VTOL tuning high yaw gains and ground oscillations with vectored tilt Quicktune LUA

ArduPlane VTOL Plane
1

Hi,

first a huge thank you to the creators of the LUA QUICKTUNE script for VTOLS! @tridge @hwurzburg @hendjoshsr71 @Iampete1 @magicrub

This is incredibly helpful and enables us to do an inital tune of our aircraft in a small space with a safety line attached to the aircraft.

We are building a Quadcopter with two big motors on the fuselage and two smaller motors on the wingtip that can be tilted for yaw control. RPM-Yaw control is not possible due to the propeller arrangement.
YAW_Headroom is set to 0.

The Quicktune code brought us a great tune on pitch and roll. On roll it is almost too direct but thats something we can manage and change later.

We do have problems/questions on YAW.

  1. We already started with a P value of 2 from our previous rough manual tuning. With extended values for the LUA script we still reached the limit both on P=3.0 and D=0.5.
    In the air this felt incredibly good on yaw. Finally we had a precise and direct actuation.
    Unfortunately these settings result in heavy oscillations while on the ground.
  2. we manually reduced the values to P=1.6 D = 0.02 → fixed the ground oscillation. But the tune in the air is much worse again.

Does anybody have comparable experience or even a hint how we can approach this better?
Higher I values instead of P/D?

-Christian

edit: we also tried lower P/D values within the suggested limits. It was barely flyable and the quicktune automatically going up to the limits again…

2

try setting the yaw axis FF term as explained here Tailsitter VTOL Tuning — Plane documentation for a vectored yaw…for vectored yaw FF is sometimes the dominant pid term…then rerun yaw QuikTune

2 Likes
3

Hardware option. You could consider to tilt/cant the motor angles to increase Yaw.

4

on vectored yaw, cant has no effect, total throw does…but I doubt that would have impact…its a tuning issue, not max throw issue

5

thanks a lot!
We didn’t look at FF yet.
Will try as soon as weather gets better.