Notch Filter Setting

ArduCopter
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1

hey there i am using Pixhawk cube orange with mini carrier board, t-motor mn6007 2 320kv customized motor, flame 70A esc, mf2211 propeller,27000 mAH 6 cell battery.
I am starting with tuning process in which i have came across a strange thing

  1. Pixhawk’s gyro1 and gyro2 is having significant amplitude change. Inside a single cube how is that possible ?

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    GYRO 1
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    GYRO 2
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  2. I have two formulae for INS_HNCTH_REF
    1st: Directly enter value of CTUN->ThH from log file
    2nd: INS_HNTCH_REF and/or INS_HNTC2_REF = hover_thrust * SQUARE(min_freq / hover_freq )

which formulae should i trust more ? in 1st method ref is 0.24 and from 2nd formulae value is 0.144 and as per filter value tool i am getting maximum attenuation at 0.21 reference value.

Thanks for your help

2

They are built different, and use different dampen systems.

The second formula is correct

3

how should i calculate hover_frequency and minimum_frequency can you help with that ?

4

for two different amplitude for GYRO1 and GYRO2 i think 0.09 and 0.02 amplitude is too much far from each other that’s why i am curious about that

5

I’ve seen the same formulas as Aayush, and just to be clear,

hover_thrust = hover_freq ?
and min_freq is the minimum frequency that we wish the notch to track down to?

6

hover_thrust = MOT_THST_HOVER (after 30 second flight in ALT_HOLD mode)
hover_freq = hover noise frequency
min_freq = the minimum frequency that we wish the notch to track down to

1 Like
7

ok that’s really interesting but how do do i calculate hover_freq = hover noise frequency ?
here is my log file: 00000055.BIN - Google Drive

8

You do not calculate it. You read it in a graph.

Install ArduPilot methodic configurator software and use it.

9

i guess methodic configurator gives value of ins_hntch_ref. That’s really good and easy but if you can help with manual calculation by graph that will be something new to me.

10

There is nothing to calculate:

  • the frequency is the frequency of the peak.
  • The min frequency is the frequency where the peak starts.
11

so in my case frequency of peak is 39 hz and 35 hz is where my peak is starting am i right ???

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12

Yes, that is correct, enter the values in the formula now

13

Your frequency resolution is not that great. But that is normal when you do not use the configurator.

14

ok thanks
i get that and now i will proceed with configurator