No worries for the optimization code, good luck with the paper. Regarding the frames, I tried to do what Thomas suggested and change the pointConstraint properties: In the default model, pointConstraint is currently with non-0 coordinates in <location_body_1> and <location_body_2>, and the bodies ar...

I tested adding frames, but it's the pointconstraint that does not respect the origin of the frame.

@felix, do you have a simple example for the optimization of the ellipsoid that you could share?

Thanks Felix, that's great I'll update if I get to set up dedicated frames to scale the PointConstraint automatically (also, potential typo in "posVec3" depending on the output of your optimizer: using [3] [5] [5], maybe it should be [3] [4] [5] ? # posVec3 = osim.Vec3(new_ell_params[3],new_ell_para...

Hi Felix, would you mind sharing your code? For this specific model, I've gotten as far as adjusting the "thorax_offset" frame of the scapulothoracic joint (that determines the origin of the ellipsoid if I understand properly), then possibly reorienting the "scapula_offset" frame to adjust the scapu...