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                                                         vForces(3),
  50                                                         vMoments(3),
  51                                                         vMaxStaticGrip(3),
  52                                                         vMaxMomentResist(3)
  53 {
  54   Name = "FGGroundReactions";
  55
  56   if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
  57 }
  58
  59 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  60
  61 bool FGGroundReactions::Run(void)
  62 {
  63   double steerAngle = 0.0;
  64   double xForces = 0.0, yForces = 0.0;
  65
  66   if (!FGModel::Run()) {
  67     vForces.InitMatrix();
  68     vMoments.InitMatrix();
  69
  70     // Only execute gear force code below 300 feet
  71     if ( Position->GetDistanceAGL() < 300.0 ) {
  72       vector <FGLGear>::iterator iGear = lGear.begin();
  73       // Sum forces and moments for all gear, here.
  74       // Some optimizations may be made here - or rather in the gear code itself.
  75       // The gear ::Run() method is called several times - once for each gear.
  76       // Perhaps there is some commonality for things which only need to be
  77       // calculated once.
  78       while (iGear != lGear.end()) {
  79         vForces  += iGear->Force();
  80         vMoments += iGear->Moment();
  81         iGear++;
  82       }
  83
  84       // Only execute this code when the aircraft ground speed is very, very small.
  85       if (fabs(Translation->GetUVW(eX)) < 0.1 &&
  86           fabs(Translation->GetUVW(eZ)) < 0.1)
  87       {
  88         // Initialize the comparison matrices.
  89         vMaxStaticGrip.InitMatrix();
  90         vMaxMomentResist.InitMatrix();
  91         iGear = lGear.begin();
  92         // For each gear that is touching the ground (which had better be all of them!)
  93         // calculate the X and Y direction maximum "gripping" power. Also, keep track
  94         // of the number of gear that have weight on wheels. This is probably unnecessary.
  95         while (iGear != lGear.end()) {
  96           // calculate maximum gripping power for each gear here based on brake
  97           // and steering settings
  98           // also calculate total number of wheels with WOW set true?
  99           if (iGear->GetWOW()) {
 100             steerAngle = iGear->GetSteerAngle();
 101             vMaxStaticGrip(eX) += (iGear->GetBrakeFCoeff()*cos(steerAngle) -
 102                  iGear->GetstaticFCoeff()*sin(steerAngle))*iGear->GetCompForce();
 103             vMaxStaticGrip(eY) += iGear->GetBrakeFCoeff()*sin(steerAngle) +
 104                   iGear->GetstaticFCoeff()*cos(steerAngle)*iGear->GetCompForce();
 105             vMaxStaticGrip(eZ)  = 0.0;
 106 //            vMaxMomentResist += 1;
 107           }
 108           iGear++;
 109         }
 110
 111         // Calculate the X and Y direction non-gear forces to counteract if needed.
 112         xForces =  -1.0 * ( Aerodynamics->GetForces(eX)
 113                           + Propulsion->GetForces(eX)
 114                           + Inertial->GetForces(eX));
 115
 116         yForces =  -1.0 * ( Aerodynamics->GetForces(eY)
 117                           + Propulsion->GetForces(eY)
 118                           + Inertial->GetForces(eY));
 119
 120         // These if statement comparisons probably need some validation and work
 121         if (fabs(xForces) < fabs(vMaxStaticGrip(eX))) { // forces exceed gear power
 122           vForces(eX) = xForces;
 123         }
 124
 125         if (fabs(yForces) < fabs(vMaxStaticGrip(eY))) { // forces exceed gear power
 126           vForces(eY) = yForces;
 127         }
 128
 129         vMoments(eZ) = -(Aerodynamics->GetMoments(eZ) + Propulsion->GetMoments(eZ));
 130       }
 131     } else {
 132       // Crash Routine
 133     }
 134
 135     return false;
 136   } else {
 137     return true;
 138   }
 139 }
 140
 141 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 142
 143 bool FGGroundReactions::Load(FGConfigFile* AC_cfg)
 144 {
 145   string token;
 146
 147   AC_cfg->GetNextConfigLine();
 148
 149   while ((token = AC_cfg->GetValue()) != string("/UNDERCARRIAGE")) {
 150     lGear.push_back(FGLGear(AC_cfg, FDMExec));
 151   }
 152
 153   return true;
 154 }
 155
 156 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 157
 158 string FGGroundReactions::GetGroundReactionStrings(void)
 159 {
 160   string GroundReactionStrings = "";
 161   bool firstime = true;
 162
 163   for (unsigned int i=0;i<lGear.size();i++) {
 164     if (!firstime) GroundReactionStrings += ", ";
 165     GroundReactionStrings += (lGear[i].GetName() + "_WOW, ");
 166     GroundReactionStrings += (lGear[i].GetName() + "_compressLength, ");
 167     GroundReactionStrings += (lGear[i].GetName() + "_compressSpeed, ");
 168     GroundReactionStrings += (lGear[i].GetName() + "_Force");
 169
 170     firstime = false;
 171   }
 172
 173   return GroundReactionStrings;
 174 }
 175
 176 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 177
 178 string FGGroundReactions::GetGroundReactionValues(void)
 179 {
 180   char buff[20];
 181   string GroundReactionValues = "";
 182
 183   bool firstime = true;
 184
 185   for (unsigned int i=0;i<lGear.size();i++) {
 186     if (!firstime) GroundReactionValues += ", ";
 187     GroundReactionValues += string( lGear[i].GetWOW()?"1":"0" ) + ", ";
 188     GroundReactionValues += (string(gcvt(lGear[i].GetCompLen(),    5, buff)) + ", ");
 189     GroundReactionValues += (string(gcvt(lGear[i].GetCompVel(),    6, buff)) + ", ");
 190     GroundReactionValues += (string(gcvt(lGear[i].GetCompForce(), 10, buff)));
 191
 192     firstime = false;
 193   }
 194
 195   return GroundReactionValues;
 196 }
 197
 198 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 199
 200 void FGGroundReactions::Debug(void)
 201 {
 202     //TODO: Add your source code here
 203 }
 204