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Harmonic notch support (ESC, Throttle, FFT)

A thread for configuration of the harmonic notch in 4.1.
Please make sure you have read https://ardupilot.org/copter/docs/common-imu-notch-filtering.html and https://ardupilot.org/copter/docs/common-imu-fft.html before posting here

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Thanks Andy for all your work on this!

These are the params currently used

pre filtering

first question: why I cannot see the control area in the prefilter graph?

post filtering

Are the params sets correctly? In particular with ESC telemetry my confusion is how to set FREQ and BW, somewhere I’ve read to use FREQ to target the lowest noise freq, is this correct?

That seems odd. Can you post both logs and your full parameter set?

@andyp1per looks like he is showing accelerations. The harmonic notch does not affect accelerations, right? @Giorgio_Rinolfi should look at gyro data to determine effectiveness of the notch.

Right

More and more words

Looking at those graphs, without the log, it looks like you need:
INS_HNTCH_ENABLE,1
INS_HNTCH_MODE,3
INS_HNTCH_REF,1
INS_HNTCH_FREQ,135
INS_HNTCH_BW,67
INS_HNTCH_ATT,40
The actual logs will tell more

In the @Giorgio_Rinolfi post there are both acc and gyro FFT graph.

From what I understood with INS_HNTCH_OPTS=2 the frequency of the 4 notch comes from the ESC telemetry RPM converted to Hz for each motor, so the params INS_HNTCH_FREQ and INS_HNTCH_BW could be leaved to default values, but this should be confirmed or confuted by @andyp1per.

My apologies. I missed that when I was viewing it from my phone.

That’s correct, but in the case INS_HNTCH_FREQ also represents the minimum frequency that will be tried so you should pick a frequency below your first harmonic and then make the BW half that

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Servers by jDrones