Home

x-IMU User Manual 1.0 - x

1. 17 2 40 Magnetometer x axis hard iron bias Address Value Description 0x0027 Q5 11 signed fixed point value between 16 and 16 Calibrated hard iron bias affecting the magnetometer x axis in G See parameter h in the magnetometer section The hard iron bias parameters will change when the x IMU s local magnetic environment is altered for example when the x IMU is fixed to the battery Use of the magnetometer and AHRS algorithm requires that the hard iron bias parameters are accurately calibrated See the hard iron calibrations section for more information 17 2 41 Magnetometer y axis hard iron bias Address Value Description 0x0028 Q5 11 signed fixed point value between 16 and 16 Calibrated hard iron bias affecting the magnetometer y axis in G See parameter hz in the magnetometer section The hard iron bias parameters will change when the x IMU s local magnetic environment is altered for example when the x IMU is fixed to the battery Use of the magnetometer and AHRS algorithm requires that the hard iron bias parameters are accurately calibrated See the hard iron calibrations section for more information 17 2 42 Magnetometer z axis hard iron bias Address Value Description 0x0029 Q5 11 signed fixed point value between 16 and 16 Calibrated hard iron bias affecting the magnetometer z axis in G See parameter h in the magnetometer section The hard iron bias parameters
2. occurs See the gyroscope calibration section for more information 15 1 6 Sample gyroscope bias at temperature 2 Command code Description 0x0005 The sample gyroscope bias at temperature 2 command is used to calibrate the gyroscope bias parameters This command should be sent while the x IMU is stationary and at the highest temperature the device is required to operate at The x IMU will measure the mean temperature and gyroscope output over approximately 16 seconds store the results to registers to and then trigger a calculate gyroscope bias parameters command The execution of this command will be aborted if a gyroscope not stationary error occurs See the gyroscope calibration section for more information 15 1 7 Calculate gyroscope bias parameters Command code Description 0x0006 The calculate gyroscope bias parameters command is used to execute the on board gy roscope bias calibration calculation The algorithm uses the register values to previously sampled by the sample gyroscope bias at temperature 1 and sample gyro scope bias at temperature 2 commands to calculate the gyroscope bias parameters and update the registers to See the gyroscope calibration section for more information 15 1 8 Look up accelerometer bias and sensitivity Command code Description 0x0007 The look up accelerometer bias and sensitivity command is used to set the accelerometer sens
3. file name must be specified in the File path text box The file conversion will start when the Convert button is clicked This process occurs in the background and may take a while if a large binary file is specified Serial Port Registers Date Time Commands View Sensor Data Auvillary Port Data Logger Convert Binary File File path Figure 14 x IMU GUI SD card tab page Once the conversion is complete a report window will be presented detailing the number of each type of packet read and the specific data files created as shown in figure 15 Total packets read 32085028 Packet read errors 0 Date time packets read 48837 Raw battery and thermometer packets read 0 Calibrated battery and thermometer packets read 781371 Raw inertial magnetic packets read 0 Calibrated inertial magnetic packets read 12501927 Quaternion packets read 6250964 Digital I O packets read 12501927 Files created 00000_DateTime txt 00000_CalBattTherm csv 00000_CallnertialMagnetic csv 00000_Quaternion csv 00000_RotationMatrix csv 00000_EulerAngles csv 00000_DigitallO csv Figure 15 x IMU GUI binary file conversion report 4 1 9 Tab page Hard iron calibration The hard iron calibration tab page provides all the functionality required for the user to calibrate for hard iron interferences affecting the x IMU It is necessary to re calibrate hard iron parameters whenever the x IMU s magneti
4. see the USB section and Bluetooth section for more information and how to find the serial port name assigned to each connection To connect to the x IMU the user first select the correct serial port name the x IMU appears as in the Port name drop down list If the name does not appear in the list the user can either press the Refresh List button to update the drop down list or type in the port name directly The Open Port button may then be pressed to connect to the device T a x IMU GUI v1 0 Registers Date Time Commands View Sensor Data Ausillary Port Data Logger SD Card Hard ron Calibration Bootloader About COM19 Refresh List Close Pot Packet Counts Packets received 649025 Packets sent 66 Figure 3 x IMU GUI serial port tab page 4 1 2 Tab page Registers The registers tab page allows the user to view edit and back up all internal settings on the x IMU see the registers section for more infomation on x IMU registers All registers are organised into sections within a tree view where the end node of each branch is an individual register name and text box or drop down list containing the register value Register values that have been read directly from the x IMU or loaded from file will appear as blue text Any registers values then edited will appear as red text A right click on any register will show the action menu To read all register on the x IMU the user sho
5. Address Value Description 0x001D Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the accelerometer x axis in lsb See parameter ba in the accelerometer section A typical value of 0 lsb is provided in the LSM303DLH datasheet This value can be set automatically using the Look up accelerometer bias and sensitivity command 17 2 31 Accelerometer y axis bias Address Value Description 0x001E Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the accelerometer y axis in lsb See parameter ba in the accelerometer section A typical value of 0 lsb is provided in the LSM303DLH datasheet This value can be set automatically using the Look up accelerometer bias and sensitivity command 72 17 2 32 Accelerometer z axis bias Address Value Description 0x001F Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the accelerometer z axis in lsb See parameter ba in the accelerometer section A typical value of 0 lsb is provided in the LSM303DLH datasheet This value can be set automatically using the Look up accelerometer bias and sensitivity command 43 17 2 33 Magnetometer full scale Address Value Description 0x0020 0x0000 1 3G 0x0001 1 9G 0x0002 2 5G 0x0003 4 0 G 0x0004 4 7G 0x0005 5 6 G 0x0006 8 1G Sets the full scale range of the magnetometer Each full scale range will have d
6. ID Address 0x0002 Value 0x0000 to OxFFFF Read only Description The unique 4 hexadecimal digit ID of the x IMU taken as the last 2 bytes of the Bluetooth MAC address 17 2 4 Button mode Address 0x0003 Value 0x0000 Disabled 0x0001 Device reset command 0x0002 Sleep Wake command 0x0003 Reset algorithm command 0x0004 Tare command Description The command to be executed when the push button is pressed See the commands section for more information on individual commands 17 2 5 Battery voltmeter sensitivity Address 0x0004 Value Q11 5 signed fixed point value between 1024 and 1024 Description Calibrated sensitivity of the battery ADC in V Isb See parameter s in the battery volt meter section The typical value is 621 V Isb 17 2 6 Battery voltmeter bias Address 0x0005 Value Q8 8 signed fixed point value between 128 and 128 Description Calibrated bias of the battery ADC in Isb See parameter b in the battery voltmeter section The typical value is 0 lsb 17 2 7 Thermometer sensitivity Address 0x0006 Value Q10 6 signed fixed point value between 512 and 512 Description Calibrated sensitivity of the thermometer in C Isb See parameter s in the thermometer section The typical value is provided as 280 C Isb in the IMU 3000 datasheet 17 2 8 Thermometer bias Address 0x0007 Value Q16 0 signed fixed point value between 32768 and 326
7. Time button will set the x IMU date and time equal to computer date and time Received date time 15 February 2011 01 29 52 Read Date Time Set Date Time Figure 5 x IMU GUI date time tab page 10 4 1 4 Tab page Commands The commands tab page is used to send commands to the x IMU See the commands section for more information on individual commands Once the x IMU has processed a command it will echo the command back and it will appear in a message box To suppress these message boxes un check the Display received command messages in message box check box Serial Port Registers Date Time 5 View Sensor Data Auilary Port Data Logger SD Card Hard Iron Calibration Bootloader About General Reset Device Sleep Sensor Calibration Sample Gyro Bias T1 Sample Gyro Bias 72_ Calc Gyro Bias Params Lookup Accel Sensitivty Measure Mag Bias Sens Algorithm Reset Algorithm _ Tare Clear Tare Received Command Messages v Display received command messages in message box Figure 6 x IMU GUI date time tab page 4 1 5 Tab page View sensor data The view sensor data tab page contains buttons to show or hide separate real time data graphic windows for incoming x IMU sensor data 11 a y IMU GUI v1 0 o 2 lees Serial Port Registers Date Time Commands View Sensor Data Au
8. USB receive buffer over error will be sent if the USB receive buffer overruns and data to be received was lost This occurs when data is transmitted to the x IMU at a rate greater than the rate it can be processed Consider reducing the rate at which data is sent to the x IMU if this error occurs repeatedly 35 16 1 4 USB transmit buffer overrun Error code Description 0x0003 A transmit buffer overrun error will be sent if the USB transmit buffer overruns and data due to be transmitted was lost This will occur when the communication channel bandwidth is unable to cope with the amount of data being transmitted Consider using lower data output rates if this error occurs repeatedly This error may be ignored in applications where USB data is not essential and the SD card is the intended data output In such applications the user need only be concerned with SD card write buffer overrun errors The x IMU will attempt to transmit data via USB while the USB is detected as connected if the USB is connect but the associated serial port not open then the USB transmit buffer will continue to overrun until the port is opened or the USB disconnected 16 1 5 Bluetooth receive buffer overrun Error code Description 0x0004 A Bluetooth receive buffer over error will be sent if the Bluetooth receive buffer overruns and data to be received was lost This occurs when data is transmitted to the x IMU at a rate greater than the rate it can be pro
