32bit with 2 IMUs Yaw automatic alignment issue
  • Just curious if I have something setup wrong or not. I have the 32bit Basecam with 2 IMUs on my multirotor. I have the 2 IMU attached to my frame.

    The gimbal is actually working really well except for one thing. I was hoping with the 2nd IMU on the frame that the gimbal would automatically align the Yaw axis when booting. I still have to manually move the gimbal Yaw (force the yaw motor to cog) into position and also use a radio channel to set the Yaw looking perfectly straight ahead (like when I had only one IMU).

    Also if I spin/yaw fast, I can cause the Yaw motor to cog and become out of alignment - I was hoping the gimbal would automatically realign with the 2nd IMU attached to the frame. I think I can adjust the power on the motor and probably prevent the motor from ever cogging in flight. Still would be nice if the gimbal could realign anyway.

    I have the 2nd IMU enabled and I can see it working in the GUI. I did 6 point calibrate both IMUs. Don't know if this is a future feature I'm looking for or I'm still missing something with my setup.

    Thank you for any suggestions
  • Have you set the off set for yaw? Did you use follow mode? You turn your multirotor quite fast? Y do you do that if you want to shoot a video? Mine turns without any cogging albeit my multirotor turns slower.
  • Did you calibrate your 2nd imu ?
  • Two rate gyros will not align yaw any better than one.
  • I'm going to go do some testing now to see if I can keep the yaw motor from cogging. I think it can be adjusted out - normal flying doesn't throw it off.

    I have Yaw follow mode turned on - pitch and roll are off. I see the compass spinning on both IMUs - I suppose if the compasses could be calibrated pointing forward with the offset relative to each other saved, then that would solve the issue I thinking about. When the board boots up the IMUs compasses align based on the previous calibration.

    Sort of a minor issue since the board is working great otherwise. Just wanted to make sure I haven't missed a step.
  • there is no compass, just a rate gyro. As it is just a rate gyro, there is no absolute bearing that could be calibrated. You could try the follow mode yaw offset. that should affect how the yaw is aligned relative to the motor poles at startup.
  • Thank you Garug - that's what I needed to know. Thank you again for your time.