simtk.org

Hello everyone,

I am little confused with the arm26. When I set and lock the r_shoulder_elev at 90, set 130 to the r_elbow_flex and then Simulate, the forearm goes in extension and doesnt "fall" in elbow flexion. After investigation, I've discovered that it is due to the passive force of the Triceps Long, maybe too high in this position. This "passive" extension leads to a non activation of the Triceps by running the CMC tool, with an extension of the elbow as an input motion.

Do you have any suggestions to fix it ?

Thanks
Alper

I don't think there is anything to fix.

The arm26 model is a toy model that is used for a specific purpose-teaching. It is not a valid model to do research with and it is especially not valid to do work at weird extremer that it was not designed to be used in. Please look at using other upper limb models for research, such as this one

If you don't want forces in your model, you could either disable the muscles by expanding the muscle set in the navigator pane, selecting a muscle, and checking 'isDisabled'. You could remove the muscles entirely from the model. Or you could spend some time and tune the muscle properties such that the passive properties are valid across the range of motion you intend to investigate.