[ODE] springs

[Floris van Breugel]

Hi,

How do you get a hinge joint to act like a torsion spring such that  
you can set the spring constant? I tried setting changing the CFM and  
ERP but don't see any differences in the system when I apply forces.  
I would like something where the joint will give some amount  
proportional to the force and spring constant like a real spring, not  
using hard constraints. Any tips would be great.

Thanks,

- Floris