Attitude change and drift during flight

Hey guys,
I’m having a problem during manual flights in Alt-hold mode without GPS.
After takeoff the quadcopter gets to the the desired height and hovers. Sometimes during that hover or after a short flight the copter suddenly tilts on one or more axes and starts drifting. I can induce this sudden tilt if I fly the copter in a relatively aggressive angle for a short period of time (~4-5 seconds).

sometimes after a manual 360 degree yaw spin the drifts disappeared (and randomly appeared later)

Here is the flight log file:
https://drive.google.com/file/d/1hX5QYyUhqx1I2lars0sZb7n3OEKN0JQA/view?usp=sharing

Thanks,
Martin

You will need to reduce the vibrations in order to get it to do what you want

You can try the Calibrate Level in MissionPlanner accel calibration section - make sure you whole aircraft is actually level first

When I first set up the copter I calibrated the acc through the mission planner menu - fo you think I should re-calibrate?

I manage to fly pretty good, the copter even keeps its height pretty well, its tgat specific problem that confuses me. Are the vibrations related to that issue or was it a general recommendation?

Do you know what the problem is?

Thanks

There’s a specific button just to calibrate level, you dont have to do the whole accel calibration procedure.
I just wondered if that would help the drift.

We have a flight controller that had failing IMUs, it thought it was flying level but really diving to the ground at crazy angles - so that can definitely happen too.
If I leave it turned on just sitting on the desk, eventually the HUD drifts pitch and roll quite a lot, much more than just heat-related.

Is that something that can be done by using the Harmonic Notch Filter? or maybe other arducopter features?
Or do I have to change it on a mechanical level?

I took a screenshot from the log to point at my problem specifically:

I hope this helps you guys :slight_smile: