mavlink_main: stream attitude as quaternion if HIL

[mbjd]

Solved Problem

Previously with SIH, for some VTOL airframes (e.g. SIH Tailsitter Duo, 1102) the attitude display on the ground station was wrong due to the body frame in forward flight differing from the usual convention.

Solution

The rotation of the body frame is already accounted for (see this PR) when sending the attitude as quaternion [1] over mavlink, but not when sending it as euler angles [2]. Therefore, if in SIH/HIL we always send it as a quaternion as well.

1: src/modules/mavlink/streams/ATTITUDE_QUATERNION.hpp
2: src/modules/mavlink/streams/ALTITUDE.hpp

Alternatives

• add similar logic as in [1] to [2] so display attitude is correct regardless of numerical representation
• enable sending quaternions only for the relevant VTOL airframes

Test coverage

• SIH test with SIH Tailsitter Duo (1102)

[sfuhrer]

I think you also need to add it in the disable HIL section below.

And I wonder if it's then not still broken for real tailsitters and we thus need to find a more generic solution.

[KonradRudin]

I think you also need to add it in the disable HIL section below.

The problem is that it might be already enabled, so you don't want to disable in every case. Also a change of the parameter requires a reboot, so the else case does not make much sense, no?

And I wonder if it's then not still broken for real tailsitters and we thus need to find a more generic solution.

Would need to test this then and report if it is still a problem.