Walking Tutorial with Muscles

Hi,

I created a model similar to the walking tutorial but with the addition of muscles. I have created two models, one with normal walking and the other with abnormal walking which has low knee flexion during swing phase. I ran the inverse and forward dynamics and then changed the knee spline data to obtain a low knee flexion. Now the second model is performing walking gait, but with a drag foot. This is exactly what I want.

But the problem is that when I plot the muscle force curves, I do not get the result which I expect. In real life, a person will have a drag foot when the muscles which cause knee flexion is dysfunctional. I am mainly focusing on the muscles semitendinuous and bicep femoris. So in my models, the model with normal walking gait should produce a muscle force curve much higher than the muscle force curve produced by the abnormal gait. But for my case these two muscles have a much larger muscle force during abnormal gait, rather than in normal gait. This is the opposite of what Im expecting.

Since this did not work, without modifying the splines of the knee, I tried modifying the splines of the two muscles. When I plot the data the knee joint angle for both models remain the same (no drag foot), and the muscle force for both mucles are represented by a constant value approximately 1.0.

I think that my joints may have a dominant effect on the model when compared to muscles. Due to this reason I have reduced the PGAN and DGAIN for the joints to 1e4 and 1e3 respectively. If I go lower than this, the model does not perform walking gait as expected.

i would much appreciate if you could provide me with feedback as to what might the issue here.

Regards,

Chathuri