[ODE] Stabilization force

[Jeffrey Smith]

> Hi Im trying to add a stabilizer force to an object that I want to be
> primarly upright, that is, it should be pretty hard to tilt over, a small
> tilt angle should result that it "bounces back" to upright position...

Have you considered position the center of mass very low on the object (like
a Weeble, if you remember them)?  This may cause a little bit of rocking,
but some angular velocity damping should fix that.

-jeff