simtk.org

Hello,
I am trying to use an upper limb model to simulate a simple elbow flexion movement. However, when I try to scale the model, it does not take on the static pose correctly (the elbow is flexed in the static pose). The bones even get mixed up and move around in the scaled version and the markers are no where near the input data.
What could the problem be?

There are two issues:

1. Since this model has its own geometries, which do not come with OpenSim, the GUI cannot locate them. To solve the issue, you can a) copy the geometries into OpenSim's geometry folder, 2) to append an additional geometry folder in the preferences (Edit tab I think), 3) save the scaled model next to the geometry folder and re-open it.

2. For the scaling issue, if the thorax is fixed with respect to the ground, then IK may not be able to find a correct solution. Typically, you add six degrees of freedom between the thorax (base) body and the ground.