Inverse Dynamics API

[Joel Quarnstrom]

Hello,

I have some questions about the Inverse Dynamics system on the API. What does the program consider to be the design variables, is it the coordinates of the model? If so, in order to make it work, would u_dot just be the acceleration of all the coordinates in the order that they are listed in the model?

I am using a model that is just the rib cage, and one arm. Do I need to calculate the forces at the ground body in order for the solver to work properly?

Also, what does it mean for the inverse dynamics solver to generate generalized forces? If all of the coordinates are rotations, are these all torques at the joints?

If the inverse dynamics solver has been run for a state, and then the active or passive muscle force is calculated for that state, but no muscle activation has been specified, will there be any calculated muscle force?

Thank you,
Joel Quarnstrom