src/FDM/JSBSim/models/FGMassBalance.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGMassBalance.cpp
   4  Author:       Jon S. Berndt
   5  Date started: 09/12/2000
   6  Purpose:      This module models weight and balance
   7
   8  ------------- Copyright (C) 2000  Jon S. Berndt (jon@jsbsim.org) --------------
   9
  10  This program is free software; you can redistribute it and/or modify it under
  11  the terms of the GNU Lesser 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 Lesser General Public License for more
  18  details.
  19
  20  You should have received a copy of the GNU Lesser 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 Lesser 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 This class models the change in weight and balance of the aircraft due to fuel
  31 burnoff, etc.
  32
  33 HISTORY
  34 --------------------------------------------------------------------------------
  35 09/12/2000  JSB  Created
  36
  37 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  38 INCLUDES
  39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  40
  41 #include "FGMassBalance.h"
  42 #include "FGPropulsion.h"
  43 #include "FGBuoyantForces.h"
  44 #include "input_output/FGPropertyManager.h"
  45 #include <iostream>
  46 #include <cstdlib>
  47
  48 using namespace std;
  49
  50 namespace JSBSim {
  51
  52 static const char *IdSrc = "$Id$";
  53 static const char *IdHdr = ID_MASSBALANCE;
  54
  55 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  56 CLASS IMPLEMENTATION
  57 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  58
  59
  60 FGMassBalance::FGMassBalance(FGFDMExec* fdmex) : FGModel(fdmex)
  61 {
  62   Name = "FGMassBalance";
  63   Weight = EmptyWeight = Mass = 0.0;
  64
  65   vbaseXYZcg.InitMatrix(0.0);
  66   vXYZcg.InitMatrix(0.0);
  67   vLastXYZcg.InitMatrix(0.0);
  68   vDeltaXYZcg.InitMatrix(0.0);
  69   baseJ.InitMatrix();
  70   mJ.InitMatrix();
  71   mJinv.InitMatrix();
  72   pmJ.InitMatrix();
  73
  74   bind();
  75
  76   Debug(0);
  77 }
  78
  79 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  80
  81 FGMassBalance::~FGMassBalance()
  82 {
  83   for (unsigned int i=0; i<PointMasses.size(); i++) delete PointMasses[i];
  84   PointMasses.clear();
  85
  86   Debug(1);
  87 }
  88
  89 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  90
  91 bool FGMassBalance::InitModel(void)
  92 {
  93   if (!FGModel::InitModel()) return false;
  94
  95   vLastXYZcg.InitMatrix(0.0);
  96   vDeltaXYZcg.InitMatrix(0.0);
  97
  98   return true;
  99 }
 100
 101 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 102
 103 bool FGMassBalance::Load(Element* el)
 104 {
 105   Element *element;
 106   string element_name = "";
 107   double bixx, biyy, bizz, bixy, bixz, biyz;
 108
 109   FGModel::Load(el); // Perform base class Load.
 110
 111   bixx = biyy = bizz = bixy = bixz = biyz = 0.0;
 112   if (el->FindElement("ixx"))
 113     bixx = el->FindElementValueAsNumberConvertTo("ixx", "SLUG*FT2");
 114   if (el->FindElement("iyy"))
 115     biyy = el->FindElementValueAsNumberConvertTo("iyy", "SLUG*FT2");
 116   if (el->FindElement("izz"))
 117     bizz = el->FindElementValueAsNumberConvertTo("izz", "SLUG*FT2");
 118   if (el->FindElement("ixy"))
 119     bixy = el->FindElementValueAsNumberConvertTo("ixy", "SLUG*FT2");
 120   if (el->FindElement("ixz"))
 121     bixz = el->FindElementValueAsNumberConvertTo("ixz", "SLUG*FT2");
 122   if (el->FindElement("iyz"))
 123     biyz = el->FindElementValueAsNumberConvertTo("iyz", "SLUG*FT2");
 124   SetAircraftBaseInertias(FGMatrix33(  bixx,  -bixy,  bixz,
 125                                       -bixy,  biyy,  -biyz,
 126                                        bixz,  -biyz,  bizz ));
 127   EmptyWeight = el->FindElementValueAsNumberConvertTo("emptywt", "LBS");
 128
 129   element = el->FindElement("location");
 130   while (element) {
 131     element_name = element->GetAttributeValue("name");
 132     if (element_name == "CG") vbaseXYZcg = element->FindElementTripletConvertTo("IN");
 133     element = el->FindNextElement("location");
 134   }
 135
 136 // Find all POINTMASS elements that descend from this METRICS branch of the
 137 // config file.
