Oscillation even at minimum gains!

I put an APM on a small 160 sized quad (I know it’s not meant for tiny quads…), but I can’t get it to stop oscillating. It flies best with all acro gains at their minimums, but still oscillates pretty bad. Is there any way to disable the minimum gains in Mission Planner so that I can lower them further?

Please provide tlogs and/or dataflash logs to help troubleshoot your issue.

Here are the logs from a couple short flights (less than 5 seconds because of the oscillations). I hope this is the right file type.

The logs should be up once an admit approves my post…

Update: The main problem is the roll axis. The quadcopter is an H frame, so it has enough rotational inertia in the pitch and yaw axes, but very little in the roll axis. Just for test purposes I attached a horizontal beam stretching out from the roll axis and attached little weights to each end, to increase roll rotational inertia. It worked. It was the first time I was able to fly for more than 5 seconds. This is only a temporary solution, though, because the horizontal boom makes the 160 size quad into a 300 size footprint, and it adds a lot of weight.

I’m at a loss. The flight controller is more than capable of stabilizing this quad. My only hurdle is the completely arbitrary and useless (and dumb!) minimum that the software (Mission Planner or APM Planner 2.0) enforces on the P gains.

Any ideas to get past the minimums?

I’m planning to put an APM micro on a 120 quad so very interested in your results. I have a 250 quad with APM micro flying good; had to lower pid values below that allowed in the Extended Tuning screen. You can go lower by using the Full Parameters List. I had to go down to P=.04 I=.04 D-.004.