9. every 3 seconds to indicate that the device is in sleep mode Sleep mode is enabled through the sources listed below The x IMU will reset upon wake up so that the same behaviour may be expected when the devices is powered on reset or awakened The wake up sources are listed below Sleep mode enable sources e Push button in sleep wake mode e Sleep command via USB or Bluetooth e Low battery voltage detection e Sleep timer 7 Wake up sources e Push button in sleep wake mode e Motion trigger wake up 29 12 5 Sleep timer The sleep timer will trigger sleep mode after the period of time defined in the sleep timer register has elapsed The sleep timer countdown starts when the x IMU starts up and may be reset by the sources listed below These sources enable the detection of motion the user or the host software to prevent the x IMU from entering sleep mode The sleep timer is disabled by specifying a sleep timer register value of 0 seconds The sleep timer is disabled while USB is connected Sleep timer reset sources e Reset sleep timer command e Motion trigger wake up 12 6 Motion triggered wake up The motion trigger wake up is enabled via the motion trigger wake up register and may be either disabled or set to a low or high sensitivity Motion is detected using accelerometer If motion is detected while the x IMU is in sleep mode then the x IMU will wake up While the x IMU is not in
10. fr in the gyroscope section The x IMU has build in algorithms to accuracy evaluate this parameter automatically using the Calculate gyroscope bias parameters command 7 see the gyroscope calibration section for more information 7 40 17 2 16 Gyroscope y axis bias temperature sensitivity Address Value Description Ox000F Q6 10 signed fixed point value between 32 and 32 Calibrated bias temperature sensitivity of the gyroscope y axis in lsb C See parameter fy in the gyroscope section The x IMU has build in algorithms to accuracy evaluate this parameter automatically using the Calculate gyroscope bias parameters command 7 see the gyroscope calibration section for more information 17 2 17 Gyroscope z axis bias temperature sensitivity Address Value Description 0x0010 Q6 10 signed fixed point value between 32 and 32 Calibrated bias temperature sensitivity of the gyroscope z axis in Isb C See parameter f in the gyroscope section The x IMU has build in algorithms to accuracy evaluate this parameter automatically using the Calculate gyroscope bias parameters command 7 see the gyroscope calibration section for more information 7 17 2 18 Gyroscope sample 1 Temperature Address Value Description 0x0011 Q8 8 signed fixed point value between 128 and 128 Temperature at gyroscope bias sample 1 in C Gyroscope bias samples 1 and 2 are required for the automatic
11. full scale range in the LSM303DLH datasheet Accurate values can be set automatically using the Measure magnetometer bias and sensitivity command 17 2 37 Magnetometer x axis bias Address Value Description 0x0024 Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the magnetometer x axis in lsb See parameter bm in the magne tometer section The typical values are provided for each full scale range in the LSM303DLH datasheet Accurate values can be set automatically using the Measure magnetometer bias and sensitivity command 44 17 2 38 Magnetometer y axis bias Address Value Description 0x0025 Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the magnetometer y axis in lsb See parameter bm in the magne tometer section The typical values are provided for each full scale range in the LSM303DLH datasheet Accurate values can be set automatically using the Measure magnetometer bias and sensitivity command 17 2 39 Magnetometer z axis bias Address Value Description 0x0026 Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the magnetometer z axis in lsb See parameter bm in the magne tometer section The typical values are provided for each full scale range in the LSM303DLH datasheet Accurate values can be set automatically using the Measure magnetometer bias and sensitivity command
12. has build in algorithms to accuracy evaluate this parameter automatically using the Calculate gyroscope bias parameters command see the gyroscope calibration section for more information 17 2 13 Gyroscope y axis bias Address Value Description 0x000C Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the gyroscope y axis at 25 C in lsb See parameter bg in the gyroscope section The typical value is provided as 0 lsb in the IMU 3000 datasheet The x IMU has build in algorithms to accuracy evaluate this parameter automatically using the Calculate gyroscope bias parameters command see the gyroscope calibration section for more information 17 2 14 Gyroscope z axis bias Address Value Description 0x000D Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the gyroscope z axis at 25 C in lsb See parameter bg in the gyroscope section The typical value is provided as 0 Isb in the IMU 3000 datasheet The x IMU has build in algorithms to accuracy evaluate this parameter automatically using the Calculate gyroscope bias parameters command see the gyroscope calibration section for more information 17 2 15 Gyroscope x axis bias temperature sensitivity Address Value Description 0x000E Q6 10 signed fixed point value between 32 and 32 Calibrated bias temperature sensitivity of the gyroscope x axis in lsb C See parameter
13. on minimising power consumption section 7 The x IMU has an on board battery charger specially designed for LiPo battery cells The battery is charged automatically while the x IMU is connected to a USB port The red charging LED will remain lit while the battery is charging Charging stops automatically once complete The x IMU may be used as normal while the battery is charging It is not necessary for the connected computer to have the USB drivers installed for charging however the charging process will be faster if the drivers are installed 12 3 Low battery voltage detection The calibrated battery voltmeter is used to trigger sleep mode once the battery voltage falls below a specific level defined in the battery shutdown voltage register This allows the x IMU to execute critical tasks prior to power failure for example closing the file on the SD card and notifying the user or host software of the situation By entering sleep mode prior to power failure the x IMU also ensures that the date and time of the real time clock and calendar are not lost The low battery voltage detection is disabled while USB is connected 12 4 Sleep mode In sleep mode the x IMU remains powered but all on board components are shutdown This allows the device to be effectively turned off without disabling power to essential components for example the real time clock and calendar The green status LED will blink once
14. packet header This error is only relevant users developing their own communication software and not using the x MU API or x IMU GUI 16 1 13 Invalid register address Error code 0x000C Description An invalid register address error will be sent if the read or write register packet contains an invalid register address This error is only relevant users developing their own communica tion software and not using the x IMU API or x IMU GUI 16 1 14 Register read only Error code 0x000D Description A register read only error will be sent if the write register packet represents an attempt to write a read only register This error is only relevant users developing their own communi cation software and not using the x IMU API or x IMU GUL 16 1 15 Invalid register value Error code 0x000E Description An invalid register value error will be sent if the write register packet contains an invalid register value for the specific address This error is only relevant users developing their own communication software and not using the x IMU API or x IMU GUL 16 1 16 Invalid command Error code Ox000F Description An invalid command error will be sent if the command code within the command packet is not valid This error is only relevant users developing their own communication software and not using the x IMU API or x IMU GUL 16 1 17 Gyroscope not stationary Error code 0x0010 Description A gyroscope not stationary error will
15. that users ensure accurate gyroscope bias temperature sensitivity calibration and use an integral feedback gain of 0 to avoid instabilities See the IMU AHRS algorithms section for more information 17 2 46 Algorithm initial proportional gain Address Value Description 0x002D Q10 6 signed fixed point value between 0 and 512 Algorithm initial proportional feedback gain used each time the algorithm resets The effec tive proportional gain will ramp down from the initial proportional gain to the proportional gain over a specified period of time See the IMU AHRS algorithms section for more information 17 2 47 Algorithm initilasation period Address Value Description 0x002E Q8 8 signed fixed point value between 0 and 128 Algorithm ramp down period in seconds used each time the algorithm resets The effective proportional gain will ramp down from the initial proportional gain to the proportional gain over a specified period of time See the IMU AHRS algorithms section for more information 17 2 48 Algorithm minimum valid magnetic field magnitude Address Value Description 0x0041 Q5 11 signed fixed point value between 16 and 16 The minimum valid magnetic field magnitude in G that may be used by the algorithm in the estimation of heading Magnetic fields of an invalid magnitude will be ignored by the AHRS algorithm so that heading is determined from gyroscope measurements alon
16. to the x IMU via USB is buffered in the USB receive buffer before being processed The time required to process the received data is dependent on the data If data is sent to the x IMU via USB at arate at a rate greater than it can be processed then the receive buffer will overflow and some data will be lost When this happens a USB receive buffer overrun error will be generated 6 Bluetooth The x IMU streams all communication data simultaneously and identically via USB Bluetooth and to a file on the SD card The USB and Bluetooth connections are also be used to send commands 7 read write registers and settings and control the auxiliary port outputs from the host computer As both USB and Bluetooth connections appear as serial ports use of either communication channel is identical The on board Bluetooth radio is a class I device with a maximum range of 100 m The radio uses the Serial Port Profile SPP to enable connection to any Bluetooth host without the need to install specific drivers Once paired with a host computer the x IMU will appear as a serial port and be assigned an available port name for example COM3 The computer connects to the x IMU via Bluetooth by opening this serial port This is achieved via the Serial Port tab page of the x IMU GUI The Bluetooth connection will be lost when the x IMU is switch off enters sleep mode or is out of range The connection status of the x IMU is indicated by
