[ODE] RE: Wheel rotation problem

[Nate W]

On Thu, 17 Oct 2002, McEvoy, Nick wrote:

> Thanks Russ for the nice long answer (in physics terms) but no real
> (good) solution (in the short term at least). :(

I must admit I have very little experience using ODE to simulate a car,
but I thought he did offer a good solution... or at least he said
something that sounded to me like the beginnings of a solution to the
wheel problem: fake them.

When ODE generates contacts for the wheel-ground intersection, treat it as
a frictionless contact, so ODE just keeps things from interpenetrating
(you'll also get sideways forces if you're on a slope, which is probably
good).  Then, use your own code to compute the forces that *should* be
there. ODE's friction model is pretty simple (as it should be, IMO), so if
you want a really good model of tire forces for your project, you'll end
up calculating those forces outside of ODE anyhow.

Maybe you could apply the forces directly to the wheel body - but don't
use an axle joint, instead have the wheel attached in such a way that it
moves for suspension and steering but not for rotation.  You could then
apply a force at the contact point (or at the center of the contact patch,
if you wanna get sophisticated), and apply a torque where the axle would
be.

-- 

Nate Waddoups
Redmond WA USA
http://www.natew.com