Running CMC without lumbar markers

[William Clark]

Hello! I am currently trying to use CMC to determine individual muscle force during normal gait. I am using the Gait2392 model but I do not have any marker data to determine MTP angle, subtalar angle, and lumbar extension, bending, and rotation.

Is it possible to run CMC without these markers? I have tried locking these joints in the model and I have been able to reduce residuals but CMC fails after ~10 time steps.

I get the error message:
Model cannot generate the forces necessary to achieve the target acceleration.
Possible issues: 1. not all model degrees-of-freedom are actuated,
2. there are tracking tasks for locked coordinates, and/or
3. there are unnecessary control constraints on reserve/residual actuators.

Any guidance would be much appreciated.
-Billy

[jimmy d]

Locking the coordinates means that any forces required to maintain the current coordinate value are provided by the underlying system. So any failures are not caused by a lack of forces crossing those coordinates.

Are you still seeing the issue?