wheel.h

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/***************************************************************************

    file                 : wheel.h
    created              : Sun Mar 19 00:09:18 CET 2000
    copyright            : (C) 2000-2017 by Eric Espie, Bernhard Wymann
    email                : torcs@free.fr
    version              : $Id$

 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef _WHEEL_H__
#define _WHEEL_H__

#include "differential.h"

typedef struct
{

    /* internal data */
    tSuspension  susp;      /* associated suspension */
    tBrake       brake;     /* associated brake disk */

    /* dynamic */
    t3Dd    forces;     /* forces acting on car */
    tdble   rollRes;    /* Rolling Resistance (summed over the car) */
    tdble   rideHeight; /* height of the bottom of the car */
    tdble   zRoad;      /* z of the road */
    t3Dd    pos;        /* world related */
    t3Dd    bodyVel;    /* world related */
    tdble   driveTq;    /* engine torque */
    tdble   vt;

    tdble   spinTq;     /* spin torque feedback */
    tdble   spinVel;    /* spin velocity */
    tdble   prespinVel;     /* spin velocity */
    int         state;      /* wheel state */
    /* 1 and 2 are for suspension state */
#define SIM_WH_ONAIR 4  /* the wheel has no contact to the ground although the suspension is not fully extended */
    tdble   axleFz;     /* force from axle (anti-roll bar) */
    tTrkLocPos  trkPos;     /* current track position */
    t3Dd    surfaceNormal;  // Normal of the surface under this wheel
    tPosd   relPos;     /* relative pos / GC */
    tdble   sa;     /* slip angle */
    tdble   sx;     /* longitudinal slip value */
    tdble   steer;
    
    /* static */
    tPosd   staticPos;  /* pos relative to the GC (z is suspension travel at rest) */
                /* and angles are camber (ax), caster (ay) and toe (az) */
    tdble   rollCenter;

    tdble   weight0;    /* initial weight on this wheel */
    tdble   tireSpringRate;
    tdble   radius;
    tdble   mu;
    tdble   I;          /* I = inertial moment of the wheel */
    tdble   curI;           /* Current inertia for the wheel (including transmission) */
    tdble   mfC;        /* Magic Formula C coeff */
    tdble   mfB;        /* Magic Formula B coeff */
    tdble   mfE;        /* Magic Formula E coeff */
    tdble   lfMax;      /* Load factor */
    tdble   lfMin;      /* Load factor */
    tdble   lfK;        /* Load factor */
    tdble   opLoad;     /* Operating load */
    tdble   mass;       /* total wheel mass (incl. brake) (unsprung mass) */
    tdble   camber;     /* camber, negative toward exterior on both sides */
    tdble   pressure;   /* initial tire pressure, environment temperature */
    tdble   rel_vel;    /* relative velocity - used for realstic suspension movement*/
    tdble   tirewidth;  /* width of tire, used for surface property blending */

    tDynAxis    in;
    tDynAxis    feedBack;

    tdble   preFn, preFt;
    
    // Additional parameters for the tire wear model
    tdble treadMass;                // Initial mass of the tread
    tdble baseMass;                 // Mass of the tire minus the tread
    tdble treadThinkness;           // Thinkness of the initial tread (brand new tire)
    tdble tireGasMass;              // Mass of the gas in the tire (constant)
    tdble tireConvectionSurface;    // Surface area regarding the convection model
    tdble initialTemperature;       // Initial temperature of the tire (initial pressure, p0/T0=constant)
    tdble hysteresisFactor;         // Factor to adjust the hysteresis (model fitting), usually close to 1.0.
    tdble wearFactor;               // Factor to adjust the wear (model fitting), usually close to 1.0.
    tdble idealTemperature;         // Ideal tire temperature for best grip.
    
    // Dynamic Tire properties (temp, wear, etc.)
    tdble currentPressure;          // current tire pressure considering temperature
    tdble currentTemperature;       // current temperature
    double currentWear;             // [0..1], 1 means totally worn (tread thickness 0)
    tdble currentGraining;          // [0..1], 1 means totally grained
    tdble currentGripFactor;        // [0..1], 1 means best grip
    
    tdble tireSlip;                 // Slip of the tire from tire model calculation
    tdble tireZForce;               // Force on tire
    
} tWheel;

    

#endif /* _WHEEL_H__ */