero 0 75 m s 1 Lock yaw when GPS speed is near zero Restart on Over range 0 Do not restart the system after a sensor over range 1 restart the system after a sensor over range Dynamic Motion 0 vehicle is static force high gain corrections 1 vehicle is dynamic use nominal corrections Reserved N A Internal External Mags 0 use the internal magnetometer 1 use the external magnetometer NOTE whether or not the magnetometer is used to update the heading is set in the Use Mags bit of the User Behavior configuration Internal External GPS 0 use the internal GPS 1 use the external GPS Note whether or not the GPS input is used in the algorithm is set in the Use GPS bit of the User Behavior configuration Reserved 9 15 N A The following table clarifies the relationship of the Use Mags bit and the Internal External Mags bit Table 59 Internal External Mags Bit Use Mags Internal External Mags Result 0 0 The magnetometer is not used 1 The magnetometer is not used 1 0 The heading is updated with the internal magnetometer 1 1 The heading is updated with the external magnetometer Hard and Soft Iron Values These fields allow access to hard iron bias and soft iron scale ratio values for magnetometer alignment The calibration values for the internal magnetometer Table 60 Internal Magnetometer C
20. 120 GNAV540 User Manual 7430 0808 01 Rev B MOOG Example payload from Angle Data Packet 2 A2 5555 4132 1e ey preamble type length 0006ffe4ed91 fffofffdffed fff7fffof331 Hex Value Data deg 0006 0 033 roll FFE4 0 154 pitch ED91 25 922 yaw Angular Rates Hex Value Data deg s FFF9 0 13 roll FFFD pitch FFED 0 37 yaw Hex Value Data g FFF7 0 0027 x FFF9 0 0021 y F331 1 0007 z Hex Value Data deg C 2C64 34 680 2CE1 35 062 2D85 35 562 timelTOW Hex Data Value s 00010b1c 68380 0006ffe4ed91 fffOfffdffed fff7fffof331 2c642ce12d85 00010b1c 0300 6945 T CRC invalid 2c642ce12d85 00010b1c 0300 CN EC o TN e Dem eo GNAV540 User Manual 7430 0808 01 Rev B Page 121 MOOG Example payload from Nav Data Packet 1 N1 5555 4e31 2a 001bffdf3a5bfffe0000ffe fff8fff70000002d1900288a3e0300 a3ad tid preamble type length CRC invalid 001bffdf3a5b fffe0000ffea ffrefff7f337 0015fda9fd4f 00000000000000000000 2d19 00288a3e 0300 Hex Value Data g FFF8 0 0024 FFF7 0 0027 F337 0 9988 Velocity Hex Value Data m s 0015 0 164 FDA9 4 680 FD4F 5 383 Hex Value Data deg C 2D19 35 233 timelTOW Hex Data Value s 00288a3e 2656830 me CEN CCSN CN CE CC KEN Ee emensus o CN eee Hex Value Data deg 001b
21. 2 will show the corresponding image of the unit so it easy to visualize the mode of operation Refer to Orientation Field on page 86 for the twenty four possible orientation settings The default setting points the connector AFT The Freely Integrate setting allows a user to turn the unit into a free gyroscope In free gyroscope mode the roll pitch and yaw are computed exclusively from angular rate with no Kalman filter based corrections of roll pitch and yaw When turned on there is no coupling of acceleration based signals into the roll and pitch or magnetometer based signal to the yaw As a result the roll pitch and yaw outputs will drift roughly linearly with time due to sensor bias For best performance the Freely Integrate mode should be used after the algorithm has initialized This allows the Kalman Filter to estimate the roll and pitch rate sensor bias prior to entering the free gyroscope mode Upon exiting the free gyroscope mode OFF one of two behaviors will occur Iftheunit has been in freely integrate mode for less than sixty seconds the algorithm will resume operation at normal gain settings Ifthe unit has been in freely integrate mode for greater than sixty seconds the algorithm will force a reset and reinitialize with high gains automatically The Use GPS setting enables turning on and offthe GPS feedback The default setting is ON When Use GPS is turned OFF the unit s behavior will revert to that of AHRS Function
22. Aircraft A fixed wing aircraft is a heavier than air craft where movement of the wings in relation to the aircraft is not used to generate lift The term is used to distinguish from rotary wing aircraft where the movement of the wing surfaces relative to the aircraft generates lift The fixed wing aircraft can range in size from the smallest experimental plane to the largest commercial jet The dynamic characteristics of the fixed wing aircraft depend on the type of aircraft such as glider propeller aircraft and jet aircraft and mission phases such as launch landing and maneuver For best results per dynamic condition the appropriate settings must be applied Table 94 below shows four examples of dynamic conditions with recommended configurations Table 94 Recommended Settings for Fixed Wing Aircraft Recommended Dynamic Condition Setti erungs Pre launch or known Launch Normal High Dynamics straight and level un Dynamics accelerated flight Default UseMags ON O ON UseGPS ON 4g 0 ON lt 4g ON N ON N Turn Switch Threshold 0 5 deg s 0 5 deg s 0 5 deg s 0 5 deg s Rotorcraft Rotorcraft is a category of heavier than air flying machines that use lift generated by rotors They may also include the use of static lifting surfaces but the primary distinguishing feature being lift provided by rotating lift structures Rotorcraft includes helicopters autogyros gyrodynes and tiltrotors The rotor blade dynamics are fas
23. Function has additional measurement output packets including the default A2 Angle Packet which outputs the roll angle pitch angle and digital IMU data NO and N1 packets are also available for use with an external GPS receiver For more information refer to Chapter 9 Communicating with the GNAV540 Unit and Chapter 10 Programming Guidelines for packet descriptions VG Function Advanced Settings In addition to the configurable baud rate packet rate axis orientation and sensor low pass filter settings VG Function provides additional advanced settings that are selectable for tailoring the unit to a specific application requirements The settings are listed in Table 8 below Table 8 VG Function Advanced Settings Setting Default Value Comments Baud Rate 38 400 baud 9600 19200 57600 also available Packet Type A2 S1 S2 NO N1 also available Packet Rate 25Hz This setting sets the rate at which selected Packet Type packets are output If polled mode is desired then select Quiet If Quiet is selected the unit will only send measurement packets in response to GP commands Orientation See Figure 4on To configure the axis orientation select the desired measurement for each axis page 24 NAV VIEW 2 2 will show the corresponding image of the unit so it easy to visualize the mode of operation Refer to Orientation Field on page 86 for the twenty four possible orientation settings The default setting points the connector AFT GNAV
24. Installation Requirements utin it i ater tha AA legeret ut p tired NAA aa ee dr 43 1 InstallSoftware NAV VIEW 2 2 daan GAGA Er 44 lsti 4 m1 0 E E 44 2 Prepare the Communication Port A a eee 44 3 CONMECE NE GPS AM a 44 o_o AA a aE EE 44 4 Turnon theGNAVSAO e Aa a ANG ee 45 ao AAA AA AA 45 Trouble Sho ting A MM 46 Chapter 6 Viewing and Logging Data with NAV VIEW 2 2 mnt 47 Communication POLE ssissccsnasesseicossinasenrsneessniibecssases 48 Record RA PR O MM 49 IN Kee a E a a a R A A AA 50 Raw Data Co io 51 Horizon and Compass A as 52 Packet Statistics AE s M 52 Chapter 7 Configuring GNAV540 with NAV VIEW 2 2 nent 53 Viewing Current Configurations u a ea aag 53 Gonfiguringthe O 54 Ic M 54 PAV iaa 56 BITCONISUFATION 56 Aligning the Magneto micte rs E 57 Technical QV CR VLC Wa o mn AA irum nn ton EE Sedo ILU DE att dante 57 Alignment InStr Ct ONS jasc een 58 Page 4 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 8 Data Pa
25. May 2011 S McGuigan First release R Ayeras 25 Sept 2011 J Zhang Add information about USER PORT SEL CONN p 35 46 S McGuigan Update logo and business name R Ayeras Technical corrections per ECO 2023 A Malerich GNAV540 User Manual Page 131 7430 0808 01 Rev B MOOG Moog Inc Navigation Guidance and Sensors 1421 McCarthy Blvd Milpitas CA 95035 Phone 408 965 3300 Fax 408 324 4840 Email info moog crossbow com Website www moog crossbow com MOOG Page 132 GNAV540 User Manual 7430 0808 01 Rev B
26. Sample Packet Parser Code Overview This section includes an example of code written in ANSI C for parsing packets from data sent by the GNAV540 Inertial Systems This example is for reading data directly from the GNAV540 unit or from a log file Sample Code The sample code contains the actual parser as well as several support functions for CRC calculation and circular queue access Table 99 Code Functions Function Description process xbow packet Parse out packets from a queue Returns these fields in structure XBOW PACKET see below Checks for CRC errors Empty Return 1 if queue is empty 0 if not Full Return 1 if full 0 if not full The parser will parse the queue looking for packets Once a packet is found and the CRC checks out the packet s fields are placed in the XBOW PACKET structure The parser will then return to the caller When no packets are found the parser returns the value 0 to the caller The XBOW PACKET structure is defined as follows typedef struct xbow packet unsigned short packet_type char length unsigned short CBC char data 256 XBOW PACKET Typically the parser would be called within a loop in a separate process or in some time triggered environment reading the queue looking for packets A separate process might add data to this queue when it arrives It is up to the Page 114 GNAV540 User Manual 7430 0808 01 Rev B MOOG user to ensure circular queue integrity by using some
27. compensate magnetic readings either heading readings will be incorrect or error messages will be displayed Compensation for Magnetic Fields Magnetic sensors measure magnetic fields which are then used to compute heading A correct heading angle is based only on the earth s magnetic field However the magnetic fields of the GNAV540 unit and the surroundings such as the system vehicle in which the unit is installed are also measured which affect the magnetic reading To compensate for these magnetic fields and ensure accurate heading readings the GNAV540 unit must be calibrated The GNAV540 unit compensates for the extra magnetic field s by taking a series of measurements and then applying those measurements to a two dimensional algorithm The algorithm is used to calculate the hard iron and soft iron effects the values of which are then stored as constants in the EEPROM ofthe unit Those constants are used for correcting the magnetic readings ensuring accurate heading output Hard iron effects are shifts in the magnetic field from ferrous objects or other magnetic material in the proximity of the magnetic sensor Soft iron effects are the change of direction of a magnetic field this change is caused by hard iron on the input direction Hard iron magnetic fields are permanent whereas soft iron magnetic fields are temporary soft iron can be magnetized and then demagnetized or have varying effects during operation Following is an overview
28. error has an associated message with low level error signals The hardwareError flag in the BITstatus field is the bit wise OR of the hardwareBIT field Table 79 hardwareBIT Field hardwareBIT Field Bits Values Category powerError 0 0 normal 1 error Soft environmentalError 1 0 normal 1 error Soft reserved 2 15 N A hardwarePowerBIT Field The hardwarePowerBIT field contains flags that indicate low level power system errors The powerError flag in the hardwareBIT field is the bit wise OR of the hardwarePowerBIT field Table 80 hardwarePowerBIT Field hardwarePowerBIT Field Bit Values Category inpPower 0 0 normal 1 out of bounds inpCurrent 1 0 normal 1 out of bounds 2 1 Soft Soft inpVoltage 0 normal 1 out of bounds Soft Soft fiveVolt 3 0 normal 1 out of bounds GNAV540 User Manual Page 101 7430 0808 01 Rev B MOOG hardwarePowerBIT Field i Values Category threeVolt 0 normal 1 out of bounds Soft twoVolt 0 normal 1 out of bounds Soft twoFiveRef 0 normal 1 out of bounds Soft sixVolt 0 normal 1 out of bounds Soft grdRef 0 normal 1 out of bounds Soft fourVolt 0 normal 1 out of bounds Soft Reserved 10 15 N A N A hardwareEnvironmentalBIT Field The hardwareEnvironmentalBIT field contains flags that indicate low level hardware environmental errors The environmentalError flag in the hardwareBIT field is the bit wise OR of the hardwareEnvironmentalBIT fie
29. for an external magnetometer If the calibration process is run with the GNAV540 by itself not installed in the field system there will be no corrections for the magnetism in the field system Afterwards when the GNAV540 unit is installed in the system such as a vehicle and if magnetic fields are present in the system errors will occur due to the magnetism of the system After completing the alignment procedure the heading accuracy should be verified with all third party systems actively using a known reference such as a compass rose GPS track or a calibrated compass Heading inaccuracies GNAV540 User Manual 7430 0808 01 Rev B Page 57 MOOG greater than the values specified on the data sheet or fluctuating heading performance may indicate magnetic field disturbances near the unit NOTE An acceptable calibration will provide X and Y Hard Iron Offset Values of 0 1 and a Soft Iron Ratio 50 95 If this procedure generates calibration parameters significantly outside of this range the system will assert the softwareError gt dataError gt magAlignOutOfBounds error flag Refer to Chapter 11 Built In Test BIT for details about error flag handling For more information about magnetic fields and the effects on readings and alignment refer to Chapter 4 Magnetometer Calibration and Alignment Guidelines on page 39 Alignment Instructions Following are the magnetometer alignment instructions using NAV VIEW 2 2
30. or Yaw axis the softwareStatus bit can be configured to go high 1 during a turn In VG Function the default value of turnSwitch is 10 0 deg sec about the z axis NAV 0 nominal 1 Algorithm Initialization or High Gain For additional visibility or alerts relative to the GPS sensor status or algorithm status configure additional triggers for both softwareStatus and hardwareStatus For information about configuring this status field refer to BIT Configuration on page 56 and SoftwareStatus Field on page 105 and Configuring masterStatus on page 106 Page 100 GNAV540 User Manual 7430 0808 01 Rev B MOOG Status Byte Field Default Values sensorStatus e AHRS 0 nominal bit 12 1 Sensor Over Range IMU 0 nominal 1 Sensor Over Range Sensor Over Range only applies to the rotational rate sensors over range is not triggered for accelerometer readings In many applications vibration causes instantaneous acceleration levels to exceed the accelerometer sensor range VG 0 nominal 1 Sensor Over Range e NAV 0 nominal 1 Sensor Over Range For information about configuring this status field refer to BIT Configuration on page 56 and sensorStatus Field on page 106 and Configuring masterStatus on page 106 GPSStatus e NAV 0 GPS data valid bit 13 1 GPS data not valid e AHRS IMU VG N A hardwareBIT Field The hardwareBIT field contains flags that indicate various internal hardware errors Each hardware
31. packet in response to a ping command Echo Command Table 16 Echo Command Echo CH 0x4348 0x5555 0x4348 echo payload CRC U2 gt The echo command allows testing and verification of the communication link The unit will respond with an echo response containing the echo data The echo data is N bytes long Echo Response Table 17 Echo Response Echo Payload Contents Byte Name Format Scaling Units Description Offset 0 echoData0 U1 first byte of echo data 1 echoData1 U1 Second byte of echo data U1 Echo data N 2 echoData U1 Second to last byte of echo data N 1 echoData U1 Last byte of echo data GNAV540 User Manual Page 67 7430 0808 01 Rev B MOOG Interactive Commands Interactive commands are used to interactively request data from the GNAV540 unit and to calibrate or reset the unit Get Packet Request Table 18 GP Request Get Packet GP 0x4750 0x5555 0x4750 lt GP payload gt lt CRC U2 gt This command allows the user to poll for both measurement packets and special purpose output packets including TO VR and ID Table 19 GP Payload GP Payload Contents Byte Name Format Scaling Units Description Offset 0 requestedPacketType U2 The requested packet type Refer to the sections below for Packet Definitions sent in response to the GP comman
32. page 68 or a hard reset recycle power of the GNAV540 unit takes place Page 60 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 8 Data Packet Structure NOTE This section of the manual assumes the reader is familiar with ANSI C programming language and data type conventions The unit supports a common packet structure that includes both command or input data packets and measurement output or response packet formats This section of the manual explains these packet formats as well as the supported commands NAV VIEW 2 2 also features a number of tools that can help a user understand the packet types available and the information contained within the packets For an example of the code required to parse input data packets please see refer to Appendix B Sample Packet Parser Code General Settings The serial port settings are RS232 with 1 start bit 8 data bits no parity bit 1 stop bit and no flow control Standard baud rates supported are 9600 19200 38400 and 57600 Common definitions include e Aword is defined as 2 bytes which are 16 bits e All communications to and from the unit are packets that start with a single word alternating bit preamble 0x5555 This is the ASCII string UU e All multiple byte values are transmitted Big Endian Most Significant Byte First e All communication packets end with a single word CRC 2 bytes CRC s are calculated on all packet bytes excluding the preamble and
33. sort of mutual exclusion mechanism within the queue access functions Code Listingtinclude stdio h buffer size define MAXQUEUE 500 circular queue Ki typedef struct queue tag int count int front int rear char entry MAXQUEUE QUEUE TYPE crossbow packet ST typedef struct xbow packet unsigned short packet char unsigned short cns char XBOW PACKET QUEUE TYPE circ buf _type length data 256 KKK KK RAR k k k k k k k k k k k k k k kk kk kk kk kk kok kk kok kok kok kok kok kok kk ER ke ke kkk FUNCTION process xbow packet looks for packets in a queue will contain the parsed info when return value is 1 RARE KE KR 2 22 KA 2 2 2 2 KA 2 2 22 2 2 2 2 2 2 2 2 2 2 2 2 22 2 2 2 2 k k k k k k kk 2 kk k ck k 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2072 E_TYPE queue_ptr XBOW_PACK packet_type ARGUMENTS queue_ptr is pointer to queue to process x result RETURNS 0 when failed i 1 when successful int process xbow packet QUEU unsigned short myCRC 0 packetCRC 0 char packet 100 tempchar dataLength if Empty queue ptr return 0 empty buffer find header for numToPop 0 numToPop 1 lt Size queue_ptr if 0x5555 peekWord queue ptr numToPop break ET result 0 numToPop 0 counter 0 numToPop 1
34. that will logically flow up to the masterStatus flag Table 92 sensorStatus Fields sensorStatus Field Values overRange 0 not asserted 1 asserted Reserved N A Configuring masterStatus The masterStatus byte and its associated programmable alerts are configured using the Read Field and Write Field command as described in Chapter 10 Programming Guidelines Table 93 below shows the definition of the bit mask for configuring the status signals Table 93 masterStatus Fields Configuration Fields Field ID Valid Values Description hardwareStatusEnable 0x0010 A Bit mask of enabled hardware status signals A ny comStatusEnable 0x0011 ny Bit mask of enabled communication status signals softwareStatusEnable 0x0012 Any Bit mask of enabled software status signals sensorStatusEnable 0x0013 Any Bit mask of enabled sensor status signals hardwareStatusEnable Field This field is a bit mask of the hardwareStatus field refer to BIT Status Fields on page 98 This field allows the user to determine which low level hardwareStatus field signals will flag the hardwareStatus and masterStatus flags in the BITstatus field Any asserted bits in this field imply that the corresponding hardwareStatus field signal if asserted will cause the hardwareStatus and masterStatus flags to be asserted in the BITstatus field Page 106 GNAV540 User Manual 7430 0808 01 Rev B MOOG comStatusEnable Field This field is a bit mask of the comStatu