 138
 139   element = el->FindElement("pointmass");
 140   while (element) {
 141     AddPointMass(element);
 142     element = el->FindNextElement("pointmass");
 143   }
 144
 145   double ChildFDMWeight = 0.0;
 146   for (int fdm=0; fdm<FDMExec->GetFDMCount(); fdm++) {
 147     if (FDMExec->GetChildFDM(fdm)->mated) ChildFDMWeight += FDMExec->GetChildFDM(fdm)->exec->GetMassBalance()->GetWeight();
 148   }
 149
 150   Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetTotalPointMassWeight()
 151     + BuoyantForces->GetGasMass()*slugtolb + ChildFDMWeight;
 152
 153   Mass = lbtoslug*Weight;
 154
 155   FGModel::PostLoad(el);
 156
 157   Debug(2);
 158   return true;
 159 }
 160
 161 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 162
 163 bool FGMassBalance::Run(void)
 164 {
 165   double denom, k1, k2, k3, k4, k5, k6;
 166   double Ixx, Iyy, Izz, Ixy, Ixz, Iyz;
 167
 168   if (FGModel::Run()) return true;
 169   if (FDMExec->Holding()) return false;
 170
 171   RunPreFunctions();
 172
 173   double ChildFDMWeight = 0.0;
 174   for (int fdm=0; fdm<FDMExec->GetFDMCount(); fdm++) {
 175     if (FDMExec->GetChildFDM(fdm)->mated) ChildFDMWeight += FDMExec->GetChildFDM(fdm)->exec->GetMassBalance()->GetWeight();
 176   }
 177
 178   Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetTotalPointMassWeight()
 179     + BuoyantForces->GetGasMass()*slugtolb + ChildFDMWeight;
 180
 181   Mass = lbtoslug*Weight;
 182
 183 // Calculate new CG
 184
 185   vXYZcg = (Propulsion->GetTanksMoment() + EmptyWeight*vbaseXYZcg
 186             + GetPointMassMoment()
 187             + BuoyantForces->GetGasMassMoment()) / Weight;
 188
 189   // Track frame-by-frame delta CG, and move the EOM-tracked location
 190   // by this amount.
 191   if (vLastXYZcg.Magnitude() == 0.0) vLastXYZcg = vXYZcg;
 192   vDeltaXYZcg = vXYZcg - vLastXYZcg;
 193   vDeltaXYZcgBody = StructuralToBody(vLastXYZcg) - StructuralToBody(vXYZcg);
 194   vLastXYZcg = vXYZcg;
 195   Propagate->NudgeBodyLocation(vDeltaXYZcgBody);
 196
 197 // Calculate new total moments of inertia
 198
 199   // At first it is the base configuration inertia matrix ...
 200   mJ = baseJ;
 201   // ... with the additional term originating from the parallel axis theorem.
 202   mJ += GetPointmassInertia( lbtoslug * EmptyWeight, vbaseXYZcg );
 203   // Then add the contributions from the additional pointmasses.
 204   mJ += CalculatePMInertias();
 205   mJ += Propulsion->CalculateTankInertias();
 206   mJ += BuoyantForces->GetGasMassInertia();
 207
 208   Ixx = mJ(1,1);
 209   Iyy = mJ(2,2);
 210   Izz = mJ(3,3);
 211   Ixy = -mJ(1,2);
 212   Ixz = -mJ(1,3);
 213   Iyz = -mJ(2,3);
 214
 215 // Calculate inertia matrix inverse (ref. Stevens and Lewis, "Flight Control & Simulation")
 216
 217   k1 = (Iyy*Izz - Iyz*Iyz);
 218   k2 = (Iyz*Ixz + Ixy*Izz);
 219   k3 = (Ixy*Iyz + Iyy*Ixz);
 220
 221   denom = 1.0/(Ixx*k1 - Ixy*k2 - Ixz*k3 );
 222   k1 = k1*denom;
 223   k2 = k2*denom;
 224   k3 = k3*denom;
 225   k4 = (Izz*Ixx - Ixz*Ixz)*denom;
 226   k5 = (Ixy*Ixz + Iyz*Ixx)*denom;
 227   k6 = (Ixx*Iyy - Ixy*Ixy)*denom;
 228
 229   mJinv.InitMatrix( k1, k2, k3,
 230                     k2, k4, k5,
 231                     k3, k5, k6 );
 232
 233   RunPostFunctions();
 234
 235   Debug(0);
 236
 237   return false;
 238 }
 239
 240 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 241
 242 void FGMassBalance::AddPointMass(Element* el)
 243 {
 244   Element* loc_element = el->FindElement("location");
 245   string pointmass_name = el->GetAttributeValue("name");
 246   if (!loc_element) {
 247     cerr << "Pointmass " << pointmass_name << " has no location." << endl;
 248     exit(-1);
 249   }
 250
 251   double w = el->FindElementValueAsNumberConvertTo("weight", "LBS");
 252   FGColumnVector3 vXYZ = loc_element->FindElementTripletConvertTo("IN");
 253
 254   PointMasses.push_back(new PointMass(w, vXYZ));
 255   PointMasses.back()->bind(PropertyManager, PointMasses.size()-1);
 256 }
 257
 258 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 259
 260 double FGMassBalance::GetTotalPointMassWeight(void)
 261 {
 262   double PM_total_weight = 0.0;
 263
 264   for (unsigned int i=0; i<PointMasses.size(); i++) {
 265     PM_total_weight += PointMasses[i]->Weight;
 266   }
 267   return PM_total_weight;
 268 }
 269
 270 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 271
 272 FGColumnVector3& FGMassBalance::GetPointMassMoment(void)
