torcs-users Mailing List for TORCS - The Open Racing Car Simulator

Hello. I was just wondering if you'd had any time to look into this 
problem. I tried your suggestion of making the cars stationary at low 
velocities. Unfortunately, this doesn't seem to work in many cases. If 
the car is braking softly, the forces acting on the car are strong 
enough to start moving it in an unintended direction (rolling backwards, 
for example) before it slows down enough.  Also, this fix doesn't stop 
the car from twisting around its center of gravity. I tried omitting the 
component of the wheels' body velocity that's based on the angular 
acceleration when the car is below the threshold velocity, but that 
results in the car "hopping" intermittently for reasons I don't 
understand yet.

Have you had any luck with using wheel friction in the top-level simulation?

thanks,
-frank


Christos Dimitrakakis wrote:
> There are some problems with friction - since the car is not really a 
> rigid object, the correct calculation of friction
> forces is tricky.  At low speeds there is an inherrent 'jitter' which 
> is unfortunately slightly biased - the calculations are tuned for 
> higher speeds. I think it is possible to do a quick fix for this 
> behaviour by making the cars stationary when their speed is below a 
> certain threshold - I will try it out and see if this solves it.
>
> However, when the road is inclined this fix will not help.  Fixing it 
> with a more accurate simulation is possible but it may slow things 
> down considerably.  There's a possible easy fix by passing the 
> friction limitts for each wheel to the top-level simulation, which I 
> can try out now and see if it can help anything.
>
>

This is an enormously lengthy posting, sorry about that.
Definition of sloppy driving: Intentionally or by accident hitting a nearby car even if enough space to drive in exists

The reasoning below is not Torcs specific, it applies to all simulations,
past, current and future with "sloppy robots".

An example race: CG-track 3
berniw two 9
Olethros 5
bt 5
berniw 7
berniw 9
bt 6
berniw two 8
Olethros 2
berniw 2
berniw 1
Olethros 9
bt 1
berniw 4
berniw two 7
berniw 6
berniw two 4
Olethros 7
Inferno 3
bt 10
You (Porsche GT3RS)
berniw two 6
bt 9
berniw 5
Damned 2
Olethros 6
berniw two 2
berniw two 10
bt 3
bt 4

A wild mixture as you can se but I hoped it would be interesting. Some cars,
as Olethros 4, would be fast enough to be included but they cause too many
accidents. The start order is more to avoid mass crashes in the start than
after lap times.

A quick race; fairly long, say, 25 laps. To be able to start with this many
cars change in Linux and FreeBSD: (your home
directory)/.torcs/config/raceman/quickrace.xml
  <section name="Drivers">
    <attnum name="maximum number" val="40"/>
or some number you fancy. I do not know where quickrace.xml is hidden in
Windows, I hope you can find it.
In the tracksdata directory for inferno 3 create a g-track-3.xml file
containing:
<?xml version="1.0" encoding="UTF-8"?>
<!--
    file                 : e-track-2.xml
    created              : Thu May 10 20:19:12 /etc/localtime 2001
    copyright            : (C) 2001 by Eric Espi<E9>
    email                : Eri...@to...
    version              : $Id: default.xml,v 1.2 2003/06/24 21:02:02 torcs
Exp $

-->

<!--    This program is free software; you can redistribute it and/or modify
-->
<!--    it under the terms of the GNU General Public License as published by
-->
<!--    the Free Software Foundation; either version 2 of the License, or
-->
<!--    (at your option) any later version.
-->

<!DOCTYPE params SYSTEM "../../../libs/tgf/params.dtd">

<params name="" type="template">

  <section name="Simulation Parameters">
    <attnum name="PGain"     val="0.05"/>
    <attnum name="AGain"     val="0.008"/>
    <attnum name="PnGain"    val="0.04"/>
    <attnum name="Advance"   val="2.0"/>
    <attnum name="Advance2"  val="10.0"/>
    <attnum name="AdvStep"   val="3.0"/>
    <attnum name="VGain"     val="0.0005"/>
    <attnum name="preDy"     val="0"/>
    <attnum name="spdtgt"    val="120.0"/>
    <attnum name="spdtgt2"   val="0.0"/>
    <attnum name="steerMult" val="2.0"/>
    <attnum name="damage threshold" val="50000"/>
  </section>

