Problem with rotations output field

[barney75]

Hi guys,
I had some problems in understanding the rotation output field in the viewer. Therefore I gave a look to the doc., in particular I'm referring to the user manual section "1.2.2 Conventions". At the end of the first example (i.e. 60 degrees about z-axis, 90 degrees about beam axis and then rotate beam onto z-axis) both using VELOCITY (incremental) option and DISPLACEMENT (absolute) option and after the formulation for the Explict module finally it is given the following output for the rotation field when using the viewer:

UR1 = 1.927, UR2=-0.5163, UR3=1.927

Can anyone explain me how to get from the rotation components given in the example input file (wether incremental or absolute) to the rotation field output. I read this sentence "The final rotation output represent the rotation vector required to obtain the final orientation in a single step" but I don't understand how to compute it starting from the rotation component I used in the input file.

Thanks a lot

Bye

 

[potf]

Hi barney75,

compound finite rotations are computed by quaternion multiplication. The final rotation components are extracted from the resulting quaternion.

See theory manual, look for quaternion parametrization.

Hope this helps,

potf