simtk.org

I have made a model both with and without kinematic coordinate coupler constraints and have made a motion file for both which puts them through the same motion. When using the static optimization and CMC tools I get very different results for both models for the exact same motions. It seems that the overall muscle activation is much greater when using the model without kinematic constraints. Could anybody tell me why these outputs are different seeing as all the joints in the model are moving in the same way in both models?

Are you talking about the knee translation and knee flexion coupler?

Yes, I have tried it with that model and also with the neck model. I guess I'm just not understanding how or when to use them correctly. Besides the user guide is there anywhere that offers a more in depth explanation into coupler constraints?