CMC - Muscle and tendon Stiffness

[Rodrigo Mateus]

Hi there,

I am performing CMC on a dataset of abrupt deceleration tasks, and I am having difficulties in reducing the reserve actuators during the analysis. Here you can the reserves I have been getting. I am using OpenSim 4.0 and the gait2392 MSK.

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When I was trying to debug the situation, I analyzed the muscles force profiles and came across this strange profile along the left bifemsh

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Once I realized that, I performed an Output report to check in detail what could be causing this. There are strange sudden changes in the muscle and tendon stiffness properties of said muscle.

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I already checked the source code and performed the troubleshooting tips regarded by OpenSim, however I cannot seem to pinpoint the origin of this situation. Has anyone come across this same situation and knows how to solve it?

Thank you in advance for the help!

Best regards,
Rodrigo

[jimmy d]

It may be useful to investigate the fiber lengths and velocities-- perhaps the fiber velocity is such that the muscle cannot generate hardly any force so the optimizer preferentially uses other actuators.

[Rodrigo Mateus]

Firstly, thank you for the response!!

I increased the maximum contraction velocity of the muscles in the model. This is the plot for the normalized fiber velocity length, respectively. How should one proceed to reduce this if the problem resides in the maximum contraction velocity or fiber length? Trial and error until it goes right, or is there a line of thought to be carried out?

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