17. used to log all data generated by the x IMU to an SD card The x IMU supports standard SD and HCSD cards formatted as either FAT16 or FAT32 A new file is created and logging starts each time the x IMU is switch on wakes up or is reset The file is automatically closed when the x IMU enters sleep mode or is reset The file must be closed before the SD card is removed or the x IMU switched of otherwise the current file will corrupt and data lost See the SD card section for more information 3 6 Bluetooth radio The on board Bluetooth radio is used to connect the x IMU to a computer via Bluetooth The on board Bluetooth radio is a class I device with a maximum range of 100 m The radio uses the Serial Port Profile SPP to enable connection to any Bluetooth host without the need to install specific drivers Power to the Bluetooth radio can be disabled to converse power See the Bluetooth section for more information 3 7 Battery connector The on board battery connector allows the x IMU to be powered by any single cell Lithium Polymer battery The battery is automatically charged while the x IMU is connected via USB See the battery and charging section for more information 4 Software overview 4 1 x IMU GUI 4 1 1 Tab page Serial port The serial port tab page is used to manage the USB or Bluetooth connection between the software and the x IMU The USB and Bluetooth connections will each appear as a separate serial port
18. will change when the x IMU s local magnetic environment is altered for example when the x IMU is fixed to the battery Use of the magnetometer and AHRS algorithm requires that the hard iron bias parameters are accurately calibrated See the hard iron calibrations section for more information 17 2 43 Algorithm mode Address Value Description 0x002A 0x0000 Disabled 0x0000 IMU 0x0001 AHRS Sets the algorithm mode see the IMU AHRS algorithms section for more information The algorithm mode can be set to Disabled to reduce power consumption when the algo rithms are not required 45 17 2 44 Algorithm proportional gain Address Value Description 0x002B Q8 8 signed fixed point value between 0 and 128 Algorithm proportional feedback gain The proportional gain governs the rate at which the algorithm output converges to an orientation assumed by the accelerometer and mag netometer a low value will trust the gyroscope data more and the accelerometer and magnetometer less a high value will trust the gyroscope less and the accelerometer and magnetometer more See the IMU AHRS algorithms section for more information 17 2 45 Algorithm integral gain Address Value Description 0x002C Q2 14 signed fixed point value between 0 and 2 Algorithm integral feedback gain The integral gain governs the rate at which the algo rithm compensates for gyroscope bias drift It is recommended
19. 2 bit magnetometer Configurable range up to 8 1 G e 16 bit thermometer e Battery level e Calibrated and temperature compensated gyroscope only e Configurable sample rates up to 256 Hz On board algorithms e IMU algorithm for real time measurement of pitch and roll relative to the Earth surface immune to magnetic inferences e AHRS algorithm for real time measurement of full orientation relative to the Earth coordinate frame e Sensor calibration algorithms for user maintenance Connectivity e USB e Bluetooth Class 1 100m range SPP e Micro SD card Supports SDHC and FAT16 32 for capacities up to 2 TBs Power options e USB e LiPo battery On board charging via USB e External source 3 6 V to 7 7 V e Low power consumption 35 mA to 100 mA dependant on settings and usage 130 A sleep mode Low profile e Dimensions 33 x 42 x 10 mm e Weight 12g Other features e Motion triggered wake up and sleep e Real time clock and calendar e Configurable command button e Configurable 8 channel auxiliary port Auxiliary port modes e Digital I O Outputs controlled via USB or Bluetooth 1 2 x IMU Software The x IMU GUI Graphical User Interface provides interface to all features and functionality of the x IMU via the x IMU API The x IMU GUI is open source and is intended to serve as a comprehensive template for those using the x IMU API to develop their own applications Additional software examples using the x IMU API fo
20. 77 Description Calibrated bias of the thermometer in lsb See parameter b in the thermometer section The typical value is provided as 23 000 lsb in the IMU 3000 datasheet 17 2 9 Gyroscope x axis sensitivity Address 0x0008 Value Q6 10 signed fixed point value between 32 and 32 Description Calibrated sensitivity of the gyroscope x axis in s lsb See parameter sg in the gyroscope section The typical value is provided as 16 4 s Isb in the IMU 3000 datasheet 39 17 2 10 Gyroscope y axis sensitivity Address Value Description 0x0009 Q6 10 signed fixed point value between 32 and 32 Calibrated sensitivity of the gyroscope y axis in s Isb See parameter sg in the gyroscope section The typical value is provided as 16 4 s Isb in the IMU 3000 datasheet 17 2 11 Gyroscope z axis sensitivity Address Value Description Ox000A Q6 10 signed fixed point value between 32 and 32 Calibrated sensitivity of the gyroscope z axis in s Isb See parameter sg in the gyroscope section The typical value is provided as 16 4 s Isb in the IMU 3000 datasheet 17 2 12 Gyroscope x axis bias Address Value Description 0x000B Q8 8 signed fixed point value between 128 and 128 Calibrated bias of the gyroscope x axis at 25 C in lsb See parameter b in the gyroscope section The typical value is provided as 0 lsb in the IMU 3000 datasheet The x IMU
21. For this the power switch must be in the off position 3 2 Push button The push button may be configured to execute x IMU commands The mode of the push button is defined in the Button mode register The default mode is sleep wake 3 3 LEDs 3 3 1 Status LED Green The green LED indicates the status of the x IMU The green LED will remain lit while the device is sampling and sending data packets and will otherwise be extinguished for example during the execution of commands In sleep mode the green LED will blink once every 3 seconds The green LED will flash rapidly while the on board bootloader is active 3 3 2 SD card LED Amber The amber LED indicates SD card activity Details on the SD LED behaviour are provided in the SD card LED section 7 3 3 3 Bluetooth LED Blue The blue LED indicates the state of the Bluetooth connection and power status Details of the Bluetooth LED behaviour are summarised in Table 3 3 4 Charging LED Red The red LED indicates the charging state of the battery The red LED will remain lit while the battery is charging and will be extinguished once the battery is charged 3 4 USB socket The USB mini B socket is used to connect the x IMU to a computer via a standard USB A to mini B 5 pin type cable The USB connect can also be used to power the x IMU See the USB section for more information 3 5 micro SD card socket The micro SD card socket is
22. Optimising Bluetooth performance The practical range and quality of the Bluetooth connection are dependent on a number of factors A poor Bluetooth connection will be unable to handle higher data output rates and so result in missing data and Bluetooth transmit buffer overrun errors The use of lower data output rate settings e g can help achieve a more reliable Bluetooth communication channel The x IMU uses a class I Bluetooth radio which represents a maximum range of 100 m However the practical performance is limited by computer s 21 Bluetooth class for example a class II Bluetooth dongle representing a range of 10 m will limit the x IMU s operating range to 10 m Performance also varies between Bluetooth dongle brands a dongle from a reputable brand may be expected to perform better than a low cost budget product Bluetooth is a radio system and so the location of the antennae usually built into the dongle should be given consideration For example a miniature Bluetooth dongle plugged in to the back a desktop PC can be expected to achieve worse performance than if the dongle was fixed to a front USB port with line of sight to the x IMU 7 SD card The x IMU streams all communication data simultaneously and identically via USB Bluetooth and to a file on the SD card The SD card may therefore be used in conjunction with the USB and or Bluetooth or as the sole communication channel allowing the x IMU to fun
23. U will not enter sleep mode due to the sleep timer or low battery voltage detection while the USB is connected The USB connection can be used to power the x IMU and is used by the on board charging circuit to charge the battery if attached The on board USB interface is powered directly by the USB connection this means that the x IMU will remain detectable and the serial port held open by the computer even while the x IMU is switched off or in sleep mode 7 5 1 Installing USB drivers The Windows USB drivers can be downloaded from the x IMU webpage Drivers for other operating systems are available of the FTDI website To install the Windows drivers simply run the exe file This will automatically detect specific Windows operating system being used and install the correct drivers Once the drivers have been installed and the x IMU connected to the computer the x IMU will appear as a serial port and be assigned an available port name for example COM2 The port name assigned to the x IMU USB connection can be confirmed at any time by viewing the computer s Ports in Windows device manager as shown in Figure File Action mmmn Help eo mE RR SIPRS 4 MECH RV170 JE Computer x Disk drives Display adapters 43 DVD CD ROM drives oR Human Interface Devices c IDE ATA ATAPI controllers g IEEE 1394 Bus host controllers lt gt Keyboards A Mice and other pointing devices E Monitors KP Network adapters gt Other devic
24. ad The x IMU will respond with a register write packet containing the register address and value Non read only registers may be written by sending a register write packet containing the register address to be written to and the new register value The x IMU will respond with a register write packet containing the register address and new value If a read register or register write packet is sent containing an invalid register address the x IMU will respond with an invalid register address error message If a register write packet is sent containing an read only register address the x IMU will respond with a register read only error message If a register write packet is sent containing register value that is invalid for the specified address the x IMU will respond with an invalid register value error message Sending a read register or register write packet packet to the x IMU will cause the x IMU to momentarily pause sensor sampling and processing while the packet is processed This may cause discrepancies in the otherwise fixed data output rates 17 2 Individual register details 17 2 1 Firmware version major number Address 0x0000 Value 0 to 65535 Read only Description The major number of the current firmware version loaded on the x IMU 17 2 2 Firmware version minor number Address 0x0001 Value 0 to 65535 Read only Description The minor number of the current firmware version loaded on the x IMU 38 17 2 3 Device
25. ata will be saved to myFile_EulerAngles csv and myFile_DateTime txt J x IMU GUI v1 0 Serial Port Registers Date Time Commands View Sensor Data Auxillary Port Log Received Data To file File path C Users Seb Madgwick Documents LoggedData Figure 12 x IMU GUI data logger tab page The Start Stop Logging button is used to start and stop the data logger When logging is stopped a report window will be presented detailing the number of each type of packet logged and the specific data files created as shown in figure 14 Total packets received 87898 Packet reception errors 0 Date time packets received 136 Raw battery and thermometer packets received 0 Calibrated battery and thermometer packets received 545 Raw inertial magnetic packets received 0 Calibrated inertial magnetic packets received 34885 Quaternion packets received 17443 Digital V O packets received 34886 Files created LoggedData_DateTime bt LoggedData_CalBattTherm csv LoggedData_CallnertialMagnetic csv LoggedData_Quaternion csv LoggedData_RotationMatrix csv LoggedData_EulerAngles csv LoggedData_DigitallO csv Figure 13 x IMU GUI data logger report 4 1 8 Tab page SD card The SD card tab page allows the user to convert binary files bin saved to the SD card in to readable data files These files may be imported to user software such as Microsoft Excel and MATLAB The location and
26. aternion stored to compute the algorithm output after a tare operation has been preformed The tare quaternion can be set using the tare command and cleared using the clear tare command 7 See the IMU AHRS algorithms section for more information 17 2 53 Tare quaternion element 3 Address 0x0032 Value Q1 15 signed fixed point value between 1 and 1 Description Quaternion stored to compute the algorithm output after a tare operation has been preformed The tare quaternion can be set using the tare command and cleared using the clear tare command See the IMU AHRS algorithms section for more information 17 2 54 Sensor data mode Address 0x0033 Value 0x0000 Raw ADC results 0x0001 Calibrated measurements Description Sets the data output mode of the sensors See the sensors section for more details 17 2 55 Date time data output rate Address 0x0034 Value 0x0000 Disabled sent on reset wake only 0x0001 1 Hz Description Output rate of the date time data packets Data rates can be reduced or disabled to conserve power 47 17 2 56 Battery and thermometer data output rate Address 0x0035 Value 0x0000 Disabled 0x0001 1 Hz 0x0002 2 Hz 0x0003 4 Hz 0x0004 8 Hz 0x0005 16 Hz 0x0006 32 Hz 0x0007 64 Hz 0x0008 128 Hz 0x0009 256 Hz Description Output rate of the battery and thermometer data packets Data rates can be reduced or disabled to conserve powe
27. be sent if the gyroscope was detected as not being stationary during the execution of a sample gyroscope bias command or and the execution of the process was aborted See the gyroscope calibration section for more information 37 16 1 18 Magnetometer saturation Error code 0x0011 Description A magnetometer saturation error will be sent if the measurements taken during the execution of the measure magnetometer bias and sensitivity command were detected as having saturated and the execution of the command was aborted See the magnetometer calibration section for more information 16 1 19 Incorrect auxiliary port mode Error code 0x0012 Description An incorrect auxiliary port mode error will be sent if an auxiliary port action is requested while the auxiliary port is not in the correct mode for that action For example an incorrect auxiliary port mode error will be sent if a digital IO data packet is received while the auxiliary port mode is Disabled See the auxiliary port section for more information 17 Registers All x IMU settings are saved in a bank of registers stored to non volatile flash memory Each register has a 16 bit address and 16 bit value These values may be viewed edited read written and backed up to file using the x IMU GUI via the registers tab page 17 1 Reading and writing registers Any register may be read by sending a read register packet containing register address to be re
28. c characterises are changed for example when the x IMU if fitted to a battery or mounting that includes ferromagnetic elements The 3 group boxes Step 1 Clear Hard Iron Bias Registers Step 2 Collect Hard Iron Calibration Dataset and Step 3 Run Hard Iron Calibration Algorithm represent the 3 steps that must be performed in order See the hard iron calibration section for more information x IMU GUI v1 0 Serial Port Registers Date Time Commands View Sensor Data Auxilary Port Data Logger SD Card Step 1 Clear Hard Iron Bias Registers Clear Hard Iron Regsiters Step 2 Collect Hard Iron Calibration Dataset File path C Users Seb Madgwick Documents HardlronCalDataset_CalinertialMagnetic csv Step 3 Run Hard Iron Calibration Algorithm File path C Users Seb Madgwick Documents HardlronCalDataset_CallnertialMagnetic csv Figure 16 x IMU GUI hard iron calibration tab page 4 1 10 Tab page Bootloader The bootloader tab page allows the x IMU firmware to be updated The bootloader may only be used while the x IMU is connected via USB and the serial port closed See the bootloader section for more information 16 4 2 x IMU API The x IMU API Application Programming Interface is a code library that contains all the classes data structures and methods required to interface to all features and functionality of the x IMU The x IMU API is an open source pro
29. calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 1 is recorded using the Sample gyroscope bias at temperature 1 command See the gyroscope calibration section for more information 7 17 2 19 Gyroscope sample 1 x axis bias Address Value Description 0x0012 Q8 8 signed fixed point value between 128 and 128 x axis bias at gyroscope bias sample 1 in lsb Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 1 is recorded using the Sample gyroscope bias at temperature 1 command See the gyroscope calibration section for more information 7 17 2 20 Gyroscope sample 1 y axis bias Address Value Description 0x0013 Q8 8 signed fixed point value between 128 and 128 y axis bias at gyroscope bias sample 1 in lsb Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 1 is recorded using the Sample gyroscope bias at temperature 1 command See the gyroscope calibration section for more information 7 17 2 21 Gyroscope sample 1 z axis bias Address Value Description 0x0014 Q8 8 signed fixed point value betwe
30. cessed Consider reducing the rate at which data is sent to the x IMU if this error occurs repeatedly 16 1 6 Bluetooth transmit buffer overrun Error code Description 0x0005 A transmit buffer overrun error will be sent if the Bluetooth transmit buffer overruns and data due to be transmitted was lost This will occur when the communication channel bandwidth is unable to cope with the amount of data being transmitted Consider using lower data output rates if this error occurs repeatedly Transmit buffer overrun errors may be expected in the Bluetooth communication channel quality deteriorates for example if out of range This error may be ignored in applications where the Bluetooth data is not essential and the SD card is the intended data output In such applications the user need only be concerned with SD card write buffer overrun errors 16 1 7 SD card write buffer overrun Error code Description 0x0006 An SD card buffer over error will be sent if the SD card buffer is overrun and data to be written to the SD was lost Consider using lower data output rates if this error occurs repeatedly An occurrence of this error may go unnoticed while the USB and Bluetooth are not used The red SD card LED indicates SD card activity if this LED behaviour approaches that of being solidly on then it is likely that the this error is occurring 16 1 8 Too few bytes in packet Error code Description 0x0007 A too few bytes in
31. ction as a standalone data logger Data is logged to the SD card on separate files binary files that are automatically created each time the x IMU is switched on reset or wakes up Logging is only then stopped once the x IMU is reset or enters sleep mode The binary files bin created may be read form the SD card on to any PC and then converted to individual Comma Separated Variable csv and text txt files using via the x IMU GUI SD Card tab page Alternatively the x IMU Binary File Converter may be used for command line based or automated conversion of multiple files Converted CSV and text files can be directly imported into programmes such as MATLAB and Microsoft Excel The MATLAB x IMU Library includes all the tools required to import structure and plot x IMU data The x IMU supports conventional SD cards and HCSD cards Cards may be formatted as FAT16 usually cards equal or less than 2 GB and FAT32 for card greater than 2 GB For reliable performance it is reeommended that the SD card is formatted prior to each use 7 1 Creating and closing files The x IMU automatically creates a new file on the SD card each time the x IMU is switched on reset or wakes up If an SD card is not accessible at this point the x IMU will not create a file and the SD card will not be used The new file name is created as the 5 digit number stored in the SD card new file name register for example 00000 bin The number stored in this register is au
32. d by equation Parameters sq Say Saz Dazs ba and ba are defined in the separate accelerometer calibration parameter registers to The sensitivities and biases will be different for each full scale measurement range 1 Az Sa 0 0 Gz ba ay 0 8 0 Gy ba 4 Az 0 0 Sa az ba 9 5 Magnetometer The triple axis magnetometer and provides a measurement of the magnetic flux along the xz y and z axes The magnetometer must be correctly calibrated in order for the AHRS algorithm to be able to function correctly the algorithm uses the magnetometer to measure the Earth s magnetic field and provide an absolute reference for the heading component of the estimated orientation The magnetometer has 12 bit resolution and selectable ranges from 1 3 G to 8 1 G The measurement range of the magnetometer is defined in Magnetometer full scale register See the LSM303DLH datasheet for further information on the magnetometer s characteristics Raw ADC data In raw data mode the magnetometer data is the ADC integer values between 4096 and 4095 linearly proportional to magnetic flux This data is provided in the Raw inertial magnetic data packets A value fo 4096 will be provided when the measurement saturates in either direction Calibrated data In calibrated data mode the magnetometer data are calibrated accelerations in G This data is provided in the Calibrated inertial magnetic data packets The calibrated
