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reducing number of muscles on a full body model

Posted: Thu May 20, 2021 5:25 am
by francescad1
Hello everyone!
I am working on the development of a Full Body Model for the simulation of human walking with an exoskeleton and crutches. My aim is to perform dynamic simulations too using GRFs acquisitions.

The model I am using is the Full Body Model from Opensim, the problem is that it has too many muscles while the ones I am interested in are those included in the gait10dof18mus, so I want to reduce the number of muscles. However, I can not simply copy the <ForceSet> from gait10dof18mus to FullBodyModel because gait10dof18mus uses Millard muscle type while I would like to have Thelen muscles.
So my question is about which is the better way to do it.

1) I could copy the <ForceSet> from gait10dof18mus and then change the muscle type from Millard to Thelen, opening the .osim file with a text editor.
In this case, do I simply change the muscle class or do I need to change some muscle properties as well?

2) I could delete some of the muscles from the FullBodyModel and just keep the 18 ones I am interested in.
In this case would I have to modify the maximum force muscles are able to produce? Because I am afraid that, as they were part of a bigger muscle set, they are not able, on they own, to generate enough force to sustain a walking movement.

I hope I was clear. Any advice or suggestion would be really appreciated.

Regards,
Francesca