AC3.1 rc5 yaw issue

i got a weird problem with yaw control like this:

- when yaw left, my quadcopter tend to move to the right side of copter

- when yaw right, my quadcopter tend to move to backward

note these happen in stab mode and loiter mode. in loiter mode, quadcopter move a large circle before return back to one position.

at first i thought it was my frame/motor/esc, so i switch to new frame/motors/esc, same issue!

also, change to kk2 controller did not have this problem.

i use external compass, and rise the compass & ublox gps 10cm separate to mag interference sources.

i think there is something need to improve in term of control algorithm.

pid.png

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  • Developer

    We think we've found and fixed a problem with how AHRS_TRIM was applied.

    I've tested it with an APM2 mounted at quite an extreme angle (leaning about 5.5deg forward) and the impact on Loiter is dramatic.  With the current AC3.1 code the copter drifts off badly when it's yawed.  With the new code it stays in place mostly.

    This won't make it into the aC3.1.1 release but it will be in AC3.2.

    Sorry for the troubles!

    • Thank you very much Randy! Can't wait to test the new firmware on the same platform...

  • Have similar yaw problem with HK SK450 "DeadCat"

    Yaw left - copter drift left, yaw right - drift right. Faster yaw - faster drift.

    Read about changing the angle in the Arducopter code, but new Arducopter has V-frame. Maybe wrong place of buttery or APM on frame? Is it important where to place APM - at the center of gravity or at the center of thrust?

  • I'm not sure how the AHRS values are derived and in the parameter list? If its from aan APM setup routine then maybe not a bug. If it arrives in firmware updates then it needs to be sorted.
    Since manually zeroing the values my quad behaves but I've got a horizon lean in the MP HUD.
  • basically speaking, turn a copter some degree, have to trim again in order to make it stay still ! 

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