Using multiples IMU

[Fabien-B]

Hi,
I am trying to use multiple IMU. How can I specify their relative rotation ?
I assume I should fill the body_to_sensor field, but how can I get what values I should put here ?
I already calibrated both IMUs, and merged their calibration in the airframe file:

<define name="IMU_ACCEL_CALIB" value="{{.abi_id=24, .calibrated={.neutral=true, .scale=true},.neutral={-72,-70,148}, .scale={{23269,19648,18259},{38058,31995,29742}}}, {.abi_id=9, .calibrated={.neutral=true, .scale=true},.neutral={-15,-10,-98}, .scale={{32610,6121,64910},{6647,1249,13457}}}}"/>

I also assume that once I find the correct body_to_sensor, I should use the same for the magnetometer calibration?

[fvantienen]

You can have a default rotation in your imu module, see modules/imu/imu_cube.c as an example where all 3 have a different default rotation.

The IMU_..._CAL can overwrite this default rotation and this is applied after the calibration of the neutral and scale such that this isn't influenced. In order to set this rotation you need to set .rotation = true in the calibrated and then set a body_to_sensor with a 3x3 RMAT (<<INT32_TRIG_FRAC).
Note that the body_to_imu is applied on top of the body_to_sensor. This rotation can thus be set per sensor and the body_to_imu is applied to all.

[dewagter]

NPS issue: with 3 accelerometers the imu does not align in NPS: #3135: @fvantienen any idea why?