ALT Hold (no sonar) problem

Hi guys,

I’m getting a very strange behavior when I enable the AltHold mode (or loiter…), my copter don’t stabilizes at all the altitude, getting big oscillations in altitude. In the first flights the behavior was a little better but i heard a constant “pulsing” noise from motors when AltHold activated.

The barometer is covered with foam, the apm case have black tape to avoid light, and my vibrations are under control ( I guess…).

In the previous firmwares the machine was flying great in all modes, now with 3.1 stable I’m desperate with this issue. I tried to play with Alt_Hold value, and tuning down the THR_ACCEL_P to the min value of 0,450 (default is 1,000) but no luck.

I have here a dataflash log (with IMU enabled) that you can analyze to tell me if I have some problem in my setup.

Thanks in advance!

No help? Anyone? :neutral_face:

This is the APM:Plane forum, probably best to try post it in the APM:Copter forum: viewforum.php?f=3

I’m pretty sure it’s a vibration problem. They look like they’re within limits but it’s borderline at times and I can also see that the CTUN Baro Alt diverges by >1m from the GPS Rel Alt (which is actually the inertial nav altitude estimate) so that’s normally a vibration problem. More vibration dampening required!
hope this helps.