Problem in forward dynamics

Provide easy-to-use, extensible software for modeling, simulating, controlling, and analyzing the neuromusculoskeletal system.
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Saurabh Kothari
Posts: 12
Joined: Fri Aug 19, 2016 10:23 am

Problem in forward dynamics

Post by Saurabh Kothari » Mon May 25, 2020 10:45 am

Hi All,

I am trying to run the forward dynamics simulation with attached model and controls. The simulation runs smoothly for about 0.6 sec after which it stopped working. I inspected the resulting states file and found nan values in the last two rows where last second row has all joint velocities as "-nan(ind)" and last row has all joint angles as "nan" and all joint velocities and fiber lengths as "-nan(ind)".

Any idea why this is the case? Any solution to this problem?

Thanks,
Saurabh
Attachments
controls.xml
(310.52 KiB) Downloaded 5 times
test.osim
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Ayman Habib
Posts: 2248
Joined: Fri Apr 01, 2005 12:24 pm

Re: Problem in forward dynamics

Post by Ayman Habib » Mon May 25, 2020 1:29 pm

Hello,

The model has some bodies with very small masses, if the forces being applied are large (due to bad initialization of muscles for example) then accelerations will be huge and forward simulation will stop or be extremely slow. Did you modify muscle properties or the muscle model? If not then you should contact the model authors to see what functionality is supported by this model.

Best regards,
-Ayman

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