Pitch axis Oscillation in auto mode, big copter

ArduCopter Copter 3.5
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1

Hi, I have a problem in auto mode with a quadcopter, flight well at started but a little oscilations begin after a few waypoints. It flight well in stabilize and Althold, in Loiter mode isn´t perfect, the wind affect a little its altitude and position, autotune already did it.

The follow things was proved:

  • Change EK2_ALT_SOURCE to 2, and EK2_ALT_M_NSE to 6, this improved the AltHold Mode.

  • reduce LOIT_JERK from 1000 to 500, and LOIT_MAXA from 200 to 100. It seems works, a little. but I don´t want reduce more because is out of limits.

  • Reduce ATC_ACCEL_P_MAX from 4000 to 3000, no change noted.

  • Limit ANGLE_MAX to 25. no change noted.

  • Also change the PID values of Pitch axis to same in Roll, the picture shows the original PIDs after autotune.

    PARAMETROS_AUTOTUNE_Abril
    PARAMETROS_AUTOTUNE_Abril.png1370×770 138 KB

The oscilation it can noted in the follow image, the bin file is also attached. This logs is from 3 days of test.

imagen
imagen.png960×565 33.1 KB

https://drive.google.com/file/d/1XO-BmHHbsUIV-BtWJteSd9NN8djWeIR1/view?usp=sharing
https://drive.google.com/open?id=1UOCsVhIxKEvHzHzIAbL7EyHhta2YNhgT
https://drive.google.com/file/d/1WerqKhiigx7QVU9Ka9S8yG1AObsMA7r5/view?usp=sharing

2

The quadcopter hardware:

  1. motors U8 pro 135Kv.
  2. ESC Turnigy 120A.
  3. Battery 16000mAh 6S x 2, 12S serial conection.
  4. 22x6.4 T-motor propellers.
  5. Frame 1200mm
  6. Total weight is 9.5Kg with Gimbal (tuned and powered).
  7. Pixhawk with RDF900 telemetry (issues with telemetry too, but it’s other history).
3

Joab,

I don’t have a chance to open your logs right now, but your setup is quite similar to my current one in terms of size (24x7.9, 14kg TOW, 135KV). The one thing I notice is that you have a fairly low Filter setting of 5Hz only on Roll/Pitch axis - is that intentional? I found for my setup that 10Hz works better - have you tried that?

Also your throttle accel parameters seem to diverge from the recommended 2:1 ratio - is that intentional? might not be related to your issue, just noticed it…

Christian

4

Hi Christian, thanks for your reply. The filter configuration is intentional, when i tried to use 10Hz it caused vibrations increment. I’ll check the throttle accel parameters just in case.
Reagards.