I am hoping that I can find some help for a problem that I have been having for awhile.
When I first installed the APM on my TRex 450 I was running the ESC (Align 35X) in normal mode, not governor. I had the PIDs for yaw tuned for good tail control. This was with the 3.0.1 code. I am now running 3.1, with no change.
In pursuit of increased flight time and a constant rotor speed when climbing and descending, I switched the ESC to governor mode. Ever since the switch, I am unable to get rid of a constant tail wag (about 3-4" in amplitude at the tail rotor). My current settings are:
Stab Yaw P: 3
Rate Yaw P: 0.1
Rate Yaw I: 0.15
Rate Yaw D: 0
Rate Yaw IMAX: 20
It seems to be more pronounced at lower rotor speeds but can I not totally eliminate it with governor mode enabled. I can lower the rate P and the oscillation amplitude becomes more like 1-2" at the tail rotor, but then I have poor tail holding. I have played with different values of I and D as well, with no luck.
As I understand it, the throttle output from the APM to the ESC is fixed when in RSC mode and should not be affected by PIDs. Is this correct? (Was wondering if what I’m seeing is a motor torque induced yaw)
Has anyone else experienced this with an ESC in governor mode? Is running the governor at 51% throttle too low? Any other thoughts/fixes?
Edit: Rate Yaw FF: 0.04