Using vehicle_acceleration UORB message using MAVSDK

Erkam · February 28, 2023, 5:13am

@JulianOes Could you help me about this topic? Does Telemetry::Imu of MAVSDK take accelerometer values from vehicle_acceleration() or If not which UORB function does it use?

JulianOes · March 5, 2023, 10:44pm

This comes from the MAVLink message HIGHRES_IMU:

github.com

mavlink/MAVSDK/blob/ab24200b9df9176890ec5e80c332708ba72d2a59/src/mavsdk/plugins/telemetry/telemetry_impl.cpp#L903-L925


      
          void TelemetryImpl::process_imu_reading_ned(const mavlink_message_t& message)
          {
              mavlink_highres_imu_t highres_imu;
              mavlink_msg_highres_imu_decode(&message, &highres_imu);
              Telemetry::Imu new_imu;
              new_imu.acceleration_frd.forward_m_s2 = highres_imu.xacc;
              new_imu.acceleration_frd.right_m_s2 = highres_imu.yacc;
              new_imu.acceleration_frd.down_m_s2 = highres_imu.zacc;
              new_imu.angular_velocity_frd.forward_rad_s = highres_imu.xgyro;
              new_imu.angular_velocity_frd.right_rad_s = highres_imu.ygyro;
              new_imu.angular_velocity_frd.down_rad_s = highres_imu.zgyro;
              new_imu.magnetic_field_frd.forward_gauss = highres_imu.xmag;
              new_imu.magnetic_field_frd.right_gauss = highres_imu.ymag;
              new_imu.magnetic_field_frd.down_gauss = highres_imu.zmag;
              new_imu.temperature_degc = highres_imu.temperature;
              new_imu.timestamp_us = highres_imu.time_usec;
          
          
    set_imu_reading_ned(new_imu);
          
          
    std::lock_guard<std::mutex> lock(_subscription_mutex);

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And that’s sent here:

github.com

PX4/PX4-Autopilot/blob/7edce94b939f98a708b4ce96557120509d2adce1/src/modules/mavlink/streams/HIGHRES_IMU.hpp

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And it’s using the data from the primary/used IMU, see:

github.com

PX4/PX4-Autopilot/blob/7edce94b939f98a708b4ce96557120509d2adce1/src/modules/mavlink/streams/HIGHRES_IMU.hpp#L85


      
          	{
          		bool updated = false;
          
          
		sensor_selection_s sensor_selection{};
          		_sensor_selection_sub.copy(&sensor_selection);
          
          
		vehicle_imu_s imu;
          
          
		for (auto &imu_sub : _vehicle_imu_subs) {
          			if (imu_sub.update(&imu)) {
          				if (imu.accel_device_id == sensor_selection.accel_device_id) {
          					updated = true;
          					break;
          				}
          			}
          		}
          
          
		if (updated) {
          			uint16_t fields_updated = 0;
          
          
			fields_updated |= (1 << 0) | (1 << 1) | (1 << 2); // accel

Erkam · March 7, 2023, 10:08am

Thanks for replying to the message.