simtk.org

Hi everyone,

I am using the IMU placer and Inverse Kinematics tools to calculate joint angles. I would be grateful if anyone could help me with the following matter:
After using the IMU placer, it is possible to change the orientation of some IMUs and then use the IMU inverse kinematics tool. I want to know how the IMU orientations will be considered in the IK tool then; because the primary source of IMU data is the input for the IK tool; So, does the IK tool reset the orientation changes, or will consider the modifications in IK calculating?

Best Regards,
Nastaran.

Hello,

You can change the position of IMUs for visualization purposes.

You can also change the orientation of IMUs placed on the model by the IMUPlacer, however this is meant to be for troubleshooting purposes rather than as a permanent solution. The IK Solver will try to track the modified orientation of the IMUs as expected but if the transform from IMU coordinate system to OpenSim's used by IMUPlacer was incorrect and then it was applied to the orientation data during IK then it's unlikely to result in correct results for IK.

Hope this helps,
-Ayman

Dear Dr. Ayman,
many thanks for your response,

you mentioned that changing the position of IMUs is for visualization purposes, does it mean that if (after using IMU placer) I change the place of IMUs (in the sidebar menu, properties window of each IMUs) from Center of mass into the correct place of sensors, it will not be considered in the Inverse Kinematics calculation?

and regarding IK tool, I am thankful for your explanation, I realized the way orientation correction works.

However, I wish there was the option to fix the IMU orientations using IMU placer and also modify them later (in the sidebar in the properties window of each IMUs); then IK tool would not need the orientation correction anymore. I think having this option would reduce the possible errors, if possible.

Best Regards,
Nastaran