I'm trying to simulate force generation using the Holzbaur upper limb model.
To start off with, I want to simulate isometric force generation at the level of the wrist. The wrist is locked, so that the force being applied to the wrist acts to flex and extend the elbow and shoulder. So I have locked all but 4 DOF - the elbow flexion-extension, and 3 DOF at the shoulder.
I have added mass and inertia by entering order of magnitude guesses, my assumption being that since there is no motion, it should have little effect.
I can simulate this scenario using CMC, but not static optimization. When I use CMC, I use the slow target to get it to work.
When I use static optimization, I get #QNAN for muscle forces generated by shoulder muscles while I get alternating values and 0's for the elbow muscles.
What is happening here? Static Op is part of CMC, so what could be causing this issue?