I am in the process of building a very large quadcopter with 25" props and T-Motor U11 Motors, which is currently very overpowered but still flies ok. Due to its size and power it does not fly at all well on the standard PID gains of arducopter, I have decreased the PIDs to a point that it is now possible to fly after some interesting first flight attempts. However now I am looking to conduct an autotune. However as I currently understand it when autotune is engaged the PIDs are reset to default, when these are reset the quadcopter will crash, period! So my question/request is… is there a way of making the autotune start from the PIDs that are currently programmed, i.e. not using the defaults?
I’d also say be sure to follow the wiki guidance of “For large copters (with props at least 13inch or 33cm diameter) set the Rate Roll and Pitch filters to 10hz (in Copter-3.3 these are RATE_RLL_FILT_HZ and RATE_PIT_FILT_HZ, in Copter-3.4 they are ATC_RAT_RLL_FILT, ATC_RAT_PIT_FILT)”
On my quad with 15in props it looks like reducing the initial P for pitch and roll to 0.06 and yaw to 0.1 and reducing aggressiveness to 0.05 helped to do autotune.
Cheers for all your help!
Ok thank you for clearing up that autotune does use the current PIDs it does make an awful lot more sense!
I had already set the roll and pitch filters too 10Hz.
Yes that is the strange thing though, I reduced all the gains by half and was able to fly the copter in stabilise mode and althold, however as soon as I switched into autotune the copter started overcompensating massively to correct the initial input, causing the copter to flip and crash.
Could this be caused by motor sync issues perhaps?