Constant drift towards left

PX4 Autopilot
1

Hey all !
Hope you all had safe landings! I am stuck in a loop where my multirotor is constantly drifting on left and I did account for the offset w.r.t to my IMUs as I have mounted the FC at rear section of the bird. And also the flight controller alignment to 270deg(as shown in the picture.) Am running on Px4 - 1.16.0alpha.
NOTE: I am using MTF - 01 MicoAir tech but the drift is happening in Stabilized flight mode and even in position flight mode.

  • I would like to know if the IMU offset should be done with respect to the IMU (on the FC) and the CG of the Aircraft or should it be considered with respect to the CG of the aircraft and the center of the FC.

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I believe that the offsets are between CG and IMU, as set using EKF2_IMU_POS_X, _Y, _Z.

I’m not sure how much difference it makes though given most won’t know the precise position of the IMU within the FC.

The drift could possibly be a number of things. If you’re not sure the cause is this, you might want to link a log.

@bresch Flight Controller Orientation just talks about orientation. My assumptions are:

  • that you should mount FC near CG
  • That PX4 can’t guess the offsets - you have to set them as per EKF > Precisions about the position output
  • Approximate is good enough - i.e. if you estimate CG and use around centre of FC you’ll be find in most cases if you’re within a few CM.

This is really a question about when you have to set the offset, and how precise you should be?

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