</params>

and a car_g-track-3.xml file containing:
<?xml version="1.0" encoding="UTF-8"?>

<!-- 
    file                 : porsche-gt1.xml
    created              : Sun Mar 25 01:36:37 CET 2001
    copyright            : (C) 2001 by Eric Espi                        
    email                : Eri...@to...   
    version              : $Id: porsche-gt1.xml,v 1.15 2005/02/15 15:42:56 
olethros Exp 
$                                  
-->

<!--    This program is free software; you can redistribute it and/or modify  
-->

<!--    it under the terms of the GNU General Public License as published by  
-->

<!--    the Free Software Foundation; either version 2 of the License, or     
-->

<!--    (at your option) any later version.                                   
-->
<!DOCTYPE params SYSTEM "../../../../src/libs/tgf/params.dtd">

<params name="Porsche GT1" type="template">

  <!--  Designed by Christophe Guionneau -->

  <section name="Car">
    <attnum name="initial fuel" unit="l" min="1.0" max="100.0" val="80.0"/>
  </section>

  <section name="Rear Wing">
    <attnum name="angle" unit="deg" min="0" max="30" val="10"/>
  </section>

  <section name="Gearbox">
    <section name="gears">
      <section name="r">
        <attnum name="ratio" min="-3" max="0" val="-2.0"/>
      </section>
      <section name="1">
        <attnum name="ratio" min="0" max="5" val="2.0"/>
      </section>
      <section name="2">
        <attnum name="ratio" min="0" max="5" val="1.5"/>
      </section>
      <section name="3">
        <attnum name="ratio" min="0" max="5" val="1.2"/>
      </section>
      <section name="4">
        <attnum name="ratio" min="0" max="5" val="1.00"/>
      </section>
      <section name="5">
        <attnum name="ratio" min="0" max="5" val="0.7"/>
      </section>
      <section name="6">
        <attnum name="ratio" min="0" max="5" val="0"/>
      </section>
    </section>
  </section>

  <section name="Steer">
    <attnum name="steer lock" unit="deg" min="1" max="45" val="45"/>
    <attnum name="max steer speed" unit="deg/s" min="1" max="360" val="120"/>
  </section>

  <section name="Brake System">
    <attnum name="front-rear brake repartition" min="0.3" max="0.7" 
val="0.33"/>
    <attnum name="max pressure" unit="kPa" min="100" max="150000" 
val="30000"/>
  </section>

  <section name="Rear Differential">
    <!-- type of differential : SPOOL (locked), FREE, LIMITED SLIP -->
    <attstr name="type" in="SPOOL,FREE,LIMITED SLIP" val="FREE"/>
    <attnum name="ratio" min="0" max="10" val="4.5"/>
  </section>

  <section name="Front Right Wheel">
    <attnum name="ride height" unit="mm" min="100" max="300" val="120"/>
    <attnum name="toe" unit="deg" min="-5" max="5" val="-5"/>
    <attnum name="camber" min="-5" max="0" unit="deg" val="-3"/>
  </section>

  <section name="Front Left Wheel">
    <attnum name="ride height" unit="mm" min="100" max="300" val="120"/>
    <attnum name="toe" unit="deg" min="-5" max="5" val="5"/>
    <attnum name="camber" min="-5" max="0" unit="deg" val="-3"/>
  </section>

  <section name="Rear Right Wheel">
    <attnum name="ride height" unit="mm" min="100" max="300" val="120"/>
    <attnum name="toe" unit="deg" val="0"/>
    <attnum name="camber" min="-5" max="0" unit="deg" val="-1"/>
  </section>

  <section name="Rear Left Wheel">
    <attnum name="ride height" unit="mm" min="100" max="300" val="120"/>
    <attnum name="toe" unit="deg" val="0"/>
    <attnum name="camber" min="-5" max="0" unit="deg" val="-1"/>
  </section>

