Get imu data in PX4 ROS2 using micro XRCE-DDS

ROS 1 / ROS 2
1

I need to get the imu data from the FCU using XRCE-DDS agent, so I can use the LIO-SAM pkg for mapping.

I can find /fmu/out/sensor_combined but it is note pure imu data

any thoughts?

2

The fmu/out/sensor_combined ROS2 topic gives you accelerometer and gyro values. The topic output looks like:

---
timestamp: 1730371541868279
gyro_rad:
- -0.00030451154452748597
- -0.0012424546293914318
- -0.0009538612212054431
gyro_integral_dt: 4000
accelerometer_timestamp_relative: 0
accelerometer_m_s2:
- -0.18315644562244415
- 0.058658115565776825
- -9.815031051635742
accelerometer_integral_dt: 4000
accelerometer_clipping: 0
gyro_clipping: 0
accel_calibration_count: 0
gyro_calibration_count: 1
---

I don’t know why you think they are not pure IMU data.

It gives you the three accelerations measured by the 3 accelerometers and the three gyro measure for the 3 direction. This is what a basic IMU measures.

I don’t know if such measures are actually pre filtered by the IMU itself, but I am pretty sure, that this is what you get from the IMU.

Also there aren’t other topics from where you can get such data. For the ROS2 XRCE-DDS agent this is the only solution.

3

Here’s a description of the fields in the message perhaps this helps illustrate the topic better