Get Body frame relationship (transformation matrix) in Matlab

[Hilary Cheng]

Hi,

How can I know the Transformation matrix between 2 Body frames at certain State? (eg. between the humerus frame and clavicle frame or even ground frame) Are there any codes that I can use in Matlab to extract the Transformation relationship?

Thanks!

Regards,
Hilary

[Thomas Uchida]

I think you are looking for the Frame::findTransformBetween() method: https://simtk.org/api_docs/opensim/api_ ... 902fd30aa3.

[Hilary Cheng]

Hi,

Thanks for the reply!
I have tried the following:

dsrFrame = osimModel.getGround();
body = osimModel.getBodySet().get(0)
transform = body.findTransformBetween(state,dsrFrame)

what I get in Matlab is:
transform =
org.opensim.modeling.Transform@2676dc05

I would like to know how can I convert the value above to a Matlab readable Matrix?

Thanks!

Hilary

[Hilary Cheng]

Problem Solved! =)

for reference:
rotationmatrix = transform.R();
positionvector = transform.p();

Thanks for helping!
Hilary