From: "Jussi Pajala"
To: "Rars mailing-list" 
Subject: RE: Hello Again
Date: Wed, 23 Aug 2000 09:59:04 +0300

>-----Original Message-----
>From: Ralph Scott

>I wonder if Jussi P. is still around.  I am tempted to have the 
>car i gave him
>made public.  (My rars directory is on an unconnected hard drive 

Yes, still hanging in here... I have two of your bots, named Ralph2
and Ralph2a. You want them?

>I wish i understood how to use spirals.  I could never figure out 
>the formula
>that the car makes (for instance) when braking and turning.

I thought about spirals too but gave up before I got even started.
They seemed to be too hard to figure out and too time taking to compute.

Instead I developed a global optimization algorithm that can be used
in any track. It takes quite a while to compute, but results were quite
promising. I never got enough spare time to finish the algorith and
do the driver algorith for the optimal line.

The algorithm is based on A* search. It is based on an idea that at any
time step you have approximately 8 possible actions you can make:

- accelerate
- brake
- turn left
- turn right
- acc + left
- acc + right
- brake + left
- brake + right

Then by calculating position after each time step (using RARS internal 
functions) you get a huge search tree and finally A* gives you the optimal
driving line.

I'll send one gif with this mail.  It is from track tremblnt. Different 
colored points in the track are points that the search algorithm has gone
through. You can prety much see what was the problem with algorithm:
it traps into every corner for a long time because it thinks that it is
the most optimal path when you are driving as fast as possible. That's why
it get lots of nicely colored dots into corners... This path was computed
so that the algorithm made only 4 actions in a second (maximum in RARS is

If you want to have more pictures from different tracks, I can send them. 
I just don't want to send  them to the list.