Harmonic Notch Filter Setup – Y6 QuadPlane with 30" Props

General
1

Hi everyone,

I’m looking for guidance on the Harmonic Notch Filter configuration for our Y6 QuadPlane and would appreciate recommended parameter values based on the measured vibration spectrum.

Aircraft setup:

  • Y6 QuadPlane – 6 lift motors

  • 30" 2-blade propellers

  • CubeOrangePlus

  • ArduPlane 4.6.3

  • ICM45686 primary IMU

  • Normal PWM ESC control; no DShot/Bidirectional DShot

  • ESC RPM telemetry: ~10 Hz with ~4% dropouts

  • Hover RPM: ~2558 RPM (~43 Hz fundamental)

Vibration data:

  • VIBE average: ~8–9 m/s²

  • VIBE peak: ~23 m/s²

  • No clipping

  • Raw gyro FFT shows:

    • 1P: ~43 Hz

    • 2P: ~85 Hz

    • 3P: ~127 Hz

    • 4P: ~169 Hz

    • 5P/6P: near noise floor

Current Q_M_THST_EXPO = 0.77.

Questions

  1. With no Bidirectional DShot and only 10 Hz ESC telemetry, should we use throttle-based notch (INS_HNTCH_MODE=1), or is the ESC telemetry usable for frequency tracking?

  2. With measurable energy up to 4P, what would be the appropriate INS_HNTCH_HMNCS value—3, 7, or higher?

  3. What would be a suitable starting INS_HNTCH_FREQ, BW, and ATT for this 43 Hz fundamental and 30" prop setup?

  4. Is the harmonic notch worthwhile given the relatively low VIBE levels, or would you recommend tuning without it?

  5. Does Q_M_THST_EXPO = 0.77 require any consideration when using throttle-based frequency tracking?

  6. Any concerns with enabling the notch on both IMUs of different types?

I will attach the .bin log and Filter Review results.

The main objective is to determine the least aggressive notch configuration that adequately attenuates the measured 1P–4P harmonics while minimizing phase lag.

Thanks.

2

You already had a thread with answers. Why open a new thread?

3

This is for a different bird with a different configuration and a separate set of flight logs. The vibration characteristics and filter requirements are different, so I’ve opened a separate thread to get recommendations specific to this aircraft.

4

Got it, thanks.