Measurement related to the COP of AnyForceSurfaceContact


i am working on a FDK knee model and I have a question regarding the COP.
My goal is to determine the velocity of the COP on the implant surface.
My idea was to drive a segment with the current position of the COP and do different measurements witch respect of the tibial and femoral coordinate system, but it does not work.
I tried different things, but I can not do a measurement on the COP.
I get Errors like: argument will not be ready for evaluation until moment ‘ForceVar’
ERROR(SYS1) : Model load : Unknown error
Closing model…
Deleting loaded model…

Does anyone have any idea how to solve my problem?

My last option is to make a separate model, load all implant surfaces with their calculated motions and than drive a dummy Segment witch the fully calculated trajectory of the COP. But I want to avoid creating a new model.

Thank you for your help!


You are right in what you have seen it is not possible to make a kinematic measure on the CoP location that comes out of the surface contact.

The reason is that the CoP is depending on forces and can not be determined while the kinematics is being resolved.

Your suggestion to solve the problem is the only way it can be done.

Best regards

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