35. unit was physically installed If necessary select the appropriate values under X Y and Z to position the axes correctly For more information refer to GNAV540 Default Coordinate System on page 24 Figure 17 Unit Configuration BER General Advanced BIT Configuration External Mag Field Modify Current Value Value to Set Baud Rate sano baud 57600 baud Packet Type pao cago sensor d PacketRate M Hz ke y Z x Y z x Y Orientation Mz Feux fu DD DI X z UX Y Uy Fd Uz GPS Baud Rate I fruto baua GPS Protocol I fautodetect y Get All Values Set Values Temporary reset after reboot C Permanant saved after reboot Figure 18 Orientation External Magnetometer UX Uy Uz NOTE Ensure that the settings selected are compatible with the system that is being configured In most cases a FAIL message will appear if incompatible selections are made NOTE Unit orientation selections must conform to the right hand coordinate system as noted in GNAV540 Default Coordinate System page 24 Selecting orientations that do not conform to these criteria are not allowed GNAV540 User Manual 7430 0808 01 Rev B Page 55 Advanced MOOG The Advanced tab provides access to more complex configurations such as user behavior settings Viewing Current Configuration To view the current configuration click the Get All Values button The current settings will be displaye
36. view all current configurations on one page refer to Viewing Current Configuration on page 53 Additional configuration options are described in the following sections Page 54 GNAV540 User Manual 7430 0808 01 Rev B MOOG Viewing Current Configuration To view the current configuration click the Get All Values button The current settings will be displayed in the text fields Changing Configurations To change a configuration setting 1 Checkmark the desired item s in the left Colum 2 Using the drop menus in the right column select the new values 3 Select either Temporary or Permanent Temporary The configuration will not be stored in non volatile memory EEPROM The configuration will be applied but the unit will return to the Permanent configuration when it is rebooted Permanent The configuration will be stored in non volatile memory The unit will continue to use the configuration after being rebooted 4 Click the Set Values button The configuration values will be saved as specified Temporary or Permanent Orientation Orientation refers to the magnetic orientation of the unit to the body of the system in which the unit is installed The axes of the unit should be positioned as illustrated e The GNVA540 is displayed when the magnetometer is internal Figure 17 e The magnetometer is displayed when the magnetometer is external Figure 18 The directions of the axes are related to how the
37. 0 ffd7ffba000100000000ffffffZ2ff5cOlaeO0000000000000000000000000000 GNAV540 User Manual Page 51 7430 0808 01 Rev B Horizon and Compass Views MOOG NAV VIEW 2 2 provides a compass and a simulated artificial horizon view e To activate these views click View at the menu bar and then select Horizon View and or Compass View from drop down menu Figure 13 Horizon and Compass Views Packet Statistics View To view packet statistics click View at the menu bar and then select the Packet Statistics This view provides a short list of vital statistics including Packet Rate CRC Failures and overall Elapsed Time that are calculated over a one second window This tool should be used to gather information regarding the overall health of the user configuration Incorrectly configured communication settings can result in a large number of CRC Failures and poor data Transfer Compass View HOG 30 0 Figure 14 Packet Statistics Packet Statistics Packets Received 146442 CRC Failures Avg Packet Rate Hz 102 30 Elapsed Time 00 24 23 Reset Done Page 52 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 7 Configuring GNAV540 with NAV VIEW 2 2 It is assumed the GNAV540 unit and NAV VIEW 2 2 have been set up For instructions refer to Chapter 5 Installation Guidelines This section provides instructions to configure the unit via NAV VIEW 2 2 a GUI application For information ab
38. 0 148 FFFD 0 181 3A5B 82 062 Angular Rates Hex Value Data deg s il 7 E 7 GPS 00000000 0 000000000 Rad 00000000 0 000000000 Rad u Page 122 GNAV540 User Manual 7430 0808 01 Rev B MOOG GNAV540 User Manual Page 123 7430 0808 01 Rev B MOOG Appendix D Mechanical Specifications J1 Connector Interface J1 is a 37 pin circular connector Recommended plug and backshell to interface to J2 e D38999 26FD35SN Circular mil spec connectors straight plug 37 pin size 15 AERO ELECTRIC Specifications Environment Operating Temperature 40 to 71 C Enclosure IP66 compliant Electrical Input Voltage 9 to 32 VDC Power Consumption lt 4 W Digital Interface 10 100 Ethernet or RS 422 Physical Size 5 3 w x 4 8 1 x 2 7 h Weight 2 7 lbs 1 2 kg Interface Connector Mil C 38999 37 Page 124 GNAV540 User Manual 7430 0808 01 Rev B MOOG Mechanical Drawings Figure 30 GNAV540 Casing GNAV540 User Manual Page 125 7430 0808 01 Rev B MOOG Interface Cable Accessory NOTE This cable is provided when the GNAV540 is purchased with the developer s kit Figure 31 Interface Cable Accessory cad AE Ethernet cable a RJ45 pd 7 P NG a Be Z 96 IN T PIN 1 RS232 TO RS 422 CONVERTER JS p A A p NOTE The ON OFF switch on the MAGNETOMETER port is normally switche
39. 0808 01 Rev B MOOG Angle Data Packet 0 Table 43 AO Data Packet Angle Data A0 0x4130 0x5555 0x4130 A0 payload CRC U2 gt This packet contains angle data and selected sensor data scaled in most cases to a signed 2 16 2 s complement number Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angles scaled to a range of pi pi or 180 deg to 180 deg e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Magnetometers scaled to a range of 1 1 Gauss e Temperature scaled to a range of 100 100 C Table 44 AO Payload AO Payload Contents Byte Name Format Scaling Units Description Offset 0 rollAngle I2 2 pi 2 16 Radians Roll angle 360 2 16 2 pitchAngle 12 2 pi 2 16 Radians Pitch angle 360 2 16 4 yawAngleMag 12 2 pi 2 16 Radians Yaw angle magnetic north 360 2 16 6 xRateCorrected I2 7 pi 2 16 rad s X angular RateCorrected 1260 2 16 sec 8 yRateCorrected I2 7 pi 2 16 rad s Y angular Rate Corrected 1260 2 16 sec 10 zRateCorrected I2 7 pi 2 16 rad s Z angular Rate Corrected 1260 2 16 sec 12 xAccelCorrected I2 20 2116 g X Accel Corrected 14 yAccelCorrected I2 20 2116 g Y Accel Corrected 16 zAccelCorrected
40. 0Hz 10Hz 5Hz 1 packet rate divider 0x0001 20 25 50 4Hz 2Hz 2 Serial Port A BAUD rate 0x0002 0 1 2 3 9600 19200 38400 57600 Not all output packets available for all products See detailed field descriptions below 3 Continuous packet type 0x0003 Any output packet type 7 0x0007 Determine forward rightward and downward facing sides 8 User Behavior Switches 0x0008 Refer to User Behavior Switches page 88 9 X Hard Iron Bias 0x0009 I2 scaled from 1 1 10 YHard Iron Bias 0x000A 12 scaled from 1 1 11 Soft Iron Scale Ratio 0x000B U2 scaled from 0 2 12 Heading Track Offset 0x000C Heading Track Offset to use in NAV filter track update mode 73 65535 ich ti i 13 Turn Switch Threshold 0x000D Sets yaw rate above which tilt feedback is 0 4 360 s attenuated Angle of major axis of the ellipse generated by Soft Iron m caia 360 degree swing in radian 15 reserved 0x000F 16 hardwareStatusEnable 0x0010 Any Bit mask of enabled hardware status signals GNAV540 User Manual Page 85 7430 0808 01 Rev B MOOG index Configuration fields Field ID Valid Values Description 17 comStatusEnable 0x0011 ub of enabled communication status 18 Bit mask of enabled software status signals 19 Bit mask of enabled sensor status signals 20 Auto baud 9600 19200 38400 57600 21 GPS support protocol ICD 153 S N A 23 Roll offset external Mag 0x0017 SE OR external MEETS SHE ody 24 Pitch off
41. 1 0138 0 000 0 000 0 000 Communication Port The GNAV540 can be accessed via serial or Ethernet port which is selected in the Setup menu To select a port click Setup and then select the NAV desired port from the drop menu A dialog j Hel window then opens enabling configuration dee Port LIVE Mode from DMU Ethernet Page 48 GNAV540 User Manual 7430 0808 01 Rev B MOOG Figure 9 Configure Serial Port Serial Port The Configure Serial Port dialog shows the current Port and Baud rate which can both be COM Port Current Port configured To do so COM5 coms 1 Select the desired COM Port SYA Current Baud Rate 2 Fither manually select the desired C TRUE A IP E 38400 Baud Rate or select Auto EN O To apply the configuration click Apply Disconnect 4 To ensure the configuration is saved in Detect Unit Baud Rate Bs NAV VIEW click Save and Close onw Figure 10 Configure Ethernet Port Ethernet Port The Ethernet settings are configured in the EthernetForm dialog To do so 1 Enterthe Ethernet address of the GNAV540 unit 2 Enterthe Ethernet Port number 10001 3 Toapply the configuration and activate the connection click Connect 4 To ensure the configuration is saved after rebooting the unit click Save and Close Record Data NAV VIEW 2 2 can be used to log data to a text fi
42. 10 g e Temperature scaled to a range of 100 100 C e Velocities scaled to a range of 256 256 m s e Altitude scaled to a range of 100 16284 m using a shifted 2 s complement representation e Longitude and latitude scaled to a range of pi pi or 180 deg to 180 deg Table 48 NO Payload NO Payload Contents Byte Name Format Scaling Units Description Offset 0 rollAngle I2 2 pi 2 16 Radians Roll angle 360 2 16 2 pitchAngle I2 2 pi 2 16 Radians Pitch angle 360 2 16 4 yawAngleTrue I2 2 pi 2 16 Radians Yaw angle true north 360 2 16 6 xRateCorrected I2 7 pi 2 16 rad s X angular rate corrected Page 78 GNAV540 User Manual 7430 0808 01 Rev B MOOG NO Payload Contents Byte Name Format Scaling Units Description Offset 1260 2716 sec 8 yRateCorrected I2 7 pi 2 16 rad s Y angular rate corrected 1260 2 16 sec 10 zRateCorrected I2 7 pi 2 16 rad s Z angular rate corrected 1260 2 16 sec 12 nVel I2 512 2 16 m s North velocity 14 eVel I2 512 2 16 m s East velocity 16 dVel I2 512 2 16 m s Down velocity 18 longitudeGPS I4 2 pi 2 32 Radians GPS Longitude 360 2 32 22 latitudeGPS 14 2 pi 2 32 Radians GPS Latitude 360 2 32 26 altitudeGPS I2 2 14 2 16 m GPS altitude 100 16284 28 GPSITOW U2 truncated ms GPS ITOW lower 2 bytes 30 BITstatus U2
43. 2 512 2 16 m s GPS Down velocity 24 longitudeGPS I4 2 pi 2 32 Radians GPS Longitude 360 2 32 28 latitudeGPS 14 2 pi 2 32 Radians GPS Latitude 360 2 32 32 altitudeGPS I2 2 14 2 16 m GPS altitude 100 16284 34 GPS heading I2 2 pi 2 16 Radians heading angle from GPS 360 2116 measurement 36 xRateTemp I2 200 2 16 deg C Xrate sensor temperature 38 UTCTime OfDay U4 Milli sec UTC time of the day 42 UTC Day of Year U2 44 UTC Year U2 46 BITstatus U2 Master BIT and Status NOTE If no GPS available the UTC time second and UTC ms are the time since the unit is powered on The year and day will be set to 0 Nav Data Packet 4 Table 53 N4 Data Packet Nav Data N4 0x4E34 0x5555 0x4E34 lt N4 payload lt CRC U2 gt This packet is identical to the NAV1 packet with the exception of having a 4 byte output of altitude which allows for altitudes greater than 8192 meters This packet contains navigation data and selected sensor data scaled in most cases to a signed 2 16 2 s complement number Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angles scaled to a range of pi pi or 180 deg to 180 deg e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Temperature scaled to a range of 100 100 C
44. 53 Figure 16 View Current Configuration nent 54 Figure 17 Unit Con figurations iP V 55 Figure 18 Orientation External Magnetometer ear recen 55 Figure 19 Advanced A A ta 56 Figure 20 BIT Configuration iii AA AA a 57 Figure 21 Internal Magnetometer Alignment Dialogues 58 Figure 22 Magnetometer Alignment Values esset reee 59 Fig re 23 Offset Alignment 2 cee an tuus ad 59 Figure 24 External Magnetometer Alignment Dialogues 60 Figure 25 Magnetometer Alignment Values essere tnnt ear recen 60 Figure 26 Orientation Fields Figure 27 Orientation Field Figure 28 BIT Error and Status Hierarchy Figure 29 Flight Profiles Fixed Wing Aircraft Corresponding Settings Figure 30 GNAV540 Casing Figure 31 Interface Cable Accessory GNAV540 User Manual Page 11 7430 0808 01 Rev B MOOG Page 12 GNAV540 User Manual 7430 0808 01 Rev B MOOG Preface This document provides information about GNAV540 including operational functions and configuration options Intended Audience This document is intended for those who install configure extract data and use inertial systems It is assumed the reader is familiar with the technology of navigation For advanced use of the GNAV540 knowledge of C programming is required NOTE Uploading firmware DMU upgrade to the unit is outside the scope of this document For information contact Customer Service re
45. 540 User Manual 7430 0808 01 Rev B MOOG measure zero g along the x and y axes and 1 g along the z axis Normal Force acceleration is directed upward which would be defined as negative for the GNAV540 z axis The angular rate sensors are aligned with the 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 GNAV540 product 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 The magnetic sensors are aligned with the same axes definitions and sign as the linear accelerometers For example when oriented towards magnetic North you will read approximately 0 25 Gauss along X 0 0 Gauss along Y and 0 35 Gauss along Z direction North America Magnetic values at other geographic locations are available at http www ngdc noaa gov geomag WMM DoDWMM shtml Pitch is defined positive for a positive rotation around the y axis pitch up Rollis defined as positive for a positive rotation around the x axis roll right Yaw is defined as posit
46. 540 User Manual Page 27 7430 0808 01 Rev B Setting Freely Integrate Restart On Over Range Dynamic Motion Turn Switch threshold Default Value OFF 10 0 deg sec MOOG Comments The Freely Integrate setting allows configuring the unit into a free gyroscope In free gyroscope mode the roll pitch and yaw are computed exclusively from angular rate with no Kalman filter based corrections of roll pitch or yaw When turned on there is no coupling of acceleration based signals into the roll and pitch As a result the roll pitch and yaw outputs will drift roughly linearly with time due to sensor bias For best performance the Freely Integrate mode should be used after the algorithm has initialized This allows the Kalman Filter to estimate the roll and pitch rate sensor bias prior to entering the free gyroscope mode Exiting the free gyroscope mode OFF causes one of the following behaviors to occur e Ifthe unit has been in freely integrate mode for less than sixty seconds the algorithm will resume operation at normal gain settings If the unit has been in freely integrate mode for greater than sixty seconds the algorithm will force a reset and reinitialize with high gains automatically This setting forces an algorithm reset when a sensor over range occurs i e a rotational rate on any ofthe three axes exceeds the maximum range The default setting is OFF Algorithm reset returns the unit to a high gain state
47. 8 BIT Error and Status Hierarchy s Field hardwareError hardwarBIT Field powerError hardwarePowerBIT Field inpPower inpCurrent inpVoltage five Volt threeVolt twoVolt twoFiveRef sixVolt grdRef environmentalError hardwareEnvironmentalBIT Field pebTemp comError comBIT Field comSerialABIT Field transmitBufferOverfiow receiveBufferOverflow comSerialABIT Field transmitBufferOverfiow receiveBufferOverflow framingError breakDetect parityError I I framingError N breakDetect N parityError serialBError comSenalBBIT Field I transmitBufferOverflow I receiveBufferOverflow I framingError breakDetect E parityError softwareError softwareBIT Field algorithmError softwareAlgorithmBIT Field initialization overRange missedintegrationStep dataError softwareDataBIT Field calibrationCRCError magAlignOutOfBounds NACOCOCS hardwareStatus Field unlocked1PPS unlockedinternalGPS noDGPS unlockedEEPROM comStatus comStatus Field noExternalGPS softwareStatus softwareStatus Field algorithminitialization highGain attitudeOnlyAlgorithm tumSwitch GPSStatus Page 108 GNAV540 User Manual 7430 0808 01 Rev B MOOG GNAV540 User Manual Page 109 7430 0808 01 Rev B MOOG Appendix A Application Examples This section provides recommended advanced settings for tailoring the GNAV540 unit of inertial systems to different types of application and platform requirements Fixed Wing
48. B MOOG softwareBIT Field The softwareBIT field contains flags that indicate various types of software errors Each type has an associated message with low level error signals The softwareError flag in the BITstatus field is the bit wise OR of the softwareBIT field Table 86 softwareBIT Field softwareBIT Field Bits Values Category algorithmError 0 0 normal 1 error Soft dataError 1 0 normal 1 error Soft Reserved 2 15 N A softwareAlgorithmBIT Field The softwareAlgorithmBIT field contains flags that indicate low level software algorithm errors The algorithmError flag in the softwareBIT field is the bit wise OR of the softwareAlgorithmBIT field Table 87 softwareAlgorithmBIT Field SoftwareAlgorithmBIT Field Category initialization 0 normal 1 error during algorithm Hard initialization overRange 0 normal 1 fatal sensor over range Hard missedNavigationStep 0 normal 1 fatal hard deadline Hard missed for navigation Reserved softwareDataBIT Field The softwareDataBIT field contains flags that indicate low level software data errors The dataError flag in the softwareBIT field is the bit wise OR of the softwareDataBIT field Table 88 softwareDataBIT Field SoftwareDataBIT Field Values Category calibrationCRCError 0 normal 1 incorrect CRC on Hard calibration EEPROM data or data has been compromised by a WE command magAlignOutOfBounds 1 0 normal 1 hard and soft iron Hard parameters
49. Bias Stability over temp 4 mg Signal Interface The J1 port of the GNAV540 provides the connections listed in Table 6 below Details of the signal interface including I O pin out is provided in Chapter 3 Hardware Interface on page 35 Table 6 J1 Interface Connector Connection Description There are three serial interfaces RS422 e Mag connect to external Magnetometer e GPS Connect to external GPS e User Connect to computer or host CPU Ethernet Connect to user interface The default IP address of the unit 192 168 1 2 Power Input Labeled 12 30 VDC and Ground connect to DC power source Software Compatibility Crossbow s GNAV540 Inertial Systems are generally software compatible with the 440 series of Crossbow products The GNAV540 utilizes the 440 series extensible communication protocol which is described in Chapter 9 Communicating with the GNAV540 Unit GNAV540 Unit The GNAV540 is Crossbow s fourth generation of MEMS based Inertial Systems building on over a decade of field experience and encompassing thousands of deployed units and millions of operational hours in a wide range of land marine airborne and instrumentation applications Summary of GNAV540 features 6 DOF IMU 3 Axis Internal Magnetometer Dynamic Velocity Dynamic Roll Pitch and Heading GPS Receiver for Position e Atthecore of the GNAV540 unit is a rugged 6 DOF Degrees of Freedom MEMS inertial sensor cluster The 6 DOF MEMS inertial se
50. CII NAK NAK 0x1515 0x5555 0x1515 NAK payload CRC U2 gt The unit will send this packet in place of a normal response to a failedinoutPacketType request if it could not be completed successfully NAK Payload Contents Byte Name Format Scaling Units Description Offset 0 failedInputPacketType U2 the failed request Output Packets Polled The following packet formats are special informational packets which can be requested using the GP command Identification Data Packet Table 32 ID Data Packet Identification Data ID 0x4944 0x5555 0x4944 lt ID payload gt CRC U2 gt This packet contains the unit serialNumber and modelString The model string is terminated with 0x00 The model string contains the programmed versionString 8 bit ASCII values followed by the firmware part number string delimited by a whitespace Table 33 ID Payload Contents ID Payload Contents Byte Name Format Scaling Units Description Offset 0 serialNumber U4 Unit serial number 4 modelString SN Unit Version String 4 N 0x00 U1 Zero Delimiter Version Data Packet Table 34 Version Data PKT Version Data VR 0x5652 0x5555 0x5652 VR payload CRC U2 gt GNAV540 User Manual Page 71 7430 0808 01 Rev B MOOG This packet contains firmware version information majorVersion changes may introduce ser
51. CRC itself Input packets with incorrect CRC s will be ignored e Each complete communication packet must be transmitted to the GNAV540 inertial system within a four 4 second period Number Formats Number Format Conventions include e Oxasa prefix to hexadecimal values e Single quotes to delimit ASCII characters e No prefix or delimiters to specify decimal values The following table defines number formats Table 12 Number Formats Descriptor Description Size bytes Comment Range U1 Unsigned Char 0 to 255 U2 Unsigned Short 0 to 65535 U4 Unsigned Int 0 to 2 32 1 Signed Short 2 s Complement 2 15 to 2 15 1 I2 I2 Signed Short Shifted 2 s Complement Shifted to specified range 14 Signed Int 2 s Complement 2 31 to 231 1 GNAV540 User Manual Page 61 7430 0808 01 Rev B MOOG Descriptor Description Size bytes Comment Range F4 Floating Point 4 IEEE754 Single 1 2 127 to 2 127 Precision SN String N ASCII Packet Format All of the Input and Output packets except the Ping command conform to the following structure 0x5555 lt 2 byte packet type U2 gt payload byte length U1 gt lt variable length payload lt 2 byte CRC U2 gt The Ping Command does not require a CRC so a GNAV540 unit can be pinged from a terminal emulator To Ping a GNAV540 unit type the ASCII string UUPK If properly connected the GNAV540 unit will respond with PK All other communications w
