Accel 1 Clipping with PX4, no problems with Arducopter

Hello all,

I have a hexacopter on a custom built CF frame. It uses a Pixhawk 6c, and 13x4.5 plastic propellers. I have been experiencing problems with clipping lately. Most of the time I don’t get an error message until I switch from Stabilize to any semi-autonomous/autonomous flight mode. My frame isn’t super stiff, but it’s also much better than your average plastic DJI flamewheel.

Could anyone point me to troubleshooting this clipping issue?

Perhaps my allowed rates for acceleration and deg/s is too high? I know the plastic propellers probably deflect in high torque situations.


Log file: log_39_2023-5-16-10-38-50.ulg - Google Drive

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Here is another log, this time with the high logging rate. I attempted a short waypoint mission, and had to stop it halfway through due to erratic behavior.

That’s odd. @bresch could you maybe check this?

@JulianOes and @peterscache12 Are there any updates on this?

I’ve had a similar problem. I am experiencing very high acceleration metrics only when I run PX4 but normal levels when I run Arducopter. I have this system from UAV Systems International.

You can find the log files for two back to back flights - one with PX4 and one with Arducopter - that I did today here: Log files in google drive
I added the PX4 flight as a flight report in Flight Review. It can be found here:

The PX4 version I am using is the beta 1.14 because I needed a feature that it has for compatibility with my companion computer. The oddest thing about this vibration issues is that it appears IMUs 1 and 2 have higher accel than IMU 3 for in the flight controller (PixCube Orange+). The accel metrics from the PX4 flight are below:

I’ve done a lot of testing on this and pretty much ruled out a hardware issue (especially since Arducopter doesn’t show high vibration). This vibe issue has been killing me and nearly caused a crash in the log file I am sending (see the oscillations near the end of the flight).

Is there a better place than this to post this issue? I’ll likely post it in the Discord as well.


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I’ll look into the problem this week.

See in other thread: High vibration in Cube Orange+ - #35 by sibujacob

My conclusion is that the vibrations “look” big but as long as there is no accel clipping, this should be fine and any other issues would be from tuning and filter settings.

The Cube Orange and Orange+ uses some of the same sensors as other Pixhawks and also the same settings (mostly high rate and no on-device filtering). The filtering is then done on the PX4 side as far as I’m aware.