33. e See the IMU AHRS algorithms section for more information 17 2 49 Algorithm maximum valid magnetic field magnitude Address Value Description 0x0042 Q5 11 signed fixed point value between 16 and 16 The maximum valid magnetic field magnitude in G that may be used by the algorithm in the estimation of heading Magnetic fields of an invalid magnitude will be ignored by the AHRS algorithm so that heading is determined from gyroscope measurements alone See the IMU AHRS algorithms section for more information 46 17 2 50 Tare quaternion element 0 Address 0x002F Value Q1 15 signed fixed point value between 1 and 1 Description Quaternion stored to compute the algorithm output after a tare operation has been preformed The tare quaternion can be set using the tare command and cleared using the clear tare command See the IMU AHRS algorithms section for more information 17 2 51 Tare quaternion element 1 Address 0x0030 Value Q1 15 signed fixed point value between 1 and 1 Description Quaternion stored to compute the algorithm output after a tare operation has been preformed The tare quaternion can be set using the tare command and cleared using the clear tare command See the IMU AHRS algorithms section for more information 17 2 52 Tare quaternion element 2 Address 0x0031 Value Q1 15 signed fixed point value between 1 and 1 Description Qu
34. ed put the x IMU into bootloader mode in order to upload new firmware A reset command is sent by the x IMU to the host computer as confirmation of reset power on and wake up 15 1 3 Sleep Command code 0x0002 Description A sleep command will put the device into sleep mode The x IMU will close any open files on the SD card before entering sleep mode The x IMU may be taken out of sleep mode by using the push button configured in sleep wake mode or using the motion triggered wake up functionality 15 1 4 Reset sleep timer Command code 0x0003 Description The reset sleep timer command will reset the sleep timer countdown and so postpone sleep An example usage of this command is to create behaviour where the x IMU will automatically enter sleep mode when communication with the host software ends or connection is lost 33 15 1 5 Sample gyroscope bias at temperature 1 Command code Description 0x0004 The sample gyroscope bias at temperature 1 command is used to calibrate the gyroscope bias parameters This command should be sent while the x IMU is stationary and at the lowest temperature the device is required to operate at The x IMU will measure the mean temperature and gyroscope output over approximately 16 seconds store the results to registers to and then trigger a calculate gyroscope bias parameters command The execution of this command will be aborted if a gyroscope not stationary error
35. en 128 and 128 z axis bias at gyroscope bias sample 1 in lsb Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 1 is recorded using the Sample gyroscope bias at temperature 1 command See the gyroscope calibration section for more information 7 41 17 2 22 Gyroscope sample 2 Temperature Address Value Description 0x0015 Q8 8 signed fixed point value between 128 and 128 Temperature at gyroscope bias sample 2 in C Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 2 is recorded using the Sample gyroscope bias at temperature 2 command See the gyroscope calibration section for more information 7 17 2 23 Gyroscope sample 2 x axis bias Address Value Description 0x0016 Q8 8 signed fixed point value between 128 and 128 x axis bias at gyroscope bias sample 2 in lsb Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 2 is recorded using the Sample gyroscope bias at temperature 2 command See the gyroscope calibration section for more infor
36. ercise 32 15 Commands Commands are executed by either sending a command packet to the x IMU or by pressing the push button which may be configured to execute a specific command Commands may be send using the x IMU GUI via the Commands tab page Once a command has been executed the x IMU will echo the command packet back to the host computer as confirmation As all communication from the x IMU to the host computer is logged to the SD card all command confirmations will be logged on the SD card If a command packet is sent containing an invalid command code the x IMU will respond with an invalid command error message Sending a command packet to the x IMU will cause the x IMU to momentarily pause sensor sampling and processing while the packet is processed This may cause discrepancies in the otherwise fixed data output rates 15 1 Individual commands 15 1 1 Null command Command code 0x0000 Description A null command is a valid command code but will result in no action As all commands sent to the x IMU are echoed back to the sender a null command may be used by the host software to confirm communication with the x IMU 15 1 2 Reset Command code 0x0001 Description A reset command causes a software reset of the x IMU The x IMU will close any open files on the SD card before reset in this way the reset command may be of use to users wishing to break up a logging session into multiple files The reset command is us
37. es 1 Ports COM amp LPT Y Communications Port COM1 DF USB Serial Port COM2 pa Processors P Security Devices Sound video and game controllers lt gt Storage controllers JE System devices Universal Serial Bus controllers Figure 17 Confirming the port name assigned to the x IMU USB connection 18 Windows serial mouse bug Windows may misinterpret the constant stream of data from the x IMU as the behaviour of a serial mouse when the x IMU USB is connected This will lead to the mouse cursor being hi jacked by apparent random behaviour If this happens the x IMU should be unplugged and reconnected while switched off or in sleep mode for the first few seconds of connection The hi jacked activity may leave the mouse buttons disabled which can be undone by entering and then leaving the Ctrl Alt Del screen 5 2 USB bandwidth It is possible for the user to define data output rate settings e g so that the data being generated by the x IMU exceeds the bandwidth of a communication channel If the USB bandwidth is exceed the USB transmit buffer will overrun and some data will be lost When this happens a USB transmit buffer overrun error will be generated As this error message is sent immediately after the buffer has overrun the error message will be successfully transmitted This error can be avoided by reducing the data output rate settings e g All data sent
38. ides a measurement of the angular velocities around the x y and z axes of the x IMU The gyroscope must be correctly calibrated in order for the IMU and AHRS algorithms to be able to function correctly the algorithms use measurements of angular velocities to filter out errors in the estimated orientation caused by linear accelerations and temporal magnetic distortions The gyroscope has 16 bit resolution and a range of 2000 s See the IMU 3000 datasheet for further information on the gyroscope s characteristics Raw ADC data In raw data mode the gyroscope data is the ADC integer values between 32 768 and 32 767 linearly proportional to angular velocities This data is provided in the Raw inertial magnetic data packets Calibrated data In calibrated data mode the gyroscope data are calibrated angular velocities in s This data is provided in the Calibrated inertial magnetic data packets The calibrated measurements gz gy and gz are calculated from the raw ADC measurements gz g and g according to the defined sensitivities s Sg and s temperature of the device 7 biases at 25 C b bg and bg and bias temperature sensitivities fr fy and fz The calibrated measurmndts are described by equation Parameters Sg Sg Sg Dga bg bg fa fy and fz are defined in the separate gyroscope calibration parameter registers to 1x IMUs of generations prior to version 1 3 use the ITG 3200 gyroscope x IMUs of ge
39. ifferent associated sensitivity to and bias to values The Measure magnetometer bias and sensitivity command may be used to measure the correct calibrated sensitivity and bias values for the selected full scale range using an on board algorithm 17 2 34 Magnetometer x axis sensitivity Address Value Description 0x0021 Q11 4 signed fixed point value between 2048 and 2048 Calibrated sensitivity of the magnetometer x axis in G Isb See parameter sm in the magnetometer section The typical values are provided for each full scale range in the LSM303DLH datasheet Accurate values can be set automatically using the Measure magnetometer bias and sensitivity command 17 2 35 Magnetometer y axis sensitivity Address Value Description 0x0022 Q11 4 signed fixed point value between 2048 and 2048 Calibrated sensitivity of the magnetometer y axis in G Isb See parameter sm in the magnetometer section The typical values are provided for each full scale range in the LSM303DLH datasheet Accurate values can be set automatically using the Measure magnetometer bias and sensitivity command 17 2 36 Magnetometer z axis sensitivity Address Value Description 0x0023 Q11 4 signed fixed point value between 2048 and 2048 Calibrated sensitivity of the magnetometer z axis in G Isb See parameter sm in the magnetometer section The typical values are provided for each
40. itivity to and bias registers to to the calibrated parameters defined by the accelerometer manufacturer This command should be used each time the ac celerometer full scale range is changed See the accelerometer calibration section for more information 15 1 9 Measure magnetometer bias and sensitivity Command code Description 0x0008 The measure magnetometer bias and sensitivity command is used to run an on board magnetometer calibration algorithm The x IMU use the magnetometer s internal field generator to measure the mean magnetometer bias and sensitivity over approximately 16 seconds independent of external magnetic interference The magnetometer sensitivity to and bias to registers and then automatically updated This command should be used each time the accelerometer full scale range is changed The exe cution of this command will be aborted if a magnetometer saturation error occurs See the magnetometer calibration section for more information 34 15 1 10 Reset algorithm Command code 0x0009 Description The reset algorithm command will re start the algorithm from initial conditions This command can be used to force the algorithm to converge to steady state conditions if previous distortions to magnetic or other extreme sensor measurements have left the IMU or AHRS algorithm output at an erroneous orientation See the IMU AHRS algorithms section for more info
