At my tuning-wits end

Log Analysis -- deprecated Copter Logs -- deprecated
1

I guys,

I have been struggling to rebuild my quad after my original 3DR frame crashed. I’m using a DJI F450 frame with 800kV Turnigy motors, 11 x 5.5 APC propellers, 3S 500 mA hours battery, and some added stuff such as a camera gimbal and video TX. Ready to fly it weighs around 1.7 kg and it hovers around 50%.

My problem is that I appear to be completely unable to tune it properly. This may of course relate to the quite large degree of vibration I am seeing. I have balanced the motors by putting tapes on the side of the barrel and feeling for the least vibration in the frame, I have balanced the propellers in a prop balancer by pitting crew on the side of the hub and tape way out on the blades so that it holds position in any stance on the balancer. Finally, the APM is mounted on one small ante vibration pad in each corner and secured with a piece of rubber band. Still, as you can see from the attached log, vibration is still significant when flying.

As for the tuning, I tried using autotune which set rate-P quite low (0.09). I have attached two screenshots, one showing the vibration issue and another showing the roll input versus actual roll.

I have fought with this for quite some time now, so I would very much appreciate any input you guys have on either reducing vibration or getting the tuning right. I have attached a screenshot of the APM Mount for your convenience.

2

I don’t see anything obvious that would cause that, the vibrations are high but not to the point where it should cause major issues in stabilize. It would probably be helpful to see a log of the autotuning process. If all else fails, I’d suggest using this method youtube.com/watch?v=aq1jXHMiJgg to tune the copter manually. I was able to achieve pid values very close to what autotune got.

I must ask, are you sure you are saving the autotuned parameters? When it’s done, you must switch back out of autotune, then back in to test the pid’s, then land and disarm with autotune engaged. I’ve also had problems in the past with APM Planner resetting my pid values when I connected through telemetry.

For reducing vibrations, you can’t beat a mount like this thingiverse.com/thing:160655 (I had a friend print me one).