GH reaction force calculation with Bergmann GH model

Main Forum
1

Hi there,

I am working with the GH Bergmann Model and I am looking at the GH joint reaction force at the moment.

  • I don’t really understand how the Ftotal in the coordinate system of the Humerus (to compare to results with Bergmann)is calculated:

-Main-file:
GHReaction=
(Model.HumanModel.Right.ShoulderArm.Seg.Humerus.gh.Bergmann.Axes’*Model.HumanModel.Right.ShoulderArm.Jnt.GHReactions.ResultanForce.FTotalLocal’)’;

If I understand it right, FtotalLocal is in the local coordinate system of the Scapula, to calculate Ftotal in the coordinate system of the Humerus, don’t you have to take FtotalGlobal instead of FtotalLocal?

Thanks for your answer!
Daniela

2

Hi Daniela,

I looked in the application and the original code is the following:

AnyVec3 GHReactionInHumerus = -(Model.HumanModel.Right.ShoulderArm.Seg.Humerus.gh.Bergmann.Axes’ *Model.HumanModel.Right.ShoulderArm.Jnt.GHReactions.ResultanForce.FTotal’)’;

You can see that the variable for the gh force is called FTotal. This is actually outdated. In the previous versions of the repository FTotal was reaction force vector in global coordinates.
Now we changed this variable to FTotalGlobal and FTotalLocal as you could see. So as you said it is FTotalGlobal that has to be used now.

Best regards, Sylvain.