Euler Angles from rotation matrix

Hello

I'm new to biomechanical analysis, maybe my questions are a little bit silly. I'm sorry.

I have built an orthogonal coordinate system at the ankle with three vectors and the origin O. Now, when I move the ankle, the vectors will point in a different direktion. I want to get the angles whicht describe this rotation. The first rotation is arround the Z-Axis, then the Y-Axis and the last arround the floatig axis which ist perpendicular to the Z and Y-axis.

Could someone help me with that?

And a second question: The position of the ankle changes also. But I think that doesn't matter for the orientation of the coordinate system. Right? I will need the position change for the calculation of the angle speed.

Thank you in advance.

Best wishes, Oliver

Answer 1

[James Tursa]

You might start with this FEX submission called SpinCalc by John Fuller:

http://www.mathworks.com/matlabcentral/fileexchange/20696-function-to-convert-between-dcm--euler-angles--quaternions--and-euler-vectors

[Oliver Kumar]

Hello,

Thanks for the fast reply. It looks that I could use that. But what I don't understand is, wher do I have to put my input matrix and my output matrix. For example I'll call my first (3x3) matrix R1 and the second R2. Thank you!