Removing muscles from a model

[Nafiseh Ebrahimi]

Hello everyone
In a normal walking model 2392 I disabled all the muscles of one leg but I have not seen any change in the style of walking when I run the model in GUI. Do you know why it does not show me any change?

Regards,

[Thomas Uchida]

Unfortunately, generating novel movements ("predictive simulation") is still rather involved. Here are a couple relevant papers:

Dorn TW, Wang JM, Hicks JL, Delp SL (2015) Predictive Simulation Generates Human Adaptations during Loaded and Inclined Walking. PLoS ONE 10(4): e0121407. http://nmbl.stanford.edu/publications/pdf/Dorn2015.pdf

Ong CF, Hicks JL, Delp SL (2015) Simulation-Based Design for Wearable Robotic Systems: An Optimization Framework for Enhancing a Standing Long Jump. IEEE Transactions on Biomedical Engineering. http://nmbl.stanford.edu/publications/pdf/Ong2015.pdf

You can find more information about OpenSim in the User's Guide: http://simtk-confluence.stanford.edu:80 ... %27s+Guide

[Nafiseh Ebrahimi]

Hello, I have the same problem with disabling the muscles. I expect that the model fail to walk after that or at least changes in the walking style but I can not see any changes in walking. could you please explain more about your response? I could not realize it truly.

Regars,

That's not going to happen with Static Optimization or CMC. Static Optimization is an inverse method and CMC is a tracking controller, both compute muscle forces to match an experimental movement.

Once you have those muscle forces, then you can run a Forward Dynamics simulation. Taking muscles out of that simulation would result in a model falling down.

[Thomas Uchida]

I have the same problem with disabling the muscles. I expect that the model fail to walk after that or at least changes in the walking style but I can not see any changes in walking.

How are you generating your simulations of walking? The Static Optimization and CMC Tools perform inverse analyses, where the model tracks a motion observed experimentally and OpenSim estimates the muscle forces that would have been required to generate that motion. If you want the model's kinematics to change when muscles are disabled, you will need to use the Forward Tool and specify excitations for the remaining muscles. More information can be found in the User's Guide (http://simtk-confluence.stanford.edu:80 ... %27s+Guide). You might also be interested in the tutorials and examples (http://simtk-confluence.stanford.edu:80 ... y+Examples), which demonstrate OpenSim's capabilities.