PX4 IMU data logging

Good morning

I want to inquire about the logging of the data from the IMU sensors on Pixhawk 6X.

I see the following:

  • There are 3 logging files (topics) where the accelerometer data (as an example) is logged: sensor_accel, vehicle_imu and vehicle_accel.
  • If I set these topics in the logger_topics.txt to be sampled at 200 Hz, it is generally sampled at this rate.

However, I have a couple of questions:

  1. Why are there 3 different files for logging this data. It seems like the vehicle_accel file is bias corrected and the vehicle_imu gives the delta velocities (and delta angles), but are they then the same apart from that?
  2. How to I know which IMU is defined to be 0, 1 or 2? It searched the code for the device_id listed in the logged file, but could not find it.

Thanks for your assistance.

Edit: And now I have found another one: sensor_accel_fifo that also contains the accelerometer data.
And a another one: sensor_combined