52. Chapter 9 Communicating with the GNA540 Unit and Chapter 10 Programming Guidelines GNAV540 User Manual Page 25 7430 0808 01 Rev B MOOG NOTE The Delta Theta Delta V packet is only recommended for use in continuous output mode at 5H7 or greater Polled requests for this packet will produce values accumulated since the last poll request they are subject to overflow data type wrap around IMU Advanced Settings The IMU advanced settings are described in Table 7 below All of the advanced settings are accessible thru NAV VIEW 2 2 under the Configuration Menu gt Unit Configuration settings For information about using NAV VIEW 2 2 refer to Chapter 7 Configuring GNAV540 with NAV VIEW 2 2 Table 7 IMU Function Advanced Settings Setting Default Value Comments Baud Rate 38 400 9600 19200 57600 also available Packet Type S1 S2 also available Packet Rate 100Hz This sets the rate at which the selected Packet Type packets are output If polled mode is desired then select Quiet If Quiet is selected the unit will only send measurement packets in response to GP commands Orientation See Figure 4on To configure the axis orientation select the desired measurement for each axis page 24 NAV VIEW 2 2 will show the corresponding image of the unit so it easy to visualize the mode of operation Refer to Orientation Field on page 86 for the twenty four possible orientation settings The default setting points the connector AFT
53. Configurable Reserved 5 7 N A Status Byte Fields masterStatus 0 nominal 1 one or more status alerts occurred hardware com software sensor hardwareStatus 0 nominal 1 programmable alert refer to Programmable Status below comStatus 10 0 nominal 1 programmable alert refer to Programmable Status Fields below softwareStatus 11 0 nominal 1 programmable alert refer to Programmable Status Fields below sensorStatus 12 0 nominal 1 programmable alert refer to Programmable Status Fields below GPSStatus 13 0 GPS data valid 1 GPS data not valid HeadingStatus 14 0 heading verified 1 heading not verified P Y code detected 15 0 no P Y code detected 1 P Y code detected Programmable Status Fields The BIT status fields can be configured The operation modes AHRS IU VG and NAV affect the default value of the hardware com software and sensor status bits The default settings are appropriate for most installations NOTE The settings should not be configured unless determined necessary incorrect configurations can adversely affect operations NOTE Error fields cannot be configured The default values are listed in Table 78 below Table 78 Programmable BIT Status Default Values per Function Status Byte Field Default Values masterStatus The masterStatus flag is asserted when an enabled alert signal is asserted bit 8 For information about configuring this status field refer to BIT Configur
54. ENTS queue_ptr is pointer to the queue RETURNS return 1 if empty 0 if not KK 22 22 22 22 22 22 22 22 22 22 22 2 2 22 22 22 2 2 22 22 22 2 2 22 2 2 22 22 22 2 2 22 22 22 2 2 22 2 2 2 2 int Empty QUEUE TYPE queue ptr return queue ptr gt count lt 0 VE EEE EEE RR RR 22 2 k KA KA 2 2 2 2 2 2 22 2 2 2 2 2 k 2 2 kk 2 2 2 22 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ke e ke ek FUNCTION Full ARGUMENTS queue_ptr is pointer to the queue RETURNS return 1 if full O if not full Koko kk kk kk kk kk kk kk k k kk k 22 22 22 22 22 22 2 2 kk kk k k 22 k 22 2 2 22 2 2 22 2 2 22 22 22 2 2 22 2 2 2 2 int Full QUEUE TYPE queue ptr return queue ptr count gt MAXQUEUE GNAV540 User Manual Page 119 7430 0808 01 Rev B MOOG Appendix C Sample Packet Decoding Example payload from Scaled Sensor 1 data packet S1 5555 5331 18 0000fffef332 fff30001fff8 23b9242624ca2aff 9681 0300 248a preamble type length counter CRC invalid BIT status Field masterFail hardwareError o Hex Value Data deg C 23B9 28 241 2426 28 741 24CA 33 591 2AFF 38 968 Hex Value Data g i p FFFE 0 001 7 Angular Rates Hex Value Data deg s i u ui comError softwareError reserved 0000 masterStatus hardwareStatus comStatus softwareStatus o sensorStatus reserved Page
55. ETURNS queue ptr is pointer to queue holding area to be CRCed startIndex is offset into buffer where to begin CRC calculation num is offset into buffer where to stop CRC calculation 2 byte CRC FA AAA 2 2 22 2 2 KA 2 KA 2 KA 2 2 2 2 2 2 KA 2 2 22 2 2 2 2 2 2 2 2 2 2 22 2 k 2 2 k 2 2 k 2 2 2 2 2 2 2 EE EK ke oe eoe e e unsigned short calcCRC QUEUE TYPE queue ptr unsigned int startIndex unsigned int num unsigned int 1 0 j 0 unsigned short crc 0x1D0F non augmented inital value equivalent to augmented initial value OxFFFF for i20 i lt num i 1 crc peekByte queue ptr startIndex i lt lt 8 for 3 0 3 lt 8 3 1 if crc 0x8000 crc crc lt lt 1 0x1021 else crc cre lt lt 1 return crc KKK IK RR AK AK AA RR 2 KA 22 2 2 2 2 2 2 2 2 2 2 2 k 2 2 k 2 2 22 2 2 kk 2 2 2 2 2 2 22 2 2 2 2 2 2 2 2 2 ke e ke ek FUNCTION ARGUMENTS Initialize initialize the queue queue ptr is pointer to the queue Kk kk kk kok kok kok k k kok 22 212 22 212 22 212 212 22 22 2 2 k k 22 22 22 22 22 22 22 22 22 22 22 22 22 2 2 2 2 void Ini tialize QUEUE TYPE queue ptr queue ptr count 0 queue ptr gt front 0 queue ptr gt rear 1 KKK IK KR RR k k k k k k k k k k kk kk kk kk kk kk kk kok kk kok kok kok kok 2 Kk ke ke ke ke ke kk kk KKK FUNCTION ARGUMENTS RETURNS
56. I2 20 2116 g Z Accel Corrected 18 xMag I2 2 2 16 Gauss X magnetometer 20 yMag I2 2 2 16 Gauss Y magnetometer 22 zMag I2 2 2 16 Gauss Z magnetometer 24 xRateTemp I2 200 2 16 deg C Xrate temperature Page 76 GNAV540 User Manual 7430 0808 01 Rev B MOOG AO Payload Contents Byte Name Format Scaling Units Description Offset 26 GPSITOW U2 truncated ms GPS ITOW lower 2 bytes 28 BITstatus U2 Master BIT and Status Angle Data Packet 1 Default AHRS Data Table 45 A1 Data Packet Angle Data A1 0x4131 0x5555 0x4131 A1 payload CRC U2 gt This packet contains angle data and selected sensor data scaled in most cases to a signed 2 16 2 s complement number Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angles scaled to a range of pi pi or 180 deg to 180 deg e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Magnetometers scaled to a range of 1 1 Gauss e Temperature scaled to a range of 100 100 C Table 46 A1 Payload A1 Payload Contents Byte Name Format Scaling Units Description Offset 0 rollAngle I2 2 pi 2 16 Radians Roll angle 360 2 16 2 pitchAngle I2 2 pi 2 16 Radians Pitch angle 360 2 16 4 yawA
57. Inertial Systems to satisfy a wide range of applications and performance requirements with a single mass produced hardware platform The basic configurability includes parameters such as baud rate packet type and update rate and the advanced configurability includes the defining of custom axes and how the sensor feedback is utilized in the Kalman filter during the navigation process The GNAV540 unit is packaged in a fully sealed lightweight housing that provides EMI vibration and moisture resistance to levels consistent with most land marine and airborne environments The GNAV540 utilizes an RS 422 serial link or Ethernet interface for data communication and each data transmission includes a BIT Built In Test message providing system health status The GNAV540 is supported by Crossbow s NAV VIEW 2 2 a powerful PC based operating tool that provides complete field configuration diagnostics charting sensor performance and data logging with playback GNAV540 User Manual Page 19 7430 0808 01 Rev B MOOG Page 20 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 2 GNfAV540 Functions This chapter provides an overview of the hardware and software systems of the GNAV540 unit and the functions provided e GNAV540 System page 21 e Configuring GNAV540 Functions page 21 e Software Structure page 22 e GNAV540 Default Coordinate System page 24 e IMU Function page 25 e Vertical Gyroscope VG Function page 26 e AH
58. Italics Emphasizes important information or indicates the title of a document Bold Stronger emphasis of important information i Indicates a sample of screen output a command in the body of the document or an System items example of a command to enter GNAV540 User Manual Page 15 7430 0808 01 Rev B MOOG Glossary Table 4 Glossary E Environmental Stress Screening EKF Extended Kalman Filter F Finite Impulse Response ECEF Earth Centered Earth Fixed GB GRAM Ground Based GPS Receiver Application Module MEMS Micro Electro Mechanical Systems S Soft error Persistent error repeated many times within a period of time T P SS IR S IMU Inertial Measurement Unit LLA Latitude Longitude and Altitude LSB S S Least Significant Byte I GP Global Positioning System Hard failure Fatal condition non operational MSB Most Significant Byte P Hard iron Magnetism is retained permanent Soft iron Magnetism is not retained magnetism only occurs while the material exposed to a magnetic field VDC Voltage Direct Current VG Vertical Gyroscope WAAS Wide Area Augmentation System enhanced accuracy of GPS positioning Page 16 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter1 Overview This chapter provides a high level summary of the GNAV540 Features page 17 Software Compatibility page 18 GNAV540 Unit page 18 Features e Pitch and roll accuracy of lt 0 4 heading error 0 75 e Ethernet user
59. MO O C3 Navigation Guidance and Sensors GNAV540 User Manual Installation Configuration Reference www moog crossbow com Moog Inc 1421 McCarthy Blvd Milpitas CA 95035 MOOG 02011 Moog Inc All rights reserved Information in this document is subject to change without notice Crossbow and GNAV540 are registered trademarks of Moog Inc Other product and trade names are trademarks or registered trademarks of their respective holders Page 2 GNAV540 User Manual 7430 0808 01 Rev B MOOG Table of Contents K NARING AINA ANAKAN 13 Intended Audience bA NN DA KATING Aha paa 13 enu EE 13 Related DoS IEe 15 DER A ia 15 GlOSS APY aa M 16 Chapter 1 OVO VIC ce 17 ru 17 System Performance ooa beta etn MK ANM E MT 17 Signal Interface m M 18 Software Boysvoriilellvd e 18 L I AA RE 18 Chapter2 GNIAV540 FunctiOns recurrere saze teresa tuu sta bebe rene AAKALA 21 NAS O A EC 21 Configuring GNAV540 Functions encina 21 TT 22 GNAV540 Default Coordinate SYST M iii ra 24 Advanced e 25 IMU FUNCUON 220 at t ne 25 IMU Advanced S
60. NGARA UID ID AA 72 Table 36 12 Payload a ete deese LE Ue e d e 72 Table37 SO Data o Te com 73 Table 38 SO Payload DEAS As 73 Table SI S1 Data Pa aii 74 Table40 SP O bid 74 Table 41 S2 Dr EBA 75 Table42 32 Payload KOR ae mda E Table 43 AO Data Packet Table 44 AO Payload Table 45 A1 Data Packet Table 46 Ad Payload E t 060 77 Table 47 NO Data o C T 78 Table SSMUS 78 Table 49 NI De ee o 79 Table 50 NE Payload res Ja 80 Table 51 Data Pagkata did 80 Table 52 N3 Payload acu ERA anime a lien ID 81 Table 53 N4 Data Packet 82 Table Ee de den dia 83 Table 55 Configuration Fields ette cec ten NANA Lee Et en 85 Table 56 Orientation Fields c e Gm BA aa 87 Table 57 Orientation Field Vall it do 87 Table 58 Behavior AS int tn Table 59 Internal External Mags Bit Table 60 Internal Magnetometer Calibration Values Table 61 External Magnetometer Calibration Values nn 90 Table 62 WE Command Aa 90 Table 63 WE Payload E M 91 Table 64 WE RESPONS E 91 Table 65 WE E 91 EE SEORSUM i
61. Packet 2 Delta Theta Delta MN 75 Angle Data Packet Du oa 76 Angle Data Packet 1 Default AHRS Data unes 77 Nav Data Packet O maa 78 Nay Data Paridad 79 GNAV540 User Manual Page 5 7430 0808 01 Rev B Nav Data Packet 3 default packet enne Nav Data Packet Chapter 10 Programming Guidelines Configuration Fields Continuous Packet Type Field Orientation Held I User Behavior Switches un Hard and Soft Iron Values nn Heading Track Offset nenn Commands to Program Configuration Write Fields Command cerit ai Write Fields ReSpOnse esee nennen eno ttn ttt nitens Set Fields Command 25er is Write Fields Response inner Table RF Command Read Fields Command Read Fields Response iii Get Fields Command sn Get Fields REeSpONSC erubuit ake Chapter 11 Built In Test BIT BIT Status Fields a dua oa Programmable Status Fields hardw reBlIT Field iii ads hardwarePowerBIT Field hardwareEnvironmentalBIT Field el EK WT EE comSerialABIT Field im a comSerialBBIT Fields antenne idet nae Rete comSerialCBIT WT ee software BIT Piel dh e nennen ae softwareAlgorithmBIT Field softwareD taBlT Field urit remettre a hardwareStatus Field ere comstat s Field iaa SoftwareStatus Field e sensorStatus Piel coins Configuring masterStatus emocionar MOOG Page 6 GNAV540 User Manual 7430 0808 01
62. RS Function page 29 e NAV Function page 31 GNAV540 System GNAV540 is a compact MEMS based GPS inertial navigation system It delivers continuous GPS position true heading and vehicle attitude tracking information for ground tactical vehicles and other platform navigation applications The system integrates advanced MEMS inertial gyros and accelerometers embedded or optional remote 3 axis magnetometer a SAASM or C A code GPS receiver and 10 100 Ethernet interface in a fully sealed enclosure for tactical vehicles operating in combat or homeland security environments Figure 1 on page 22 shows the GNAV540 system configuration block diagram To maximize system performance and reduce cost the GNAV540 provides RS422 interfaces for an external magnetometer and a SAASM GPS receiver interface to pre existing equipment The internal GPS receiver is the Rockwell Collins Polaris Link card Configuring GNAV540 Functions Based on the User Behavior settings the GNAV540 can be configured to fulfill various functions 1 Using only the calibrated sensor data the GNAV540 functions as an Inertial Measurement Unit IMU to output angular rates and accelerations 2 Incorporating the gyroscope and accelerometer data with the EKF the GNAV540 can output roll and pitch attitude information functioning as a Vertical Gyroscope VG unit 3 Building on the VG function and combining magnetic field measurement the GNAV540 can function as an Attitude Heading
63. Reference System AHRS provide a heading angle estimate in addition to the VG roll and pitch The GNAV540 is provided with an internal magnetometer an external magnetometer can be integrated with the unit and configured to override the internal magnetometer 4 Combining GPS sensor data into the EKF the GNAV540 can provide a complete attitude system as well as outputting 3D velocity and position measurements thereby functioning as a Navigation unit NAV An internal C A code GPS receiver is provided an external SAASM GPS receiver can be integrated with the unit and configured to override the internal receiver The following sections provide details about the system level and functional operations of the GNAV540 GNAV540 User Manual Page 21 7430 0808 01 Rev B MOOG Figure 1 GNAV540 System Polaris Link GPS module Ethernet AHRS GPS BIT PRE and Sensor Data car Software Structure Figure 2 below shows the software block diagram The 6 DOF inertial sensor cluster data is fed into a high speed 100Hz signal processing chain These 6 DOF signals pass through one or more ofthe processing blocks and these signals are converted into output measurement data as shown Measurement data packets are available at fixed continuous output rates or on a polled basis The type of measurement data packets available depends on the unit type according to the software block diagram and system configuration Aiding sensor data is used by an Exten
64. Rev B MOOG hardwaresStat sEnable Field KA a eiae goa 106 comstatu sEnable Field aci 107 SOU All e dee Ja KN Jana a ne An ia 107 sensorStatusEnable Field near 107 BIE Field Hierarchy Hase A 107 Appendix A Application Examples aaa NA AGAIN ALA NAKAKA 110 Fixed Wing Aircraft tsm ANAN asinine Aa 110 e 110 band le E UdeMM eM EIE 111 Water Vehicle tiem A E SII LUE DLL END enamine 111 locui 112 Appendix B Sample Packet Parser Code ama BAEK 114 AN AA 114 Sample o a SR SES MR 114 Appendix C Sample Packet Decoding ctemennnenemsnesrneseeenrnisiniionenese 120 Appendix D Mechanical Specifications men 124 ji Connector INCE le 124 SJ S Lor Le Lo OSS a AA een ARA entre Environment Electrical Physical eec ei Mechanical DraWiNg c 125 Interface Cable ACCOSSOYY E 126 Appendix E Crossbow Service Policies sc tesis 128 C stomer EEN 128 VAT ah 128 Returning Eq it 128 Packing HAIR ai e 128 Return Address echada AA AA 129 Source Code Li iii dada 129 Contact Into AA 129 Appendix F Revision Historia 131 GNAV540 User Manual Page 7 7430 0808 01 Rev B MOOG Tables Table 1 Chapter Summaries iere EEN 13 Table 2 Reference DOCUMENTS ii dns 15 Table Text enia 15 Table AAA UT 16 Table GNAV540 MEASUTEMENTS P
65. S receiver will not work properly if signals are blocked such as objects cover the antenna or the receiver is located underground or other confined area e Signals can also be blocked or distorted with a poor quality antenna or RF cable or in band jamming e Placing the antenna on a 16 square inch e g 4 x 4 or larger ground plane is recommended Instructions e Secure the antenna to the SMA jack on the enclosure Figure 6 GNAV540 Unit J1 37 pin connector J2 SMA connector Page 44 GNAV540 User Manual 7430 0808 01 Rev B MOOG 4 Turn on the GNAV540 Instructions a Ensure the voltage level of the power supply is set between 8 VDC and 32 VDC and then turn off the power supply b Secure the cable to the GNAV540 unit a Connect the unit cable to the DC voltage power supply Connect the red plug to the positive terminal Connect the black plug to the ground terminal ground CAUTION If the input power leads are reversed the unit may be damaged The warranty for the unit does not cover damage caused by neglect or incorrect use Moog Inc will assume no responsibility for the repair or replacement of the unit b Turnonthe power supply Ensure the total power drawn does not exceed 5 watts c Start NAV VIEW 2 2 on the computer click the NAV VIEW 2 2 icon d Ifthe GNAV540 unit is connected directly to a computer via serial port the unit may immediately be connected If there are
66. Status Fields u nee Table 94 Recommended Settings for Fixed Wing Aircraft nn Table 95 Recommended Advanced Settings for Rotorcraft une Table 96 Recommended Advanced Settings for Land Vehicle Table 97 Recommended Advanced Settings for Water Vehicle Table 98 Flight Profile IECIT Table 99 Code BEUnctlOnDS ut itio nte ce atte ani Table 100 Document Revision HiStOTY EEN 131 Figures Figure GNAV540 SM emu uL ILI ML LI QM DIU EU DE 22 Figure 2 GNAV540 Software Block Diagram nn 23 Page 10 GNAV540 User Manual 7430 0808 01 Rev B MOOG Figure 3 GNAV540 Functions aa 24 Figure 4 GNAV540 Default Coordinate System sans 24 Figure IPPS UU at ru LE eus 37 Figure 6 GNAVS AO UNIE P M 44 Figure 7 No Display A A AR einen aed 47 Figure 8 Main SCre n annaba 48 Figure 9 Configure Serial POFLE d aa 49 Figure 10 Configure Ethernet POTFEL eite tration a aa 49 Figure LL Log to File Menus aspi ied n eu was edad oa 50 Figure 12 Raw Data Console aaa MM 51 Figure 13 Horizon and Compass VIEWS nier sannnntemennnninnntnnnnnnnenenneimnenntnennunnenmnimeenmonnl 52 Figure 14 Packet Statistics ads 52 Figure 15 Current Configurations sain AA A ida
67. a WC command to initiate the calibration and then rotate the user system 360 degrees The WC command has two options auto termination and manual termination e With auto termination the unit tracks the yaw movement and after 380 degrees of rotation returns the calibration complete response CC The auto termination sequence can falsely terminate if the 360 degree rotation is not completed within two 2 minutes of the WC command initiation e Manual termination requires sending a second WC command with the termination code in the payload Manual termination is a good option when the user system moves very slowly e g large marine vessel and completing the 360 degree rotation may require more than two minutes The status of the magnetometer calibration is indicated by the softwareError gt dataError gt magAlignOutOfBounds error flag available in the TO packet You can access the hardIronScaleRatio and softIronScaleRatio calibration data as configuration fields in NAV VIEW 2 2 or by using the communication protocol Also the softwareError bit of the masterFail byte within the BIT word is transmitted in every measurement packet When the unit has not been properly calibrated this softwareError bit will be set to fail high The calibration complete CC command response message contains the X and Y hard iron bias as well as the soft iron ratio This information can be interpreted to give an indication of the quality of the calibration For more
