Hi,

Have recently built up an Octocopter, which is using a 3DR pixhawk with 3.2.1 and has been calibrated (compass MOT etc), auto tuned and generally is running really rather well, but for one issue, YAW whilst in automatic mode.

The below graph shows the desired and actual yaw whilst performing a small mission at 60m AGL.  As you can see it is slow and a bit sloppy when yawing around to its next  heading from waypoints where a delay command was in effect, hunts a little whilst travelling from one waypoint to the next (note this was an almost windless day), and most annoyingly will yaw around randomly whilst coming into land.

I had similar issues with my older Y6 but fixed them quite easily by increasing RATE_YAW_P from its default of 0.15 to 0.3 and RATE_YAW_I from its default of 0.015 to 0.03.  However I cannot do this with the octocopters parameters, as RATE_YAW_P can only be increased to a mximum of 0.25 (from its default of 0.2) and RATE_YAW_I cannot be increased any further from its current default of 0.02.

I am under the impression that it is unable to maintain its heading and therefore these values need to increase slightly (usually by the same amount each, which in this case is not possible), rather than decreaseing them as I dont think it is osciliating.  I have tried increasing RATE_YAW_P to 0.22 (leaving RATE_YAW_I at its maximum of 0.02)  and repeated the mission but it had no obvious effect.

So before I just try randomly altering numbers up and down can any give me any hints as to an easy way of tuning the YAW and what to avoid?  Also, should I be thinking of altering RATE_YAW_D ?

I have attached the log of this flight, thanks in advance for any help :)

Regards,

S.

2015-06-09 17-58-00.log