Hi,

I was wondering if the following approach is possible. In the end, I would like to model one chewing cycle of the mandible. Problem is that I have no idea how I should define the joint. But I have the whole movement of the mandible recorded, so I have the kinematics. Question is if, when I attach the muscles, I can analyse the response of the muscles on the movement regardless on the joint?

I started with an easier example (see the attachment) – a bar which moves in the vertical direction, therefore no joints needed (prescribed translation, fixed rotation). The kinematics works fine, but if I add one muscle to the top node and one to the bottom node and I want to see , how the muscles would perform such movements, it does not work (kinematics works, but for inverse dynamics I get: “No solution found : There are fewer unknown forces (muscles and reactions) than dynamic equations.“). I have no idea, which reaction I should switch on/off, which kinematic measure I should include, etc.

Or can the problem be, that the muscles are aligned with the bar, therefore the muscle´s arms are zero? So if I had two instead on one muscle in each location, it could work?

Could anybody have a look at it?

Any comments are welcome.

Thanks

Michala