@JoshW I was recently helping a user out with what we call the toilet bowl effect where the heli will oscillate in a circle about a point over the ground when it is in Loiter mode. I had tuned my attitude controller for my Synergy 626 with @Leonardthall and hadn’t really had the chance to enlist him to help me with the loiter mode. So I did a flight with my 626 to look at loiter and found a significant difference in my settings and what we have as default settings for Tradheli. The reason why many of our users are having this issue in a hover is that we don’t use any PSC_VELXY_D gain. My set up has this gain set to 0.5 and my aircraft holds a rock solid hover.
So it got me thinking back to the data you provided for your flight and I was concerned with the pitch oscillations that the aircraft was experiencing on accel and mostly on decel. If you look at the desired and actual velocities of the position controller you get this.
Notice how out of phase the desired and actual velocities are. I think if you add in some PSC_VELXY_D gain, you wont get the oscillations that you are experiencing on the decels. I’m not sure what the reason was that this gain was defaulted to zero for tradheli. But I think it will make a big difference in the loiter control. Just though I would follow up with you on this and see if you wanted to investigate that.
By the way here are the full set of PSC_VELXY settings. I have not taken these beyond 10 to 15 m/s. So I’m not sure if the aircraft will be stable throughout the envelope with these.
PSC_VELXY_D,0.5
PSC_VELXY_D_FILT,5
PSC_VELXY_FILT,5
PSC_VELXY_I,1
PSC_VELXY_IMAX,1000
PSC_VELXY_P,2
Regards,
Bill