I’ve done some initial test flights of an OMP M4 (Pixhawk 6c Mini) and I’d like a second opinion before I start autotune. Here’s the log:
(Note, it was windy during this test, but in previous flights with ideal wind it hovers more or less in place)
A couple specific questions:
I’ve set up the notch filter using the throttle, rather than the RPM from the ESC. When I tested the RPM on the bench it seemed to work fine, but in flight the numbers don’t seem steady enough. I’m using the ESC governor (50% - 2000 rpm) and it seems to be stable. I set up the filter using the same methodology I would have for a quad using the filter webtool. Looks good to me, but I’m open to comment.
The OMP instructions suggest -5/+12 for a pitch range for “hover” or non-aerobatic flying so I’ve set up min and max based on that. It seems okay to me, but I can’t shake the idea that -5 is too much for the min angle. I’ve set LANDING_MIN to -2. I haven’t seen any behavior to make me think there’s an issue so if this is all in my head then let me know.
The tail does wag back and forth in flight but I’m assuming that will get cleaned up in tuning.
I’m open to any comments or suggestions before I start tuning. I’d like to try the auto tune method.
The RPM feedback looks bad, I would suggest to set a static notch instead centered at 33.3 Hz.
Looking at FFT it seems that 2/rev and Z accel are quite high. Is the rotor tracking perfectly tuned? I understand on small and very rigid rotors is difficult to track to perfect equality, but I would spend some time and check if something better would be achievable.
This range looks fine to me. I run -6 /+12 on my Protos 380, handling is perfect.
More of a discussion question: Given the fixed throttle setting on this heli is there any real difference between using a static filter versus a throttle based filter? Do you see an advantage to using the static filter? I’m guessing it would use fewer CPU resources.
I didn’t notice anything obvious in flight but I’m going to try to do some manual tracking on the bench and see if I can improve it.
I believe the throttle based filter slides along with throttle (so collective movement in our case) - not the RSC output. That’s why I thought a static notch might be a more appropriate choice, you want it at the rotor frequency.
That makes sense. It never occurred to me that the filter would chase the collective. That’s no use. I’ll update to the static filter and go from there. Thanks again!