simtk.org

Thanks for this explanation - it was extremely helpful.

Just to check,, does this mean that the JointReaction analysis will only produce non-zero reactions for the constrained DOFs while the other moments (corresponding to the generalized coordinates) can only be determined from ID?

Thanks a million,
adila

Ideally yes. If you you're interested in a generalized force then Inverse Dynamics will tell you exactly that. JointReactions should give you zero moment/force along a generalized coordinate, however it is possible to set up the analysis so that it mistakenly reports forces in these free directions. For example, if you have kinematics that are produced or associated with a certain set of external forces, muscles, and coordinate actuators (reserves and residuals), but accidentally omit the knee reserve actuator in future analyses , JointReactions will report a reaction moment about the knee axis. This happens because the missing moment must be taken up by the joint to preserve consistent dynamics of the tibia and femur bodies.

ah, got it.
Thanks!