How to add external load to the ankle and see the resultant change in the muscle's force (Fm) using Inverse Dynamics

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1

Hey, I am trying to add external load to the ankle but it is not giving any change in the muscle forces using Inverse dynamics. I tried to run the following script by adding it to mannequin.any but Fm is coming out to be constant for all muscles with or without the load.
AnyFolder Load = {
AnyVec3 TopVertebra = {0.000, 0.000, 0.000};

AnyFolder Right = {
  AnyVec3 Shoulder  = {0.000, 0.000, 0.000};
  AnyVec3 Elbow     = {0.000, 0.000, 0.000};
  AnyVec3 Hand      = {0.000, 0.000, 0.000};
  AnyVec3 Hip       = {0.000, 0.000, 0.000};
  AnyVec3 Knee      = {0.000, 0.000, 0.000};
  AnyVec3 Ankle     = {0.000, 0.000, -500.000};
};
AnyFolder Left = {
  AnyVec3 Shoulder  = {0.000, 0.000, 0.000};
  AnyVec3 Elbow     = {0.000, 0.000, 0.000};
  AnyVec3 Hand      = {0.000, 0.000, 0.000};
  AnyVec3 Hip       = {0.000, 0.000, 0.000};
  AnyVec3 Knee      = {0.000, 0.000, 0.000};
  AnyVec3 Ankle     = {0.000, 0.000, 0.000};
};

};

I am using AnyBody 5.3.

2

Hi @Suyash

what you have here is only a a vector containing you force values.
You need to specify a force object - a AnyForce3D for instance. and then apply that force to the ankle via a node or segment.

try to read this tutorial on the subject:

best regards,
bjørn

3

Thank you for your reply.
I added the following script but still, the muscle forces are showing no change even with a 500N force.

AnyFolder Loads = {

  AnyForce3D belt = {
    AnyRefFrame &AnkleJnt=Main.Studies.HumanModel.BodyModel.Right.Leg.Seg.Shank.AnkleJoint;
    F = {0,-500,0}; 
  };
};
4

Have you included that force in the InverseDynamics study?
The study is the object that defines what is part of the simulations.
Often you will see something like this AnyFolder &Model = Main.Model; inside the study.
This includes the whole model folder and all subfolders in the study and thereby the inverse simulations.
If you have made you force object inside a folder that is not part of the study then it will not be part of the simulation.

This tutorial will tell you more about studies: Introduction: A Study of Studies — AnyBody Tutorials v7.4.0

Best regards,
Bjørn

5

It worked.
Thank you so much for your fast reply.

Regards,
Suyash

6

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