  <section name="Front Anti-Roll Bar">
    <attnum name="spring" unit="lbs/in" min="0" max="5000" val="0"/>
    <attnum name="suspension course" unit="m" min="0" max="0.2" val="0.2"/>
    <attnum name="bellcrank" min="1" max="5" val="2.5"/>
  </section>

  <section name="Rear Anti-Roll Bar">
    <attnum name="spring" unit="lbs/in" min="0" max="5000" val="5000"/>
    <attnum name="suspension course" unit="m" min="0" max="0.2" val="0.2"/>
    <attnum name="bellcrank" min="1" max="5" val="2.5"/>
  </section>

  <section name="Front Right Suspension">
    <attnum name="spring" unit="lbs/in" min="0" max="10000" val="8500"/>
    <attnum name="suspension course" unit="m" min="0" max="0.3" val="0.2"/>
    <attnum name="bellcrank" min="0.1" max="5" val="2.5"/>
    <attnum name="packers" unit="mm" min="0" max="10" val="0"/>
    <attnum name="slow bump" unit="lbs/in/s" min="0" max="1000" val="80"/>
    <attnum name="slow rebound" unit="lbs/in/s" min="0" max="1000" val="800"/>
    <attnum name="fast bump" unit="lbs/in/s" min="0" max="1000" val="20"/>
    <attnum name="fast rebound" unit="lbs/in/s" min="0" max="1000" 
val="1000"/>
  </section>

  <section name="Front Left Suspension">
    <attnum name="spring" unit="lbs/in" min="0" max="10000" val="8500"/>
    <attnum name="suspension course" unit="m" min="0" max="0.3" val="0.2"/>
    <attnum name="bellcrank" min="0.1" max="5" val="2.5"/>
    <attnum name="packers" unit="mm" min="0" max="10" val="0"/>
    <attnum name="slow bump" unit="lbs/in/s" min="0" max="1000" val="80"/>
    <attnum name="slow rebound" unit="lbs/in/s" min="0" max="1000" val="800"/>
    <attnum name="fast bump" unit="lbs/in/s" min="0" max="1000" val="20"/>
    <attnum name="fast rebound" unit="lbs/in/s" min="0" max="1000" 
val="1000"/>
  </section>

  <section name="Rear Right Suspension">
    <attnum name="spring" unit="lbs/in" min="0" max="10000" val="5500"/>
    <attnum name="suspension course" unit="m" min="0" max="0.3" val="0.2"/>
    <attnum name="bellcrank" min="0.1" max="5" val="1"/>
    <attnum name="packers" unit="mm" min="0" max="10" val="0"/>
    <attnum name="slow bump" unit="lbs/in/s" min="0" max="1000" val="80"/>
    <attnum name="slow rebound" unit="lbs/in/s" min="0" max="1000" val="800"/>
    <attnum name="fast bump" unit="lbs/in/s" min="0" max="1000" val="100"/>
    <attnum name="fast rebound" unit="lbs/in/s" min="0" max="1000" 
val="1000"/>
  </section>

  <section name="Rear Left Suspension">
    <attnum name="spring" unit="lbs/in" min="0" max="10000" val="5500"/>
    <attnum name="suspension course" unit="m" min="0" max="0.3" val="0.2"/>
    <attnum name="bellcrank" min="0.1" max="5" val="1"/>
    <attnum name="packers" unit="mm" min="0" max="10" val="0"/>
    <attnum name="slow bump" unit="lbs/in/s" min="0" max="1000" val="80"/>
    <attnum name="slow rebound" unit="lbs/in/s" min="0" max="1000" val="800"/>
    <attnum name="fast bump" unit="lbs/in/s" min="0" max="1000" val="100"/>
    <attnum name="fast rebound" unit="lbs/in/s" min="0" max="1000" 
val="1000"/>
  </section>

</params>


Inferno 3 will drive a sane but slow race, it's inclusion is of course to have 
a car that will not try to pit in the unusable pit position. Why not make it 
run fast? I have not been able to make it run fast and without crashing. I 
hope the above files don't get mangled in the mail, if so you must correct 
them yourself in the same fashion as the correct files in the tracksdata 
directory.