68. able 96 Recommended Advanced Settings for Land Vehicle Dynamic Condition Recommended Settings Heavy Equipment Application N OFF N ON Automotive Testing Restart Over Range 0 Dynamic Motion 0 Turn Switch Threshold 5 0 deg s 10 0 deg s When not in distorted magnetic environment Water Vehicle Water vehicle is a craft or vessel designed to float on or submerge and provide transport over and under water Table 97 provides the recommended advanced settings for two applications Table 97 Recommended Advanced Settings for Water Vehicle Recommended Product GNAV540 Recommended Settings Application GNAV540 User Manual Page 111 7430 0808 01 Rev B MOOG Stationary Yaw Lock OFF OFF Restart Over Range OFF OFF Dynamic Motion ON ON Turn Switch Threshold 10 deg s 5 deg s Example Table 98 below shows a typical flight profile of the fixed wing aircraft and the corresponding advanced settings that can be configured per flight phase Table 98 Flight Profile Phases Phase Description Prelaunch The phase of flight in which an aircraft goes through a series of checkups hardware and software on the ground before takeoff The aircraft is a static condition Takeoff The phase of flight in which an aircraft goes through a transition from moving along the ground taxiing to flying in the air usually along a runway The aircraft is under horizontal acceleration and may suffer from vibrations coming from an engine
69. alibration Values Field Name X Hard Iron Bias Field ID Format Scaling Units 0x0009 I2 2 2 16 Gauss GNAV540 User Manual 7430 0808 01 Rev B Page 89 MOOG Y Hard Iron Bias 0x000A I2 2 2 16 Gauss Soft Iron Scale Ratio 0x000B U2 2 2 16 Soft Iron Angle 0x000E I2 2 pi 2 16 Radians Note that the calibration values for an external magnetometer are contained in distinct fields Table 61 External Magnetometer Calibration Values Field Name Field ID Format Scaling Units X Hard Iron Bias 0x001C I2 2 2 16 Gauss Y Hard Iron Bias 0x001D I2 2 2 16 Gauss Soft Iron Scale Ratio 0x001E U2 2 2 16 Soft Iron Angle 0x001F I2 2 pi 2 16 Radians For an external magnetometer there are also configuration fields that allow a user to specify roll and pitch offsets 0x0017 0x0018 and magnetometer orientation 0x0020 The hard iron bias values are scaled from 1 1 Gauss These values are subtracted from the tangent plane magnetometer vector before heading is calculated The soft iron scale ratio is scaled from 0 2 and is multiplied by the tangent plane x magnetometer value before heading is calculated Heading Track Offset This field is used to set the offset between vehicle heading and vehicle track to be used by the navigation mode filter when no magnetometer heading measurements are available Field Name Field ID Format Scaling Units 2 pi 2 16 i ing Heading Track Offset 0x000C 12 pi Pa
70. and ground contact forces transmitted from its landing gear The phase of a flight after takeoff consisting of getting the aircraft to the desired flight level altitude More generally the term climb means increasing the altitude The aircraft is under vertical acceleration until it reaches the steady state climb rate Straight and level The phase of flight in which an aircraft reaches its nominal flight altitude and maintains its flight speed and altitude The aircraft is under equilibrium Maneuver The phase of flight in which an aircraft accelerates decelerates and turns The aircraft is under non gravitational acceleration and or deceleration Descent The phase of flight in which an aircraft decreases altitude for an approach to landing The aircraft is under vertical deceleration until it captures a glide slope Landing The last part of a flight where the aircraft returns to the ground When not in distorted magnetic environment Page 112 GNAV540 User Manual 7430 0808 01 Rev B MOOG Figure 29 Flight Profiles Fixed Wing Aircraft Corresponding Settings Pre launch or known straight and level un accelerated flight Straight and level Normal Dynamics Pre launch or Climb Maneuver Descent known straight and level un accelerated High Dynamics Prelaunch Takeoff Landing Recommended Advanced Settings GNAV540 User Manual Page 113 7430 0808 01 Rev B MOOG Appendix B
71. ans heading track 3609 2 16 Commands to Program Configuration Write Fields Command Table 62 WF Command Write Fields WEI 0x5746 0x5555 0x5746 1 numFields 4 WF payload lt CRC U2 gt This command allows the user to write default power up configuration fields to the EEPROM Writing the default configuration will not take effect until the unit is power cycled NumFields is the number of words to be written The fieldo field1 etc are the field IDs that will be written with the fieldOData field1Data etc respectively The unit will not write to calibration or algorithm fields Page 90 GNAV540 User Manual 7430 0808 01 Rev B MOOG e fat least one field is successfully written the unit will respond with a write field response containing the field IDs ofthe successfully written fields e Ifany field is unable to be written the unit will respond with an error response Both write fields and an error response may be received as a result of a write fields command Attempts to write a field with an invalid value is one way to generate an error response To view a table of field IDs and valid field values refer to Configuration Fields on page 85 Table 63 WF Payload WF Payload Contents Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields to write 1 fieldO U2 The first field ID to write 3 field0Data U2 T
72. are out of bounds Reserved 2 15 N A Page 104 GNAV540 User Manual 7430 0808 01 Rev B MOOG hardwareStatus Field The hardwareStatus field contains flags that indicate various internal hardware conditions and alerts that are not errors or problems The hardwareStatus flag in the BITstatus field is the bit wise OR ofthe logical AND of the hardwareStatus field and the hardwareStatusEnable field The hardwareStatusEnable field is a bit mask that enables selecting items of interest that will logically flow up to the masterStatus flag Table 89 hardwareStatus Field hardwareStatus Field Values unlocked1PPS 0 not asserted 1 asserted unlockedInternalGPS 0 not asserted 1 asserted noDGPS 0 DGPS lock 1 no DGPS unlockedEEPROM O locked WE disabled 1 unlocked WE enabled Reserved N A comStatus Field The comStatus field contains flags that indicate various external communication conditions and alerts that are not errors or problems The comStatus flag in the BITstatus field is the bit wise OR of the logical AND of the comStatus field and the comStatusEnable field The comStatusEnable field is a bit mask that enables selecting items of interest that will logically flow up to the masterStatus flag Table 90 comStatus Field comStatus Field Values noExternalGPS 0 external GPS data is being received 1 no external GPS data is available Reserved N A SoftwareStatus Field The softwareStatus field con
73. ation on page 56 and Configuring masterStatus on page 106 GNAV540 User Manual Page 99 7430 0808 01 Rev B MOOG Status Byte Field Default Values hardwareStatus AHRS disabled bit 9 IMU disabled VG disabled NAV 0 nominal 1 Internal GPS unlocked or 1PPS invalid For additional visibility or alerts relative to the GPS sensor status or algorithm status configure additional triggers for both softwareStatus and hardwareStatus For information about configuring this status field refer to BIT Configuration on page 56 hardwareStatus Field on page 105 and Configuring masterStatus on page 106 comStatus e AHRS 0 nominal bit 10 1 No External GPS Comm e IMU disabled e VG O0 nominal 1 No External GPS Comm e NAV disabled For information about configuring this status field refer to BIT Configuration on page 56 comStatus Field on page 105 and Configuring masterStatus on page 106 softwareStatus e AHRS 0 nominal bit 11 1 Algorithm Initialization or High Gain For additional visibility when the EFK algorithm estimates that the unit is turning about its Z or Yaw axis the softwareStatus bit can be configured to go high 1 during a turn In AHRS Function the default value of turnSwitch is 0 5 deg sec about the z axis IMU disabled VG 0 nominal 1 Algorithm Initialization or High Gain For additional visibility when the EFK algorithm estimates that the unit is turning about its Z
74. ble 39 S1 Data Packet Scaled Sensor Data S1 0x5331 0x5555 0x5331 S1 payload CRC U2 gt This packet contains scaled sensor data Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Temperature scaled to a range of 100 100 C Table 40 S1 Payload S1 Payload Contents Byte Offset Name Format Scaling Units Description 0 xAccel I2 20 2 16 g X accelerometer 2 yAccel I2 20 2 16 g Y accelerometer 4 zAccel I2 20 2 16 g Z accelerometer 6 xRate I2 7 pi 2 16 rad s X angular rate 1260 2 16 sec 8 yRate I2 7 pi 2 16 rad s Y angular rate 1260 2 16 sec Page 74 GNAV540 User Manual 7430 0808 01 Rev B MOOG S1 Payload Contents Byte Offset Name Format Scaling Units Description 10 zRate I2 7 pi 2 16 rad s Z angular rate 1260 2 16 sec 12 xRateTemp I2 200 2 16 deg C Xrate temperature 14 yRateTemp I2 200 2 16 deg C Y rate temperature 16 zRateTemp I2 200 2 16 deg C Z rate temperature 18 boardTemp I2 200 2 16 deg C CPU board temperature 20 Counter U2 packets Output packet counter 22 BITstatus U2 Master BIT and Status Scaled Sensor Data Packet 2 Delta Theta Delta V Ta
75. ble 41 S2 Data Packet Scaled Sensor Data S2 0x5332 0x5555 0x5332 lt S2 payload gt lt CRC U2 gt This packet contains scaled sensor data in the traditional delta theta and delta velocity format with integration time equivalent to the packet rate Changes in body axis angles and velocities are accumulated during the interval between successive packets as determined by the packet rate Polled requests for this packet will produce values accumulated since the last poll request and thus are subject to overflow data type wrap around e Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Delta Angle scaled to range of 3 5 pi pi A radians or 630 630 A degrees e Delta Velocity scaled to a range of 100 100 A m s Table 42 S2 Payload S2 Payload Contents Byte Name Format Scaling Units Description Offset 0 xDeltaVel I4 200 2 32 A m s X delta velocity 4 yDeltaVel I4 200 2 32 A m s Y delta velocity 8 zDeltaVel I4 200 2 32 A m s Z delta velocity 12 xDeltaAngle I4 7 pi 2 32 Arad X delta angle 1260 2 32 A 16 yDeltaAngle I4 7 pi 2 32 Arad Y delta angle 1260 2 32 A 20 zDeltaAngle 14 7 pi 2 32 Arad Z delta angle 1260 2 32 A 24 Counter U2 packets Output packet counter 26 BITstatus U2 Master BIT and Status GNAV540 User Manual Page 75 7430
76. cal Gyroscope VG Function on page 26 In addition to the features described in the previous sections IMU Function and Vertical Gyroscope VG Function the AHRS algorithm has two major phases of operation The first phase of operation is the high gain initialization phase During the initialization phase the unit is expected to be stationary or quasi static so the EKF weights the accelerometer gravity reference and Earth s magnetic field reference heavily in order to rapidly estimate the X Y and Z rate sensor bias and the initial attitude and heading of the unit The initialization phase lasts approximately 60 seconds and the initialization phase can be monitored in the softwareStatus BIT transmitted by default in each measurement packet After the initialization phase the unit operates with lower levels of feedback also referred to as EKF gain from the accelerometers and magnetometers to continuously estimate and correct for roll pitch and heading yaw errors as well as to estimate X Y and Z rate sensor bias The AHRS Function provides the same scaled sensor and angle mode packets of the VG Function The AHRS Function defaults to the A7 Angle Packet which outputs the roll angle pitch angle yaw angle and digital IMU data In the AHRS Function the A0 and A1 packets contain accurate magnetometer readings For more information refer to Chapter 9 Communicating with the GNAV540 Unit and Chapter 10 Programming Guidelines for packet descrip
77. cket Structure iii ita 61 General Settngs An ete eee RE aa 61 Number FOTMATS ss e M 61 Packet ARR NAA de 62 Packet Header m 62 Packet Typ ge 62 Payload Aud een 63 IN Y M 63 16 Bit CRE CCITT a 63 Messaging OVETVIEW ii e iii 63 Chapter 9 Communicating with the GNAV540 Unit omnia 67 Ping Command NAAN NAAN ANAN AA 67 Ping Response TN 67 leonum 67 ere E 67 Interactive CA Si M dk 4 68 Get Packet E ia ii 68 Algorithm Reset Command A oa 68 Algorithm Reset RESPONSE mn ABA Aa 68 Software GR Lu En DE 68 Software Reset RESPONSE EEG n 69 Calibrate Command anan e 69 Calibrate Acknowledgement Response iii a 70 Calibration Completed Parameters Response miii ers 70 Error RESpons M 71 Output Packets Pole ETE 71 Identification Data id 71 Version Data socie RUM 71 Test 2 Detailed BIT and Status Packet nee 72 Output Packets Polled r Continuous tinte stececaaseetsaagerasivec ie 73 Sealed Sensor Data Packet O rin 73 Scaled Sensor Data Packet 1 Default IMU Data sans 74 Scaled Sensor Data
78. d Algorithm Reset Command Table 20 Algorithm Reset Command Algorithm Reset AR 0x4152 This command resets the state estimation algorithm without reloading fields from EEPROM All current field values will remain in effect The unit will respond with an algorithm reset response Algorithm Reset Response Table 21 Algorithm Reset Response Algorithm Reset AR 0x4152 0x5555 0x4152 CRC U2 gt The unit will send this packet in response to an algorithm reset command Software Reset Command Table 22 Software Reset Command Software Reset SR 0x5352 Page 68 GNAV540 User Manual 7430 0808 01 Rev B MOOG This command performs a core CPU reset functionally equivalent to a power cycle All default power up field settings will apply The unit will respond with software reset response before the system goes down Software Reset Response Table 23 Software Reset Response Software Reset SR 0x5352 0x5555 0x5352 CRC U2 gt The unit will send this packet in response to a software reset command Calibrate Command Table 24 Calibrate Command Calibrate WC 0x5743 0x5555 0x5743 WC payload CRC U2 gt This command allows the user to perform various calibration tasks with the GNAV540 unit See the calibration command table below for details The unit will respond immediately with a calibrate response containing the calibrationRequest received or an error respons
79. d ID s data retrieved 5 field1 U2 The second field ID retrieved 7 field1Data U2 The second field ID s data U2 E numFields 4 3 field U2 The last field ID retrieved numFields 4 1 field Data U2 The last field ID s data retrieved GNAV540 User Manual Page 95 7430 0808 01 Rev B MOOG Page 96 GNAV540 User Manual 7430 0808 01 Rev B MOOG GNAV540 User Manual Page 97 7430 0808 01 Rev B MOOG Chapter 11 Built In Test BIT The Built In Test capability allows users to monitor health diagnostic and system status information of the unit in real time Built In Test information is transmitted in each measurement packet NOTE A diagnostic test packet T2 can be requested via GP To contains a complete set of status for each hardware and software subsystem For more information refer to Test 2 Detailed BIT and Status Packet on page 72 and Get Packet Request on page 68 BIT Status Fields A BIT word consists of two bytes Error byte and Status byte The first byte bits 0 7 is the Error byte signaled results from internal checks Four intermediate signals determine when to assert masterFail and the hardware BIT signal These signals are controlled by three categories of systems checks hardware hardwareError communication comError and software softwareError Instantaneous soft failures from any category triggers the signals a flag is raised masterFail is not t
80. d OFF It is only switched ON for upgrading firmware Page 126 GNAV540 User Manual 7430 0808 01 Rev B MOOG GNAV540 User Manual Page 127 7430 0808 01 Rev B Appendix E Crossbow Service Policies Customer Service Moog customers have access to product support services Single point return service Web based support service Same day troubleshooting assistance Worldwide Crossbow representation Onsite and factory training available Preventative maintenance and repair programs Installation assistance available Warranty The Crossbow product warranty is one year from the date of shipment Returning Equipment MOOG Before returning any equipment please contact Crossbow to obtain a Returned Material Authorization number RMA Provide the following information when requesting a RMA Contact Point Company Address Contact name Telephone Fax Email Product Details Equipment Model Number Equipment Serial Number Installation Date Failure Date Description of Failure Does the device connect to NAV VIEW 2 2 Packing Item for Return If the equipment is to be shipped to Crossbow for service or repair In all correspondence refer to the equipment by the model number the serial number and the RMA number Page 128 GNAV540 User Manual 7430 0808 01 Rev B MOOG e Attach a tag to the equipment as well as the shipping container s on the tab include the RAM and the owner e Inc
81. d acceleration data in the forms of changes in velocity and rotation angle Av and Ad The IMU Function signal processing chain consists of the 6 DOF sensor cluster analog to digital conversion and the DSP signal processor for sensor error compensation The rate and acceleration analog sensor signals are sampled and converted to digital data at 1 kHz The sensor data is filtered and down sampled to 100Hz by the DSP using FIR finite impulse response filters The factory calibration data stored in EEPROM is used by the DSP to remove temperature bias misalignment scale factor errors and non linearities from the sensor data Additionally any advanced user settings such as axes rotation are applied to the IMU data The 100Hz IMU data is continuously being maintained inside the unit Digital IMU data is output over the RS 422 or Ethernet link at a selectable fixed rate 100 50 25 20 10 5 or 2 Hz oran on request basis using the GP Get Packet command The digital IMU data is available in one of several measurement packet formats including Scaled Sensor Data S1 Packet and Delta Theta Delta V S2 Packet In the Scaled Sensor Data S1 Packet data is output in scaled engineering units In the Delta Theta Delta V format S2 Packet scaled sensor data is integrated with respect to the time of the last output packet and the data is reported in units of accumulated i e delta degrees and meters second For information about full packets refer to
82. d can be used to set configuration fields The unit will not set calibration or algorithm fields If atleast one field is successfully set the unit will respond with a set fields response containing the field IDs of the successfully set fields If any field is unable to be set the unit will respond with an error response Both a set fields and an error response may be received as a result of one set fields command Setting a field with an invalid value will generate an error response To view atable of field IDs and valid field values refer to Configuration Fields on page 85 Table 67 SF Payload SF Payload Contents Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields to set 1 field0 U2 The first field ID to set 3 fieldO Data U2 The first field ID s data to set 5 field1 U2 The second field ID to set 7 field1Data U2 The second field ID s data to set U2 sie numFields 4 3 field U2 The last field ID to set numFields 4 1 field Data U2 The last field ID s data to set Write Fields Response Table 68 WF Response Write Fields WEI 0x5746 0x5555 0x5746 1 numFields 2 WF payload lt CRC U2 gt The unit will send this packet in response to a write fields command if the command has completed without errors Table 69 WF Payload WF Payload Contents
83. d in the text fields A box filled with blue color indicates the behavior switch is enabled Refer to Figure 19 Changing Configurations 1 To enable a switch a Checkmark the desired item under Value to Set 2 Toseta value under Value to Set a Checkmark the box of the desired item s b For each item checkmark the box under Modify and enter the new value under Value to Set c Select either Temporary or Permanent Temporary The configuration will not be stored in non volatile memory EEPROM The configuration will be applied but the unit will return to the Permanent configuration when it is rebooted Permanent The configuration will be stored in non volatile memory The unit will continue to use the configuration after being rebooted 3 Clickthe Set Values button The configuration values will be saved as specified Temporary or Permanent BIT Configuration Figure 19 Advanced Settings Unit Configuration ll xi General Advanced BIT Configuration External Mag Field Modify Current Value Value to Set User Behavior Switches O Freely Integrate L O Use Mags E Use GPS v B Stationary Yaw Lock lv Wi Restart Over Range lv lll Dynamic Motion Iv O Extni Mags D Extni GPS X Hard Iron Bias 0 00668 0 00000 ES YHardlronBias M 0 00977 0 00000 Soft Iron Scale Ratio 0 99997 0 00000 3 Soft Iron Angle 0 00 Heading Track Offset 7 0 00 Turn Switch Threshold 0 40 Filter XZ Accel
