Maximum isometric moments in Dynamic Arm Simulator

[Marc Grepper]

Hello,

For my project i try to reconstruct the measurements done in this study:
Chadwick, E., Blana, D., Kirsch, R., & Bogert, A. van den. (2014). Real-Time Simulation of Three-Dimensional Shoulder Girdle and Arm Dynamics. IEEE Transactions on Biomedical Engineering

With the Dynamic Arm Simulator: das3.osim

Which analyzation tool do i need to use to get the maximum isometric moments?

cheers,
Marc

[Dimitra Blana]

Hi Marc,

The OpenSim model das3.osim was used to generate the real-time model, but the actual real-time simulations run in Matlab, not in OpenSim. The maximum isometric moments were calculated in Matlab as well, using the fmincon function in the Optimization toolbox.

We will upload a new release of the real-time model in the next couple of weeks, and we will include the Matlab code used to generate the maximum isometric moment curves.

Best wishes,
Dimitra

[Marc Grepper]

Thanks Dimitra,

But is there possibility to generate these curves by using OpenSim only?

cheers,
Marc

[Ton van den Bogert]

Marc,

You could try doing it with Opensim, but the .osim model does not include some of the model components that we coded in C and Matlab. Most importantly, the contact force between scapula and thorax is missing and this would affect muscle function. It may be OK for the shoulder and elbow moments.

Also, the Matlab optimization that Dimitra mentions also had constraints: no muscle activations were allowed that would cause dislocation of the shoulder joint, or would cause the scapula to lose contact with the thorax. Opensim would not consider these things, so may overestimate the joint moments that are possible.

If get any results from Opensim, please post your results here so we can discuss the differences with the results presented in the paper.

Ton van den Bogert