IMU Logger Sample#

Note

Third-party sensors and accessories noted on this page are for illustrative purposes. Please refer to NVIDIA® DRIVE® Hyperion™ 8.1 Sensors and Accessories for supported sensors and accessories.

Interfacing with sensors#

Serial#

Consumer grade off-the-shelve IMU sensors are usually connected over USB and implement a serial-to-USB connection with the help of FTDI devices. The Xsens IMU device can be connected through a serial-to-USB connection.

On Linux, these sensors can then be reached over the /dev/ttyUSB or /dev/ttyACM devices. Before trying out the sample, ensure the user has access to the serial device. You can do so by trying to read from the device e.g. with cat /dev/ttyACMx, and if permission is denied, add the current user to the dialout group and then log out/in again:

sudo usermod -a -G dialout $USER

On QNX, prior to accessing the device, launch the dev-serusb driver as follows:

devc-serusb -b <baudrate> -F -S -d path=/dev/usb/io-usb-otg

The serial devices can the be reached over the /dev/serusb devices.

Xsens USB#

The Xsens IMU device can also be connected directly over USB, but is only supported on Linux.

Running the Sample#

The sample requires the driver and name of the device of the IMU sensor. The command line for the sample is:

./sample_imu_logger [options]

Options#

The sample accepts the following optional arguments:

--driver=imu.virtual|imu.uart|imu.xsens|imu.novatel|imu.dataspeed|imu.xsensCan|imu.bosch|imu.continental|imu.custom[=imu.virtual]#

Allows to specify which IMU driver to use.

--params={key=value},{key=value},...[=file=data/samples/sensors/gps/1.gps]#

Comma separated list of key/value pairs. Different parameters are available for each IMU driver.

--timestamp-trace=true|false[=false]#

Allows to output only the timestamp deltas between consecutive frames.

--seek-to-event={integer}#

This applies to seekable IMU sensors. Now only imu.virtual supports this feature. IMU sensor will seek to specified event first, then start reading IMU frames.

--seek-to-timestamp={integer}#

This applies to seekable IMU sensors. Now only imu.virtual supports this feature. IMU sensor will seek to a frame whose timestamp is equal to or greater than specified timestamp, then start reading IMU frames.

--enable-dump-all=true|false[=false]#

If enable this option, all the fields for dwIMUFrame will be dumped to output in a CSV format, each line will start with dump_dwIMUFrame, you can grep by the key word and generate a *.csv file for further analysis.

See also Common Options.

Note

For a full list of key/value pairs that can be passed to --params see Sensor Enumeration Sample.

Examples#

NMEA format#

For serial devices transmitting messages in NMEA format, use the imu.uart driver. For example:

./sample_imu_logger --driver=imu.uart --params=device=/dev/ttyUSB0,baud=115200

Per default, if no baud parameter has been provided imu.uart driver assumes a baudrate of 9600. In order to change the baudrate provide baud argument as:

./sample_imu_logger --driver=imu.uart --params=device=/dev/ttyUSB0,baud=115200

On QNX, the baudrate is set when starting devc-serusb. The baud parameter will be ignored.

Xsens proprietary format#

The sample supports reading IMU packets from a Xsens device through the imu.xsens driver. To run the sample using Xsens over USB device use:

./sample_imu_logger --driver=imu.xsens --params=device=0,frequency=100

Where device=0 parameter sets the index of the Xsens device (usually 0 if only one device is installed) and frequency=100 sets the frequency in [Hz] this device should operate with.

To run the sample using Xsens over serial use:

./sample_imu_logger --driver=imu.xsens --params=device=/dev/ttyUSB0,frequency=100

Please note that even if the Xsens device is a shared device, like Xsens MTi-G-700, capable of delivering GPS and IMU packets, only the IMU packets will be parsed by the imu.xsens driver.

Note

If the device is connected to NVIDIA DRIVE AGX™ Thor UART you need also specify –stop-bits=1

Output#

For every valid IMU message that the sample receives, it prints to the console data such as:

[7156364888] Heading(True:112.07)
[7156364959] Gyro(Z:0.0756667 )
[7156369081] Orientation(R:-1.3 P:-0.9 ) Gyro(X:-0.01 Y:-0.05 ) Heading(True:112.1)
[7156389724] Heading(Magnetic:112.07)
[1475788068778749] Heading(Magnetic:112.1)
[7156389797] Orientation(R:-1.31 P:-0.89 )
[1475788068778919] Orientation(R:-1.30529 P:-0.893047 Y:112.078 ) Gyro(X:0.0229183 Y:-0.0687549 Z:0.120321 ) Acceleration(X:-0.1398 Y:-0.2612 Z:9.7838 ) Magnetometer(X:7.18 Y:3.056 Z:-16.16 )

Where the first number indicates the timestamp of the received IMU message in microseconds and the rest of the line indicates the IMU information of the sensor.

Additional Information#

For more details see IMU.

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