IMU

Synchronous IMU support improves alignment between IMU measurements and lidar data for applications that fuse motion and point-cloud data, such as SLAM, localization, mapping, and vehicle odometry.

Note: Supported in firmware v3.2 or later.

The ACCEL32_GYRO32_NMEA IMU UDP profile and related configuration fields are intended for applications that need richer IMU packets, configurable IMU packet cadence, and timing information that can be consumed alongside lidar data.

Getting Started

Use synchronous IMU data when your application needs tighter coupling between lidar frames and IMU measurements:

• SLAM or localization pipelines that compensate for sensor motion.
• Data recording workflows that must preserve IMU information with lidar packets.
• Systems using GPS/PPS/NMEA inputs and requiring lock or timing context in the IMU stream.

For general IMU packet structure and coordinate-frame information, see IMU Data Format.

Expected Sensor Behavior

The LEGACY IMU profile preserves the original 100 Hz IMU packet behavior. The ACCEL32_GYRO32_NMEA profile is designed for synchronous output: IMU readout is correlated with lidar column/frame context and packet cadence is configurable with imu_packets_per_frame.

The ACCEL32_GYRO32_NMEA profile carries 32-bit accelerometer and gyroscope data. Configure PPS/NMEA/PTP time inputs as described in Time Synchronization.

IMU Configuration

Configure synchronous IMU output with POST /api/v1/sensor/config.

$
curl -X POST http://os-991234567890.local/api/v1/sensor/config \
>
  -H 'Content-Type: application/json' \
>
  --data '{
>
    "udp_profile_imu": "ACCEL32_GYRO32_NMEA",
>
    "imu_packets_per_frame": 8
>
  }'

The related configuration fields are:

Note: The LEGACY IMU profile is supported through firmware v3.2 and will be deprecated in later releases. Use ACCEL32_GYRO32_NMEA for new integrations.

Validating Operation

Read the IMU metadata with GET /api/v1/sensor/metadata/imu_data_format:

$
curl http://os-991234567890.local/api/v1/sensor/metadata/imu_data_format

Example response:

1
{
2
  "accel_fsr": "NORMAL",
3
  "gyro_fsr": "NORMAL",
4
  "imu_packets_per_frame": 8,
5
  "imu_measurements_per_packet": 1,
6
  "udp_profile_imu": "ACCEL32_GYRO32_NMEA"
7
}

The response confirms the selected IMU profile, packet cadence, and full-scale range settings. For configurable accelerometer and gyroscope ranges, see Configurable IMU Scale.

For packet layouts, see LEGACY IMU Profile and ACCEL32_GYRO32_NMEA IMU Profile.

Recording Recommendations

When recording data for SLAM or downstream sensor-fusion workflows:

1. Configure IMU output with the sensor configuration endpoint:

$
curl -X POST http://os-991234567890.local/api/v1/sensor/config \
>
  -H 'Content-Type: application/json' \
>
  --data '{
>
    "udp_profile_imu": "ACCEL32_GYRO32_NMEA",
>
    "imu_packets_per_frame": 8
>
  }'

2. Confirm the active IMU profile and packet cadence with the IMU data format endpoint:

$
curl http://os-991234567890.local/api/v1/sensor/metadata/imu_data_format

3. If using external timing, verify timing lock state with the time endpoint or PTP status endpoint:

$
curl http://os-991234567890.local/api/v1/time
$
curl http://os-991234567890.local/api/v1/time/ptp

4. Record raw lidar and IMU UDP packets together so timestamps and packet ordering are preserved.

If synchronous IMU data appears invalid or all zero after aggressive motion, update to the latest firmware and reinitialize the sensor before collecting new data.