How to change isometric force during simulation...?

[younguk kim]

Hello.

Is it possible to change isometric force during static optimization?

For example,

in t = 0.1, isometric force of muscle = 100
in t = 0.2, isometric force of muscle = 200
in t = 0.3, isometric force of muscle = 50 ....

I want to read text file and put isometric force data during static optimization.
Please help me...

[Thomas Uchida]

I want to read text file and put isometric force data during static optimization.

Static Optimization doesn't currently support what you have described, but there are at least three approaches you could take.

1. Set the maximum isometric force (or the max_control property) for each muscle and solve for a single time point, then move to the next time point and repeat. This strategy would be slow since you would be changing properties in the model (and would, therefore, need to call initSystem() for each time point), but wouldn't take much time to set up and might suffice for short simulations.

2. Use control constraints with CMC. You would keep the maximum isometric forces constant and use control constraints to limit the maximum excitation of each muscle over time. See the documentation for CMC here: http://simtk-confluence.stanford.edu:80 ... d+with+CMC

3. Extend Static Optimization to support what you have described (e.g., by creating a plug-in). An example of extending Static Optimization can be found here: https://simtk.org/projects/synergy