Hello, I am having an issue with Copter (4.4.4, 4.5, but I think it is not version dependent).
I observer that copter may occasionally start to lean on roll or pitch axis. After several seconds it gradually returns to level position but it takes a lot of time. If I enable GPS then everything is fine. I am flying in AltHold mode, so GPS is not even used there.
I checked SITL and I see same picture there (I first thought that it might be due to vibraions on a real quad, even though they are not high there). It is interesting that AHRS2 roll/pitch actually shows that pitch/roll are not level.
Here is clearly visible that when there are no inputs after area marked with black circle AHRS shows different values. I’ve also marked another area with red circle to note that it actually repeats relative changes. Log for this case is here: 00000004.BIN - Google Drive
And here is clear that while not input given, copter just leans at different directions
Log for this graph is here: 00000001.BIN - Google Drive
It seems that maybe ardupilot is being very conservative to level copter when GPS is not aiding or something like this.
Would appreciate any help on this.
Thanks.
Edit: Yes, I’ve read all related/similar issues which people have with GPS disabled. But none of them was actually solved and vibrations are definitely not the case, nor the IMU imprecision, as issues can be reliably reproduced in SITL. Moreover if AHRS actually shows correct attitude that means that AP knows what happens to quad.