Maintain initial position of neck for time t

[Venkatesh Sripada]

Hello,

I am trying to hold the neck in the initial vertical position for a certain amount of time.
I am going about this by providing a
1) motion (.mot) file, which is zeros in all columns of joint forces as that is the only way I can keep the head from dropping.
2) Input this motion file to inverse dynamics so that I get a .sto file
3) Input the obtained .sto file to CMC and get to know the muscle excitation
4) Input the excitations to Forward Dynamics and finally get the kinematics and other properties.
Problem: The error for me occurs in the second step where in-spite of all joint angle forces (.mot file) being 0, the inverse dynamics provides a non zero value for pitch and other joints which is making the head drop. I am unable to get past this. I tried checking the CMC output with this undesired inverse dynamics but CMC does not work either as it throws up an error saying
""
CMC.computeControls: ERROR- Optimizer could not find a solution.
Unable to find a feasible solution at time = 0.
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.
""

I am attaching my .mot file here. Kindly let me know where I am going wrong and if you need more information to help me

Thanks,
Venkatesh.