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Q_Loiter and vectored yaw problem

(James Stewart) #1

So I’ve gotten my vectored yaw quadplane tiltrotor flying in Q_Stabilize and Q_Hover. But I’m seeing some behavior that I don’t understand whenever I try to switch to Q_Loiter. For reference, my setup is a quadplane with the front two motors tilting and the rear two motors fixed, on arduplane v3.9.3.

Basically, whenever I put the aircraft into Q_Loiter, the tilting mechanisms become linked to throttle. At minimum throttle, they point straight up, but they tilt forward as you advance throttle. They stop at around 45deg, at half throttle. Moving the throttle stick beyond that has no additional effect. At first I thought that the q_tilt_max parameter would have an effect on it, but it does not. I also thought that the q_vfwd_gain was involved, but I have that feature disabled.

The one thing I CAN tell is that it’s linked to the vectored yaw settings. Setting the tilt type to continuous eliminates the behavior, and my other VTOL (a similar configuration tiltrotor with non-vectored tilt) does not have this issue.

I’m tearing my hair out trying to figure this one, as none of the quadplane params I’m aware of seem to have any effect on this. Could it be a bug? I know others are having successful flights on tiltrotors using vectored yaw, but I don’t know if any of them are using Q_loiter. Any input from those people would be appreciated.

(James Stewart) #2

Followup for anyone who runs into this issue: I solved it by brute-force comparisons with a set of known working parameters, from a different aircraft. Eventually found the the SCHED_LOOP_RATE on my original setup was 50, but 300 on other aircraft, and changing that fixed the issue. Not sure how or why that works, but it does.