I want to study the influence of AFO brace on knee adduction torque. I have kinematically connected the AFO and the human body, and created conditional contact muscles between the human and the AFO through FrictionContactMuscle. The human body motion is driven by the C3D file and can run normally. But I have a few questions, and hope to get your answer sincerely:
- Whether the interaction force calculated by FrictionContactMuscle can be added as an external force to the calculation process of the knee adduction moment, which will affect the result.
- If I want to increase the interaction force between them, but their relative displacement is fixed, I don't know if there is a parameter similar to spring stiffness that can achieve my goal
- If I don’t want to consider the influence of brace gravity on my studying, how should I set CType and ReactionType in the kinematics connection?
I will try to answer your question but first a little background.
If you are using a model with a revolute knee joint, the adduction moment taken up by this joint do not have a cost in the objective function, since it is a reaction force. If you have a knee brace connected with contact muscles, these muscles will not change the knee abduction moment since this would have a cost in the objective function.
1: Yes it can be added but it may not add any adduction moment for the reason i wrote above.
2: You can change the strength... having a high strength will make them act more like a reaction force with limited cost.
3: Simplest would be to set mass properties to zero.
If these answers do not help please describe the function of your knee brace, that would help me suggest best approach.
Thanks for your great help in a very timely reply!
its working principle not only aims to adjust the centre of pressure by restricting ankle motion in the frontal plane, but also gives the lower limb tibia inward force during the human gait support phase, and thereby reducing the adduction moment. What I want to study is the effect of this force gived by AFO on the knee adduction moment?
Ok i think i understand how the AFO works, as i understand the problem it will change the loads on the knee adduction moment.
I think it should not be a problem to use the contact muscles for this, they will transmit the loads to the human model and you should see the change in the adduction moment if the AFO supplies such a load change, i think the key question will be how you defined the load function in these springs/straps that i see on the picture.
I am not sure if I really understand your answer. In my opinion, I think I can use Vicon to capture the relative displacement and Anobody will calculate the interation force by cantace muscle and this force on tibea will reduce the knee adduction moment.
I don't know why the result of kneenemont don't have any change, and hope to get your answer. You think the foce is reaction force will have no effect on knee adduction moment, i'm a little confused about this.
Sorry for the confusion adding this force to the model will change the knee reaction (adduction) moment you will see in the knee joint, but the muscles will not "feel" this added moment because the knee joint reactions will carry it, so this will change.
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