3D Rotation Matrix

Provide easy-to-use, extensible software for modeling, simulating, controlling, and analyzing the neuromusculoskeletal system.
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Rahul Agrawal
Posts: 47
Joined: Mon Aug 31, 2015 3:16 pm

3D Rotation Matrix

Post by Rahul Agrawal » Tue Jul 10, 2018 7:48 am

Hello,

I have been using custom joint between humerus and scapula, I have generated the trajectory of the humerus in matlab using 3D rotation Matrix( see the attached file). When I use those trajectory to rotate humerus in opensim, it rotates completely different , I don't know whether I have to convert this rotation angles to eulers angles before using it opensim. Please let me know any possible solution that will be helpful.

Thank you.

Regards,
Rahul
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3D Rotation Matrix
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OpenSim 3.3 and Earlier
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Dimitar Stanev
Posts: 1096
Joined: Fri Jan 31, 2014 5:14 am

Re: 3D Rotation Matrix

Post by Dimitar Stanev » Tue Jul 10, 2018 11:51 pm

That is because the coordinates are not independent and the axis of rotation are different, thus the Euler angles do not correspond to configurations that you would expect. For the MoBL model I have a function where you can specify the desired orientation of the humerus and elbow and Simbody finds the generalized coordinates that achieve these configuration. You can take the following function and adapt it according to your problem:

https://github.com/mitkof6/task-space/b ... nt.cpp#L30
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