Re: [Torcs-devel] Buxfixes

[Christos D. <dim...@id...>]

> I suspect the skidmarks are displayed all the time because there is a
> lot of slip between the road and the tire with the new camber code. If
> you plan to release 1.2.2 with simuv3 we need to readjust the setups of
> the cars, so let me know:-)
>

Actually it is because I have modified how _skid[] is calculated.
Stupid me.

car->carElt->_skid[index] = MIN(1.0, s*reaction_force*0.0002);

The slip is calculated a bit differently, but it is essentially the
same.
	sx = wvx/absolute_speed;
	sy = wvy/absolute_speed;
	sa = atan2(wvx,wvy);
	s = sqrt(sx*sx+sy*sy);

Where wvx and wvy are the relative speed of the wheel wrt the road,
taking angular velocity into account. The absolute speed only has an
effect on the calculation of Bx and the rest of the magic formula,
which I am not sure what it does. Eric?

Anyways, I'll modify it so that when s*reaction_force*0.0002 <
threshold the _skid is set to 0. That should stop the skidmarks being
there all the time.


> I think the resulting camber will be then almost 0:-( No cool look
> anymore...
>

You still have 90% of the traction when the camber is 25 degrees, so I
don't think the effect is particularly big. The camber setting should
be such that when you turn the outer wheels have a camber close to 0.
Since the car tilts anyway a little bit, they need to have a camber
setting from the beginning.

Currently I am just using cos(camber) to calculate the
traction change because of camber. But that might be wrong.

....

I tried the FWD cars and they oversteer a lot. Is that because of the
suspension settings? I have the nagging feeling it's because there's
something braking the rear wheels.

Also, when starting the race, the p406's rear wheels spin.

-- 
Christos Dimitrakakis
IDIAP (http://www.idiap.ch/~dimitrak/main.html)