src/FDM/JSBSim/FGGroundReactions.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGGroundReactions.cpp
   4  Author:       Jon S. Berndt
   5  Date started: 09/13/00
   6  Purpose:      Encapsulates the ground reaction forces (gear and collision)
   7
   8  ------------- Copyright (C) 2000  Jon S. Berndt (jsb@hal-pc.org) -------------
   9
  10  This program is free software; you can redistribute it and/or modify it under
  11  the terms of the GNU General Public License as published by the Free Software
  12  Foundation; either version 2 of the License, or (at your option) any later
  13  version.
  14
  15  This program is distributed in the hope that it will be useful, but WITHOUT
  16  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  17  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  18  details.
  19
  20  You should have received a copy of the GNU General Public License along with
  21  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  22  Place - Suite 330, Boston, MA  02111-1307, USA.
  23
  24  Further information about the GNU General Public License can also be found on
  25  the world wide web at http://www.gnu.org.
  26
  27 FUNCTIONAL DESCRIPTION
  28 --------------------------------------------------------------------------------
  29
  30 HISTORY
  31 --------------------------------------------------------------------------------
  32 09/13/00   JSB   Created
  33
  34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  35 INCLUDES
  36 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  37
  38 #include "FGGroundReactions.h"
  39
  40 static const char *IdSrc = "$Id$";
  41 static const char *IdHdr = ID_GROUNDREACTIONS;
  42
  43 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  44 CLASS IMPLEMENTATION
  45 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  46
  47
  48 FGGroundReactions::FGGroundReactions(FGFDMExec* fgex) : FGModel(fgex)
  49 {
  50   Name = "FGGroundReactions";
  51
  52   if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
  53 }
  54
  55 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  56
  57 bool FGGroundReactions::Run(void)
  58 {
  59   double steerAngle = 0.0;
  60   double xForces = 0.0, yForces = 0.0;
  61
  62   if (!FGModel::Run()) {
  63     vForces.InitMatrix();
  64     vMoments.InitMatrix();
  65
  66     // Only execute gear force code below 300 feet
  67     if ( Position->GetDistanceAGL() < 300.0 ) {
  68       vector <FGLGear>::iterator iGear = lGear.begin();
  69       // Sum forces and moments for all gear, here.
  70       // Some optimizations may be made here - or rather in the gear code itself.
  71       // The gear ::Run() method is called several times - once for each gear.
  72       // Perhaps there is some commonality for things which only need to be
  73       // calculated once.
  74       while (iGear != lGear.end()) {
  75         vForces  += iGear->Force();
  76         vMoments += iGear->Moment();
  77         iGear++;
  78       }
  79
  80       // Only execute this code when the aircraft ground speed is very, very small.
  81       if (fabs(Translation->GetUVW(eX)) < 0.1 &&
  82           fabs(Translation->GetUVW(eZ)) < 0.1)
  83       {
  84         // Initialize the comparison matrices.
  85         vMaxStaticGrip.InitMatrix();
  86         vMaxMomentResist.InitMatrix();
  87         iGear = lGear.begin();
  88         // For each gear that is touching the ground (which had better be all of them!)
  89         // calculate the X and Y direction maximum "gripping" power. Also, keep track
  90         // of the number of gear that have weight on wheels. This is probably unnecessary.
  91         while (iGear != lGear.end()) {
  92           // calculate maximum gripping power for each gear here based on brake
  93           // and steering settings
  94           // also calculate total number of wheels with WOW set true?
  95           if (iGear->GetWOW()) {
  96             steerAngle = iGear->GetSteerAngle();
  97             vMaxStaticGrip(eX) += (iGear->GetBrakeFCoeff()*cos(steerAngle) -
  98                  iGear->GetstaticFCoeff()*sin(steerAngle))*iGear->GetCompForce();
  99             vMaxStaticGrip(eY) += iGear->GetBrakeFCoeff()*sin(steerAngle) +
 100                   iGear->GetstaticFCoeff()*cos(steerAngle)*iGear->GetCompForce();
 101             vMaxStaticGrip(eZ)  = 0.0;
 102 //            vMaxMomentResist += 1;
 103           }
 104           iGear++;
 105         }
 106
 107         // Calculate the X and Y direction non-gear forces to counteract if needed.
 108         xForces =  -1.0 * ( Aerodynamics->GetForces(eX)
 109                           + Propulsion->GetForces(eX)
 110                           + Inertial->GetForces(eX));
 111
 112         yForces =  -1.0 * ( Aerodynamics->GetForces(eY)
 113                           + Propulsion->GetForces(eY)
 114                           + Inertial->GetForces(eY));
 115
 116         // These if statement comparisons probably need some validation and work
 117         if (fabs(xForces) < fabs(vMaxStaticGrip(eX))) { // forces exceed gear power
 118           vForces(eX) = xForces;
 119         }
 120
 121         if (fabs(yForces) < fabs(vMaxStaticGrip(eY))) { // forces exceed gear power
 122           vForces(eY) = yForces;
 123         }
 124
 125         vMoments(eZ) = -(Aerodynamics->GetMoments(eZ) + Propulsion->GetMoments(eZ));
 126       }
 127     } else {
 128       // Crash Routine
 129     }
 130
 131     return false;
 132   } else {
 133     return true;
 134   }
 135 }
 136
 137 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 138
 139 bool FGGroundReactions::Load(FGConfigFile* AC_cfg)
 140 {
 141   string token;
 142
 143   AC_cfg->GetNextConfigLine();
 144
 145   while ((token = AC_cfg->GetValue()) != string("/UNDERCARRIAGE")) {
 146     lGear.push_back(FGLGear(AC_cfg, FDMExec));
 147   }
 148
 149   return true;
 150 }
 151
 152 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 153
 154 string FGGroundReactions::GetGroundReactionStrings(void)
 155 {
 156   string GroundReactionStrings = "";
 157   bool firstime = true;
 158
 159   for (unsigned int i=0;i<lGear.size();i++) {
 160     if (!firstime) GroundReactionStrings += ", ";
 161     GroundReactionStrings += (lGear[i].GetName() + "_WOW, ");
 162     GroundReactionStrings += (lGear[i].GetName() + "_compressLength, ");
 163     GroundReactionStrings += (lGear[i].GetName() + "_compressSpeed, ");
 164     GroundReactionStrings += (lGear[i].GetName() + "_Force");
 165
 166     firstime = false;
 167   }
 168
 169   return GroundReactionStrings;
 170 }
 171
 172 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 173
 174 string FGGroundReactions::GetGroundReactionValues(void)
 175 {
 176   char buff[20];
 177   string GroundReactionValues = "";
 178
 179   bool firstime = true;
 180
 181   for (unsigned int i=0;i<lGear.size();i++) {
 182     if (!firstime) GroundReactionValues += ", ";
 183     GroundReactionValues += string( lGear[i].GetWOW()?"1":"0" ) + ", ";
 184     GroundReactionValues += (string(gcvt(lGear[i].GetCompLen(),    5, buff)) + ", ");
 185     GroundReactionValues += (string(gcvt(lGear[i].GetCompVel(),    6, buff)) + ", ");
 186     GroundReactionValues += (string(gcvt(lGear[i].GetCompForce(), 10, buff)));
 187
 188     firstime = false;
 189   }
 190
 191   return GroundReactionValues;
 192 }
 193
 194 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 195
 196 void FGGroundReactions::Debug(void)
 197 {
 198     //TODO: Add your source code here
 199 }
 200