src/FDM/JSBSim/FGInertial.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGInertial.cpp
   4  Author:       Jon S. Berndt
   5  Date started: 09/13/00
   6  Purpose:      Encapsulates the inertial frame forces (coriolis and centrifugal)
   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 "FGInertial.h"
  39 #include "FGPosition.h"
  40 #include "FGMassBalance.h"
  41
  42 static const char *IdSrc = "$Id$";
  43 static const char *IdHdr = ID_INERTIAL;
  44
  45 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  46 CLASS IMPLEMENTATION
  47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  48
  49
  50 FGInertial::FGInertial(FGFDMExec* fgex) : FGModel(fgex),
  51     vForces(3),
  52     vOmegaLocal(3),
  53     vRadius(3),
  54     vGravity(3)
  55 {
  56   Name = "FGInertial";
  57
  58   vRadius.InitMatrix();
  59
  60   // Defaults
  61   RotationRate    = 0.00007272205217;
  62   GM              = 14.06252720E15;
  63   RadiusReference = 20925650.00;
  64   gAccelReference = GM/(RadiusReference*RadiusReference);
  65   gAccel          = GM/(RadiusReference*RadiusReference);
  66
  67   if (debug_lvl & 2) cout << "Instantiated: FGInertial" << endl;
  68 }
  69
  70 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  71
  72 FGInertial::~FGInertial(void)
  73 {
  74   if (debug_lvl & 2) cout << "Destroyed:    FGInertial" << endl;
  75 }
  76
  77 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  78
  79 bool FGInertial::Run(void)
  80 {
  81   double stht, ctht, sphi, cphi;
  82
  83   if (!FGModel::Run()) {
  84
  85     gAccel = GM / (Position->GetRadius()*Position->GetRadius());
  86
  87     stht = sin(Rotation->GetEuler(eTht));
  88     ctht = cos(Rotation->GetEuler(eTht));
  89     sphi = sin(Rotation->GetEuler(ePhi));
  90     cphi = cos(Rotation->GetEuler(ePhi));
  91
  92     vGravity(eX) = vForces(eX) = -gravity()*stht;
  93     vGravity(eY) = vForces(eY) =  gravity()*sphi*ctht;
  94     vGravity(eZ) = vForces(eZ) =  gravity()*cphi*ctht;
  95
  96     // The following equation for vOmegaLocal terms shows the angular velocity
  97     // calculation _for_the_local_frame_ given the earth's rotation (first set)
  98     // at the current latitude, and also the component due to the aircraft
  99     // motion over the curved surface of the earth (second set).
 100
 101     vOmegaLocal(eX) = omega() * cos(Position->GetLatitude());
 102     vOmegaLocal(eY) = 0.0;
 103     vOmegaLocal(eZ) = omega() * -sin(Position->GetLatitude());
 104
 105     vOmegaLocal(eX) +=  Position->GetVe() / Position->GetRadius();
 106     vOmegaLocal(eY) += -Position->GetVn() / Position->GetRadius();
 107     vOmegaLocal(eZ) +=  0.00;
 108
 109 //    vForces = State->GetTl2b()*(-2.0*vOmegaLocal * Position->GetVel());
 110
 111     vRadius(3) = Position->GetRadius();
 112     vForces += State->GetTl2b()*(vOmegaLocal * (vOmegaLocal * vRadius));
 113
 114     vForces *= MassBalance->GetMass(); // IMPORTANT !!!!!!!!!!!!!!!!!!!!!!!!!!!!
 115
 116     return false;
 117   } else {
 118     return true;
 119   }
 120 }
 121
 122 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 123
 124 bool FGInertial::LoadInertial(FGConfigFile* AC_cfg)
 125 {
 126   return true;
 127 }
 128
 129 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 130
 131 void FGInertial::Debug(void)
 132 {
 133     //TODO: Add your source code here
 134 }
 135