[ODE] Re: Slip values and Pacejka Magic Formula

[Ruud van Gaal]

> To anyone who is using ODE for vehicle simulation, has anyone 
> formulated =
> a corolation between slip values in ODE and Pacejka' s 
> formula for tire =
> forces?

I have no idea what the ODE slip means. What I do think is that you won't
use it when doing Pacejka. Tire slipping isn't something you can just put
into a Coulomb static/dynamic friction model; it's too complex (there is
hardly any dynamics slipping, but an integral over mostly static and some
dynamic friction).

Well, that's my view anyway. I use ODE for the body collisions (OBB vs.
planes from triangles), but the wheels are an entity completely outside ODE
(until they break off in a future version).

Pacejka btw is a big formula with some vibrational parts in it (A*exp(...))
and sines and cosines to estimate force curves that are found empirically.
It has some 30 or so coefficients. I think it is too high level for the
goals of ODE to implement in any way, as it takes as input slip ratio, slip
angle and such parameters that require careful treatment (keeping slip ratio
numerically stable is a chapter in itself).

Ruud