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Table of Contents

  1. VOXL IMU Server
  2. Configuration
  3. Usage
  4. Published Format
    1. Source Code

VOXL IMU Server

The VOXL IMU Server receives and publishes data from the built-in IMUs on the pipe imu#.

Configuration

The VOXL IMU server uses the configuration file located at: /etc/modalai/voxl-imu-server.conf.

The config file contains the following fields:

  • bus integer, default = 1
  • imu_sample_rate_hz integer (hz), default = 1000
  • imu_baud_rate_hz integer (baud), default = 921600
  • imu_fsr_gyro integer (dps), default = 480
  • imu_fsr_accel integer (g), default = 8

Usage

The server runs as a service in the background which can be started/stopped with systemctl start/stop voxl-imu-server. The server can also be run manually from the shell using the command voxl-imu-server. There are also optional arguments that can be added when running the server manually such as:

  • voxl-imu-server -d to enable debug prints
  • voxl-imu-server -t to enable timestamp prints for the IMU packets
  • voxl-imu-server -c to create a new config file and exit
  • voxl-imu-server -h to print a help menu

To check the satus of the server run voxl-inspect-services and find the voxl-imu-server. The data can be viewed by running the command voxl-inspect-imu imu# or by going to the IMUs tab under debug in the portal and selecting the desired IMU imu_iim.

Published Format

IMU data is published to the pipes in an imu_data_t struct which consists of the following:

  • struct imu_data_t:
  • uint32_t magic_number Set to IMU_IMAGE_MAGIC_NUMBER for frame syncing
  • float accl_ms2[3] XYZ acceleration in m/s^2
  • float gyro_rad[3] XYZ gyro rotation in rad/s
  • float temp_c temp in C, IMU_INVALID_TEMPERATURE_VALUE if no thermometer
  • uint64_t timestamp_ns timestamp in nanoseconds, uses system clock_monotonic

Source Code

The source code for VOXL IMU Server can be found here