Understanding braking to a stop behavior in loiter/posHold

So I’ve put together a S500 quad to use as a learning platform for APM and I’m experiencing this strange pendulum effect when i release the sticks while at speed in loiter mode. The copter leans back to brake but quickly pitches forward and again leans back to slow itself and repeats this two or more times until it finally comes to a stop in a stable loiter. i think i need to start working with the loiter brake parameters but my searches haven’t found anyone with my problem. Before I blindly start changing settings, I hope someone has had this issue as well and knows a cure. Thanks for any help. Mike

Position Hold is the only mode where you should be seeing braking as this is a new mode. Loiter should just float along and stop.

Seems from your description it’s over correcting or to responsive. You may want to try auto tune to see if that cleans it up. You can turn it on and after its done test your results without having to save the changes.


I’ve been flying loiter mode and not posHold but thought they used the same settings but as you pointed out, they don’t. Im off to the field for some testing of posHold and see how it flys. Thanks for your input.

OK, got flight time with pos hold and I like the way it works except for one thing, it seems to randomly switch to auto land during flight. While flying in pos hold the copter starts losing altitude and full throttle won’t arrest the descent. I switch to either stabilize or sport mode and all is fine. Twice I guided the copter and allowed it to land during this behavior and once it touched down the copter disarmed itself which leads me to believe it was in auto land mode. I have no failsafe settings set for this to happen so now I’m stumped. After work I’ll learn to pull and read logs to see if I can find any clues for this.

DCM/EKF failsafe! I think this is the culprit. I’m running APM 2.6 and not pixhawk but if I understand this right, the DCM part applies to me, EKF is pixhawk only… Now if I can understand what’s triggering the failsafe…

i think this is the right file. land mode is being activated during flight in pos hold. not real sure what im looking at yet.

Adjusting the DCM value from the default 0.8 to 0.98 seems to have fixed the failsafe from being tripped so easily. Position Hold really does fly nicely, with just a bit more tuning I can see it working as good or better than NAZA.