IMU Correction Heading

[Jonathan Mortensen]

Can anyone provide a more clear description of how to use the IMU correction heading, and how it works?

Should I be specifying the IMU and IMU axis that most closely aligns with the forward direction? Is it the IMU axis before or after the global rotation is applied?

The documentation says that the correction heading is optional, but the IK doesn't work unless I pick the correct IMU and orientation. Why is this? I have got it to work through trial and error, but still don't understand why the axis I chose worked for my data.

I was curious, so I tried using a different IMU and again did trial and error with the axis selection until the IK looked right. Interestingly, the results from the using the two different IMUs for the correction heading were quite different. The motion I recorded was recognizable for both, but joint angles varied. I collected data on the right arm and torso. I have attached a graph of the IK results for using an IMU on the torso for the correction heading, and using an IMU on the hand for the correction heading. The difference in shoulder rotation is quite surprising to me.

Any additional clarification, beyond what is in the documentation would be helpful. I am looking to understand which IMU axis to use for my correction heading. Also, any tips purposely placing an IMU to be used for the correction heading would be great.

Thanks!