291 lines
11 KiB
HTML
291 lines
11 KiB
HTML
<!DOCTYPE public "-//w3c//dtd html 4.01 transitional//en"
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<html>
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<!--
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copyright : (C) 2003-2004 Bernhard Wymann
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email : berniw@bluewin.ch
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version : $Id$
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.2
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
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Texts. A copy of the license is included in the section entitled "GNU
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Free Documentation License".
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<head>
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<title>car properties</title>
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<link rel="stylesheet" type="text/css" href="../../../css/format.css"/>
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<meta name="description" content="straight class"/>
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<meta name="author" content="Bernhard Wymann"/>
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#pic2 { float:left; border:0px; width:200px; height:100px; border-style:hidden;
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</head>
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<body bgcolor="#ffffff">
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<table class="maincontent">
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<tr>
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<td class="maincontent">
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<h1>5.4 Car Properties</h1>
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<h3>Introduction</h3>
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<p>
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This section will introduce you in the format of the setup files, the settings
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constraints and the most important
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properties (parameters, settings) of the TORCS cars.
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If you look up the default settings files there are many more settings available than
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presented here, but most of them you can't change (e. g. the engine). I want to
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mention here that you can set all these properties up without a setup file, so you
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are able to compute settings at the startup of the race.
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</p>
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<h3>Setup File Format</h3>
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<p>
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The setup files are XML files. The structure is very simple, you will see just sections,
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subsections and attributes. Numerical attributes are usually defined with a name,
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a unit and the boundaries which define the range of the allowed values.
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</p>
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<h3>Settings Constraints</h3>
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<p>
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The car belongs to a car category, which defines some constraints like the range of
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the allowed size, engine power, weight and more. The car model settings defines then
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the values for its specific car and must not conflict with the constraints from the
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car category. After that we will load our own setup files which must not violate
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the constraints from the above definitions.
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</p>
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<h3>Properties</h3>
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<p>
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You can find all mentioned properties in the file 0/default.xml (relative to
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the <span style="color:red;">bt</span> directory).
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</p>
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<h4>Initial Fuel</h4>
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<p><pre class="lbcolor"> <section name="Car">
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<attnum name="initial fuel" unit="l" min="1.0" max="100.0" val="100.0"/>
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</section></pre>
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</p>
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<p>
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The amount of initial fuel for the setup. Perhaps you want to compute that
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setting at startup instead of putting it into a setup file. Feel free to improve it.
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For qualifying and short races you want just the minimal amount of fuel you need, for
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longer races it will depend on your strategy (but we need to implement pit stops first).
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</p>
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</td>
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</tr>
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</table>
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<table class="maincontent">
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<tr>
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<td class="maincontent">
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<h4>Spoilers</h4>
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<p><pre class="lbcolor"> <section name="Rear Wing">
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<attnum name="angle" unit="deg" min="0" max="30" val="10"/>
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</section></pre>
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</p>
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<p>
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<img id="pic1" src="images/aoa.jpg" alt="spoiler angle of attack" border="0"></img>
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This section defines the angle of attack of the rear spoiler relative to the floor.
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When you increase the angle of attack you get more downforce and drag. If the race
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track has very long straights and just a few narrow turns you want a small angle
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of attack to reduce the drag. If there are many turns you want a big angle of attack to
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increase the downforce, so you can drive faster through the turns. For some cars
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there is also a front wing section available. The front spoiler helps to avoid
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understeering if you set up the rear spoiler with a high angle of attack.
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</p>
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</td>
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</tr>
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</table>
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<table class="maincontent">
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<tr>
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<td class="maincontent">
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<h4>Gearbox</h4>
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<p><pre class="lbcolor"> <section name="Gearbox">
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<section name="gears">
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<section name="r">
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<attnum name="ratio" min="-3" max="0" val="-2.0"/>
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</section></pre>
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<pre> ...</pre>
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<p><pre class="lbcolor"> </section>
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</section></pre>
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</p>
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<p>
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The gearbox section defines the properties of the gears.
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The "r" subsection specifies the ratio of the reverse gear. The reverse gear ratio needs
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to be negative.
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The wheel velocity is proportional to the engine rpm divided by the ratios, so for
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the highest gear you need the least value. For quick starts you need a very high value
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for the first gear.
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</p>
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<h4>Differential</h4>
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<p><pre class="lbcolor"> <section name="Rear Differential">
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<attstr name="type" in="SPOOL,FREE,LIMITED SLIP" val="LIMITED SLIP"/>
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</section></pre>
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</p>
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<p>
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Here the differential type is defined. The "Free" type distributes the power without
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any control, so it is the classic differential you can find in most of the normal
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cars. The "Free" differential is a good choice for tracks with high friction and
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not many bumps for the qualifying. When you leave the track with the "Free" differential
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you perhaps get stuck in the grass, sand or dirt.
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</p>
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<p>
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The "Limited Slip" differential allows just a certain amount of speed difference between
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the left and right wheel. This allows you to come back to the track from grass and dirt.