41. ity and bias values for the selected full scale range 42 17 2 27 Accelerometer x axis sensitivity Address Value Description Ox001A Q11 4 signed fixed point value between 2048 and 2048 Calibrated sensitivity of the accelerometer x axis in g Isb See parameter sq in the ac celerometer section The typical values are provided for each full scale range in the LSM303DLH datasheet These values can be set automatically using the Look up accelerometer bias and sensitivity command 17 2 28 Accelerometer y axis sensitivity Address Value Description 0x001B Q11 4 signed fixed point value between 2048 and 2048 Calibrated sensitivity of the accelerometer y axis in g Isb See parameter sa in the ac celerometer section The typical values are provided for each full scale range in the LSM303DLH datasheet These values can be set automatically using the Look up accelerometer bias and sensitivity command 17 2 29 Accelerometer z axis sensitivity Address Value Description 0x001C Q11 4 signed fixed point value between 2048 and 2048 Calibrated sensitivity of the accelerometer z axis in g Isb See parameter s in the ac celerometer section The typical values are provided for each full scale range in the LSM303DLH datasheet These values can be set automatically using the Look up accelerometer bias and sensitivity command 17 2 30 Accelerometer x axis bias
42. ject written in C and targets Microsoft NET 3 5 Documentation for use of the API is represented by the XML comments throughout the source code which is accessed automatically by Visual Studio s Intellisense The open source x IMU GUI serves as a comprehensive template for use of all features of the x IMU API Further examples for specific applications are provided on the x IMU Examples web page 17 5 USB The x IMU streams all communication data simultaneously and identically via USB Bluetooth and to a file on the SD card The USB and Bluetooth connections are also be used to send commands 7 read write registers and settings and control the auxiliary port outputs from the host computer As both USB and Bluetooth connections appear as serial ports use of either communication channel is identical The x IMU can be connected to a computer via a standard USB A to mini B 5 pin type cable The on board FTDI USB chip is widely used USB interface with drivers available for Windows Mac OS X and Linux Once the drivers have been installed and the x IMU connected to the computer the x IMU will appear as a serial port and be assigned an available port name for example COM2 The computer may then communicate with the x IMU by opening this serial port This is achieved via the Serial Port tab page of the x IMU GUI The USB connection is a reliable communication channel that cannot be comprised by user settings the x IM
43. mation 7 17 2 24 Gyroscope sample 2 y axis bias Address Value Description 0x0017 Q8 8 signed fixed point value between 128 and 128 y axis bias at gyroscope bias sample 2 in lsb Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 2 is recorded using the Sample gyroscope bias at temperature 2 command See the gyroscope calibration section for more information 7 17 2 25 Gyroscope sample 2 z axis bias Address Value Description 0x0018 Q8 8 signed fixed point value between 128 and 128 z axis bias at gyroscope bias sample 2 in lsb Gyroscope bias samples 1 and 2 are required for the automatic calculation of the gyroscope bias parameters to using the Calculate gyroscope bias parameters command The gyroscope bias sample 2 is recorded using the Sample gyroscope bias at temperature 2 command See the gyroscope calibration section for more information 7 17 2 26 Accelerometer full scale Address Value Description 0x0019 0x0000 2 g 0x0001 4 g 0x0002 8 g Sets the full scale range of the accelerometer Each full scale range will have different associated sensitivity to and bias to values The Look up accelerometer bias and sensitivity command may be used to recall the correct calibrated sensitiv
44. measurements My My and m are calculated from the raw ADC measurements mz My and m according to the defined sensitivities Sma Sm aNd Sm biases bm bm and bm and hard iron biases hz hy and h as described by equation Parameters Sm Smy Sm Oma bm Dm ha hy and hz are defined in the separate magnetometer calibration parameter registers to The sensitivities and biases will be different for each full scale measurement range 25 0 0 Sm 26 10 Sensor calibration This section is currently unavailable but can be updated on request 27 11 IMU AHRS algorithms This section is currently unavailable but can be updated on request 28 12 Power management The x IMU may be powered via USB an external supply or a single cell lithium polyer LiPo battery cell 12 1 External supply The x IMU may be powered by a 3 5 to 7 7 V external supply via the auxiliary port The supply should be connected to the GND and EXT pins This power supply is only enabled while the power switch is in the off position In this situation the battery volt meter will measure the voltage of the external supply 12 2 Battery and charging The x IMU has a standard connector for a 3 7 V single cell Lithium Polymer LiPo battery cell These batteries are widely available in range of capacities for example 1000 mAh and 2000 mAh The battery life is dependent on user settings and usage See the tips
45. ndlary Port Data Logger SD Card Hardon Calibration Bootloader About Battery And Thermometer Data Show Battery Graph Show Thermometer Graph Inertial Magnetic Sensor Data Show Gyroscope Graph Show Accelerometer Graph Show Magnetometer Graph Legend X Y Z Orientation Data Show 3D Cuboid Show Euler Angle Graph Legend 8 wy Figure 7 x IMU GUI view sensor data tab page The data from individual sensors is displayed in real time data graphs as seen in Figure The controls bar at the bottom of each graph allow the view and scaling to be adjusted B Gyroscope Data o meson Wael a o ye beams doggies E Hide panei Disconnect Figure 8 x IMU GUI gyroscope data window Orientation data received may be displayed in a graph as ZYX Euler angles and displayed as the orientation of a 3D cuboid as seen in figure The cuboid is displayed in a screen coordinate frame where the x axis is aligned to the width of the screen left to right the z axis aligned to the height bottom to top and the y axis projects into the screen To align the motion of the physical x IMU and 3D cuboid displayed on the screen the user should first align the axes of the physical x IMU to the screen coordinate frame and then use the Tare command 12 a 3D Cuboid Figure 9 x IMU GUI 3D cuboid window 4 1 6 Tab page Auxilla
46. nerations prior to version 1 3 use the ITG 3200 gyroscope 24 i iS 1 Gx Sg 0 0 Ix bg fe 0 0 7 25 G 9 Ss 0 Gy lbo 10 fy 0 7 25 3 gz 0 0 Sy Gz bg 0 O f 7 25 9 4 Accelerometer The triple axis accelerometer and provides a measurement of the accelerations along the x y and z axes of the x IMU The accelerometer must be correctly calibrated in order for the IMU and AHRS algorithms to be able to function correctly the algorithms use the accelerometer to measure the direction of gravity and provide an absolute reference for the pitch and roll components of the estimated orientation The acceleroemter has 12 bit resolution and selectable ranges from 2 g to 8 g The measurement range of the accelerometer is defined in Accelerometer full scale register See the LSM303DLH datasheet for further information on the accelerometer s characteristics Raw ADC data In raw data mode the accelerometer data is the ADC integer values between 4096 and 4095 linearly proportional to accelerations This data is provided in the Raw inertial magnetic data packets Calibrated data In calibrated data mode the accelerometer data are calibrated accelerations in g This data is provided in the Calibrated inertial magnetic data packets The calibrated measurements az ay and az is calculated from the raw ADC measurements Gz y and a according to the defined sensitivities sq Sa and Sa and biases ba ba and ba as describe
47. only 0x0001 1 Hz 0x0002 2 Hz 0x0003 4 Hz 0x0004 8 Hz 0x0005 16 Hz 0x0006 32 Hz 0x0007 64 Hz 0x0008 128 Hz 0x0009 256 Hz Description Output rate of the digital I O data packets See the digital I O mode section for more information 50
48. packet error will be sent if the received packet does not contain enough bytes to be valid This error is only relevant users developing their own communication software and not using the x IMU API or x IMU GUL 16 1 9 Too many bytes in packet Error code Description 0x0008 A too many bytes in packet error will be sent if the received packet does not contains too many bytes to be valid This error is only relevant users developing their own communication software and not using the x IMU API or x IMU GUL 36 16 1 10 Invalid checksum Error code 0x0009 Description An invalid checksum error will be sent if the received packet contains a valid number of bytes but contains an invalid checksum This error is only relevant users developing their own communication software and not using the x IMU API or x IMU GUL 16 1 11 Unknown packet header Error code Ox000A Description An Unknown packet header error will be sent if the received packet contains a valid number of bytes and checksum but the header is not recognised This error is only relevant users developing their own communication software and not using the x IMU API or x IMU GUL 16 1 12 Invalid number of bytes for packet header Error code 0x000B Description An invalid number of bytes for packet header error will be sent if the received packet contains a valid number of bytes checksum and packet header but the number of bytes does not match that expected for the specific
