Tricopter - Yaw servo not moving

Dear all,

This is a tricopter which flies reasonable well with 3.1.5. It does have a yaw problem, which I was trying to tune out (RATE_YAW_I). The hardware 6S battery, 390kv motors and 15x5.5 cf props @ 1.9kg Runs like a bat out of xxxx for 30 mins. Everything works, including RTL with an external compass

I have just upgraded the APM 2.6 (external compass) to 3.2, calibrated INS, Radio and compass. Recalibrated ESC’s for good measure.

However, I can see that the yaw servo is stuck on 1517 (this is from mission planner). The tri can take off, but with no yaw control at all.

After the update, I did do a load defaults in the Mission Planner.

Any idea where to start?

Thank you.


Please provide tlogs and/or data flash logs to help troubleshoot your issue.

Thanks for the quick followup. I have downloaded the log from the APM, ended up as four files. Please find two of them attached.


Dear all,

I have solved the initial problem by uploading the firmware again. Noted that the original problem was partly due to the yaw servo not moving at no throttle. This is probably by design, need to read the manual for 3.2 more carefully.

After the upgrade the yaw servo is now correctly twitching on disarm. I have not checked on arm (normally holding my breath on the first flight of new firmwares).

The frame is still slowly rotating when hovering, but I will look into tuning this later.

Case closed for now.


Yep. Gotta say a big thanks to the devs for the yaw servo upgrade. So many times in past versions i’d chip a blade while trying to disarm (servo would move with spinning blades at zero throttle).

So from a hardcore tricopterer, cheers guys! :mrgreen:

Bighans, try using more Rate_Yaw_I and Imax. Especially the Imax, I’d bet that’s your problem with the yaw not holding.