Opensim RRA

[Jonathan Sinclair]

Hi all

I am trying to use opensim 3.2 to simulate muscles forces during football kicking

CMC.computeControls: ERROR- Optimizer could not find a solution.
Unable to find a feasible solution at time =
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

a. I assume something is wrong with my RRA setup file, I am quite new to using opensim so am a little unsure as to what needs to be altered in order to solve the above issue.
b. Is it likely that the CMC setup file is also not configured correctly for the data which I want to process given that the RRA script did not run correctly.


Any help would be welcome.

[Ross Miller]

Re: Opensim RRA

Hi Jonathan,

The error looks to me like it is in the "Computed Muscle Control" (CMC) step, not the "Residual Reduction Algorithm" (RRA) step. I would guess it means your data contains joint moments that CMC needs supramaximal muscle activations to produce. You could try cranking up the maximum isometric muscle forces in the model (multiply them x10 or something and just see if it runs). This will not be a "good" (realistic) solution but it should help determine where the problem is at least.

You would probably have better luck posting your question on the OpenSim forum:

https://simtk.org/forums/viewforum.php?f=91

They respond very quickly and are very helpful in my experience.

Good luck,
Ross