Position Control Gain Parameter

I need to lower the gain for position control. When it’s windy my plane rocks in the wind. What parameter am I looking for? Every other mode works well just not position control.

log here http://logs.uaventure.com/view/dfztG6auv7PTQsot7ZXGGD

Horizontal position error MPC_XY… it is set to 1.25. i think it is to high. for me 0.9 is ok

I believe that is a multirotor parameter I am using a flying wing

Hi Justin,

It’s truly remarkable how badly the system tracks the roll setpoint but just in position control.
I’ll open an issue and check what’s going on. Maybe something is screwed up with the turn coordination.
Thanks for reporting!

See this issue here https://github.com/PX4/Firmware/issues/4511
However, I was confused by the logging and therefore, the performance is not as bad as I thought.
I’ll see if there’s anything else I can find.

@tumbili I have been doing more testing and the issue persists in light winds. As soon as I let off the sticks in a bank I see the wings rock up and down for a couple seconds while its flying straight. The only mode it happens in is position control all other modes work without issue.

I have identified the problem in the log and I will fix it. At the moment I’m not so well so it’ll take me some time. Thanks for testing!

Here is the issue: https://github.com/PX4/Firmware/issues/4523

The problem is clearly visible in the log but I have no idea yet what is causing it.
I’ve been trying to reproduce it in SITL without any luck. Even if I apply a side force to the model (simulating wind) I can’t reproduce it. If you have time to do some testing could be please do the following.
Can you setup a missing which flies a lot of straight lines in different directions? I want to find out if this is a position control only problem. Because what the position controller does at the end of the day is to fly a mission along a short line.



See log link for the flight you requested. I noticed when it rocks hard when I come out of a turn sometimes it changes direction on me.


Justin, I’ll give master a test on another airframe today. Should give some more insights on what’s going on.