Michael Sherman

One thing to consider with any state-perturbing method is that all the constraints must be satisfied after the perturbation. So we have to perturb, lock the perturbed state, satisfy all...

Nice! BTW in case you don't already know, Simbody has a much more efficient way to do prescribed motion -- see the [Motion](https://simbody.github.io/3.8.0/classSimTK_1_1Motion.html#details) base class for a description. There is...

Oh, actually I think the Motion object is restricted to treating all the dofs the same, which is probably why you used the more-flexible Constraint version! Nvm ...

My preference would be to add some adjectives to the name (so we don't use up a generic name like "Beam") that describe the existing implementation and merge it without...

Very cool! Paul and I are looking at this now. One small comment we both made: > with hopefully an alternative option for quaternions You shouldn't need to worry about...

One random thought: is angular velocity the best choice for generalized speeds? The other obvious alternative would be to use the qdots (Euler angle time derivatives) directly. Other than the...

BTW this is a beautiful way to propose a new feature! Thanks for all the thought you have put into this and the great presentation. Much appreciated!

FYI in case useful: Simbody does have elliptic integral utility functions. [overview](https://simbody.github.io/3.8.0/group__EllipticIntegralsGroup.html) [completeEllipticIntegralsKE()](https://simbody.github.io/3.8.0/namespaceSimTK.html#a7d13984ecd931506e33a8c935343b1c3) [approxCompleteEllipticIntegralsKE()](https://simbody.github.io/3.8.0/namespaceSimTK.html#ace92d2fd5a890de2aa211d589da1a5b7)

Any interest in this one, @nickbianco ?

Changing anything in MBP that alters its use of state variables does imply some ability at the System level to deal with post-creation changes in the Context dimensions. But I...