High residuals CMC Catelli Model

[Nathan Paillou]

Hello everyone,

I wanted to reach out regarding an issue I'm currently facing while analyzing a sidestep cutting movement on OpenSim. Specifically, I am working with the Catelli model and I'm trying to perform CMC (Computed Muscle Control). However, I'm encountering persistently high residuals, which are considerably higher than the acceptable values mentioned in the OpenSim documentation.

I have made several attempts to reduce these residuals, but unfortunately, I haven't been successful so far. I have tried modifying the optimal forces of the actuators, adjusting the minimum and maximum control values, and optimizing the tracking task weights. However, none of these methods have led to a reduction in the residuals.

On a positive note, I have managed to achieve satisfactory translational and rotational errors, and I was able to reduce the residuals for RRA (Residual Reduction Algorithm) prior to attempting CMC.

I'm reaching out to this forum in the hopes that someone might have encountered a similar issue or could provide some valuable insights. If you have any ideas, solutions, or requests, I would greatly appreciate your input.

Thank you all in advance for your help.

[Edward Syrett]

Hi there,
I just ran into a similar issue, albeit with the gait2392 model. I found a rather odd solution. Are you filtering the RRA kinematics file using the 6Hz filter in the GUI? I found that when I unchecked that box, my residuals dropped dramatically. I have no idea why that worked, but it worked for my data.

Dan

[Nathan Paillou]

Hi Dan,

Thank you for your reply. Unfortunately, I find same residuals with and without filtering RRA kinematics.

Nathan

[Brody Hicks]

Hi Nathan,

It could be that your model is poorly scaled - i.e. that the mass/center of mass/inertial parameters of bodies in your model are incorrect. I've run into this issue before and a more properly scaled model almost always helps lower the residuals.

Another thing to think about would be adding reserve coordinate actuators if you haven't done that already. If it is a model strength issue, that may give you a good idea of which muscles you need to strengthen moving forward. I would also double check that your motion is occurring within the ranges of motion that the model is validated for. If this is not the case, then some of your model's muscles could be exhibiting strange behavior or be too long/short to produce any meaningful amount of force, regardless of how much you strengthen the muscles.

Finally, if I'm not mistaken, the bounds for acceptable residuals on the documentation page are expected for walking. Those typical residual values may be a little bit higher when dealing with things like higher-acceleration sidestep cuts.

Best,
Brody

[Molly Shepherd]

Hi Nathan,

I am also currently working with a sidestep. I am not utilizing CMC, but am running RRA and experiencing high pelvis reserves (specifically Fy). I was wondering what ended up working for you to get these values down.

Thanks,
Molly