84. d the CRC field itself A discussion of the 16 bit CRC CCITT and sample code for implementing the computation of the CRC is included at the end of this document This 16 bit CRC standard is maintained by the International Telecommunication Union ITU Width 16 bits Polynomial 0x1021 Initial value OXFFFF No XOR is performed on the final value Refer to Appendix B Sample Packet Parser Code for sample code that implements the 16 bit CRC algorithm Messaging Overview The following table summarizes the messages available with the GNAV540 unit Packet types are assigned mostly using the ASCII mnemonics defined above and are indicated in the summary table below and in the detailed sections for each command The payload byte length is often related to other data elements in the packet as defined in the table below The referenced variables are defined in the following sections Output messages are sent from the GNAV540 inertial system to the user system as a result of a poll request or a continuous packet output setting Input messages are sent from the user system to the GNAV540 inertial system and will result in an associated Reply Message or NAK message Reply messages typically have the same lt 2 byte packet type U2 as the input message that evoked it but with a different payload Table 14 Message Table payload ASCII lt 2 ket Availabl Ss fte packe byte length Description po ab S Mnemonic type U2 gt Functions U1 gt Link Te
85. ded Kalman Filter EKF for drift correction Built In Test and Status data are available in the measurement packet or via the special Status Packet T2 Page 22 GNAV540 User Manual 7430 0808 01 Rev B MOOG Figure 2 GNAV540 Software Block Diagram u Measurement epee he Angle NAV Nav Packets Data Available to 91 ackets NO N1 N2 N3 u User Fixed Rate en A0 A1 A2 NAV AHRS VG mwuummuuuuuumum y Pole NAYIAHHSNG BEBEEBBEBBEBEEBNEEN NENA BEEBE EERE DUU 6 DOF Sensor Cluster Pas l adi WI gE RBBB EERE BEE EE BEEBE NEON BERN X Y ZBody n Rates E a u u 100Hz B Du SC Sensor Integration to L Integration to 100 Hz X Y ZBody u Chain Calibration Velocity GPS Accelerometers u Axes Rotation Position Output u u u Un umu u KAPA d e A CA AAA AAA AAA AAA AE u u u Unit Settings amp Profile E u Extended Kalman Filter EKF u BuiltIn Test m u Drift Correction Module u amp Status u u u x Data u u u Availableto m x User E Kalman Filter and Dynamic State Model u ba u u u u u Ing U u u u u u u u u u u LI u u u u u u u u m Hard Soft Iron Free Integrate UseGPS u u u u m Calibration TurnSwitch Stationary Yaw u al u u u UseMags Threshold Lock u M d Packe T0 u u u A uoa eerie Ron Ml u LU BERBER RRR RRR RRR RRR BANN u E Aiding Sensors u u LU u u ka u u u X Y Z Gravity Refere
86. e 58 GNAV540 User Manual 7430 0808 01 Rev B MOOG Fi 22 M t ter Ali t Val After completing the rotation data will be mE HY ipe lolx displayed with the calibration values The X and Y offset values indicate how far the magnetic New Settings has been shifted due ba kaa iron affects X Hard Iron Offset Y Hard Iron Offset Soft Iron Ratio I rom components surrounding the unit el mmm map The soft iron ratio will also be displayed which is the effect of soft iron on the GNAV540 unit For external mag align i A Before clicking Apply button you must set switch 6 The save the calibration values click the Apply to communicate with NAV VIEW not external mag button a Cancel Apply The new configuration settings will be saved but E they will not be implemented until either a soft reset via software see Interactive Commands on page 68 or a hard reset recycle power ofthe GNAV540 unit takes place Aligning External Magnetometer NOTE By default the GNAV540 uses the internal magnetometer To use and configure an external magnetometer it must be selected under the Advanced configuration tab Refer to Advanced on page 56 NOTE Two configurations must be applied when using an external magnetometer Leveling and Rotational Configuring the Leveling must be performed before the Rotational alignment Figure 23 Offset Alignment Leveling Alignment External Mag Leveling Alignment
87. e Aligning Internal Magnetometer page 58 e Aligning External Magnetometer page 59 Aligning Internal Magnetometer 1 Ensure the unit is configured to use the internal magnetometer Refer to Advanced on page 56 2 Onthe menu bar see Figure 8 click Configuration and then select Magnetometer Alignment from the drop menu 3 Ifthe 360 degree turn can be completed within 120 seconds check Auto Terminate 4 Under Rotational Alignment select the Start button to begin the alignment Follow the instructions displayed in the screen Refer to Figure 21 5 Rotate the GNAV540 for 380 degrees of rotation or until the message is displayed that alignment is complete Figure 21 Internal Magnetometer Alignment Dialog ini x a X Hard Iron Offset Y Hard Iron Offset Soft Iron Ratio Soft Iron Angle E Internal Mag 0 00000 0 00000 1 00000 C External Mag Instructions Slowly rotate the unit on a level surface about the Z axis until N V VIEW reports that the calibration is done The operation will timeout in 120 seconds If you want to stop make sure switch is OFF before clicking STOP External ag Leveling Alignment Rotational Alignment Start Start Jv kuto Terminate BRENNEN Roll Offset Pitch Offset stop Cancel 0 00 Gaus Rol 14 Pitch 18 Yaw Wi ing Hienment Roll Offset Pitch Offset Y Field Gauss 1 0 5 D X Field Gauss Pag
88. e Optional For laboratory test a cable is provided with the Crossbow evaluation kit Refer to Figure 31 on page 126 NOTE The kit cable is only suitable for laboratory test it is not designed for field use Refer to Figure 31 on page 126 GNAV540 User Manual Page 43 7430 0808 01 Rev B MOOG 1 Install Software NAV VIEW 2 2 Instructions a Insert the CD GNAV540 Inertial System in the CD ROM drive b Onthe CD go to the NAV VIEW 2 2 folder and double click the setup exe file c Follow the wizard instructions to install NAV VIEW 2 2 and if necessary the NET 4 0 framework 2 Prepare the Communication Port The GNAV540 unit can communicate to the computer via Ethernet or directly to the computer via serial port determine which communication port to use e Fora serial port note which COM port e For the Ethernet note the port IP number and the IP address of the GNAV540 e Ensure the switch on Port C the serial interface for the External Magnetometer is set to OFF Setting up the port will be handled in step 4 Turn on the GNAV540 3 Connect the GPS Antenna NOTE The GNAV540 unit is shipped with an external active antenna To clearly receive signals from many satellites a clear view from the antenna to the sky is required e Poorvisibility may result in position drift or a prolonged Time To First Fix TTFF The following setups can obstruct the signal resulting in poor results for navigation e The GP
89. e Velocities scaled to a range of 256 256 m s e Altitude scaled to a resolution of 0 125 meters e Longitude and latitude scaled to a range of pi pi or 180 deg to 180 deg Page 82 GNAV540 User Manual 7430 0808 01 Rev B MOOG Table 54 N4 Payload N4 Payload Contents Byte Name Format Scaling Units Description Offset 0 rollAngle I2 2 pi 2 16 Radians Roll angle 360 2 16 5 2 pitchAngle I2 2 pi 2 16 Radians Pitch angle 360 2 16 4 yawAngleTrue I2 2 pi 2 16 Radians Yaw angle true north 360 2 16 6 xRateCorrected I2 7 pi 2 16 rad s X angular rate corrected 1260 2 16 sec 8 yRateCorrected I2 7 pi 2 16 rad s Y angular rate corrected 1260 2 16 sec 10 zRateCorrected I2 7 pi 2 16 rad s Z angular rate corrected 1260 2 16 sec 12 xAccel I2 20 2 16 g X accelerometer 14 yAccel I2 20 2 16 g Y accelerometer 16 zAccel I2 20 2 16 g Z accelerometer 18 nVel I2 512 2 16 m s North velocity 20 eVel I2 512 2 16 m s East velocity 22 dVel I2 512 2 16 m s Down velocity 24 longitudeGPS I4 2 pi 2 32 Radians GPS Longitude 360 2 32 28 latitudeGPS I4 2 pi 2 32 Radians GPS Latitude 360 2 32 5 32 altitudeGPS I4 2 29 2 32 m GPS altitude 36 xRateTemp I2 200 2 16 deg C X rate sensor temperature 38 timeITOW U4 1 ms DMU ITOW sync to GPS 42 BITstatus U2 Master BIT and Status
90. e debugging tools that may assist programmers in the development process One such tool is the Raw Data Console From the View drop down menu simply select the Raw Data Console This console provides users with a simple display of the packets that have been transmitted to the unit Tx and the messages received Rx An example is provided below Figure 12 Raw Data Console 2 Raw Data Console EIER TX 5555 9ef4 5555 4944 233d 5555 0300010003071c 49 9 5555 5652 4287 5555 9ef4 5555 4944 233d 5555 0300010003071c 49f9 5555 5652 4287 ffd8ffba0002000000020000ff21ff5c01ae0000000000000000000000000000 ffdSffba00020000000Z2FFffff21ff5c01ae0000000000000000000000000000 ffdeffba000200000001ffffffZlff5cOlaeO0000000000000000000000000000 ffdSffba000200000001ffffffZlff5cOlaeO0000000000000000000000000000 ffdSffba000200000001ffffffZlff5cOlaeO0000000000000000000000000000 ffd8ffba000200000001ffffffZlff5cOlaeO0000000000000000000000000000 ffdSffba000200000001ffffffZZff5cOlaeO0000000000000000000000000000 ffd8ffba000200000000ffffffZ2ff5cOlaeO0000000000000000000000000000 ffdSffba000200000000ffffffZ2Zff5cOlaeO0000000000000000000000000000 ffd8ffbb0O00Z200000000fffeff22ff5c01ae0000000000000000000000000000 ffdSffbbO00100000000fffeff22ff5c01ae0000000000000000000000000000 ffd8ffbb0O00100000000fffeff22ff5c01ae0000000000000000000000000000 ffdSffba000100000000ffffffZ2ff5cOlaeO000000000000000000000000000 ffd7ffba000100000000fffeff22ff5c01ae000000000000000000000000000
91. e first field ID to read 3 field1 U2 The second field ID to read U2 More field IDs to read numFields 2 1 Field U2 The last field ID to read Read Fields Response Table 71 RF Response Read Fields RF 0x5246 0x5555 0x5246 1 numFields 4 RF payload CRC U2 gt The unit will send this packet in response to a read fields request if the command has completed without errors Table 72 RF Payload RF Payload Contents GNAV540 User Manual Page 93 7430 0808 01 Rev B MOOG Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields read 1 field0 U2 The first field ID read 3 field0Data U2 The first field ID s data read 5 field1 U2 The second field ID read 7 field1Data U2 The second field ID s data read Ss U2 e numFields 4 3 field U2 The last field ID read numFields 4 1 field Data U2 The last field ID s data read Get Fields Command Table 73 GF Command Get Fields GF 0x4746 0x5555 0x4746 1 numFields 2 lt CRC U2 gt This command allows the user to get the unit s current configuration fields NumFields is the number of fields to get The fieldo field1 etc are the field IDs to get GF may be used to get configuration calibration and algorithm fields from RAM Multiple a
92. e if the command cannot be performed Table 25 WC Payload WC Payload Contents Byte Name Format Scaling Units Description Offset 0 calibrationRequest U2 The requested calibration task Currently magnetic alignment is the only function supported by the calibrate command There are two magnetic alignment procedures supported 1 magnetic alignment with automatic yaw tracking termination and magnetic alignment without automatic termination Table 26 Magnetic Alignment calibrationRequest Description 0x0009 Begin magnetic alignment without automatic termination Rotate vehicle through gt 360 degrees yaw and then send 0x000B calibration request for termination 0x000B Terminate magnetic alignment The unit will send a CC response containing the hard iron and soft iron values To accept the parameters store them using the write magnetic calibration command 0x000C Begin magnetic calibration with automatic termination Rotate the unit through 380 degrees in yaw The unit will send a CC response containing the hard iron and soft iron values upon completion of the turn To accept the parameters store them using the write magnetic GNAV540 User Manual Page 69 7430 0808 01 Rev B MOOG calibrationRequest Description calibration command 0x000E Write magnetic calibration The unit will write the parameters to EEPROM and then send a calibration response
93. e selected 2 5 10 20 or 50 seconds per time frame The bottom ofthe page indicates information about the unit and connection to the unit e How the unit is connected COM or Ethernet e The baud rate e Ifthe unit is connected and working the following messages will be displayed Unit Connected Packet Rate The serial number of the GNAV540 unit The version of NAV VIEW 2 2 Figure 7 No Display If the unit is not connected the following message will be displayed If Unit Not Connected is displayed check the following e Are the power supply levels are correct e If using the serial port verify that the correct serial connector of the cable is being used A and if used the setting of the RS422 RS 232 Unit Not Connected adaptor Check Port Setup e fusingthe Ethernet port verify the IP address and the Port number are correct GNAV540 User Manual Page 47 7430 0808 01 Rev B Figure 8 Main Screen NAY YIEW la x File View Setup Configuration Window Help 0 M LogFile Data Source LIVE Mode from DMU E i W PlaybackFile i m D Je Graph NAY3 E H E A 3 2 E Es ly Es o Velocity m s 8 O V Roll VV Fitch WV Yaw true 4 X Rate corr VY Y Rate corr VY Z Rate corr VV X Accel com V Y Accel con W ZAccel com N Vel North 4 Vel East VY Vel Down 1 362 1 752 0 027 0 000 0 000 530 000 0 0308 0 0250
94. ettings ran nn nee ea 26 Vertical Gyroscope VG Function A a 26 VG Function Advanced Settings ti 27 e Ile Co 29 NK UE EE TE 29 NAY PUD COLON d nel 31 NAW Advanced Settin g8 sz UR 32 Chapters Hardware Int rface ct NANGANAK AA anand 35 Y UA AO Ree tO d nU 35 JZ GPS Antenna Connector u a di a a cepa e ne ine 35 TO Port Interf ce re M 36 ei EU TE OSS tees 36 Hardware BIT Error Output nea aee ed etes a siete a BAKUNA RN HALA tiennent diana 36 L PPS Input Interface nun 36 T PPS Output Interface ee ias 37 GNAV540 User Manual Page 3 7430 0808 01 Rev B MOOG Chapter 4 Magnetometer Calibration and Alignment Guidelines es 39 Compensation for Magnetic Fields nn 39 Magnetometer Alignment Using NAV VIEW 2 2 re 39 Magnetometer Alignment Using Code nn 40 Installation Guidelines External Magnetometer mii er 40 Field Installation S 40 EMI Protection and Grounding 5c te dal 40 Serial Data O o CO e D 41 Chapter 5 Installation Guidelines nn 43 O ba ATEN REELEESSEEINE RER SE 43
95. feedback for yaw heading stabilization e The default setting is ON When Use Mags is turned ON the GNAV540 unit uses the magnetic field sensor readings to stabilize the drift in yaw and it slaves the yaw to the compass reading provided from the magnetic field sensor readings When Use Mags is turned OFF the heading yaw angle measurement of the unit will drift and freely integrate In effect this setting converts the functionality to VG However unlike a unit in the VG Function this can be done on a selectable basis and changed in real time during a mission This setting enables turning off the magnetometer stabilization when severe magnetic distortion may be occurring This setting is desirable when the system temporarily moves in close proximity to a large ferrous object When the Use Mags switch is turned from OFF to ON the unit will reinitialize the yaw heading angle with the compass reading provided from the magnetic field sensor readings Page 30 GNAV540 User Manual 7430 0808 01 Rev B MOOG Setting Default Value Comments Restart On OFF This setting forces an algorithm reset when a sensor over range occurs i e a Over Range rotational rate on any ofthe three axes exceeds the maximum range The default setting is OFF Algorithm reset returns the unit to a high gain state where the unit rapidly estimates the gyroscope bias and uses the accelerometer feedback heavily This setting is recommended when the source of ove
96. fer to page 128 Contents Table 1 Chapter Summaries Chapter Appendix Chapter 1 Overview Chapter 2 GNfAV540 Functions Chapter 3 Hardware Interface Chapter 4 Magnetometer Calibration and Alignment Guidelines Chapter 5 Installation Guidelines Chapter 6 Viewing and Logging Data with NAV VIEW 2 2 Chapter 7 Configuring GNAV540 with NAV VIEW 2 2 Chapter 8 Data Packet Structure Chapter 9 Communicating with the GNAV540 Unit Chapter 10 Programming Guidelines Summary Summary of features In depth descriptions of IMU VG AHRS and NAV functions Connectors and pin outs Detailed information to set up and prepare for aligning the magnetometer Instructions to install the GNAV540 unit and NAV VIEW 2 2 software application Viewing data via GUI application NAV VIEW 2 2 Configuring and calibrating the unit via GUI application NAV VIEW 2 2 Overview of the data packet structure Clanguage fields and interactive commands for communication test the unit request and read data Clanguage fields and interactive commands for configuration and calibration Description ofthe operation and the coding for BIT details of the BIT status fields and bit masks GNAV540 User Manual 7430 0808 01 Rev B Page 13 MOOG Chapter Appendix Built In Test BIT Appendix A Application Examples Configuration examples of the unit installed in various vehicles Appendix B Sample Packet Example of pa
97. gned int index unsigned short word firstIndex secondIndex firstIndex queue ptr gt front index MAXQUEUE Page 118 GNAV540 User Manual 7430 0808 01 Rev B MOOG secondIndex queue ptr gt front index 1 5 MAXQUEUE word queue ptr entry firstIndex lt lt 8 OxFF00 word 0x00FF queue ptr 5entry secondIndex return word PARAR RRA RR RR k k RRA AIA AA kk 2 2 22 2 2 2 2 2 2 2 2 2 2 2 2 2 2 22 2 2 2 2 2 ok kkk FUNCTION Pop discard item s from queue ARGUMENTS queue_ptr is pointer to the queue numToPop is number of items to discard RETURNS return the number of items discarded KK 2 2 22 22 22 22 22 22 22 22 22 22 22 2 2 22 22 kk k kk k 22 2 2 22 22 22 22 22 2 2 22 22 2 2 2 2 22 2 2 2 2 int Pop QUEUE TYPE queue ptr int numToPop int i 0 char tempchar for i 0 i lt numToPop i if DeleteQueue amp tempchar queue ptr break return 1 KKK KA kK KA KA KA RR RARA RR KR AK RR RR RR RR RR RAR RR RRA RARA RRA FUNCTION Size ARGUMENTS queue_ptr is pointer to the queue RETURNS return the number of items in the queue AA int Size QUEUE_TYPE queue_ptr return queue pLr count J KCOKCKCKCKCECKC RR RAR RR RRA 2 2 k 2 k 2 k k k 2 2 kk kk kk 2 2 22 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ke e ke kk FUNCTION Empty ARGUM
98. gravity forces from turning dynamics or threshold coordinated turn the unit monitors the yaw rate If the yaw rate exceeds a given TurnSwitch threshold the feedback gains from the accelerometer signals for attitude correction are reduced because they are likely corrupted NAV Function The NAV Function supports all the features of the IMU VG and AHRS functions In addition the NAV function integrates the sensor information from an internal or external GPS receiver and runs internal software on the DSP processor for computing navigation and orientation information In this function the unit outputs GPS information Latitude Longitude and Altitude inertial aided 3 axis velocity information as well as heading roll and pitch measurements in addition to digital IMU data At a fixed 100Hz rate the unit continuously maintains the following digital IMU data the dynamic roll pitch and heading data as well as the navigation data As shown in Figure 2 on page 23 after the Sensor Calibration block the IMU data is passed into an Integration to Orientation block The Integration to Orientation block integrates body frame sensed angular rate to orientation at a fixed 100 times per second For improved accuracy and to avoid singularities when dealing with the cosine rotation matrix a quaternion formulation is used in the algorithm to provide attitude propagation Following the integration to orientation block the body frame accelerometer signal
99. he first field ID s data to write 5 field1 U2 The second field ID to write 7 field1Data U2 The second field ID s data E U2 e numFields 4 3 field U2 The last field ID to write numFields 4 1 field Data U2 The last field ID s data to write Write Fields Response Table 64 WF Response Write Fields WEI 0x5746 0x5555 0x5746 1 numFields 2 WF payload lt CRC U2 gt The unit will send this packet in response to a write fields command if the command has completed without errors Table 65 WF Payload WF Payload Contents Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields written 1 fieldO U2 The first field ID written 3 field1 U2 The second field ID written sig E U2 More field IDs written numFields 2 1 Field U2 The last field ID written GNAV540 User Manual Page 91 7430 0808 01 Rev B MOOG Set Fields Command Table 66 SF Commands Set Fields SF 0x5346 0x5555 0x5346 1 numFields 4 SF payload CRC U2 gt This command allows the user to set the unit s current configuration SF fields immediately which will then be lost on power down NumFields is the number of words to be set The field0 field1 etc are the field IDs that will be written with the fieldOData field1Data etc respectively This comman
100. include the factor pi in the scaling and can be interpreted in either radians or degrees e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Magnetometers scaled to a range of 1 1 Gauss e Temperature scaled to a range of 100 100 C Table 38 SO Payload SO Payload Contents Byte Name Format Scaling Units Description Offset 0 xAccel I2 20 2 16 g X accelerometer 2 yAccel I2 20 2 16 g Y accelerometer 4 zAccel I2 20 2 16 g Z accelerometer 6 xRate I2 7 pi 2 16 rad s X angular rate 1260 2 16 sec GNAV540 User Manual Page 73 7430 0808 01 Rev B MOOG SO Payload Contents Byte Name Format Scaling Units Description Offset 8 yRate I2 7 pi 2 16 rad s Y angular rate 1260 2 16 sec 10 zRate I2 7 pi 2 16 rad s Z angular rate 1260 2 16 sec 12 xMag I2 2 2 16 Gauss X magnetometer 14 yMag I2 2 2 16 Gauss Y magnetometer 16 zMag I2 2 2 16 Gauss Z magnetometer 18 xRateTemp I2 200 2 16 deg C Xrate temperature 20 yRateTemp I2 200 2 16 deg C Y rate temperature 22 zRateTemp I2 200 2 16 deg C Zrate temperature 24 boardTemp I2 200 2 16 deg C CPU board temperature 26 GPSITOW U2 truncated ms GPS ITOW lower 2 bytes 28 BITstatus U2 Master BIT and Status Scaled Sensor Data Packet 1 Default IMU Data Ta
