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Oscilations when switching to mission from hover

Hi guys, I’m hoping someone can help shed some light on some odd behaviour I’m seeing.
I’m running a cube orange with the beta from about 4 weeks ago as I need the scripting functionality for camera control with herelink.

When I take off in loiter everything is nice and stable now. I then switch to a loaded mission and I get large oscilations, mainly in pitch, but also to a certain degree in yaw from what I can see from the ground, and the copter doesn’t move towards the programmed waypoint. The log below is from a test flight this morning that showed this behavior. (I had to tweak my yaw tuning at the beginning of the flight hence the small oopsie before the second take off)
https://drive.google.com/file/d/1L_MMJfhSfV0KPxxfJNrqyNae6uxXjet4/view?usp=sharing

On a previous flight where I saw the same behaviour, I then did a test by sending a “go to here” commande via QGC and this worked correctly, and I thought this would use the same functions, though I may be wrong there.

Hi @StefanHafner,

Thanks for giving Copter-4.1.0-beta a try.

I haven’t looked super deeply at the logs but it looks like a tuning issue with the pitch axis. In particular the ATC_RAT_PIT_P/I values look really high at 0.581. I’m pretty sure this number is the result of an AutoTune so I think it just hasn’t worked very well.

Could you try reducing this number by at least 10% (e.g. 0.522) to 20% (0.464) to see if this helps? You could try even lower if it is flying ok. Also normally it is good to drop P, I and D values together by equal percentages.

Hi @rmackay9

Thanks for the feedback. I did have to reduce the P value after the autotune, from memory from about 10.2 to 9.5, to reduce some high frequency vibrations, and it seemed to be flying well after that in position hold and loiter, but I guess as the contreols are manual they were a bit more gentle than in missions.

I’ll reduce the values tonight and give that a try again tonight, fingers crossed the wind dies down to let me do that :crossed_fingers:

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Hi @rmackay9

Thanks for your advice yesterday regarding the P/I values. I did a few short test flights reducing the values progressively and I can now fly missions without any vibrations. In the end I ended up taking them down to 0.28 and 0.27 respectively, but its flying well so I’m not going to doubt the values :slight_smile:

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@StefanHafner,

Ah, excellent news, thanks for the feedback!

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