I have a QAV400 with Pixhawk, under which I am mounting a stabilized gimbal. The gimbal has rubber vibration damping balls to isolate vibration. Trying to tune the PIDs, the copter shakes the gimbal on the rubber, kind of swinging it in about a 5Hz oscillation. When I adjust the PIDs down to stop this, I have so little control left, I can hardly keep it flying. If I zip tie the rubber balls flat, I can tune the PIDs to fly really well, but then more vibrations get to the camera.
I balance my props, whether Graupners or cheap carbon fiber ones, and I have a few types of gimbals with different stiffness of rubber, manual PID tuning or autotune, it still does this. I have been ready to give up on this whole thing, but since I can't find anything like this in diydrones or Google, I know it is something I'm not thinking about right. Has anyone else seen this?
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I should also add that I am using AC 3.3-rc7, but no different in this case than earlier AC versions. This also doesn't have anything to do with tunings in the gimbals as it does it even with them turned off.