Confusion about the hinge constraint

[dotsquid]

Hi there.
I'm embedding Bullet Physics into my game engine and almost all things are understandable and easy to use.
However, I've noticed a weird (or not?) behaviour of the hinge constraint. I've created a simple bridge. It has n sections (boxes) connected to each other with the hinge joints. In some cases (when a lot of balls are thrown on the bridge) it twists It means that the hinge constraint allow rotation around another axis.
Does anyone have any explanation / solution? I believe that such behaviour isn't right, because we can use a point2point constraint to achieve such effect.
Thanks in advance.

hinge.jpg

[dotsquid]

Ah, and another question.
I've tried to make the bridge more elastic and played with _softness, _biasFactor, _relaxationFactor parameters of btHingeConstraint::setLimit. But I haven't seen any changes. I've tried values from 0.01f to 10.0f. How to use them correctly?

[dotsquid]

Anyone?

[dotsquid]

What's wrong with this forum?

[Dirk Gregorius]

The iterative solver might have some problems with such a relative complex scene. It is a tough problem to make larger articulated structures stiff. You can try higher iterations count and smaller timesteps. Both result in stiffer simulations.