49. provides accurate measurement of the date and time and is pre programmed to account for leap years between the year 2000 and 2099 The real time clock and calendar data can be viewed and synchronised with the computer clock using the x IMU GUI via the Date Time tab page The real time clock and calendar data a is provided by the x IMU in the write date time data packets The output rate of these packets of either disabled or 1 Hz is specified in the date time data rate register A single date time data packet is always sent on device reset regardless of user settings so that the date and time are is hardcoded as the first packet written to the SD card The real time clock and calendar is set by sending a write date time data packet to the x IMU once the new date and time have been set the x IMU will respond with a write date time data containing the real time clock and calendar data This data may also be requested by sending a read date time data packet to the x IMU 8 1 Maintaining clock power The real time clock and calendar require power to operate If power is lost for the x IMU switch off then the date and time will reset to 01 01 2000 00 00 00 Applications that require date and time to be maintained should ensure that the x IMU is never switched off and instead take advantage of sleep mode 9 Sensors The x IMU s on board sensors include a triple axis gyroscope triple axis accelerometer triple axis magne tometer the
50. r 17 2 57 Inertial and magnetic data output rate Address 0x0036 Value 0x0000 Disabled 0x0001 1 Hz 0x0002 2 Hz 0x0003 4 Hz 0x0004 8 Hz 0x0005 16 Hz 0x0006 32 Hz 0x0007 64 Hz 0x0008 128 Hz 0x0009 256 Hz Description Output rate of the inertial and magnetic data packets Data rates can be reduced or disabled to conserve power 17 2 58 Quaternion data output rate Address 0x0037 Value 0x0000 Disabled 0x0001 1 Hz 0x0002 2 Hz 0x0003 4 Hz 0x0004 8 Hz 0x0005 16 Hz 0x0006 32 Hz 0x0007 64 Hz 0x0008 128 Hz 0x0009 256 Hz Description Output rate of the quaternion data packets Data rates can be reduced or disabled to conserve power 17 2 59 SD card new file name Address 0x0038 Value 00000 to 65535 Description The file name used to be used when the next file is created on the SD card See the SD card section for more information 7 48 17 2 60 Battery shotdown voltage Address 0x0039 Value Q4 12 signed fixed point value between 3 5 and 8 Description Minimum voltage threshold for the device to shutdown See the low battery voltage detec tion section for more information 17 2 61 Sleep timer Address 0x003A Value 0 to 65535 Description Sleep timer value in seconds Once this period has elapsed the x IMU will enter sleep mode A value of 0 seconds will disable the sleep timer See the sleep timer section for more information 17 2 62 Motion t
51. r different applications can be found on the x IMU Examples webpage Features e View edit and backup all internal x IMU settings e Real time 2D and 3D data graphics e Control panels for auxiliary port e Data logger and file converter for exporting data e g to MATLAB Microsoft Excel etc e Magnetic calibration tools e Firmware bootloader to access new features in future x IMU firmware versions 2 Getting started 1 Install the USB drivers and or pair the x IMU as a Bluetooth device 7 2 Download and install the latest version of the x IMU GUI 3 Connect to the x IMU via the Serial port tab page of the x IMU GUI The x IMU and accompanying software were designed to be versatile and intuitive New users are advised to explore the x IMU through the x IMU GUI and consult this user manual when required If you are struggling to use the system and feel that this user manual is not providing you with appropriate documentation please contact us so that we update the document appropriatly 3 Hardware overview CHa canm Musa om cs ms oe x IMU 1 3 CTRI WWwWex 10 CO uUk MT TETTTTA E LLLLLLLLLLL 4 pa V6V1L0999000 e Figure 2 x IMU bottom 3 1 Power switch The power switch is used to switch the battery and USB power on or off The battery and USB power is completely disconnected when the switch is in the off position The x IMU may be powered by an external supply via the auxiliary port
52. rate battery and thermometer data packets The calibrated measurement v is calculated from the raw ADC measurements according to a sensitivity s and bias b as described by equation Parameters b and s are defined in the battery voltmeter sensitivity and bias registers v by 1 9 2 Thermometer The thermometer is built in to the gyroscope and provides a measurement of the temperature of the device The thermometer must be correctly calibrated for calibrated gyroscope measurements to compensate for gyroscope bias temperature sensitivity The thermometer has 16 bit resolution and has a range of 30 C to 85 C See the IMU 3000 datasheet for further information on the thermometer s characteristics Raw ADC data In raw data mode the thermometer data is the ADC integer value between 32 768 and 32 767 linearly proportional to temperature This data is provided in the Raw battery and thermometer data packets Calibrated data In calibrated data mode the thermometer data is the calibrated temperature in C This data is provided in the Calibrate battery and thermometer data packets The calibrated measurement T is calculated from the raw ADC measurement 7 according to a defined sensitivity s and bias b as described by equation Parameters b and s are defined in the battery voltmeter sensitivity and bias 7 registers r 7 br 2 9 3 Gyroscope The triple axis gyroscope prov
53. rigger wake up Address 0x003B Value 0x0000 Disabled 0x0001 Low sensitivity 0x0001 high sensitivity Description Enables the sensitivity of the motion trigger wake up See the motion trigger wake up section for more information 7 17 2 63 Bluetooth power Address 0x003C Value 0x0000 Disabled 0x0001 Enabled Description Enables or disables Bluetooth The Bluetooth can be disabled to conserve power 17 2 64 Auxiliary port mode Address 0x003D Value 0x0000 Disabled 0x0001 Digital I O Description Sets the auxiliary port mode See the auxiliary port section for more information 7 17 2 65 Digital I O direction Address 0x003F Value 0x0000 All channels are inputs 0x0001 Channels 0 1 2 3 4 5 and 6 are inputs 7 is an output 0x0002 Channels 0 1 2 3 4 and 5 are inputs 6 and 7 are outputs 0x0003 Channels 0 1 2 3 and 4 are inputs 5 6 and 7 are outputs 0x0004 Channels 0 1 2 and 3 are inputs 4 5 6 and 7 are outputs 0x0005 Channels 0 1 and 2 are inputs 3 4 5 6 and 7 are outputs 0x0006 Channels 0 and 1 are inputs 2 3 4 5 6 and 7 are outputs 0x0007 Channel 0 is an input 1 2 3 4 5 6 and 7 are outputs 0x0008 All channels are outputs Description Sets the direction of the auxiliary port channels when in digital I O mode See the digital I O mode section for more information 49 17 2 66 Digital I O data output rate Address 0x0040 Value 0x0000 On change
54. rmation 15 1 11 Tare Command code 0x000A Description The tare command is used to set the algorithm datum orientation and store the reference quaternion to the tare quaternion registers to These registers may be then be cleared using the clear tare command See the IMU AHRS algorithms section for more information 15 1 12 Clear tare Command code Ox000B Description The clear tare command is used to clear the tare quaternion registers to and return the datum orientation to alignment with the Earth coordinate frame 16 Error messages Error messages are sent by the x IMU to warn the user or host software of any internal errors that have occurred The x IMU GUI will display these errors in message boxes for user acknowledgment As all communication from the x IMU to the host computer is logged to the SD card all error messages will be logged on the SD card 16 1 Individual error messages 16 1 1 NoError Error code 0x0000 Description No error 16 1 2 Low battery Error code 0x0001 Description A low battery error is sent when the low battery voltage detection detects that the battery voltage has fallen below the specific level defined in the battery shutdown voltage register This message is sent immediately before the x IMU enters sleep mode See the low battery voltage detection section for more information 16 1 3 USB receive buffer overrun Error code 0x0002 Description A
55. rmometer and a battery voltmeter The user may access individual sensor data as either Raw un calibrated ADC results or as Calibrated units by specifying the mode in the Sensor data mode register The data from individual sensors is proved in either the Raw inertial magnetic data and Raw battery and thermometer data packets or the Calibrated inertial magnetic data and Calibrated battery and ther mometer data packets The output rate of these packets of up to 256 Hz is specified in the Battery and thermometer data output rate and Inertial magnetic data output rate registers 9 1 Battery voltmeter The battery voltmeter allows the battery voltage to be monitored by the user application The battery voltmeter must be correctly calibrated if the low battery voltage detection functionality is to be used The battery voltmeter has 12 bit resolution and a range of 0 V to 6 6 V When the power switch is in the off position so that the x IMU may be powered from an external source via the auxiliary port the battery voltmeter will instead measure the voltage of the external source 23 Raw ADC data In raw data mode the battery voltmeter data is the ADC integer value between 0 and 4096 corresponding to a voltage between 0 V and 6 6 V This data is provided in the Raw battery and thermometer data packets Calibrated data In calibrated data mode the battery voltmeter data is the calibrated measurement in Volts This data is provided in the Calib
56. ry port The auxiliary port tab page contains buttons to show or hide individual control windows for the different modes of the auxiliary port a9 x IMU GUI v1 0 noe Ex Serial Port Registers Date Time Commands View Sensor Data f indliary Por Data Logger SD Card Hard Iron Calibration Bootloader About Digital 1 0 Show Digital 1 0 Panel Figure 10 x IMU GUI auxiliary port tab page Digital I O control panel The digital I O control panel displays the state and mode of each channel of the auxiliary port when in digital I O mode as shown in figure Each channel is represented by a check box If the channel mode is output then the check box is enabled and may be checked or un checked to set the channel high or low respectively If the channel is an input the check box is disabled and will be checked or un checked if the channel is high or low respectively 13 Figure 11 x IMU GUI digital I O control panel 4 1 7 Tab page Data logger The data logger tab allows the user to log incoming real time data to file These files may be imported to user software such as Microsoft Excel and MATLAB The user may select the location and first part of the file name in the File path text box This file name will be extended with an appropriate description and extension when the individual data files are created For example if a file name of myFile is specified Euler angle and date time d
