[Help] Autoland issue – Motor cut in flare, aircraft slowed to stall speed and crashed

PX4 Autopilot
1

Hello,

during an autoland with our Cube Orange fixed-wing, the motor shut down in the flare and the aircraft slowed all the way down to stall speed (~15 m/s). At the same time, it tried to align with the runway centerline from a small lateral offset and commanded almost 45° roll. With throttle cut and airspeed at stall margin, the wing couldn’t produce enough lift and the plane stalled and crashed.

In normal flight (airspeed >20 m/s), the aircraft can handle 40–45° bank with no issue. The problem only appears during flare, when PX4 cuts the throttle and allows the speed to drop very close to stall. Log attached for review. https://review.px4.io/plot_app?log=72e1fefe-0c19-4402-9327-be3f6cd6066e

2

Sounds like the autoland has room for improvement. Contributions welcome.

Let me ping @ryanjAA if he has any tips.

3

Just set a target landing speed. If you don’t it uses min speed.

The roll like that is strange. I was inclined to say it was a stall but it is a set point. I’ll look a bit more in detail soon.