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This is most often the best setting for races.
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</p>
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<p>
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The "Spool" setting links together the right and the left wheel, so it's usually a bad
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setting for all turns. It could make sense on a very bumpy road or for offroad races.
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</p>
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<h4>Brakes</h4>
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<p><pre class="lbcolor"> <section name="Brake System">
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<attnum name="front-rear brake repartition" min="0.3" max="0.7" val="0.52"/>
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<attnum name="max pressure" unit="kPa" min="100" max="150000" val="11000"/>
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</section></pre>
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</p>
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<p>
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The front-rear brake repartition defines how to distribute the pressure in the brake
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system. If the value is 0.0 all pressure goes to the rear brakes, if it is 1.0 all
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pressure hits the front brakes.
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The max pressure setting defines the pressure for applying full brakes.
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</p>
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</td>
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</tr>
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</table>
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<table class="maincontent">
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<tr>
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<td class="maincontent">
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<h4>Wheels</h4>
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<p><pre class="lbcolor"> <section name="Front Right Wheel">
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<attnum name="ride height" unit="mm" min="100" max="200" val="100"/>
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<attnum name="toe" unit="deg" min="-5" max="5" val="0"/>
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<attnum name="camber" min="-5" max="0" unit="deg" val="0"/>
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</section></pre>
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</p>
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<p>
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<img id="pic2" src="images/toecam.jpg" alt="toe and camber" border="0"></img>
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The ride height setting defines the initial distance of the cars floor to the track.
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When you decrease the ride height the downforce increases because of the ground effect,
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but you cars floor may hit the track.
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With toe (on the left on the sketch) you can define the initial angle of the wheel to the
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car. You can improve the stability or the response to steer commands with these
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settings.
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Camber (on the right on the sketch) defines the angle of the wheel to the track. At the
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moment it increases simply the adherence on the track in the simulation when you
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decrease the angle (toward negative values).
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</p>
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</td>
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</tr>
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</table>
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<table class="maincontent">
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<tr>
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<td class="maincontent">
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<h4>Anti Roll Bar</h4>
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<p><pre class="lbcolor"> <section name="Rear Anti-Roll Bar">
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<attnum name="spring" unit="lbs/in" min="0" max="5000" val="0"/>
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<attnum name="suspension course" unit="m" min="0" max="0.2" val="0.2"/>
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<attnum name="bellcrank" min="1" max="5" val="1.8"/>
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</section></pre>
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</p>
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<p>
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<img id="pic3" src="images/rotate.jpg" alt="rotation of car body" border="0"></img>
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The anti-roll bars prevents the car body from rolling (e. g. in fast turns). When the
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car body rolls (on the bottom of the sketch) the tire contact patch becomes smaller and
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the grip drops down. The spring
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setting defines how strong the anti-roll bar is linked. With a high bellcrank value
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you can increase the strength of the link further.
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</p>
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<p>
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</td>
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</tr>
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</table>
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<table class="maincontent">
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<tr>
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<td class="maincontent">
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<h4>Suspension</h4>
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<p><pre class="lbcolor"> <section name="Front Right Suspension">
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<attnum name="spring" unit="lbs/in" min="0" max="10000" val="2500"/>
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<attnum name="suspension course" unit="m" min="0" max="0.2" val="0.2"/>
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<attnum name="bellcrank" min="1" max="5" val="2"/>
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<attnum name="packers" unit="mm" min="0" max="10" val="0"/>
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<attnum name="slow bump" unit="lbs/in/s" min="0" max="1000" val="80"/>
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<attnum name="slow rebound" unit="lbs/in/s" min="0" max="1000" val="80"/>
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<attnum name="fast bump" unit="lbs/in/s" min="0" max="1000" val="100"/>
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<attnum name="fast rebound" unit="lbs/in/s" min="0" max="1000" val="100"/>
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</section></pre>
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</p>
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<p>
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The spring setting defines how stiff the spring is. The suspension course defines the
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distance which the suspension can move. With the bellcrank you can make the whole
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suspension system more stiff (higher values) or soft (lower values). The packers
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limit the suspension movement. You need this if you want a soft setup and avoiding
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the car floor hitting the track on fast track sections. Slow bump and rebound allow you
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to set up the damping of low frequency oscillations, e. g. caused by braking and steering. Fast
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bump and rebound are for damping high frequency oscillations, e. g. caused by bumps on
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the track or if you hit the curbs.
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</p>
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<h3>Summary</h3>
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<ul style="list-style-type:disk; color:black;">
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<li>You know the most important car parameters and what they are good for.</li>
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</ul>
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<br/>
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</td>
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</tr>
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</table>
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<table class="navigation_foot">
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<tr>
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<td class="navigation_foot">
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<a href="./creating.html">
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<p style="text-align:left;">Back</p>
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</a>
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</td>
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<td class="navigation_foot">
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<a href="./customprop.html">
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<p style="text-align:right;">Custom properties.</p>
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</a>
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</td>
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</tr>
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</table>
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</body>
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</html>
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