101. information on the hard iron bias and soft iron ratio effects refer to Compensation for Magnetic Fields on page 39 Refer to Chapter 9 Communicated with the GNAV540 Unit for details of WC and CC commands Installation Guidelines External Magnetometer Field Installation e For a proper calibration and alignment the GNAV540 unit must be installed in its operating environment such as the land vehicle or aircraft in which it will be used e fusingan external magnetometer o The magnetometer must be mounted at least 24 away from large ferrous objects and fluctuating magnetic fields Failure to locate the magnetometer in a clean magnetic environment will affect the attitude solution o Configuring the pitch and level offsets of the magnetometer must be performed before calibrating the GNAV540 unit EMI Protection and Grounding e Ensure the magnetometer is not exposed to large magnetic fields This could permanently magnetize internal components and degrade magnetic heading accuracy e For EMI protection the magnetometer must be connected with a shielded cable that is connected to the 1 0 connector shell o Ensure the case of the magnetometer is electrically connected to the I O connector shell o The shell should be electrically connected to the user s cable shield Page 40 GNAV540 User Manual 7430 0808 01 Rev B MOOG Serial Data Interface The GNA540 receives information through a serial interface that is dedicated for a
102. interface e MIL C 38999 connector e GPS aiding from GPS ICD 153C Compliant Receivers e Altitude operating 10 000M e Velocity Range NAV message limit 256 m s e TTFF lt 100 sec cold e Lessthan 4W power e Optimized for ground vehicle e Rugged sealed enclosure meeting MIL STD 810G and MIL STD 46IE EMI immunity e Internal C A code GPS module interchangeable with GB GRAM SAASM receiver e Switch between embedded GPS and external GPS e Switch between embedded magnetometer and external magnetometer e Tested to military standards for environmental conditions including temperature vibration and shock e Three independent RS422 serial interfaces and precise time pulse outputs e 12 channel continuous satellite tracking for true All In View operation e Field reprogrammable or easy updates of application software e WGS84 datum e High reliability with MTBF 575 000 hours calculated System Performance Table 5 GNAV540 Measurements Measurement Accuracy Position Velocity Position Accuracy 2 m CEP SDGPS Velocity Accuracy 0 05 m s steady state Heading Accuracy 1 0 rms magnetic 0 75 rms with GPS aiding GNAV540 User Manual Page 17 7430 0808 01 Rev B MOOG Measurement Accuracy Attitude Range Roll Pitch 180 x90 Accuracy 0 4 Angular Rate Range Roll Pitch Yaw 200 Bias Stability in run lt 10 hr Bias Stability over temp 0 02 sec Acceleration Input Range 4 g Bias Stability in run 1 mg
103. ion This pin is open collector and requires a 1k to 10k ohm pull up resister The system will drive this pin low to assert a system failure 1 PPS Input Interface The 1PPS input signal allows the user of the GNAV540 to force synchronization of sensor data collection to a 1Hz rising edge signal The signal must maintain 0 0 0 2 V zero logic and 3 0 5 0 volts high logic and stay within 100ms ofthe internal system 1 second timing Sending this signal to the system will align the sensor data collection and algorithm processing to its rising edge and 10ms boundaries thereafter When the system is synchronized to 1PPS the hardwareStatus gt unlocked1PPS flag will be zero otherwise the flag will be one Page 36 GNAV540 User Manual 7430 0808 01 Rev B MOOG 1 PPS Output Interface The 1PPS output signal is provided by the internal GPS receiver when GPS timing is known on the GNAV540 The 1PPS output signal is open collector and should be interfaced to a rising edge trigger with pull up resistor between 1k and 10k ohms The GNAV540 synchronizes sensor data collection to this 1PPS signal internally when available Therefore the 100Hz navigation algorithm will run exactly 100 times each second with no slip when locked to 1PPS Packet data is valid on the rising edge of 1PPS and 10ms boundaries thereafter There is however up to 500us of additional latency in sensor data collection If 1PPS is provided by the internal GPS receiver in NAV products
104. ious incompatibilities minorVersion changes may add or modify functionality but maintain backward compatibility with previous minor versions patch level changes reflect bug fixes and internal modifications with little effect on the user The build stage is one of the following 0 release candidate 1 development 2 alpha 3 beta The buildNumber is incremented with each engineering firmware build The buildNumber and stage for released firmware are both zero The final beta candidate is v w x 3 y which is changed to v w x 0 1 to create the first release candidate The last release candidate is v w x 0 z which is changed to v w x 0 0 for release Table 35 VR Payload VR Payload Contents Byte Name Format Scaling Units Description Offset 0 majorVersion U1 Major firmware version 1 minorVersion U1 Minor firmware version 2 patch U1 Patch level 3 stage Development Stage 0 release candidate 1 2 development 2 alpha 3 beta 4 buildNumber U1 Build number Test 2 Detailed BIT and Status Packet Test T2 0x5432 03 3x5555 0x5432 T2 payload CRC U2 gt This packet contains detailed BIT and status information Full BIT Status details are described in Chapter 11 Built In Test BIT Table 36 T2 Payload T2 Payload Contents Byte Name Format Scaling Units Description
105. is associated with the rate sensor bias terms The Extended Kalman Filter EKF module provides an on the fly calibration for drift errors including the rate sensor bias by providing corrections to the Integration to Orientation block and a characterization of the gyroscope bias state In the VG Function the internally computed gravity reference vector provides a reference measurement for the EKF when the unit is in quasi static motion to correct roll and pitch angle drift and to estimate the X and Y gyroscope rate bias Because the gravity vector has no horizontal component the EKF has no ability to estimate either the yaw angle error or the Z gyroscope rate bias Page 26 GNAV540 User Manual 7430 0808 01 Rev B MOOG VG Function adaptively tunes the EKF feedback in order to best balance the bias estimation and attitude correction with distortion free performance during dynamics when the object is accelerating either linearly speed changes or centripetally false gravity forces from turns Because centripetal and other dynamic accelerations are often associated with yaw rate the unit maintains a low pass filtered yaw rate signal and compares it to the turnSwitch threshold field user adjustable When the platform the unit is attached to exceeds the turnSwitch threshold yaw rate the unit lowers the feedback gains from the accelerometers to allow the attitude estimate to coast through the dynamic situation with primary reliance on angular ra
106. is running then the filter will revert to the AHRS function In either function the EKF formulation will continue without GPS velocity The UTC packet synchronization will drift due to internal clock drift The status of GPS signal acquisition can be monitored from the hardwareStatus BIT refer to Chapter 11 Built In Test BIT From a cold start it typically takes 40 90 seconds for GPS to lock The actual lock time depends on the antenna s view of the sky and the number of satellites in view The DSP performs time triggered trajectory propagation at 100Hz and synchronizes the sensor sampling with the GPS UTC Universal Coordinated Time second boundary when available As with the AHRS and VG Functions the algorithm has two major phases of operation Immediately after power up the unit uses the accelerometers and magnetometers to compute the initial roll pitch and yaw angles The roll and pitch attitude will be initialized using the accelerometer s reference of gravity and yaw will be initialized using the leveled magnetometers X and Y axis reference of the earth s magnetic field During the first 60 seconds of startup the unit should remain approximately motionless in order to properly initialize the rate sensor bias The initialization phase lasts approximately 60 seconds and the initialization phase can be monitored in the softwareStatus BIT transmitted by default in each measurement packet After the initialization phase the unit operates wi
107. is setting forces an algorithm reset when a sensor over range occurs i e a rotational rate on any of the three axes exceeds the maximum range The default setting is OFF Algorithm reset returns the unit to a high gain state where the unit rapidly estimates the gyroscope bias and uses the accelerometer feedback heavily This setting is recommended when the source of over range is likely to be sustained and potentially much greater than the rate sensor operating limit Large and sustained angular rate over ranges result in unrecoverable errors in roll and pitch outputs An unrecoverable error is one where the EKF cannot stabilize the resulting roll and pitch reading If the over ranges are expected to be of short duration 1 sec and a modest percentage over the maximum operating range it is recommended that the restart on over range setting be turned off Handling of an inertial rate sensor over range is controlled using the restartOnOverRange switch If this switch is off the system will flag the overRange status flag and continue to operate through it If this switch is on the system will flag a masterFail error during an over range condition and continue to operate with this flag until a quasi static condition is met to allow for an algorithm restart The quasi static condition required is that the absolute value of each low pass rate sensor falls below 3 deg sec to begin initialization The system will then attempt a normal algori
108. ith the GNAV540 unit require the 2 byte CRC NOTE A GNAV540 unit will also respond to a ping command using the full packet formation with payload 0 and correctly calculated CRC Example 0x5555504B009ef4 Packet Header The packet header is always the bit pattern 0x5555 Packet Type The packet type is always two bytes long in unsigned short integer format Most input and output packet types can be interpreted as a pair of ASCII characters As a semantic aid consider the following single character acronyms Table 13 Character Acronyms Get Gets current volatile fields or settings G W Write Writes default non volatile fields These fields are stored in non volatile memory and determine the unit s behavior on power up Modifying default fields take effect on the next power up and thereafter Set Sets current volatile fields or settings Modifying current fields will take effect immediately by modifying internal RAM and are lost on a power cycle Page 62 GNAV540 User Manual 7430 0808 01 Rev B MOOG Payload Length The payload length is always a one byte unsigned character with a range of 0 255 The payload length byte is the length in bytes of the variable length payload portion of the packet ONLY and does not include the CRC Payload The payload is of variable length based on the packet type 16 Bit CRC CCITT Packets end with a 16 bit CRC CCITT calculated on the entire packet excluding the 0x5555 header an
109. ive for a positive rotation around the z axis turn 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 The position output from GPS is represented in Latitude Longitude and Altitude LLA convention on the WGS84 Ellipsoid This is the most commonly used spherical coordinate system The GPS velocity is defined in North East and Down reference frame which can be converted to the Cartesian coordinate system Earth Centered Earth Fixed ECEF ECEF uses three dimensional XYZ coordinates in meters to describe the location of a GPS user or satellite Several online resources are available to help users with this transformation Application notes are available on the Crossbow website http www moog crossbow com Advanced Settings The GNAV540 Inertial Systems have a number of advanced settings that can be changed The specific settings available vary from unit to unit and a detailed description of each unit is found in the subsequent sections of this manual All units support baud rate power up output packet type output rate and custom axes configuration The units can be configured via two methods e NAV VIEW 2 2 a GUI application Chapter 7 Configuring GNAV540 with NAV VIEW 2 2 e C Language Programming Chapter 10 Programming Guidelines IMU Function Inertial Measurement Unit IMU Function provides inertial rate an
110. iver needs to receive signals from as many satellites as possible A GPS receiver does not work properly in narrow streets and underground parking lots or if objects or human beings cover the antenna Poor visibility may result in position drift or a prolonged Time To First Fix TTFF A good sky visibility is therefore a prerequisite Even the best receiver can t make up for signal loss due to a poor antenna in band jamming or a poor RF cable The unit ships with an external active antenna that must be connected properly to SMA jack on the unit case Placing the antenna on a 16 square inch or larger ground plane is highly recommended GNAV540 User Manual Page 35 7430 0808 01 Rev B MOOG 1 0 Port Interface The following ports are accessible through the J1 connector Refer to J1 1 0 Connector on page 35 for the pin out listing NOTE The GNAV540 can be purchased with a developer s kit a cable is provided with a 37 pin connector on one end and five connectors on the other end to connect to external devices This cable is designed only for laboratory use See Figure 31 on page 126 Port A User computer RS422 serial data interface This serial interface is standard RS 422 9600 19200 38400 or 57600 baud 8 data bits 1 start bit 1 stop bit no parity and no flow control and will output at a user configurable output rate These settings allow interaction via a standard PC serial port Port B External GPS RS422 serial inte
111. ld Table 81 hardwareEnvironmentalBIT Field hardwareEnvironmentalBIT Field Bits Values Category pcbTemp 0 0 normal 1 out of bounds Soft Reserved 9 15 N A comBIT Field The comBIT field contains flags that indicate communication errors with external devices Each external device has an associated message with low level error signals The comError flag in the BITstatus field is the bit wise OR of the comBIT field Table 82 comBIT Field comBIT Field Bits Values Category serialAError 0 0 normal 1 error Soft serialBError 1 0 normal 1 error Soft serialCError 2 0 normal 1 error Reserved 3 15 N A comBIT Field stickyness e With each error or overflow the related comSerialBit field flag s will remain sticky until reported in a packet The algorithm task is responsible for clearing the BIT flag void handleComBIT e Requesting a packet does not clear the flag s Only when the unit is configured to continuously output a packet will the flag s be cleared e When a substantial number of consecutive errors have occurred in a short period of time the master fail bit is set and the flags cannot be cleared without doing a reset Page 102 GNAV540 User Manual 7430 0808 01 Rev B MOOG comSerialABIT Field The comSerialABIT field contains flags that indicate low level errors with external serial port A the user serial port The serialAError flag in the comBIT field is the bit wise OR of the comSerialABIT fie
112. ld Table 83 comSerialABIT Field comSerialABIT Field Bits Values Category transmitBufferOverflow 0 normal 1 overflow Soft receiveBufferOverflow 0 normal 1 overflow Soft framingError 0 normal 1 error Soft breakDetect 0 normal 1 error Soft parityError 0 normal 1 error Soft Reserved comSerialBBIT Field The comSerialBBIT field contains flags that indicate low level errors with external serial port B the aiding serial port The serialBError flag in the comBIT field is the bit wise OR of the comSerialBBIT field Table 84 comSerialBBIT Field comSerialBBIT Field Bits Values Category transmitBufferOverflow 0 normal 1 overflow Soft receiveBufferOverflow 0 normal 1 overflow Soft framingError 0 normal 1 error Soft breakDetect 0 normal 1 error Soft parityError 0 normal 1 error Soft Reserved comSerialCBIT Field The comSerialABIT field contains flags that indicate low level errors with external serial port c the user serial port The serial Error flag in the comBIT field is the bit wise OR of the comSerialCBIT field Table 85 comSerialABIT Field comSerialCBIT Field Bits Values Category transmitBufferOverflow 0 normal 1 overflow Soft receiveBufferOverflow 0 normal 1 overflow Soft framingError 0 normal 1 error Soft breakDetect 0 normal 1 error Soft parityError 0 normal 1 error Soft Reserved GNAV540 User Manual Page 103 7430 0808 01 Rev
113. le txt How data is logged can be configured data type logging rate recording length The instructions follow GNAV540 User Manual Page 49 7430 0808 01 Rev B MOOG Figure 11 Log to File Menu 1 Locate the icon at the top ofthe page or click File and then select Log to File from the drop down menu The dialog window opens HORS Browse 2 Click the Browse button and select the location 2 Log to File for saving data SURE SEIS Enginerring Data Fractional Rate Full Sample Rate 3 Inthe Log Type section select the type of data PEERS bes to record C Raw Packets Hex C 4 4 Sample Rate E Pr Dat dsth ted 1 C 1410 Sample Rate ngineering Data records the converted values Test Duration ee provided from the system in engineering units E Days 0 r default selection Ph Hex Data provides the raw hex values Minutes o Seconds sample 1 zi separated into columns displaying the value seconds Im 2 Raw Packets records the hex strings as they are sent from the unit cancel 4 Inthe Logging Rate section the following options are available e Fractional Rate e Sample Rates 5 Inthe Test Duration section define the desired duration of the data logging in terms of Days Hours Minutes and or Seconds The default setting is 10 seconds 6 After setting all the options click the OK button The display will return to the main window To start the recording proces
114. lgorithm fields will not necessarily be from the same algorithm iteration If at least one field is successfully collected the unit will respond with a get fields response with data containing the field IDs of the successfully received fields If any field is unable to be received the unit will respond with an error response Note that both a get fields and an error response may be received as the result of a get fields command Table 74 GF Payload GF Payload Contents Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields to get 1 field0 U2 The first field ID to get 3 field1 U2 The second field ID to get gt U2 More field IDs to get numFields 2 Field U2 The last field ID to get 1 Get Fields Response Table 75 GF Response Get Fields GF 0x4746 Page 94 GNAV540 User Manual 7430 0808 01 Rev B MOOG Get Fields GF 0x4746 0x5555 0x4746 1 numFields 4 lt CRC U2 gt The unit will send this packet in response to a get fields reguest if the command has completed without errors Table 76 GF Payload GF Payload Contents Byte Offset Name Format Scaling Units Description 0 numFields U1 The number of fields retrieved 1 fieldO U2 The first field ID retrieved 3 field0Data U2 The first fiel
115. lude a description of the service or repair required a description of the problems with the unit and the conditions that the problems occurred such what function was being used e 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 e Oneachside of the container clearly label the container with FRAGILE HANDLE WITH CARE e Seal the shipping container s with heavy tape or metal bands strong enough to handle the weight of the equipment and the container Return Address Use the following address for all returned products Moog Inc 1421 McCarthy Blvd Milpitas CA 95035 Attn RMA Number XXXXXX Source Code License For qualified commercial OEM users a source code license of NAV VIEW 2 2 can be made available under certain conditions Please contact your Moog representative for more information Contact Information United States Phone 1 408 965 3300 8 AM to 5 PM PST Fax 1 408 324 4840 24 hours Email techsupport moog crossbow com Outside of the Visit website www moog crossbow com United States GNAV540 User Manual Page 129 7430 0808 01 Rev B MOOG Page 130 GNAV540 User Manual 7430 0808 01 Rev B MOOG Appendix F Revision History Table 100 Document Revision History Revision Date Contributor s Comments A 26
