[ODE] Usage question

[Adam Moravanszky]

Hello,

I am wondering how to model something like the hip or shoulder joint of a
human with ODE.  Initially ball joints come to mind, but as far as I can
tell, these have three rotational DOFs, while I want a shoulder to only have
two (no rotation around the arm axis!)  Further, it would be great if I
could add stops like for hinge joints so the arm cannot get into impossible
poses relative to the body.  The next guess is to use two orthogonal 1-DOF
hinge joints to create a 2-DOF joint, complete with stops.  I've seen robots
which work like this.  The problem here is that there is a singularity in
certain poses that prevent motion in directions which SHOULD be possible.
Thus, perhaps it would be beneficial to add a new joint to ODE wich has 2
rotational DOFs, and there is the possibility of specifying stops.  The
question that remains is how to specify the 2D manifold of motion the joint
is limited to by the stops?

--
-- Adam Moravanszky
http://n.ethz.ch/student/adammo/