Hi, I ran FFT analysis of the flight logo to enable the notch harmonic filter, but instead of a pronounced peak at a certain frequency, I see a lot of them from zero to 400Hz. Here the log: https://drive.google.com/file/d/1umHaak5GCsl-EQtvycb6opmm7Nx4ZIOO/view?usp=share_link
Suggestions?
Thank you
There’s definitely a lot of peaks there
It looks like the base frequency is 35Hz and the harmonics are 70Hz and so on.
You should be able to use:
INS_HNTCH_FREQ,35
INS_HNTCH_BW,10 // your peaks are quite narrow
and start with
INS_HNTCH_HMNCS,7
and increase as necessary after testing using the pop-up dialog to get the correct bitmask
There’s quite some level of vibrations, you might want to try and reduce that.
EDIT:
I’m not sure about Heli, but in multirotors we would also set:
INS_ACCEL_FILTER,10
Can the analysis be affected by the presence of training gear?
@xfacta thanks for helping Walter out. Yes the heli vibration frequencies are very narrow since we run constant rotor speeds. Hear are some slight modifications that I would make to your recommendations.
@Brighela
Set INS_HNTCH_HMNCS,11
Typically for a two bladed heli the first, second and forth harmonics are the strongest source of vibration.
Set INS_ACCEL_FILTER,20
Unless there is a good reason, I stay away from setting this filter below 20.
I’m not sure what is causing the 400hz spike. Especially for an electric heli.
The gear could affect the magnitude of the resulting vibrations but the frequency will be the rotor speed since it is the forcing frequency.
So your vibrations could reduce when you pull the training gear off. However I don’t think they would be causing any significant vibrations as their natural frequency is probably much lower than the rotor speed.
Today, after entering the notch filter data, I did three flights. In the first one, shortly after take-off, a very intense vibration developed (I think resonance of the learning trolley), I landed and I received some error messages that I didn’t understand. Then at one point the helicopter drifted hard left/forward. So I disconnected and reconnected the batteries but I was getting errors all the time, even though on the last flight the helicopter seemed to be fine except for a slight left drift. Can you help me understand the errors and how to act accordingly? Thank you
https://drive.google.com/drive/folders/1R2gT9r3XiV0wde-EY9ozFmha1CYq1gaa?usp=share_link