Motion Capture OpenSim

[Feras Kiki]

Hello,
I am trying to use visual based motion captured data and feed it to OpenSim and do an analysis after that. The problem is I am getting the angles in quaternions and not Euler angles. Is there a way to use quaternions in OpenSim?
Another problem is that the way the joints work in OpenSim is different from simple Euler angles data. For example, in upper extremity model and specifically the shoulder joint, I cannot rotate around all 3 axis directly. I need sometimes to change elv_anlge then shoulder_elv to be able to make the rotation I want. I don't know why the program doesn't allow other simpler ways to express the angles. I would like to ask is there is a simple way to rotate the shoulder directly ?
All your help is much appreciated,

[Carmichael Ong]

It's possible that the IMU Inverse Kinematics tool (OpenSense) could be helpful for your problem as this tool uses quaternions reported by IMUs to pose the model.

Documentation on IMU Inverse Kinematics: https://simtk-confluence.stanford.edu:8 ... Kinematics

Example using OpenSense: https://simtk-confluence.stanford.edu:8 ... h+IMU+Data