 273 {
 274   PointMassCG.InitMatrix();
 275
 276   for (unsigned int i=0; i<PointMasses.size(); i++) {
 277     PointMassCG += PointMasses[i]->Weight*PointMasses[i]->Location;
 278   }
 279   return PointMassCG;
 280 }
 281
 282 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 283
 284 FGMatrix33& FGMassBalance::CalculatePMInertias(void)
 285 {
 286   unsigned int size;
 287
 288   size = PointMasses.size();
 289   if (size == 0) return pmJ;
 290
 291   pmJ = FGMatrix33();
 292
 293   for (unsigned int i=0; i<size; i++)
 294     pmJ += GetPointmassInertia( lbtoslug * PointMasses[i]->Weight, PointMasses[i]->Location );
 295
 296   return pmJ;
 297 }
 298
 299 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 300
 301 FGColumnVector3 FGMassBalance::StructuralToBody(const FGColumnVector3& r) const
 302 {
 303   // Under the assumption that in the structural frame the:
 304   //
 305   // - X-axis is directed afterwards,
 306   // - Y-axis is directed towards the right,
 307   // - Z-axis is directed upwards,
 308   //
 309   // (as documented in http://jsbsim.sourceforge.net/JSBSimCoordinates.pdf)
 310   // we have to subtract first the center of gravity of the plane which
 311   // is also defined in the structural frame:
 312   //
 313   //   FGColumnVector3 cgOff = r - vXYZcg;
 314   //
 315   // Next, we do a change of units:
 316   //
 317   //   cgOff *= inchtoft;
 318   //
 319   // And then a 180 degree rotation is done about the Y axis so that the:
 320   //
 321   // - X-axis is directed forward,
 322   // - Y-axis is directed towards the right,
 323   // - Z-axis is directed downward.
 324   //
 325   // This is needed because the structural and body frames are 180 degrees apart.
 326
 327   return FGColumnVector3(inchtoft*(vXYZcg(1)-r(1)),
 328                          inchtoft*(r(2)-vXYZcg(2)),
 329                          inchtoft*(vXYZcg(3)-r(3)));
 330 }
 331
 332 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 333
 334 void FGMassBalance::bind(void)
 335 {
 336   typedef double (FGMassBalance::*PMF)(int) const;
 337   PropertyManager->Tie("inertia/mass-slugs", this,
 338                        &FGMassBalance::GetMass);
 339   PropertyManager->Tie("inertia/weight-lbs", this,
 340                        &FGMassBalance::GetWeight);
 341   PropertyManager->Tie("inertia/empty-weight-lbs", this,
 342     &FGMassBalance::GetWeight, &FGMassBalance::SetEmptyWeight);
 343   PropertyManager->Tie("inertia/cg-x-in", this,1,
 344                        (PMF)&FGMassBalance::GetXYZcg);
 345   PropertyManager->Tie("inertia/cg-y-in", this,2,
 346                        (PMF)&FGMassBalance::GetXYZcg);
 347   PropertyManager->Tie("inertia/cg-z-in", this,3,
 348                        (PMF)&FGMassBalance::GetXYZcg);
 349 }
 350
 351 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 352
 353 void FGMassBalance::PointMass::bind(FGPropertyManager* PropertyManager, int num) {
 354   string tmp = CreateIndexedPropertyName("inertia/pointmass-weight-lbs", num);
 355   PropertyManager->Tie( tmp.c_str(), this, &PointMass::GetPointMassWeight,
 356                                        &PointMass::SetPointMassWeight);
 357
 358   tmp = CreateIndexedPropertyName("inertia/pointmass-location-X-inches", num);
 359   PropertyManager->Tie( tmp.c_str(), this, eX, &PointMass::GetPointMassLocation,
 360                                            &PointMass::SetPointMassLocation);
 361   tmp = CreateIndexedPropertyName("inertia/pointmass-location-Y-inches", num);
 362   PropertyManager->Tie( tmp.c_str(), this, eY, &PointMass::GetPointMassLocation,
 363                                            &PointMass::SetPointMassLocation);
 364   tmp = CreateIndexedPropertyName("inertia/pointmass-location-Z-inches", num);
 365   PropertyManager->Tie( tmp.c_str(), this, eZ, &PointMass::GetPointMassLocation,
 366                                            &PointMass::SetPointMassLocation);
 367 }
 368
 369 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 370 //    The bitmasked value choices are as follows:
 371 //    unset: In this case (the default) JSBSim would only print
 372 //       out the normally expected messages, essentially echoing
 373 //       the config files as they are read. If the environment
 374 //       variable is not set, debug_lvl is set to 1 internally
 375 //    0: This requests JSBSim not to output any messages
 376 //       whatsoever.