116. multiple serial ports it may be necessary to set up the serial port Refer to the Serial Port Instructions below If using the Ethernet the Ethernet connection will need to be set up Refer to the Ethernet Port Instructions below Serial Port Instructions a b C d f Start NAV VIEW 2 2 on the computer double click the NAV VIEW 2 2 icon on the desktop On the menu bar click Setup and then select Port from the drop menu The Configure Serial Port dialog window opens Select the appropriate COM port Set the baud rate Auto is recommended Click Connect and then click Save and Close Ethernet Port Instructions a b c d e f Start NAV VIEW 2 2 on the computer double click the NAV VIEW 2 2 icon on the desktop On the menu bar click Setup and then select Ethernet from the drop menu The EthernetForm window opens Enter the IP address of the GNAV540 unit Enter the number of the IP port Click Connect and then click Save and Close e Ifthe connections are correct and the unit is functional information should be displayed on the screen Refer to Chapter 6 Viewing and Logging Data with NAV VIEW 2 2 on page 47 GNAV540 User Manual Page 45 7430 0808 01 Rev B MOOG Trouble Shooting Tips e Ifthe unit is connected but not working check the following o The power supply is connected and the output voltage and current levels are correct o Ifusing the serial port verify the correct serial connect
117. n external magnetometer Refer to Table 11 on page 35 for the signal pin out of the J1 connector GNAV540 User Manual Page 41 7430 0808 01 Rev B MOOG Page 42 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 5 Installation Guidelines This chapter provides information to set up the GNAV540 unit and NAV VIEW 2 2 software for laboratory test NOTE Directions to install a unit in a vehicle for field use is outside the scope of this document e Overview page 43 e Installation Requirements page 43 e 1 Install Software NAV VIEW 2 2 page 44 e 2 Prepare the Communication Port page 44 e 3 Connect the GPS Antenna page 44 e 4 Turnon the GNAV540 page 45 Overview The following instructions are for connecting the GNAV540 unit to a computer and using NAV VIEW 2 2 to verify basic functions ofthe unit in a laboratory setting Installation Requirements Computer e CPU 21GHz e RAM Memory 2 3GB e Hard Drive Free Memory 2 60MB e Operating System Windows XP 32 bit or 64 bit Windows 7 32 bit or 64 bit e Microsoft NET 4 0 or higher Communication Port e Fora serial connection which COM port to use e For an Ethernet connection the IP address of the GNVA540 unit and the IP port number NOTE The default IP address of the unit is 192 168 1 2 Power and Hardware Power e Voltage 9 VDC to 32 VDC e Power gt 5W Hardware e Ensure all necessary hardware has been determined and provided
118. nce u u u u Magnetometers Turn Rate GPS Data u Internal Internal External E u D NAV AHRS only Computation u e u u u a B BEER RPP PPR u u LEAN NNN The GNAV540 features include sensors used in the EKF for the drift correction of the 6 DOF inertial sensor cluster A 3 axis magnetometer and a GPS receiver are used for correcting the drift on yaw heading angle increasing the accuracy of the attitude estimation by incorporating these sensor signals into the EKF and providing a navigation solution The common aiding sensor for the drift correction for the attitude i e roll and pitch only is a 3 axis accelerometer Figure 3 below illustrates the unit setting and profile block which configures the algorithm to user and application specific needs This feature is one of the more powerful features in the GNAV540 architecture as it allows the GNAV540 to work in a wide range of commercial applications by setting different modes of operation GNAV540 User Manual Page 23 7430 0808 01 Rev B Figure 3 GNAV540 Functions NAV Function Attitude and velocity propagation 100 Hz Correction algorithm Roll pitch heading velocity Magnetometer Accelerometer tilt VG Function with External GPS Attitude and velocity propagation 100 Hz Roll pitch heading velocity velocity GPS position GPS velocity accels rates attitude velocity GPS position Accelerometer tilt GPS velocity
119. ngleMag I2 2 pi 2 16 Radians Yaw angle magnetic north 360 2 16 6 xRateCorrected I2 7 pi 2 16 rad s X angular rate Corrected 1260 2 16 sec 8 yRateCorrected I2 7 pi 2 16 rad s Y angular rate Corrected 1260 2 16 sec 10 zRateCorrected I2 7 pi 2 16 rad s Z angular rate Corrected 1260 2 16 sec 12 xAccel I2 20 2 16 g X accelerometer 14 yAccel I2 20 2 16 g Y accelerometer 16 zAccel I2 20 2 16 g Z accelerometer GNAV540 User Manual Page 77 7430 0808 01 Rev B MOOG A1 Payload Contents Byte Name Format Scaling Units Description Offset 18 xMag I2 2 2 16 Gauss X magnetometer 20 yMag I2 2 2 16 Gauss Y magnetometer 22 zMag I2 2 2 16 Gauss Z magnetometer 24 xRateTemp I2 200 2 16 DegC X rate temperature 26 timeITOW U4 1 ms DMU ITOW sync to GPS 30 BITstatus U2 Master BIT and Status Nav Data Packet 0 Table 47 NO Data Packet Nav Data NO Ox4E30 0x5555 Ox4E30 NO payload CRC U2 gt This packet contains navigation data and selected sensor data scaled in most cases to a signed 2 16 2 s complement number Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angles scaled to a range of pi pi or 180 deg to 180 deg e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10
120. nsor cluster includes three axes of MEMS angular rate sensing and three axes of MEMS linear acceleration sensing These sensors are based on rugged field proven silicon bulk micromachining technology Each sensor within the cluster is individually factory calibrated for Page 18 GNAV540 User Manual 7430 0808 01 Rev B MOOG temperature and non linearity effects during Crossbow s manufacturing and test process using automated thermal chambers and rate tables e Coupled to the 6 DOF MEMS inertial sensor cluster is a high performance Digital Signal Processor DSP that utilizes the inertial sensor measurements to accurately compute navigation information including attitude heading and linear velocity thru dynamic maneuvers actual measurements are a function of the GNAV540 as shown in Table 2 The DSP processor makes use of internal and external magnetic sensor and or GPS data to aid the performance of the inertial algorithms and help correct long term drift and estimate errors from the inertial sensors and computations The navigation algorithm utilizes a multi state configurable Extended Kalman Filter EKF to correct for drift errors and estimate sensor bias values This algorithm runs on a 150MHz 32 bit DSP that has approximately four times the computational power of Crossbow s earlier generation Inertial Systems e A significant feature of the GNAV540 is the extensive field configurability This field configurability allows the GNAV540
121. of the calibration process 1 Install the GNAV540 in the system in which it will be used 2 Ifan external magnetometer is used install that device in the system 3 Select an appropriate test location free of magnetic interference 4 Runthe calibration and alignment procedure 5 Setthe calibration readings in the GNAV540 NOTE Ensure the test location is appropriate for magnetic calibration The calibration process provides corrections for magnetic fields from fixed locations that are relative to the position of the unit The calibration does not compensate for time varying fields or fields created by magnetic material that moves relative to the GNAV540 unit Magnetometer Alignment Using NAV VIEW 2 2 During the calibration procedure the unit makes a series of measurements while the user system is being turned through a complete 360 degree circle A 360 degree rotation gives the unit visibility to hard and soft iron distortion GNAV540 User Manual Page 39 7430 0808 01 Rev B MOOG in the horizontal plane Using NAV VIEW 2 2 the hard and soft iron effects can be viewed by selecting the Misalignment option on the Configuration Menu and viewing the magnetic circle during the calibration For calibration instructions refer to Aligning the Magnetometer on page 57 Magnetometer Alignment Using Code The unit provides a command interface for initiating the hard iron soft iron calibration without using NAV VIEW 2 2 To do so send
122. opens Figure 15 Magnetometers Parameters Value X hard iron offset Y hard iron offset Soft iron ratio Heading Track Offset EE Turn Switch Threshold Hardware Status Enable Fields O Unlocked 1PPS O Unlocked Internal GPS O No DGPS O Unlocked Eeprom Axes Orientation Customer Axes Unit Reference Axes x Y Software Status Enable Fields O Algorithm Initializing O Use GPS O Stationary Yaw Lock O Restart Over Range D Dynamic Motion Filter Clock Rate FilterClocks FilterClock1 FilterClock2 FilterClock3 LP Cutoff Hz O High Gain O Altitude Only Ae O Turn Switch Sensor Status Enable Fields O Sensor Over Range Comm Status Enable Fields O No External GPS GNAV540 User Manual 7430 0808 01 Rev B Page 53 MOOG CROSS E w Figure 16 View Current Configuration Method 2 1 Atthe main screen select Unit Configuration from the menu bar then select Configuration from the drop menu The dialog window opens Figure 16 2 Click Get AII Values at the bottom of the screen The current configuration values will be displayed Configuring the Unit The Unit Configuration window enables viewing and configuring the system configurations There are five tabs within the Unit Configuration menu e General page 54 e Advanced page 56 e BIT Configuration page 56 General The General tab provides quick access to the most frequently used configuration features To
123. or of the cable is being used If the adaptor is being used verify the switch setting of the adaptor o If using the Ethernet port verify the IP address of the unit is correct e IfNAV VIEW does not display any data and the evaluation cable is being used Interface Cable Accessory on page 126 ensure the switch on Port C the serial interface that connects to the External Magnetometer is set in the OFF position That switch should only be turned ON when firmware is being loaded into the unit NOTE Uploading firmware DMU upgrade to the unit is outside the scope of this document For information contact Customer Service refer to page 128 Page 46 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 6 Viewing and Logging Data with NAV VIEW 2 2 NOTE It is assumed that GNAV540 and NAV VIEW 2 2 have been set up connected and turned on For instructions refer to Chapter 5 Installation Guidelines on page 43 Figure 8 on page 48 shows the main page of NAV VIEW The functions are accessed from the menu bar at the top of the page The graphs are displayed in the main body of the page e Multiple graphs are available which can be selected for viewing such as Angles Angular Rate Accel Velocity and GPS POS Which graphs are available is related to the selected packet type For details about packet types refer to Chapter 9 Communicating with the GNAV540 Unit e The time range speed of viewing the graphs can b
124. out configuring the unit via programming code refer to Chapter 10 Programming Guidelines NOTE It is recommended to read and thoroughly understand the effects of altering the settings in the Advanced tab before making changes to the unit configuration Refer to Chapter 2 GNfAV540 Functions e Viewing Current Configurations page 53 e Configuring the Unit page 54 The configuration tabs o General page 54 o Advanced page 56 o BIT Configuration page 56 o Aligning the Magnetometer page 57 NOTE To implement a configuration save the configuration in EEPROM and recycle the power of the GNAV540 unit Until the power is recycled the new configuration will not be implemented Viewing Current Configurations NAV VIEW 2 2 enables viewing the current settings and calibration data The displayed information can be printed Figure 15 Current Configuration There are two methods to view current 8 8 configuration Method 1 Read Unit Configuration Read Print Preview Unit ID Product Configuration Model Version e Atthe main screen select Unit vo Configuration from the menu bar then select Print from the drop menu O Contains Mags O Internal GPS O algorithm Enabled O External Aiding Architecture re Serial Number Unit Default Settings Packet Type Packet Rate Baud Rate External GPS GPS Baud GPS Protocol User Behavior Switch O Freely Integrate O Use Mags z The dialog window
125. p menu External Mag Leveling Alignment Rotational Alignment 4 Ifthe 360 degree turn can be completed within m 120 seconds check Auto Terminate En dL diss Roll Offset Pitch Offset 5 Under Rotational Alignment select the Start e oo button to begin the alignment Follow the 0 00 oo i Sing Gre instructions displayed in the screen Refer to Figure 21 Rol 14 Pitch 1 8 Yaw 0 0 6 Rotate the GNAV540 for 380 degrees of 7 rotation until the message is displayed that alignment is complete Roll Offset Pitch Offset o oov Y Field Gauss Fi 25 M t ter Ali t Val 7 After completing the rotation data will be bia agne ome e LA u u displayed with the calibration parameters The X and Y offset values indicate how far the New Settings magnetic field has been offset due to hard iron affects from components surrounding the unit 10 x X Hard Iron Offset Y Hard Iron Offset Soft Iron Ratio 0 02841 0 00327 0 88156 The soft iron ratio will also be displayed which is the effect of soft iron on the GNAV540 unit For external mag align i Before clicking Apply button you must set switch 8 The save the offset values click the Apply to communicate with NAV VIEW not external mag button Cancel Apply The new configuration settings will be saved but ESSI they will not be implemented until either a soft reset via software see Interactive Commands on
126. ptr gt front 1 MAXQUEUE retval 1 return retval KKK KA K IK k k k k k RAR k kk k kk kk kk kk kk kk kk FT CL kok kok kok kok kok kok rr FC ER C k erCFC ke ke ke ke ke ke ke ke e e ek FUNCTION peekByte returns 1 byte from buffer without popping ARGUMENTS queue ptr is pointer to the queue to return byte from x index is offset into buffer to which byte to return RETURNS 1 byte REMARKS does not do boundary checking please do this first Kk kk kk kk kk kk kk kk kk k k kk kk kk kk kk kk kk kk kk k 2 2 22 22 22 2 2 22 2 2 OR OR 22 2 2 2 2 2 2 2073 char peekByte QUEUE TYPE queue ptr unsigned int index char byte int firstIndex firstIndex queue ptr gt front index MAXQUEUE byte queue ptr entry firstIndex return byte KKK IKK K K k k k k k k k k k k kk k k kk kk kk kk kk RAR kok kok A KK A ko ke ke kk ke ke ke ke e e ek FUNCTION peekWord returns 2 byte word from buffer without popping ARGUMENTS queue ptr is pointer to the queue to return word from m index is offset into buffer to which word to return RETURNS 2 byte word REMARKS does not do boundary checking please do this first FR A IR A 2 KA KA KA 2 2 KA 2 2 2 2 KA KA 2 2 2 2 2 2 2 22 EL 2 2 2 2 2 2 2 2 k k 2 2 k 2 k k k kk kk 2 2 2 2 2 2 2 2 2 unsigned short peekWord QUEUE TYPE queue ptr unsi
127. r range is likely to be sustained and potentially much greater than the rate sensor operating limit Large and sustained angular rate over ranges result in unrecoverable errors in roll and pitch outputs An unrecoverable error is one where the EKF cannot stabilize the resulting roll and pitch reading Ifthe over ranges are expected to be of short duration 1 sec and a modest percentage over the maximum operating range it is recommended that the restart on over range setting be turned off Handling of an inertial rate sensor over range is controlled using the restartOnOverRange switch Ifthis switch is off the system will flag the overRange status flag and continue to operate through it If this switch is on the system will flag a masterFail error during an over range condition and continue to operate with this flag until a quasi static condition is met to allow for an algorithm restart The quasi static condition required is that the absolute value of each low pass rate sensor falls below 3 deg sec to begin initialization The system will then attempt a normal algorithm start Dynamic The default setting is ON Turning off the dynamic motion setting results in a Motion higher gain state that uses the accelerometer feedback heavily During periods of time when there is known low dynamic acceleration this switch can be turned off to allow the attitude estimate to quickly stabilize Turn Switch 0 5 deg sec With respect to centripetal or false
128. ration this switch can be turned off to allow the attitude estimate to quickly stabilize With respect to centripetal or false gravity forces from turning dynamics or coordinated turn the unit monitors the yaw rate If the yaw rate exceeds a given turn switch threshold the feedback gains from the accelerometer signals for attitude correction are reduced because they are likely corrupted Page 28 GNAV540 User Manual 7430 0808 01 Rev B MOOG AHRS Function The Attitude Heading Reference System AHRS Function utilizes a 3 axis magnetometer internal or external in addition to the accelerometers and gyroscopes as well as the associated software running on the DSP processor This enables the computation of dynamic heading as well as dynamic roll and pitch AHRS Function provides dynamic heading roll and pitch measurements in addition to the VG Function and IMU Function data The dynamic heading measurement is stabilized using the 3 axis magnetometer as a magnetic north reference The dynamic roll and pitch measurements are stabilized using the accelerometers as a long term gravity reference The unit can be configured to turn on and off the magnetic reference for user defined periods of time This function utilizes data from calibrated sensors the gyroscopes the accelerometers and a magnetometer internal or external For details of the IMU functions refer to IMU Function on page 25 For details of the VG functions refer to Verti
129. rface This serial interface is standard RS 422 which connects to the external GPS GNAV540 supports a GPS ICD 153C compliant GPS receiver Port C External Magnetometer RS422 serial interface This serial interface is standard RS 422 The settings for an external magnetometer are 38400 baud 8 data bit 1 start bid 1 stop bit no parity no flow control Cable Field Requirements CAUTION The GNAV540 is shipped with an EMI filter attached to the Amphenol MIL DTL 38999 IIT TVPO2R Receptacle 37 pins circular connector This connector must remain in place to ensure proper shielding from EMI interference The cable sent with the unit is intended to provide the user with the ability to test the unit right out of the box and will not provide adequate shielding for all environments For field use the cable must be used with the shield connected to the I O connector shell to provide the required EMI protection Case ground must be used to provide full EMI protection Ensure the cable shield is grounded on only one end of the cable Signals Hardware BIT Error Output The hardware BIT error output pin is the ultimate indication of system failure This indication is available in most software output packets as the masterFail flag It is the logical AND ofthe hardwareError comError and softwareError flags monitored by the system In the event of a communication failure the hardware BIT error pin may be used to detect a masterFail assert
130. riggered until persistency conditions are met or a hard failure has occurred The second byte bits 8 15 is the Status byte signaled status alerts Four intermediate signals determine when to assert the masterStatus flag hardwareStatus sensorStatus comStatus and softwareStatus masterStatus is the logical OR of these intermediate signals Each intermediate signal has a separate field with an indication flag Each indication flag can be enabled or disabled by the user Any enabled indication flag will trigger the associated intermediate signal and masterStatus flag The BIT fields are summarized in Table 77 below Table 78 provides additional information about the programmable status field Table 77 Default BIT Status Values BITstatus Field Bits Value Configurable Error Byte fields BIT N masterFail 0 0 normal 1 fatal error The masterFail flag is thrown when either a hard failure fatal condition or a soft failure persistent problem occurs hardwareError 0 normal 1 internal hardware error comError 0 normal 1 communication error softwareError 0 normal 1 internal software error or magAlignOutofBounds NOTE In AHRS and NAV modes this bit provides information about the status of magnetic alignment If the unit has not been properly magnetically calibrated a softwareError will be indicated GPSError 0 normal 1 GPS failure Page 98 GNAV540 User Manual 7430 0808 01 Rev B MOOG BITstatus Field Bits Value
131. rser code Parser Code Appendix C Sample Packet Examples of packet decoding Decoding Appendix D Mechanical Mechanical specifications and drawings and measurements of the enclosed Specifications model units Appendix E Crossbow Service A summary of customer support services warranty description return Page 14 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter Appendix Summary Policies process and contact information Appendix F Revision History List and description of document release updates changes Related Documents NOTE Moog Inc is I509001 2008 certified Table 2 Reference Documents Title Description Test Method Standard for Environmental Engineering Considerations and MST ATI Laboratory Tests Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment MIL HDBK 217F Military Handbook Reliability Prediction of Electronics Equipment MIL STD 461E GPS User Equipment Interface Control Document for the GPS Standard Serial Interface Protocol GSSIP of DoD Standard GPS UE Radio Receivers ICD GPS 153C IRN001 21 February 2006 Certification of Conformance vibration shock temperature altitude humidity QL 11 0382 Quanta Laboratories Certification of Compliance MILSTD 461E control of electromagnetic MET Laboratories 3277 interference Met Laboratories Text Conventions Table 3 Text Conventions Convention Definition
