Spring types on Opensim

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Daniel Iordanov
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Joined: Mon Sep 03, 2018 7:17 am

Spring types on Opensim

Post by Daniel Iordanov » Fri May 17, 2019 4:44 am

Hello, I am trying to link an otrhosis to the lower limb of an OpenSim model. As my aim is to simulate the most realistic interaction between the leg and the orthosis I was thinking of implementing a spring, which properties would be able to mimic some kind of skin and soft tissue movement.

I do not want to model the interaction as a weld joint or weld constraint, I would like a PathSpring or another type of Spring between the point of the orthosis and the point of the leg that I want to link. My question is the following

Is there a way to define a spring between 2 point of my choice and not along a muscle or a body?

All the examples I have seen in the documentation define the PathSpring along a muscle and use its geometry, so I do not know if I can choose 2 arbitrary points.

Is there any better way to link 2 objects in OpenSim to simulate certain relative movements between two bodies?

By the way, I am avoiding to use contact models because I have seen that they do not perform well on static optimization or CMC and those are features in which I am interested.

Thank you very much.

Best regards.


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Seungyeon Kim
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Joined: Mon Jul 20, 2015 12:11 am

Re: Spring types on Opensim

Post by Seungyeon Kim » Tue May 21, 2019 1:34 am

In that case, I think you can you PointToPointSpring.

Using PointToPointSpring you can make spring force between arbitrary two points you want with specific stiffness and rest length.