Plane 4.1.7 Transition issues - dangerous oscillations

ArduPlane Plane 4.1
1

We use plane firmware for 25kg VTOL medical cargo drones
After several thousand flights with version 4.0.6 we switched to version 4.1.7 because of UAVCAN Airspeed sensors which were not compatible with version 4.0.6

We noticed an abnormal behavior during the horizontal / vertical transition:

  • the transition is very smooth on version 4.0.6, the throttle of the vertical motors gradually increase

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  • the transition is abrupt, the vertical motors throttle is higher, the drone oscillates dangerously for several seconds.

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The parameters are identical on the 2 versions and this problem is present on all the drones of our fleet

My questions:

  • Were new parameters introduced in version 4.1.7 that affect the transition?
  • How to setup a smooth transition like on version 4.0.6?

I hope this comment will be useful
I thank the community for their work which allows us to fly safely and deliver medicines to remote areas in Africa

1 Like
2

I had similar issues when moving my 4+1 quadplane with tractor prop from 4.0.6 to 4.1.7. It seems to be better now, and I’m not sure what if anything I did to change it.

I had worse issues when I manually tuned the same aircraft pitch loop and yaw damper more aggressively. It was fine in FBWA, but the next flight had violent oscillations. I suspect all of this may have been because the gain scaling (logged as AETR.SS) is too aggressive at low airspeeds, but it may also been because the elevator and rudder are in the prop wash, and so, especially during transition, have a much higher airspeed than the airspeed sensor would indicate.

3

Hi Chris, problem has been solved with v4.2.1

4

Thanks! I guess the fix was them adding the bit option to force the scaling to be <=1 during takeoff?

5

No I’ve only upgraded the firmware without changing the parameters