I use PhysX to make vehicle, and I faced strange problem with wheels behavior (same I found in kings on wheels from samples folder). Wheels aren't changing they position smoothly (in Z coordinates), so if you drive on low-poly map (made with model) you can see some strange behavior, like jerking while adapting to slopes and surface angles.. I can provide demo, video and better explanation if needed, but I really want this to be fixed, so it will act smoothly as it used to in ODE.

EDIT: got some mistakes..

Wheel behavior is determined by inertia, lateral and longitudinal friction, and suspension parameters. That's what you should check at first. A wrong z value can be caused by a bad set up suspension. The wheel must not touch the chassis when the suspension is fully compressed.

Just to be sure: Are you just using the PhysX car or making one yourself? Obviously making a car is more difficult than just driving it.

I just tried to get "knights on wheels" work with different level and I got the problems I've explained above. Same I've faced while making my own car physics, so I don't think I've made something wrong. I didn't use any other car model, used same as in knights on wheels.

So, should I provide something like video or demo?

Not for me. I hope you understand that I don't have the possibility to individually help all users with their projects.

I can just advise that physics vehicles require a certain smoothness of the surface, and won't drive well on raw triangles. Use terrain for the ground. Also look in the manual about adjusting the car and suspension parameters. If you want to make your own car, you might get much more help on the nVidia PhysX forum - that was at least very helpful for me.

Ohh, sorry but you misunderstood me jcl. I don't want you to help me individually with my project (I wont dare). I think I found possible bug, thats all I wanted to tell, I've asked here cause I was thinking that may be this is problem from my side. Anyway just to make things (and explanation as well) clear I'll upload video with problem I've faced.

Ohh, sorry but you misunderstood me jcl. I don't want you to help me individually with my project (I wont dare). I think I found possible bug, thats all I wanted to tell, I've asked here cause I was thinking that may be this is problem from my side. Anyway just to make things (and explanation as well) clear I'll upload video with problem I've faced.

Maybe there's some fundamental misunderstanding about the physics engine. You posted many times here with always similar problems. Please understand two things. We haven't made PhysX and can't fix its "bugs". And what you've told does not sound like a bug anyway.

Physics engines are not perfect, and problems like jerking wheels on low-poly ground are typical and must be addressed by the game developer. We've provided a simple car and a demo to show how to use it. You can just make your game from that demo and won't have problems with jerking wheels. But if you're more ambitious and want more realistic car behavior, you're free to create you own car, maybe with ball joints for the wheels as in ODE. But then you have to dig into the matter and address the same problems like any other game developer who uses car physics.

Thats the thing jcl, there is same jerking behavior in knights on wheels from samples folder as well... My own physics based on it... Thats why I think that its implementation bug.

OK, so first, here is the video, which I've made with knights on wheels:
Youtube link
And here is the demo project, to show you the problem:
Download link