Strange oscillation in pitch axis on 10 inch FPV quad

ArduCopter Copter 4.3
1

I have a 10-inch FPV quad running copter 4.3.2 with a weird oscillation in the pitch axis.
The oscillation occurs when applying a positive pitch (braking) and worsens at a higher speed.

I have tried the following:

  • Autotune and manual tuning
  • Vibration damping on the FC
  • Activated notch filter
  • Different gyro and accel filter settings

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The drone weighs 2.3 kg and is symmetric around the roll axis. It is a bit longer in the pitch axis, and the CoG is less than 1 cm in front of the CoT.

Any idea what causes this vibration oscillation?

Log file with fast sampling activated is available here:

2

First I would set these based on MOT_THST_HOVER as per the Tuning guide:
PSC_ACCZ_I (MOT_THST_HOVER)
PSC_ACCZ_P (2X MOT_THST_HOVER)

Could you not run the Bdshot version of firmware and use ESC telemetry for the Notch filter?
And disable RAW IMU for logging so FFT can be graphed.

3

Seems like the PSC params fixed the problem. Thanks!

4

Cool. On high thrust to weight craft like yours these are important to get right.