this has been bugging me for a while and im at my point. running a ronin type gimbal on a heavy hex and the roll axis just slowly drifts left over like 30 seconds of hover. not a huge amount but enough to ruin footage. ive done the calibration proecedure probably six times at this point, always on a flat surface, always let it warm up first.

the weird thing is it doesnt do it on the bench when i run through the motors without flying, only seems to happen in actual flight. so at first i thought it was vibration getting into the IMU but ive got dampers on the mount and the copter is pretty well balanced. motors are all fresh bearings.

could this be a motor issue on the gimbal itself? or is it more likely the IMU is just bad. the gimbal is maybe two years old and has a lot of hours on it. dont really want to spend money on a new one if its something fixable

two years and a lot of hours, id check the ribbon cable connections first before anything else. those flex cables on the roll axis motor controller connection get work hardened and start giving intermittent signals, especially if the gimbal has been packed and unpacked a lot. its a really common failure mode that mimics IMU drift but isnt actually the IMU at all. just gently reseat any ribbons you can get to and see if the behavior changes.

also worth checking if there's a firmware update for it, some of the older ronin firmware had known drift issues that got patched. might be a long shot but its free

not to derail but does this happen more in windy conditions? asking because my old zenmuse would do something similar and it turned out to be a PID tuning thing in the gimbal software, the wind was causing micro corrections that added up. never thought to look there until someone pointed it out. probably not your issue but worth ruling out