 377 //    1: This value explicity requests the normal JSBSim
 378 //       startup messages
 379 //    2: This value asks for a message to be printed out when
 380 //       a class is instantiated
 381 //    4: When this value is set, a message is displayed when a
 382 //       FGModel object executes its Run() method
 383 //    8: When this value is set, various runtime state variables
 384 //       are printed out periodically
 385 //    16: When set various parameters are sanity checked and
 386 //       a message is printed out when they go out of bounds
 387
 388 void FGMassBalance::Debug(int from)
 389 {
 390   if (debug_lvl <= 0) return;
 391
 392   if (debug_lvl & 1) { // Standard console startup message output
 393     if (from == 2) { // Loading
 394       cout << endl << "  Mass and Balance:" << endl;
 395       cout << "    baseIxx: " << baseJ(1,1) << " slug-ft2" << endl;
 396       cout << "    baseIyy: " << baseJ(2,2) << " slug-ft2" << endl;
 397       cout << "    baseIzz: " << baseJ(3,3) << " slug-ft2" << endl;
 398       cout << "    baseIxy: " << baseJ(1,2) << " slug-ft2" << endl;
 399       cout << "    baseIxz: " << baseJ(1,3) << " slug-ft2" << endl;
 400       cout << "    baseIyz: " << baseJ(2,3) << " slug-ft2" << endl;
 401       cout << "    EmptyWeight: " << EmptyWeight << " lbm" << endl;
 402       cout << "    CG (x, y, z): " << vbaseXYZcg << endl;
 403       // ToDo: Need to add point mass outputs here
 404       for (unsigned int i=0; i<PointMasses.size(); i++) {
 405         cout << "    Point Mass Object: " << PointMasses[i]->Weight << " lbs. at "
 406                    << "X, Y, Z (in.): " << PointMasses[i]->Location(eX) << "  "
 407                    << PointMasses[i]->Location(eY) << "  "
 408                    << PointMasses[i]->Location(eZ) << endl;
 409       }
 410     }
 411   }
 412   if (debug_lvl & 2 ) { // Instantiation/Destruction notification
 413     if (from == 0) cout << "Instantiated: FGMassBalance" << endl;
 414     if (from == 1) cout << "Destroyed:    FGMassBalance" << endl;
 415   }
 416   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
 417   }
 418   if (debug_lvl & 8 ) { // Runtime state variables
 419   }
 420   if (debug_lvl & 16) { // Sanity checking
 421     if (from == 2) {
 422       if (EmptyWeight <= 0.0 || EmptyWeight > 1e9)
 423         cout << "MassBalance::EmptyWeight out of bounds: " << EmptyWeight << endl;
 424       if (Weight <= 0.0 || Weight > 1e9)
 425         cout << "MassBalance::Weight out of bounds: " << Weight << endl;
 426       if (Mass <= 0.0 || Mass > 1e9)
 427         cout << "MassBalance::Mass out of bounds: " << Mass << endl;
 428     }
 429   }
 430   if (debug_lvl & 64) {
 431     if (from == 0) { // Constructor
 432       cout << IdSrc << endl;
 433       cout << IdHdr << endl;
 434     }
 435   }
 436 }
 437 }