[ODE] Simulating Wheels

Amund Børsand amund at offroad.no
Wed Nov 5 17:26:09 MST 2003

Take a look at www.racer.nl, at this page: http://www.racer.nl/prgusers.htm
Also, take a look at www.racesimcentral.com. The buzzword here is
Pacejka (did I spell that correctly)? It's a tire friction model. Tire
friction have little in common with the old friction formula from school,
which is what ODE implements. Rubber tires just don't act the way a
wooden block on the floor does. Pacejka uses real test data to
interpolate between parameters such as load (pressure from car), speed,
and lateral and longtitudal forces, making you car act very
realistically in the end. But this is rather advanced, I'm sure you
don't need it for a simple car sim.

Rather, try to input some "real" data on the car. The center of gravity
is rather low, a friction coefficient of 0.5-0.8 could be used for tires
on dry tarmac, input realistic mass on the chassis and wheels, that will
do wonders. A four by six meters buggy weighing four kilograms just
won't act realistically, no matter how your driving style is. :) Trust
me, I've experimented a bith with the buggy examples (that's where it
all started), and just some realistic numbers do lots. ODE takes care of
the rest (well, maybe except correct tire friction). You could also try
using cylinders for the wheels, but I don't think that's where your
problem lies. With the power of ODE, a realistic car sim really just
need you to input the parameters of a realistic car, it's no hokus pokus.
Well, yes it is, but ODE takes care of that part! :) (What I'm saying is
that there is no need to "cheat" with helping forces here and there,
adjusting wheel speeds to clear corners and so on)

Amund Børsand <amund £ offroad . no>

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