I raced the above race, I didn't expect to win with all the McLaren F1's 
participating but I hoped to do well as I consider myself to be better in 
traffic than the robots. That was not going to happen.

I found that when I tried to pass (as in gaining a position, not lapping) a 
car in a curve it would almost inevitably crash into me whether I tried the inside
or the outside and even if I drove close to the edge to give room for the robot to
drive in. If I anyway succeded in passing the car would chase me on the 
following straight and if I did not leave the inside to the robot it would 
rearend me. If I instead drove on the outside and was remotely successfull in 
keeping my position I would be driven into despite giving plenty of room to 
the robot. The above was much less noticeable if my car was the superior one.

All of these crashes caused me to a lot of pitstops thereby hindering me from 
a good result despite a good best lap time.

As this is the internet, let me clarify once and for all, I do not mind being
passed, I oppose being crashed into when I leave space for the robot to drive 
in.

I'm sure you all have the same experience.


This and a lot of similar events involving sloppy robot driving teaches us two 
lessons:

1. Driving skill is unimportant.

2. To compete successfully you must use a superior car.


I do not think that a simulation should do that. To correct this the robots 
must drive more carefully as not to drift unintentionally when cornering and 
to look out for cars nearby.

Any comments on this would be most welcome.

Regards
Kennet


 		
---------------------------------

Stava rätt! Stava lätt! Yahoo! Mails stavkontroll tar hand om tryckfelen och mycket mer! Få den på http://se.mail.yahoo.com

Frank Broz wrote:

>Hello. I have been using TORCS as a platform for a driving experiment 
>I'm conducting. The experiment involves driving at low speeds and making 
>frequent stops, and I've had some problems getting the cars to come to a 
>complete stop. The cars seem to stop normally at first but gradually 
>start to drift even with the brake fully depressed. If the car is at an 
>angle (with respect to the direction of the track) when it stops, it 
>will start to slowly twist around it's center of gravity. If it isn't, 
>it rolls backwards slowly. Has anyone else seen this behavior in TORCS? 
>Any idea what the problem might be?
>  
>
There are some problems with friction - since the car is not really a 
rigid object, the correct calculation of friction
forces is tricky.  At low speeds there is an inherrent 'jitter' which is 
unfortunately slightly biased - the calculations are tuned for higher 
speeds. I think it is possible to do a quick fix for this behaviour by 
making the cars stationary when their speed is below a certain threshold 
- I will try it out and see if this solves it.

However, when the road is inclined this fix will not help.  Fixing it 
with a more accurate simulation is possible but it may slow things down 
considerably.  There's a possible easy fix by passing the friction 
limitts for each wheel to the top-level simulation, which I can try out 
now and see if it can help anything.

Hello. I have been using TORCS as a platform for a driving experiment 
I'm conducting. The experiment involves driving at low speeds and making 
frequent stops, and I've had some problems getting the cars to come to a 
complete stop. The cars seem to stop normally at first but gradually 
start to drift even with the brake fully depressed. If the car is at an 
angle (with respect to the direction of the track) when it stops, it 
will start to slowly twist around it's center of gravity. If it isn't, 
it rolls backwards slowly. Has anyone else seen this behavior in TORCS? 
Any idea what the problem might be?

I'm using version 1.2.4. I looked at the change log for 1.3.0 and didn't 
see anything that seemed relevant, but  I may have overlooked something.

thanks,
-frank

Bernhard,

I never received a welcome email when I signed up. My user id is: ncc
and my email is: 00...@gm.... I tried resending the sign up info,
but never receive the emails. If I try to re-sign up, it says the
email is already being used. Please help,

Thanks


-- 
http://castlehq.com, http://netcastle.net, http://bravetux.com

Bernhard,

I never received a welcome email when I signed up. My user id is: ncc
and my email is: 00...@gm.... I tried resending the sign up info,
but never receive the emails. If I try to re-sign up, it says the
email is already being used. Please help,

Thanks