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   GearUp = false;
  57   if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
  58 }
  59
  60 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  61
  62 bool FGGroundReactions::Run(void)
  63 {
  64   float steerAngle = 0.0;
  65   float xForces = 0.0, yForces = 0.0;
  66
  67   if (!FGModel::Run()) {
  68     vForces.InitMatrix();
  69     vMoments.InitMatrix();
  70
  71     // Only execute gear force code below 300 feet
  72     if ( !GearUp && Position->GetDistanceAGL() < 300.0 ) {
  73       vector <FGLGear>::iterator iGear = lGear.begin();
  74       // Sum forces and moments for all gear, here.
  75       // Some optimizations may be made here - or rather in the gear code itself.
  76       // The gear ::Run() method is called several times - once for each gear.
  77       // Perhaps there is some commonality for things which only need to be
  78       // calculated once.
  79       while (iGear != lGear.end()) {
  80         vForces  += iGear->Force();
  81         vMoments += iGear->Moment();
  82         iGear++;
  83       }
  84
  85       // Only execute this code when the aircraft ground speed is very, very small.
  86       if (fabs(Translation->GetUVW(eX)) < 0.1 &&
  87           fabs(Translation->GetUVW(eZ)) < 0.1)
  88       {
  89         // Initialize the comparison matrices.
  90         vMaxStaticGrip.InitMatrix();
  91         vMaxMomentResist.InitMatrix();
  92         iGear = lGear.begin();
  93         // For each gear that is touching the ground (which had better be all of them!)
  94         // calculate the X and Y direction maximum "gripping" power. Also, keep track
  95         // of the number of gear that have weight on wheels. This is probably unnecessary.
  96         while (iGear != lGear.end()) {
  97           // calculate maximum gripping power for each gear here based on brake
  98           // and steering settings
  99           // also calculate total number of wheels with WOW set true?
 100           if (iGear->GetWOW()) {
 101             steerAngle = iGear->GetSteerAngle();
 102             vMaxStaticGrip(eX) += (iGear->GetBrakeFCoeff()*cos(steerAngle) -
 103                  iGear->GetstaticFCoeff()*sin(steerAngle))*iGear->GetCompForce();
 104             vMaxStaticGrip(eY) += iGear->GetBrakeFCoeff()*sin(steerAngle) +
 105                   iGear->GetstaticFCoeff()*cos(steerAngle)*iGear->GetCompForce();
 106             vMaxStaticGrip(eZ)  = 0.0;
 107 //            vMaxMomentResist += 1;
 108           }
 109           iGear++;
 110         }
 111
 112         // Calculate the X and Y direction non-gear forces to counteract if needed.
 113         xForces =  -1.0 * ( Aerodynamics->GetForces(eX)
 114                           + Propulsion->GetForces(eX)
 115                           + Inertial->GetForces(eX));
 116
 117         yForces =  -1.0 * ( Aerodynamics->GetForces(eY)
 118                           + Propulsion->GetForces(eY)
 119                           + Inertial->GetForces(eY));
 120
 121         // These if statement comparisons probably need some validation and work
 122         if (fabs(xForces) < fabs(vMaxStaticGrip(eX))) { // forces exceed gear power
 123           vForces(eX) = xForces;
 124         }
 125
 126         if (fabs(yForces) < fabs(vMaxStaticGrip(eY))) { // forces exceed gear power
 127           vForces(eY) = yForces;
 128         }
 129
 130         vMoments(eZ) = -(Aerodynamics->GetMoments(eZ) + Propulsion->GetMoments(eZ));
 131       }
 132     } else {
 133       // Crash Routine
 134     }
 135
 136     return false;
 137   } else {
 138     return true;
 139   }
 140 }
 141
 142 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 143
 144 bool FGGroundReactions::Load(FGConfigFile* AC_cfg)
 145 {
 146   string token;
 147
 148   AC_cfg->GetNextConfigLine();
 149
 150   while ((token = AC_cfg->GetValue()) != "/UNDERCARRIAGE") {
 151     lGear.push_back(FGLGear(AC_cfg, FDMExec));
 152   }
 153
 154   return true;
 155 }
 156
 157 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 158
 159 string FGGroundReactions::GetGroundReactionStrings(void)
 160 {
 161   string GroundReactionStrings = "";
 162   bool firstime = true;
 163
 164   for (unsigned int i=0;i<lGear.size();i++) {
 165     if (!firstime) GroundReactionStrings += ", ";
 166     GroundReactionStrings += (lGear[i].GetName() + "_WOW, ");
 167     GroundReactionStrings += (lGear[i].GetName() + "_compressLength, ");
 168     GroundReactionStrings += (lGear[i].GetName() + "_compressSpeed, ");
 169     GroundReactionStrings += (lGear[i].GetName() + "_Force");
 170
 171     firstime = false;
 172   }
 173
 174   return GroundReactionStrings;
 175 }
 176
 177 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 178
 179 string FGGroundReactions::GetGroundReactionValues(void)
 180 {
 181   char buff[20];
 182   string GroundReactionValues = "";
 183
 184   bool firstime = true;
 185
 186   for (unsigned int i=0;i<lGear.size();i++) {
 187     if (!firstime) GroundReactionValues += ", ";
 188     GroundReactionValues += string( lGear[i].GetWOW()?"1":"0" ) + ", ";
 189     GroundReactionValues += (string(gcvt(lGear[i].GetCompLen(),    5, buff)) + ", ");
 190     GroundReactionValues += (string(gcvt(lGear[i].GetCompVel(),    6, buff)) + ", ");
 191     GroundReactionValues += (string(gcvt(lGear[i].GetCompForce(), 10, buff)));
 192
 193     firstime = false;
 194   }
 195
 196   return GroundReactionValues;
 197 }
 198
 199 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 200
 201 void FGGroundReactions::Debug(void)
 202 {
 203     //TODO: Add your source code here
 204 }
 205