I am exporting the F values of various muscles from the MoCapModel thanks to “[…].NameOfTheMuscle.RefFrameOutput.F” in Charts.
When a muscle only has two points (Insertion - Origin, e.g. one element), the Chart of RefFrameOutput.F plots 6 curves.
If I’m not wrong, they represent respectively Fx, Fy and Fz applied to both nodes, with opposite signs because of the Action/Reaction law.
Is this correct ?
Additionally, if we consider a muscle with a single via node as for example the OburatorInternus (Insertion - ViaNode1 - Origin, e.g. two elements), RefFraleOutput.F will include 9 curves.
The previous reasoning is not correct anymore in this case.
I think it would be 3 components for the first element, 3 for the second one, and 3 for a combinaison of the two.
As you can see I am a but confused, could you please provide me further information ?
First, you are right that if there are only two attachment points in a muscle,
then the F values for each node will have the same magnitude with different sign due to the action/reaction law.
But if there are more than two attachment points like the OburatorInternus muscle, then the result will depends on its situation.
For instance, in case of OburatorInternus1 muscle, you can find ‘RefFrameArr’ in the ‘RefFrameOutput’ folder like this:
So you can find that the first and the second nodes are on the pelvis segment and the third node is on the thigh segment.
Then if you can sum the F values from the first node and the second node, then you can find that that summation will have the same magnitude with the F from the third node but opposite sign.
So the relationship between those F values will depend on the relationship between those different muscle attachment nodes.
I hope that this may be helpful to you.
Best regards,
Moonki
P.S) I hope that you can update your personal information in detail in order to let us know who you are. Then we may be able to provide a better support.
Alright, thank your for your helpful answer.
Your explanation is clear to me but to be sure there is still one point I would like to be confirmed when there are more than two attachment nodes.
If we consider the ObturatorInternus1 and its ViaNode, we can see that he has two nodes attached to the “PelvisSeg” and one to the “Thigh”.
With your answer, I understood that the first 3 curves are for the first node (attached to “PelvisSeg”), the following 3 for the second node (also “PelvisSeg”) and the last 3 for the third node (attached to “Thigh”).
So, curves 1 to 6 are the components of the forces acting on the Pelvis (2x3) and curves 7 to 9 (1x3) are related to the Thigh, aren’t they ?
But if I would like to extract the forces of this muscle acting on the Thigh, will AnyForceMomentMeasure2 applied to this Thigh node only include curves 7 to 9 or also curves 1 to 6 (initially acting on the pelvis) ?