How to pass the whole body mass

OpenSim Moco is a software toolkit to solve optimal control problems with musculoskeletal models defined in OpenSim using the direct collocation method.
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Mritula Chandrasekaran
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How to pass the whole body mass

Post by Mritula Chandrasekaran » Mon Jun 01, 2020 2:11 am

Hi,
I am trying to apply Mocotrack and track the subject gait and later predict it with changed mass. How can I pass the overall mass value range like passing overall tracking weight
track.set_states_global_tracking_weight(10);
Thanks,
Mritula

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Aaron Fox
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Re: How to pass the whole body mass

Post by Aaron Fox » Mon Jun 01, 2020 4:29 pm

Hi Mritula,

This sounds like a problem you'd deal with outside of Moco. You would change the mass of your model external to the MocoTrack object (e.g. via scaling to a different mass, or manually changing the mass and inertial properties of bodies in the model) - and then simply pass the different models through the MocoTrack object on different simulation iterations. Make sense?

Aaron

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Mritula Chandrasekaran
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Re: How to pass the whole body mass

Post by Mritula Chandrasekaran » Mon Jun 01, 2020 11:21 pm

Hi Aaron,
Thanks for your reply. Yes I know to do it via scaling. Was just curious if it could be done via moco. Will stick on to do it via scaling.

Thanks,
Mritula

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Aaron Fox
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Re: How to pass the whole body mass

Post by Aaron Fox » Tue Jun 02, 2020 3:49 am

Sounds like you've got it under control :D

It makes sense to do simple changes in mass as part of scaling, given mass is a component of the model. You would probably only incorporate this in Moco if you were trying to optimise mass as a parameter for a given scenario (e.g. optimal mass distribution in the bodies to minimise residual actuation on the pelvis - similar to RRA?). The sliding mass example with Moco is a pretty simple example of a mass optimisation problem I suppose.

Good luck with your study.

Aaron

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Mritula Chandrasekaran
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Re: How to pass the whole body mass

Post by Mritula Chandrasekaran » Tue Jun 02, 2020 3:57 am

Thanks, Aaron, will definitely check it up.

Mritula

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