57. s the bandwidth of a communication channel The SD card bandwidth is greater than the USB and Bluetooth bandwidth and so the SD card may still provide reliable data logging when the USB or Bluetooth channel bandwidth is exceeded If the SD card bandwidth is exceed the SD card buffer will 22 overrun and some data will be lost When this happens an SD card write buffer overrun error will be generated As this error packet is sent immediately after the buffer has overrun the error message will be successfully logged to the SD card This error can be avoided by reducing the data output rate settings e g The SD card LED may be used to provides an indication of SD card bandwidth performance while access to error messages is not available The effective bandwidth of SD card varies between different SD card manufacturers and may decrease significantly if the SD card becomes fragmented It is therefore recommended that the SD card is formatted prior to each use 7 4 Magnetic distortions from SD card socket The SD card socket contains a ferromagnetic mechanism that may distort magnetometer measurements in different ways dependant of the presence of an SD card These distortions are removed through hard iron calibration and each x IMU is calibrated and supplied with a dummy SD card that may be used to ensure constant SD card socket magnetic characteristics 8 Real time clock and calendar The on board real time clock and calendar
58. sleep mode the motion trigger wake up is used to reset the sleep timer and thus postpone sleep while motion persists For example if the sleep timer is set to 20 seconds and there is sufficient motion once every 10 seconds the motion trigger wake up will prevent the sleep timer from expiring 12 7 Tips for minimising power consumption Battery powered applications require that power consumption is minimised in order to extend the battery life The x IMU is designed to optimised power consumption according to user settings The user may therefore expect a considerable reduction in power consumption and extended battery life simply by using register settings appropriate to their application Tips e Set data rates of unused data to Disabled e Use the minimum data rates required by application Set IMU AHRS algorithm mode to Disabled if not required Disable Bluetooth if not required e Use the sleep timer and motion trigger wake up to automatically enter sleep mode during periods of inactivity 30 13 Auxiliary port This section is currently unavailable but can be updated on request 31 14 Communication protocol This section is currently unavailable Users wishing to develop their own x IMU communication interface are advised to study the open source x IMU API The API is source code is written in C and well commented porting the API or aspects of to another language should be a straight forward ex
59. the Bluetooth LED The Bluetooth radio can be completely disabled by the user via the Bluetooth power register to conserve power 6 1 Pairing the x IMU with a Bluetooth host As with any Bluetooth device the x IMU must first be paired with the host computer before a Bluetooth connection can be made This pairing process is the same for all Bluetooth devices and will be familiar those who have used other Bluetooth devices such as printers or mobile phones To pair the x IMU with a host computer the host computer s Bluetooth must be enabled and the x IMU must be switched on and the Bluetooth radio powered The user may then use the host computer to search for and the x IMU to be paired with the computer The x IMU will appear with the name z IMU 0000 where the last 4 digits are the x IMU s Device ID For example Figure shows how this is done in Windows 7 having right clicked the Bluetooth icon the task bar 19 Select a device to add to this computer Windows will continue to look for new devices and display them here x IMU 2D49 Bluetooth Other Add a Device Allow a Device to Connect Show Bluetooth Devices Send a File Receive a File What if Windows doesn t find my device Join a Personal Area Network Figure 18 Searching for the x IMU as a new Bluetooth device in Windows 7 Once the x IMU has been found by the host computer it can be added This will require the user to enter
60. the port name assigned to the x IMU Bluetooth pairing 6 2 Bluetooth LED The blue Bluetooth LED indicates the Bluetooth radio state The LED behaviour and associated Bluetooth radio states are detailed in table LED behaviour Bluetooth state Off Switched off Power to the radio is compeltely disconected Flashing 1 Hz Fully powered and discoverable On Fully powered and connected Table 2 Bluetooth LED states 6 3 Bluetooth bandwidth It is possible for the user to define data output rate settings e g so that the data being generated by the x IMU exceeds the bandwidth of a communication channel If the Bluetooth bandwidth is exceed the Bluetooth transmit buffer will overrun and some data will be lost When this happens a Bluetooth transmit buffer overrun error will be generated As this error message is sent immediately after the buffer has overrun the error message will be successfully transmitted This error can be avoided by reducing the data output rate settings e g All data sent to the x IMU via Bluetooth is buffered in the Bluetooth receive buffer before being pro cessed The time required to process the received data is dependent on the data If data is sent to the x IMU via Bluetooth at a rate at a rate greater than it can be processed then the receive buffer will overflow and some data will be lost When this happens a Bluetooth receive buffer overrun error will be generated 6 4
61. the x IMU s Bluetooth pass code 1234 The x IMU Bluetooth pairing will be assigned an available serial port name by the host computer for example COM3 For example Figure shows this being done in Windows 7 Enter the pairing code for the device This will verify that you are connecting to the correct device 1234 The code is either displayed on your device or in the information that came with the device Configuring device What if I can t find the device pairing code Standard Serial over Bluetooth link COM3 gt WD device driver software installed successfully 3 ow Figure 19 Adding the x IMU as a new Bluetooth device in Windows 7 The port name assigned to the x IMU Bluetooth pairing can be confirmed at any time by viewing the services of the x IMU For example Figure shows how this is done in Windows 7 having right clicked the x IMU Bluetooth device icon 20 Ermy C a Ea gt Control Panel All Control Panel items Devices and Printers Bluetooth Devices I Add a device Adda printer Remove device j 4 Devices 1 I x IMU 2D49 Properties Create shortcut M General Hardware Services Bluetooth This Bluetooth device offers the following services To use a service select the check box Troubleshoot xM Remove device Bluetooth Services Z Serial port SPP SPP Properties x IMU 2D49 3 Category Other Figure 20 Confirming
62. tomatically incremented each time a new file is created This ensures that each file created by the x IMU is given a unique file name until the maxium file name of 65535 bin is reached the file name will then automatically reset to 00000 bin and start again The user can reset this value to any number by writing to the register If the x IMU attempts to create a file name that already exists on the SD card the x IMU automatically increment the file name and try again If all file names have been used the x IMU will not create a file and the SD card will not be used File must be closed before the SD card is removed or the x IMU switched off otherwise the file will be corrupted and all data written to the file will have been lost The file is automatically closed when the x IMU is reset or enters sleep mode Users wishing to frequency remove the SD card may wish to have the push button configured in sleep wake mode 7 2 SD card LED The amber SD card LED indicates SD card activity The LED remains lit each time a burst of data is written to the SD card If the user low defines data output rates then the LED will blink infrequenctly high data output rates will mean the LED will flash rapidly The SD card LED therefore provides an indication of SD card bandwidth performance 7 3 SD card bandwidth It is possible for the user to define data output rate settings e g so that the data being generated by the x IMU exceed
63. uld right click anywhere in the registers tab page and select Read all registers The software will then read each register and update the values in the tree view Individual registers or groups of registers may be read by first selecting a register or group within the tree view and then selecting Read this register only or Read all registers in this group only Register values in the tree view may be written to teh x IMU using the Write all regisers Write this register only and Write all registers in this group only options in the action menu General Expand all Quatemion Data Rate 128 Hz i SD Card Collapse all 6 Power Management mee Save all to file i Battery Shutdown Voltage V 3 5 Sleep Timer s Disabled Load from file Motion Triggered Wake Up Disabled z L Bluetooth Power Enabled Read all registers E Aundliary Port Write all registers Read this register only Write this register only Figure 4 x IMU GUI registers tab page with right click action menu 4 1 3 Tab page Date time The date time tab page allows the user to view and set the date and time of the x IMU s real time clock and calendar The Received date time text box displays the date and time each time it is received from the x IMU The Read Date Time button may be used to read the current date and time of the x IMU this is of use if date time data rate has been disabled Pressing the Set Date
64. x IMU User Manual 1 0 x io Technologies September 20 2011 Version Date Notes 1 0 10 05 2011 Initial release Compatible versions Firmware 4 x GUI 6 x API 7 x Table 1 Version history Disclaimer The x IMU and associated software are provided in an as in condition No warranties whether express implied or statutory including but not limited to implied warranties of merchantability and fitness for a particular purpose apply x io Technologies shall not in any circumstances be liable for special incidental or consequential damages for any reason whatsoever Contents 1 x IMU overview The x IMU was designed to be the most versatile IMU AHRS product available Its host of on board sensors algorithms and configurable 8 channel auxiliary port make the x IMU both a powerful sensor and controller Communication is enabled via USB or Bluetooth for wireless applications The on board SD card battery charger via USB real time clock calendar and motion trigger wake up also make the x IMU an ideal stand alone data logger The open source x IMU GUI allow users configure all internal x IMU settings view sensor data in real time and export data to software such as MATLAB and Microsoft Excel Custom user software may be developed using the x IMU API 1 1 x IMU Features On board sensors e Triple axis 16 bit gyroscope 2000 s range e Triple axis 12 bit accelerometer Configurable range up to 8 g e Triple axis 1

x-IMU User Manual 1.0 - x

Contents

Download Pdf Manuals

Related Search

Related Contents