At the end of a test flight the autopilot switched into QRTL mode and started to loose control with it suddenly yawing and dropping altitude. I switched to QHOVER to recover. I have spent some time looking though the logs but I have not been able to figure it out.
I had just finished doing a Qwiktune and a Fixedwing Autotune.
The best I have been able to come up with is it seems once the mode switched from AUTO to QRTL there were large control outputs to the rudder causing large yawing moments and a loss of lift. I have looked at the EKF as well but haven’t been able to figure out if it was healthy or not.
We are flying a MakeFlyEasy Fighter VTOL with a cube orange and Here3+.
The direction of aircraft’s heading right after RTL was triggered is exactly toward homepoint. Could it be that distance to homepoint was too short and RTL mode transitioned aircraft into Qmode immediately?
Previous two RTL had
reached WP, vtol approach, RTL, vtol airbrake, vtol position messages in that order.
but the 3rd one didn’t have VTOL appraoch and
Reached WP
VTOL airbrake v=19.6 d=205 sd=192 h=51.0 -–> lift motors started to spin
RTL
VTOL position1 v=17.8 d=222.7 h=50.2 dc=18.2
VTOL Overshoot d=222.7 cs=-15.9 yerr=141.6
I don’t clearly understand logics behind those different behaviors but it seems 3rd back transition had lift motors spinning already before RTL was triggered. That is how it could manage to turn its heading aggressively into the direction toward homepoint.
