Plugin controller with zero stimulation...

[Bonsung Koo]

I am using OpenSim 1.9.1 with Plugin FeedbackController Template.

When I tested this plugin controller with zero stimulations for all muscle actuators in arm26 example, I observed a small motion.

As I knew, if there is no stimulation, all the muscle should be in rest state.

If my understanding is wrong, please correct me.
and if you need my code, please let me know.

Best,

-Bonsung

[Ayman Habib]

Hi Bonsung,

Some muscle models produce passive force as well, what muscle model are you using?

-Ayman

[Bonsung Koo]

Hello, Dr. Habib,

I know muscle model generate passive force when the muscle length increase than the optimal fiber length.

But what I found is not that case.

I have found something in the Forward Dynamics Tools.

This is what I did.

1. I made a PD controller for the arm26 model.
2. I put 0 gain for P and D gain.
3. I put the cmc control signal to activate the Forward dynamics tools. (Red box is change white box. I hope you catch the meaning.)
4. I put a desired state file put into the state input box in Forward dynamics tools.
5. click "RUN".

after running this simulation, I observed a motion.

However, there should be no motion, because I put zero gain for P and D.

when I check the activation of each muscle, the activation tendency follows the CMC control signal.
But the amplitude scale of activation was different.

If you want to check my code, please let me know.
Best,

-Bonsung