rec.autos.simulators

Car physics: alternative tire models

J. Perki

Car physics: alternative tire models

by J. Perki » Sun, 13 Jan 2002 01:06:44

Has anyone else looked at "A Unified Semi-Empirical Tire Model
with Higher Accuracy and Less Parameters" by Guo and Ren (SAE
1999-01-0785)? It seems as if this might be a nice alternative
to the Pacejka stuff, though I'm still trying to get my head
around it all.

Jason
379

Ashley McConnel

Car physics: alternative tire models

by Ashley McConnel » Wed, 16 Jan 2002 08:02:35


How did you get on Jason?  Did you get it coded?  How did it compare to
Pacejka?

All the best,
Ash
http://www.siroccoracing.com

J. Perki

Car physics: alternative tire models

by J. Perki » Thu, 17 Jan 2002 02:05:14




> > Has anyone else looked at "A Unified Semi-Empirical Tire Model
> > with Higher Accuracy and Less Parameters" by Guo and Ren (SAE
> > 1999-01-0785)? It seems as if this might be a nice alternative
> > to the Pacejka stuff, though I'm still trying to get my head
> > around it all.

> How did you get on Jason?  Did you get it coded?  How did it compare to
> Pacejka?

I am still trying to finish up my pacejka code - it's one of
those things were the end seems so close and yet you never
quite get there. Once I get there -- if I'm not completely
sick of tire models -- I'll give it a go and report back.

Jason
379

Ruud van Ga

Car physics: alternative tire models

by Ruud van Ga » Thu, 17 Jan 2002 23:27:08


I've read it, and although it seems that the first part is quite
unrelated to the 2nd part (the steady state tire model), it's quite
interesting.

However, there are still quite a few parameters (though simpler as
they are mostly constant/first order/second order dependencies on
load).
And I don't know where to place camber exactly (but I only read it
once, so I perhaps understood 20% of the paper, lol). The combined
slip method seems very much like what Gregor was/is using in his sim
(SR=sqrt(SR_x^2+SR_y^2) and then multiplying forces by SR_x/SR
factors).

I don't think I'll switch, now that I understand Pacejka quite a bit
(although I don't use the official slip combination (G=cos.../cos...)
methods, which IIRC introduce a couple more parameters).
I don't really agree with the paper that Pacejka is so computationally
expensive anymore; these CPUs are so blindingly fast (it's just
Windows it's running on that gives the overhead). And that SAE
document is filled with exp() calls.

But given Pacejka and this method, they may be on par. Both lack a
wide range of known parameter sets. ;-)

Ruud van Gaal
Free car sim  : http://www.marketgraph.nl/gallery/racer/
Pencil art    : http://www.marketgraph.nl/gallery/


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