Rotate coordinate system of a joint

Main Forum
1

Hello,

I have motion capture data from a inertial measurement system as angles in txt-files and want to import them in AnyBody in the FreePostureMove-Model.

Because the movement is not right when I import the data, I think I have to rotate the coordinate systems of each joint. I put an example from the left shoulder in the attachment.
If I understood this image right, I have to use the first sub-image.

So I tried this at the interface:
AnyFolder &gh=…Seg.Humerus.gh;
gh={
AnyRefNode RefNode = {
ARel=.ARel*{{0,0,1},{0,…Sign*-1,0},[{…Sign1,0,0}}RotMat(-90pi/180,y)RotMat(-90pi/180,x);
};

but this seems not right. :slight_smile:

In addition, at my mocap system the definition of the direction of the movement is the other way round than at AnyBody: Flexion<0° and Extension>0°.

Maybe someone can help me with my rotational problem. :slight_smile:

Kind regards
Julika

2

Hi Julika,

Your email did not have this extra information that you’re changing the joint frames to be able to import your motion capture data.

This is indeed a lot of work! and on the face of it I really don’t think it is necessary.

Instead of changing the default frames in the model, why don’t you create a new anykinrotational measure between the existing humerus and scapula and then drive this measure using your experimental data?

Regards
Ananth

3