Hi Opensim users,
I'm attempting to generate simulations of abnormal gait using models scaled from the gait2392 model provided with OpenSim. I would like to track the kinematics of the Subtalar joint, and therefore do not want to "lock" it.
When I run the model through CMC (after residual reduction), small variations in subtalar kinematics lead to variations in the activation level of muscles that span both the subtalar and "ankle" (sagittal plane plantar-dorsi flexion) joints. This results in large muscle forces in several muscles when I don't believe there should be.
Is there a way to make the CMC process track subtalar kinematics but remove the subtalar joint torque from the cost function? That is, only require the ankle muscles to generate the correct plantar-dorsi flexion torque? Could a highly-weighted torque actuator at the subtalar joint be part of the solution?
Has anyone managed to generate a reasonable muscle-actuated simulation of walking with the subtalar joint unlocked? Any tips would be greatly appreciated.
Cheers,
Tom