Torsional Spring

[Anne Schmitz]

Hello,

I found an actuator file named TorsionalSpring.h. How can I include this in my model? I'm not sure how to use it/call it.

Thanks,

Anne

[Ayman Habib]

Hi Anne,

This class is internally used for the "corrective springs" in Forward & Perturbation Tools. It's created programmatically by these Tools and is never written to file, you only get to specify some parameters to customize it in the setup files of these Tools.

I would recommend NOT using it at this point as we may remove it or change it completely in version 2.0.

The more fundamental question is: What are you trying to model?

-Ayman

[Anne Schmitz]

I would like to model a torsional spring: a generalized torque applied to knee_angle with a value that depends on knee_angle.

[Tim Dorn]

Hi Anne!

That sounds like you want to model a passive GeneralizedForce which is what I'm doing. I can provide you with my passive GeneralizedForce plugin and you can change the computeActuations() method to calculate the torque as any function you like of generalized coordinate.

Tim

[Andrea Morelli]

Hi Tim,
can you explain (or give me a link where is explained) what your plug in can do. Is possible that can be useful for some application I would like to do.
Thank you in advance
Andrea

[Tim Dorn]

Hi Andrea,

The plugin is just a very simple passive actuator which can be used during a simulation to apply a generalized force (force or moment) at a given generalized coordinate as any function of the generalized coordinate. E.g. it can be used as a torsional spring if you supply code for the torque-angle relationship.

Tim

[Andrea Morelli]

Thank you for your explanation.
Andrea

[Anne Schmitz]

Thanks Tim. Is that the same one you gave me at the Jamboree?