I'm assuming you mean the local coordinate system for the foot, not the global. The easiest method to restrict motion to only the x-y plane will be to lock the ankle rotation coordinate in your model through the OpenSim GUI. Just click on the coordinates pane and scroll down to the ankle coordinates...

Great thank you! That would explain why the two Thelen muscles in the model are returning normalized fiber lengths but the deprecated ones are not.

Did you reconfigure OpenSim in MATLAB after you upgraded to 2015b?

Also: Is there an issue with installation if these are missing?

Thanks for the help again James, but whenever I try to downcast the muscle type, I get this error. Undefined variable "Schutte1993Muscle_Deprecated" or class "Schutte1993Muscle_Deprecated.safeDownCast". Error in getNFL (line 63) eval(['myMuscle =' muscleType '.safeDownCast(myForce);']) I was using y...

Hi, I've been working on some code to calculate Normalized Fiber Lengths throughout a walking cycle. I've been able to set up the model to run through the motion by updating the coordinates, but whenever I call either the fiber length or normalized fiber length, a value of zero is always returned. H...

Thank you for the example code! It shows how to access the normalized fiber lengths, which was exactly what I was trying to find.

This is the link with the variables you can plot:
https://simtk.org/api_docs/opensim/gui_ ... otter.html

Anthony, I had a similar problem. The fiber length of the muscle can be accessed using "FiberLength". I tried some of the other variables you were having issues with as well. It seems that if you capitalize the first letter of each word and remove all spaces from the GUI variable names, then you can...

Hi All, I have experience with both OpenSim and MATLAB, but I am having a difficult time understanding how they fit together. I have already found how to load my model, but I am not sure how to apply a .mot to it and then extract the muscle length data (as a function of the motion) to store into a M...