132. s are rotated into the NED level frame and are integrated to velocity At this point the data is blended with GPS position data and output as a complete navigation solution As shown in Figure 2 on page 23 the Integration to Orientation and the Integration to Velocity signal processing blocks receive drift corrections from the Extended Kalman Filter EKF drift correction module The drift correction GNAV540 User Manual Page 31 7430 0808 01 Rev B MOOG module uses data from the aiding sensors when they are available to correct the errors in the velocity attitude and heading outputs Additionally when aiding sensors are available corrections to the rate gyroscopes and accelerometers are performed The NAV Function blends GPS derived heading and accelerometer measurements into the EKF update depending on the health and status of the associated sensors If the GPS link is lost or poor the Kalman Filter solution stops tracking accelerometer bias but the algorithm continues to apply gyroscope bias correction and provides stabilized angle outputs The EKF tracking states are reduced to angles and gyroscope bias only The accelerometers will continue to integrate velocity However accelerometer noise bias and attitude error will cause the velocity estimates to start drifting within a few seconds The attitude tracking performance will degrade the heading will freely drift and the filter will revert to the VG Function if the magnetometer
133. s press the button at the top of the window click File and then select Start Logging from the drop menu Refer to Figure 8 on page 48 To stop the recording the data early press the M button Afterwards when you select Start Logging the new information will be appended To pause the recording press the ll button Playback Data In addition to data recording NAV VIEW 2 2 allows the user to replay saved data that has been stored in a log file 1 To playback data select Playback Mode from the Data Source drop down menu at the top Data Source LIVE Mode from DMU LIVE Mode From DMU Playback Mode fram File Selecting Playback mode will open a text prompt which will allow users to specify the location of the file they wish to play back All three file formats are supported Engineering Hex and Raw for playback In addition each time recording is stopped started a new section is created These sections can be individually played back by using the drop down menu and associated VCR controls Page 50 GNAV540 User Manual 7430 0808 01 Rev B MOOG 2 Once the file is selected users can utilize the VCR style controls at the top of the page to start stop or pause the playback of the data NAV VIEW 2 2 also provides users with the ability to alter the start time for data playback The slide bar at the top of the page can be used to adjust the starting time Raw Data Console NAV VIEW 2 2 offers some uniqu
134. s Y angular rate corrected 1260 2 16 sec 10 zRateCorrected I2 7 pi 2 16 rad s Z angular rate corrected 1260 2 16 sec 12 xAccel I2 20 2 16 g X accelerometer 14 yAccel I2 20 2 16 g Y accelerometer 16 zAccel I2 20 2 16 g Z accelerometer 18 nVel I2 512 2 16 m s North velocity 20 eVel I2 512 2 16 m s East velocity 22 dVel I2 512 2 16 m s Down velocity 24 longitudeGPS I4 2 pi 2 32 Radians GPS Longitude 360 2 32 28 latitudeGPS 14 2 pi 2 32 Radians GPS Latitude 360 2 32 32 altitudeGPS I2 2 14 2 16 m GPS altitude 100 16284 34 xRateTemp I2 200 2 16 deg C X rate sensor temperature 36 timeITOW U4 1 ms DMU ITOW sync to GPS 40 BITstatus U2 Master BIT and Status Nav Data Packet 3 default packet Table 51 Data Packet Nav Data N3 0x4E33 0x5555 0x4E33 lt N3 payload gt CRC U2 gt GNAV540 User Manual 7430 0808 01 Rev B Page 80 MOOG This packet contains navigation data and selected sensor data scaled in most cases to a signed 2116 2 s complement number Data involving angular measurements include the factor pi in the scaling and can be interpreted in either radians or degrees e Angles scaled to a range of pi pi or 180 deg to 180 deg e Angular rates scaled to range of 3 5 pi pi or 630 deg sec to 630 deg sec e Accelerometers scaled to a range of 10 10 g e Temperature scaled to a range of 100 100 C
135. s field refer to BIT Status Fields on page 98 This field allows the user to determine which low level comStatus field signals will flag the comStatus and masterStatus flags in the BITstatus field Any asserted bits in this field imply that the corresponding comStatus field signal if asserted will cause the comStatus and masterStatus flags to be asserted in the BITstatus field softwareStatusEnable Field This field is a bit mask of the softwareStatus field refer to BIT Status Fields on page 98 This field allows the user to determine which low level softwareStatus field signals will flag the softwareStatus and masterStatus flags in the BITstatus field Any asserted bits in this field imply that the corresponding softwareStatus field signal if asserted will cause the softwareStatus and masterStatus flags to be asserted in the BITstatus field sensorStatusEnable Field This field is a bit mask of the sensorStatus field refer to BIT Status Fields on page 98 This field allows the user to determine which low level sensorStatus field signals will flag the sensorStatus and masterStatus flags in the BITstatus field Any asserted bits in this field imply that the corresponding sensorStatus field signal if asserted will cause the sensorStatus and masterStatus flags to be asserted in the BITstatus field BIT Field Hierarchy Figure 28 below illustrates the hierarchy of the BIT fields GNAV540 User Manual Page 107 7430 0808 01 Rev B Figure 2
136. set external Mag 0x0018 ilm oem Mag tou RS body z T 2 T n e Angle of major axis of the ellipse generated by m Soft Iron Angle Ext nn 360 degree swing in radian 32 Orientation Ext 0x0020 See below Determine forward rightward and downward SC sides of external magnetometer m reserves a Jm DN a fem fw User Packet Data NOTE BAUD rate SF has immediate effect Some output data may be lost Response will be received at new BAUD rate NOTE Only configuration fields 1 2 3 7 8 13 16 17 18 19 22 25 26 27 and 34 are applicable for architectures 4and 5 Continuous Packet Type Field This packet type is continually output The supported packet depends on the model number Refer to Output Packets Polled or Continuous on page 73 for a complete list of the available packet types Orientation Field This field defines the rotation from the factory to user axis sets This rotation is relative to the default factory orientation connector aft base plate down The default factory axis set is Ux Uy Uz defined by the connector Page 86 GNAV540 User Manual 7430 0808 01 Rev B MOOG pointing in the Ux direction and the baseplate pointing in the Uz direction The user axis set is X Y Z as defined by this field An example ofthe factory axis set is shown below Figure 26 Orientation Fields UX Uy Uz Table 56 Orientation Fields Axis Values X Axis Sign 0 positive 1 negative X Axis
137. st PK 0x504B 0 Ping Command Input Reply Message ALL and Response CH 0x4348 N Echo Command Input Reply Message ALL and Response Interactive Commands GP 0x4750 2 Get Packet Input Message ALL Request AR 0x4152 0 Algorithm Reset Input Reply Message VG AHRS NAV SR 0x5352 0 Software Reset Input Reply Message ALL 0x1515 Error Response Reply Message ALL GNAV540 User Manual Page 63 7430 0808 01 Rev B payload byte length U1 gt ASCII Mnemonic lt 2 byte packet type U2 gt 0x5743 CC 0x4343 8 Description Calibrate Command and Response Calibration Completed Output Messages Status and Other rn Only MOOG Input Reply Message Reply Message Available Functions AHRS NAV AHRS NAV 0x4944 0x5652 0x5432 30 Identification Data Version Data Test 0 Detailed BIT and Status Output Message Output Message Output Message Output Messages Measurement Data Continuous or Polled 0x5330 S1 0x5331 24 S2 0x5332 28 Scaled Sensor 0 Data Scaled Sensor 1 Data Scaled Sensor 2 Data Output Message Output Message Output Message ALL ALL 0x4130 Angle 0 Data Output Message AHRS NAV 0x4131 0x4132 0x4E30 0x4E31 0x4E32 0x4E33 0x4E34 Advanced Commands 0x5746 0x5746 0x5346 0x5346 numFields 4 1 numFields 2 1 numFields 4 1 numFields 2 1 Angle 1 Data Angle 2 Data Nav 0 Data Nav 1 Data Nav 2 Data Nav 3 Data
138. t 92 Tabl 67 SE Payload ME 92 Table 68 WF Reenonse E E 92 Table 69 AA e i LAM E O DD AD A DULL TIE 92 Table 70 RF Payload c een innen 93 GNAV540 User Manual Page 9 7430 0808 01 Rev B MOOG Table 71 RE een ERR 93 Table 72 RF Payload i Ep uude ee Ai LUE LIU UU IDA LIU 93 T abl amp 73 GE Commande tee E M Ee mL um 94 Table 74 GF Payload sists E 94 Table 75 GF RESPONSE ur aaa nakka Ar dem ti aa in en ne Re MR Re 94 Table 76 GF Payl0 dd mamam 95 Table 77 Default BIT Status Values onera an a AA 98 Table 78 Programmable BIT Status Default Values per Function nn 99 Table 79 hardwareBIT Field Rer c Table 80 hardwarePowerBIT Field Table 81 hardwareEnvironmentalBIT Field Table 82 comBIT Fields dials eee a DELLI DIEI D ADI Table 83 comSerialABIT Piel d c een Table 84 c6omsSerialBBIT Field o ttt etes re eae d M E E Table 85 comserialABIT Field ec M Table 86 softwareBIT Field essaie las Table 87 softwareAlgorithmBIT Field er Table 88 softwareDataBIT Field dt Table 89 hardwareStatus Field uuo ee ide ee uelut de b up E dud tpm scimus Table 90 comStatus Field re Table 91 softwareStatus ee a ne Table 92 sensorStatus FieldS z 2 220 00 onec hn e ppt ec dra nus ena EE n dra test NN nn At Table 93 master
139. t configuration when it is rebooted Permanent The configuration will be stored in non volatile memory The unit will continue to use the configuration after being rebooted 4 Click the Set Values button The configuration values will be saved as specified Temporary or Permanent Aligning the Magnetometer Figure 20 BIT Configuration Unit Configuration 4 General Advanced BIT Configuration External Mag 10 x By enabling a given status BIT the signal will be included in the corresponding category BIT and in the master status BIT sent by the DMU Field Modify Current Value Enable Disable Hardware Status Enable E Unlocked 1PPS O Unlocked Internal GPS O No DGPS O Unlocked EEPROM O Invalid Air Data a la Software Staus Enable Bl Algorithm Initializing D High Gain O attitude Only Ale O Turn Switch O No Air Data aiding O No Mag Heading ref O No GPS track ref u Sensor Status Enable E O Sensor Over Range Comm Status Enable O No External GPS O No External Mag TA Get All Values Set Values Temporary reset after reboot C Permanent saved after reboot This section provides technical information about aligning the magnetometer as well as the instructions e Technical Overview page 57 e Alignment Instructions 58 Technical Overview For proper alignment the GNAV540 unit must be installed in the system the same ruling applies
140. tains flags that indicate various software conditions and alerts that are not errors or problems The softwareStatus flag in the BITstatus field is the bit wise OR of the logical AND of the softwareStatus field and the softwareStatusEnable field The softwareStatusEnable field is a bit mask that enables selecting items of interest that will logically flow up to the masterStatus flag Table 91 softwareStatus Field softwareStatus Field Bits Values algorithmlnit 0 normal 1 the algorithm is in initialization mode highGain 0 low gain mode 1 high gain mode attitudeOnlyAlgorithm 0 navigation state tracking 1 attitude only state tracking GNAV540 User Manual Page 105 7430 0808 01 Rev B MOOG softwareStatus Field Values turnSwitch 3 0 off 1 yaw rate greater than turnSwitch threshold Reserved 4 N A noMagnetometerheading 5 0 aided with Magnetometer heading reference Reference TO N A 1 no Magnetometer heading reference noGPSTrackReference TO N A 6 0 aided with GPS track reference 1 no GPS track reference Reserved 7 15 N A sensorStatus Field The sensorStatus field contains flags that indicate various internal sensor conditions and alerts that are not errors or problems The sensorStatus flag in the BITstatus field is the bit wise OR of the logical AND ofthe sensorStatus field and the sensorStatusEnable field The sensorStatusEnable field is a bit mask that enables selecting items of interest
141. te sensors This situation is indicated by the softwareStatus gt turnSwitch status flag Using the turn switch maintains better attitude accuracy during short term dynamic situations but care must be taken to ensure that the duty cycle ofthe turn switch generally stays below 10 during the vehicle mission A high turn switch duty cycle does not allow the system to apply enough rate sensor bias correction and could allow the attitude estimate to become unstable The VG Function algorithm has two major phases of operation The first phase of operation is the initialization phase During the initialization phase the unit is expected to be stationary or quasi static so the EKF weights the accelerometer gravity reference heavily in order to rapidly estimate the roll and pitch angles and X Y rate sensor bias The initialization phase lasts approximately 60 seconds and the initialization phase can be monitored in the softwareStatus BIT transmitted by default in each measurement packet After the initialization phase the unit operates with lower levels of feedback also referred to as EKF gain from the accelerometers to continuously estimate and correct for roll and pitch errors as well as to estimate X and Y rate sensor bias To reset the algorithm or re enter the initialization phase sending the algorithm reset command AR will force the algorithm into the reset phase In addition to the scaled sensor packets described in the IMU Function section the VG
142. ter than the fixed wing aircraft and contain high frequency components however it may cause severe vibrations on the airframe The overall dynamics translational and rotational motion of the rotor craft are much slower than the fixed wing aircraft Also the rotors generate significant aerodynamic forces and moments Table 95 shows two examples of dynamic conditions and the recommended configurations 1 FreelyIntegrate should only be set to ON for severe launch conditions Normal takeoff dynamics that a standard aircraft would experience will see the best performance with this setting in the OFF position Page 110 GNAV540 User Manual 7430 0808 01 Rev B MOOG Table 95 Recommended Advanced Settings for Rotorcraft Dynamic Condition Recommended Settings Normal Dynamics High Dynamics with uncoordinated tail motion FF F FF Stationary Yaw Lock 0 OF Restart Over Range O ON N Dynamic Motion ON O Turn Switch Threshold 1 0 deg s 30 0 deg s The helicopter can change its heading angle rapidly unlike the aircraft which requires banking A turn switch threshold that is too low may cause turn switch activation with high duty cycle causing random walk in roll and pitch angles due to low feedback gains Land Vehicle Some examples of land vehicles are automobiles trucks heavy equipment trains snowmobiles and other tracked vehicles Table 96 shows two examples of land vehicles and the recommended configurations T
143. th lower levels of feedback also referred to as EKF gain from the GPS accelerometers and magnetometers The NAV Function provides additional output measurement packets including the default N1 Navigation Packet which outputs the Latitude Longitude Altitude X Y Z velocities accelerations and roll angle pitch angle yaw angle and digital IMU data For more information about packets refer to Chapter 9 Communicating with the GNAV540 Unit and Chapter 10 Programming Guidelines NAV Advanced Settings In addition to the configurable baud rate packet rate axis orientation and sensor low pass filter settings the NAV Function provides additional advanced settings which are selectable for tailoring the unit to a specific application requirements The advanced settings are listed in Table 10 GNAV540 Advanced Settings below Table 10 GNAV540 Advanced Settings Setting Default Value Comments Baud Rate 38400 9600 19200 57600 also available Packet Type N3 S0 S1 S2 AO A1 A2 NO N3 N4 also available Packet Rate 25 Hz This setting sets the rate at which selected Packet Type packets are output If polled mode is desired then select Quiet Page 32 GNAV540 User Manual 7430 0808 01 Rev B MOOG Setting Default Value Orientation See Figure 4 on page 24 Freely Integrate Use GPS Stationary Yaw Lock Use Mags Comments To configure the axis orientation select the desired measurement for each axis NAV VIEW 2
144. then the rising edge of 1PPS will correspond to the UTC second boundary When the system is synchronized to 1PPS the hardwareStatus gt unlocked1PPS flag will be zero otherwise the flag will be one Figure 5 below shows the sequential order ofthe signal present at 1 PPS OUT pin The one PPS signal is aligned to the sampling clock of 23 104 MHz which results in the timing resolution of 43 ns Figure 5 1PPS Output Signal GPS 8 30 00 GPS 8 30 01 TIMEPULSE l 1000 GNAV540 User Manual Page 37 7430 0808 01 Rev B MOOG Page 38 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter 4 Magnetometer Calibration and Alignment Guidelines This chapter provides general guidelines for calibrating and aligning a magnetometer with the GNAV540 unit e Compensation for Magnetic Fields page 39 e Magnetometer Alignment Using NAV VIEW 2 2 page 39 e Magnetometer Alignment Using Code page 40 e Installation Guidelines page 40 This section provides guidelines to calibrate and align the magnetometer This information applies when implementing AHRS Function or NAV Function AHRS Function on page 29 NAV Function on page 31 NOTE For effective calibration results the GNAV540 unit must be installed in the system during the alignment process This also applies to an external magnetometer If calibrated outside of the system the magnetism of the system will not be measured Without those values the GNAV540 will not be able to
145. thm start The default setting is ON Turning off the dynamic motion setting results in a higher gain state that uses the accelerometer feedback heavily During periods of time when there is known low dynamic acceleration With respect to centripetal or false gravity forces from turning dynamics or coordinated turn the unit monitors the yaw rate If the yaw rate exceeds a given turnSwitch threshold the feedback gains from the accelerometer signals for attitude correction are reduced because they are likely corrupted Page 34 GNAV540 User Manual 7430 0808 01 Rev B MOOG Chapter3 Hardware Interface This chapter provides information about the power and signal interface connectors J1 1 O Connector NOTE Signals labeled as NC have internal pull up mechanisms To ensure proper operation of the unit ensure there are no connections to these pins Table 11 1 0 Connector PinNo Signal Pin No Signal KA Signal Ground 20 NC Chassis Ground 21 Master BIT CONN User RS 422 Tx 22 NC 2 User RS 422 Tx 3 USER PORT SEL CONN User RS 422 Rx 4 24 NC User RS 422 Rx 25 EXT PPS INPUT CONN N 6 GPS RS422 TX N 7 GPS PPS OUT_CONN 14 33 15 34 6 35 36 C 2 C 2 7 8 9 Mag RS422 Rx NC Mag RS422 Rx GPS RS422 TX 1 10 100 Base Rx MAG RS422 RX C 17 Input Power Vin N 18 Input Power Vin 37 BOOT SEL CONN 19 Signal ground J2 GPS Antenna Connector The GPS rece
146. tions NOTE For proper operation the unit relies on magnetic field readings from a 3 axis magnetometer The unit must be installed correctly and calibrated for hard iron and soft iron effects to avoid any system performance degradation Refer to Chapter 4 Magnetometer Calibration and Alignment Guidelines for information about magnetic calibration review that section before using the AHRS Function NOTE The GNAV540 unit and the external magnetometer if used must be mounted at least 24 away from large ferrous objects and fluctuating magnetic fields Failure to locate the unit in a clean magnetic environment will affect the attitude solution AHRS Advanced Settings In addition to the configurable baud rate packet rate axis orientation and sensor low pass filter settings the unit provides additional advanced settings which are selectable for tailoring the unit to a specific application requirements The AHRS advanced settings are listed in Table 9 below Table 9 AHRS Series Advanced Settings Setting Default Value Comments Baud Rate 38400 9600 19200 57600 also available Packet Type Al S0 S1 S2 AO A2 NO N1 also available Packet Rate 25 Hz This setting sets the rate at which selected Packet Type packets are output If polled mode is desired then select Quiet GNAV540 User Manual Page 29 7430 0808 01 Rev B Setting Orientation Freely Integrate Use Mags Default Value See Figure 4 on page 24

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