getMuscleStiffness function
Posted: Wed Nov 02, 2016 8:39 am
Hi everyone,
I'm trying to understand how joints are stabilized from activation of opposing muscle groups. So far, my understanding is that muscles get stiffer when they are subject to higher activation levels. This muscle stiffness generates joint stiffness even when opposing muscles cancel each other out and result in a zero net torque about the joint.
I'm using the matlab interface and the getMuscleStiffness() function to compare stiffness of muscles with and without activation. My code looks like this:
osimModel.updMuscles().get(i).setActivation(state,0)
osimModel.updMuscles().get(i).getMuscleStiffness(state)
osimModel.updMuscles().get(i).setActivation(state,1)
osimModel.updMuscles().get(i).getMuscleStiffness(state)
The problem that I am running into is that some of the muscles in my model get stiffer with activation and some do not. The getMuscleStiffness function returns zero stiffness for all muscles when activation is set to zero. However, getMuscleStiffness returns a non-zero value for only some of the muscles when the activation levels change. I can't see any major differences in the muscle settings. I am using the Millard2012AccelerationMuscle.
If anyone could give me a reason for the behavior I am seeing, that would be great.
Thanks.
I'm trying to understand how joints are stabilized from activation of opposing muscle groups. So far, my understanding is that muscles get stiffer when they are subject to higher activation levels. This muscle stiffness generates joint stiffness even when opposing muscles cancel each other out and result in a zero net torque about the joint.
I'm using the matlab interface and the getMuscleStiffness() function to compare stiffness of muscles with and without activation. My code looks like this:
osimModel.updMuscles().get(i).setActivation(state,0)
osimModel.updMuscles().get(i).getMuscleStiffness(state)
osimModel.updMuscles().get(i).setActivation(state,1)
osimModel.updMuscles().get(i).getMuscleStiffness(state)
The problem that I am running into is that some of the muscles in my model get stiffer with activation and some do not. The getMuscleStiffness function returns zero stiffness for all muscles when activation is set to zero. However, getMuscleStiffness returns a non-zero value for only some of the muscles when the activation levels change. I can't see any major differences in the muscle settings. I am using the Millard2012AccelerationMuscle.
If anyone could give me a reason for the behavior I am seeing, that would be great.
Thanks.