I am switching some airfraims from PX4 to Ardupilot and the attitude gains I have copied over from very well behaved vehicles are unflyable. In QGC the I and D gains do not have units so I was wondering if anyone was familiar with the difference in the two flight stacks PID calculations. I did notice the addition of a low pass filter on the P rates which seem to be the primary cause of the instability I am seeing.
I think you better off starting from scratch, we have autotune so its not that painful. See
I am planning on using the autotune and it worked very well on a larger airframe I have. My other vehicles are uniquely small and heavy so the quad default values are not good enough to hold the vehicle still to begin the autotune.