# Stiff joints

Hi,

I want to realize stiff joints like i.e. window handles are. E.g. they should need some force to move and then stay in this position.

I use a drive for that with a high damping constant. But this only slows down the movement. Gravity still pulls the object down (e.g. the window handle ends up facing downwards). This is obviously not what I want. Adding a spring constant works, but then the handle moves up again after the push. Is there any good solution to that? (I thought about adding a drive pulling to the current position, but this didn’t work. It still moves downward. I guess gravity still pulls the object a tiny bit downwards and then the next drive is at the new position again…)

Damping means that your joint receives an opposite force to its movement if, and only if, it moves. The magnitude of the force depends on the magnitude of the velocity. So when gravity acts, there is some equilibrium in the joint velocity (->damping force) and the gravitational force.

What you would like to have is joint friction with a static and dynamic friction constant. Here static friction would be able to maintain the joint position under gravity. Unfortunately PhysX does not provide this function… we also have it on our wish list.

From your description I think you could try to make disable gravity on the window and maintain a high damping. This make its behaviour as you probably want it to be.