CMC on MoBL_ARMS model

[Aushim Nagarkatti]

Hi,
I have been trying to run a CMC simulation on the MoBL_ARMS upper extremity model.
I initially scaled the model and ran IK. The .mot file generated in IK was used to run CMC, along with a
few tweaks in the tasks as well as constraint files. On initializing, I got the following error messages on the GUI:
Unable to find a feasible solution at time = 0.
Model cannot generate the forces necessary to achieve the target acceleration.
Possible issues: 1. not all model degrees-of-freedom are actuated,
2. there are tracking tasks for locked coordinates, and/or
3. there are unnecessary control constraints on reserve/residual actuators.

Just as a test, I ran CMC on the scaled model that came as default with the MoBL_ARMS package, and used the default constraints and task files.
However, I received the exact same error on trying to execute the tool (On OpenSim 3.3 and 4.0). Has anybody successfully used the tool on the default as well as a custom MoBL_Arms model? I'd appreciate any suggestions.
Thanks!

[Rejin Varghese]

Hi Aushim,

Did you manage to solve this problem? We are facing the same problem as you mentioned. Any help would be appreciated.

Thank you,

Regards,

Rejin

[Kristy Godoy]

Well , I don't know if this information is useful for you both, but I tried the tutorials 5 and 6 that comes with the model and they ran ok.
I'm also having trouble using CMC with my experimental data, it crashes and when I run the Inverse Dynamics obviously I get unrealistic shoulder moments (~400Nm). If you have any updates on how to use the model, it would be very helpful if you could share it.

Thanks! Good luck!