cmc for upper extremity model

Provide easy-to-use, extensible software for modeling, simulating, controlling, and analyzing the neuromusculoskeletal system.
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Giuliano Lamberto
Posts: 5
Joined: Fri Feb 24, 2012 11:48 am

cmc for upper extremity model

Post by Giuliano Lamberto » Mon Feb 27, 2012 8:53 am

Hi,
for my thesis work, I decide to use the upper extremity model by Holzbaur et al. (2005).
The aim is to apply scale tool, IK and CMC for some movements, in order to compare muscle's activations with sEMG signal.
Scale tool and IK work well but I've a problem with CMC tool. For CMC I base my setup files on the Gait2354 example and I don't use forces data. When I lanch the simulation i don't see any error and the program starts to calculate. For solving the initial frame time the software takes a little less 2 hous; furthermore, for the second frame time, the simulation seems to stop here without write any error(many hours later the message is always: executing computed muscle control).
Any suggestion?
Should I use the RRA?

Thank you.
Giuliano
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Ajay Seth
Posts: 136
Joined: Thu Mar 15, 2007 10:39 am

Re: cmc for upper extremity model

Post by Ajay Seth » Thu Mar 08, 2012 12:25 am

There are several issues that can be causing this problem. Most likely the integrator is taking tiny steps because there are massless (or very low mass or non-physical inertia) bodies. In the future OpenSim should give warning/error messages when accelerations become huge. Massless bodies are fine for kinematic analyses. Other possibilities are initial fiber lengths that cause very large passive forces.
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