SITL standard_vtol without airspeed flies too slow

[julianoes]

Describe the bug When airspeed is blocked (not published) for standard_vtol in SITL, it starts to fly slower and slower (below stall speed and starts oscillating in speed and height. I assume this is just because the cruise throttle is not set up correctly but I'm not sure.

To Reproduce Steps to reproduce the behavior:

1. Use: https://github.com/PX4/Firmware/pull/15063
2. make px4_sitl gazebo_standard_vtol
3. Plan VTOL mission in QGC and start it.
4. Enable failure injection: param set SYS_FAILURE_EN 1
5. Trigger GPS lost: failure airspeed off

Log Files and Screenshots https://logs.px4.io/plot_app?log=687fe868-4005-4494-a5a3-dc63aefaa127

FYI @sfuhrer @RomanBapst

[sfuhrer]

I think the issue (or at least part of it) is that currently airspeed failure detection is not enabled by default. The airspeed validator in that case doesn't do any failure detection, and will just publish the last airspeed data it received. In the case here, the last valid airspeed was above the trim airspeed, and thus the vehicle tried to decelerate by climbing and reducing throttle. I think what we should do is 1) make it possible to enable some of the checks (not having to enable all of them, as the checks against the wind estimator innovations are producing quite a few false positives if not tuned properly) 2) enable airspeed failure detection for data loss and "below stall speed" 3) make sure that transition from airspeed to airspeed less mode is smooth

[julianoes]

Oh, airspeed failure detection is not enabled? :astonished: I see.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.