The meaning of BodyModel-Knee-Linear-pos in the chart

[babaozhou]

Hi

Can you tell me the meaning of BodyModel-Right-Jnt-Knee-Linear-pos in the chart? And what are the meanings of KneeJoint and KneeJoint_0 under the Linear folder? Any help would be great appreciate.

Best Regards
babaozhou

[toerholm (Søren Tørholm)]

Hi

I will try to answer the questions

BodyModel.Right.Jnt.Knee.Linear.Pos is the position of the linear measure in the joint. So since the knee is a revolute joint you will see this position to be zero on both x,y,z

The linear folder is a linear measure of the joint and a linear measure needs two nodes as references, by default it will create the reference to these two nodes using the name of the joint in this case “KneeJoint” and add “_0” on the second mentioned frame. The Linear.KneeJoint points at first mentioned frame in the joint the “ThighNode” and the Linear.KneeJoint:0 points on the second frame “ShankNode”

Hope it is clear.

Best regards
Søren

[babaozhou]

Hi Søren
Thank you for your detailed reply. Is Jnt-Knee-pos the position curve of the knee joint during gait? Is it the position curve of the central node of the knee? When calculating the force arm of some forces on the knee joint. I want to know where the knee center point is. Any help will be greatly appreciated.

Best wishes
babaozhou

[toerholm (Søren Tørholm)]

Hi Babaozhou,

The kneejoint pos is the position of an AnyKinLinear between the two nodes which is used to create the knee joint. You should look at these nodes location to see the position.

So you should display the references frames used to create the knee joint.

This can be done like writing e.g. inside the kneejoint

ThighNode ={
AnyDrawRefNode drw ={};
};

or by finding the node in the modeltree and visualize by right click then select ModelView->RefFrames->show

Best regards
Søren