Loiter Mode bred vibrations on camera gimbal

ArduCopter Copter 3.1
1

hi,
i am flying a 5kg copter with apm2.6 and current 3.1.5 firmware. i have mounted a lumix gh4 on an three axes brushless gimbal.
in stabilise mode the gimbal works perfect no swinging system and no vibrations from copter parts will affect the gimbal. but if i switch to loiter mode the gimbal starts swinging. imo this is caused from aggressive corrections made from loter and/or althold pid’s.
my copter is well powered, maybe a little bit over powered.

i adjust rate_roll and rate_pitch P to 0.08 to get good performance without oscillations(stabilised mode). all other settings are the default values.

my question is how can i adjust loiter and ald hold pid’s (Throttle Accel, Throttle Rate, Altitude Hold and and maybe Rate Loiter Pid’s in a way that the motors do not make corrections in loiter and aldhold so aggressive?

currently i am not sure which controller works wrong. i read this copter.ardupilot.com/wiki/loiter-mode/#Tuning. but on loiter tuning page i found no answer at all. currently my idea is that my altitude controllers maybe works incorrect.

here is a video which show the problem.
[youtube]https://www.youtube.com/watch?v=B5Xk0v1ncBU[/youtube]
i start flying in stabilize mode. you can see that gimbal works ok in this mode. if i reach target altitude i switch to loiter. and than the gimbal becomes vibrations caused by aggressive corrections made from motors. you can see it very well and also you can hear the motors which will make a lot of fast corrections. i do not mean the first shake caused from switching to loiter. this problem is known an caused if the copter is rising while you switch to alt_hold or loiter. i mean the smaller vibrations in loiter mode after changing mode and while copter is loitering.

2

Good question and problem in here also.

Hopefully someone replies.

3

does it also happen in alt hold mode? This might isolate the issue, if it happens in alt hold too it isn’t loiter related.

4
  • Run autotune with no gimbal attached.
  • Possibly reduce THR_ACCEL_P and THR_ACCEL_I in proportion to each other. You can test this in alt_hold mode.
5

hi,
today i lower Throttle_Accel P & I to 0,5 and 1,0, lower Altitude_Hold to 0,7 and Loiter_Pid to 0,8. Now vibrations in loiter and altitude hold are better but not gone. also i today noticed some small vibrations in Stabilize Mode. So, for next fly i also will lower Rate_Roll/Pitch P from 0,08 to 0,07. maybe tis will bring me near to zero gimbal vibrations. currently my Rate_Roll/Pitch I is at 0,1 and D is at 0,004. make it more sense to adjust D and I, or is better for preventing hard motor correction simply lowering P and let I and D as default.

6

here is a small video after changing althold and loiter pid’s.
[youtube]http://www.youtube.com/watch?v=noy5Uj7XV5I[/youtube]

alt hold and loiter now caused less vibrations as before. but i noticed also vibrations in stabilized. today i try a second tuning session also with tuning Rate_Roll/Pitch Pid’s. current problems are vibrations in loiter and alt-hold while flying forward or sideways. also in stabilize while copter is sinking or if you make hard throttle corrections via transmitter.