Application of External Torque to Wrist Joint

[Enrico Piovanelli]

Hello everyone!

I am trying to run a simulation where I want to replicate an experiment where the subject has to do a isometric wrist flexion and we measure the force from outside. I would like to estimate the muscle activation for this task, to see which muscles are mainly activated.

I thought of using CMC with static kinematic data and applying an external torque to the wrist joint with amplitude equal to the torque obtained from the measured force, with a minus sign. However I still can't find a way to apply that torque to the wrist joint.

At first I created a CoordinateActuator for the flexion DOF in the model with a controller fed with a .sto containing the torque data, but being an actuator itself I realized that maybe it's not possible to make it act as an external force on a CMC simulation.

I searched in the forum as well, and I saw that other users approached the problem using 2 opposite torque applied to the bones of the joint, but in case of the wrist, where the joint include 8 carpal bones, I can't see how this approach can be applied.

I am now studying and trying to find a way to accomplish my task, but I would really appreciate if someone much more expert can give me some hints on the best way to approach the problem.

Thank you!

Enrico

[jimmy d]

I searched in the forum as well, and I saw that other users approached the problem using 2 opposite torque applied to the bones of the joint, but in case of the wrist, where the joint include 8 carpal bones, I can't see how this approach can be applied.

It is not applied to 'bones', since bones don't exist in OpenSim-- you have to apply the forces to the bodies on either side of the joint.