ContactForces TKA-KneeBendDemo Model

Hi AnyBody-Team!

As I was working with the TKA-KneeBendDemo Model from AMMR 1.6, I tried to understand the ContactForce output:

AnyForceMomentMeasure2 ContactForceMedial =
AnyForceBase &FFemurTibia = Main.HumanModel.BodyModel.Right.Leg.Jnt.TibiaFemoralContactForces.SurfaceForce.FContactFemTibMedial ;
AnySeg &s1 = Main.HumanModel.BodyModel.Right.Leg.Seg.Shank;

In the manual it is written, that the reference point of the forces (x,y,z-quantities) is “the first AnyRefFrame member”. To my understanding, this is the AnyForceBase with the class AnyForceSurfaceContact (FContactFemTibMedial). However, if I visualize the RefFrame of this class it is located in the GlobalRefFrame. I would be really thankful, if you could explain the functionality of the contact force measure for analyzing the knee joint loads.

Best regards :slight_smile:

Hi Mulle,

Sorry for the late reply. Your thought has a small mistake. The problem is that the AnyForceSurfaceContact force has an AnyRefFrame member, but it is not an AnyRefFrame. When you look in the class hierarchy of the classes (e.g. by finding it in the reference manual and follow the link to the base class) you will see that the AnySeg is derived from the AnyRefFrame class, the AnyForceSurfaceContact and AnyForceBase are not, they only have a member that is an AnyRefFrame.

I hope this helps understanding the behavior you see.

Best regards