1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 Module: FGMassBalance.cpp
5 Date started: 09/12/2000
6 Purpose: This module models weight and balance
8 ------------- Copyright (C) 2000 Jon S. Berndt (jsb@hal-pc.org) --------------
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
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
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.
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.
27 FUNCTIONAL DESCRIPTION
28 --------------------------------------------------------------------------------
30 This class models the change in weight and balance of the aircraft due to fuel
34 --------------------------------------------------------------------------------
35 09/12/2000 JSB Created
37 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
41 #include "FGMassBalance.h"
42 #include "FGPropulsion.h"
43 #include "FGBuoyantForces.h"
44 #include <input_output/FGPropertyManager.h>
48 static const char *IdSrc = "$Id$";
49 static const char *IdHdr = ID_MASSBALANCE;
51 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
53 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
56 FGMassBalance::FGMassBalance(FGFDMExec* fdmex) : FGModel(fdmex)
58 Name = "FGMassBalance";
59 Weight = EmptyWeight = Mass = 0.0;
61 vbaseXYZcg.InitMatrix(0.0);
62 vXYZcg.InitMatrix(0.0);
63 vLastXYZcg.InitMatrix(0.0);
64 vDeltaXYZcg.InitMatrix(0.0);
75 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
77 FGMassBalance::~FGMassBalance()
79 for (unsigned int i=0; i<PointMasses.size(); i++) delete PointMasses[i];
85 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
87 bool FGMassBalance::InitModel(void)
89 if (!FGModel::InitModel()) return false;
91 vLastXYZcg.InitMatrix(0.0);
92 vDeltaXYZcg.InitMatrix(0.0);
97 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
99 bool FGMassBalance::Load(Element* el)
102 string element_name = "";
103 double bixx, biyy, bizz, bixy, bixz, biyz;
105 FGModel::Load(el); // Perform base class Load.
107 bixx = biyy = bizz = bixy = bixz = biyz = 0.0;
108 if (el->FindElement("ixx"))
109 bixx = el->FindElementValueAsNumberConvertTo("ixx", "SLUG*FT2");
110 if (el->FindElement("iyy"))
111 biyy = el->FindElementValueAsNumberConvertTo("iyy", "SLUG*FT2");
112 if (el->FindElement("izz"))
113 bizz = el->FindElementValueAsNumberConvertTo("izz", "SLUG*FT2");
114 if (el->FindElement("ixy"))
115 bixy = el->FindElementValueAsNumberConvertTo("ixy", "SLUG*FT2");
116 if (el->FindElement("ixz"))
117 bixz = el->FindElementValueAsNumberConvertTo("ixz", "SLUG*FT2");
118 if (el->FindElement("iyz"))
119 biyz = el->FindElementValueAsNumberConvertTo("iyz", "SLUG*FT2");
120 SetAircraftBaseInertias(FGMatrix33( bixx, -bixy, bixz,
122 bixz, -biyz, bizz ));
123 EmptyWeight = el->FindElementValueAsNumberConvertTo("emptywt", "LBS");
125 element = el->FindElement("location");
127 element_name = element->GetAttributeValue("name");
128 if (element_name == "CG") vbaseXYZcg = element->FindElementTripletConvertTo("IN");
129 element = el->FindNextElement("location");
132 // Find all POINTMASS elements that descend from this METRICS branch of the
135 element = el->FindElement("pointmass");
137 AddPointMass(element);
138 element = el->FindNextElement("pointmass");
141 double ChildFDMWeight = 0.0;
142 for (int fdm=0; fdm<FDMExec->GetFDMCount(); fdm++) {
143 if (FDMExec->GetChildFDM(fdm)->mated) ChildFDMWeight += FDMExec->GetChildFDM(fdm)->exec->GetMassBalance()->GetWeight();
146 Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetTotalPointMassWeight()
147 + BuoyantForces->GetGasMass()*slugtolb + ChildFDMWeight;
149 Mass = lbtoslug*Weight;
155 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
157 bool FGMassBalance::Run(void)
159 double denom, k1, k2, k3, k4, k5, k6;
160 double Ixx, Iyy, Izz, Ixy, Ixz, Iyz;
162 if (FGModel::Run()) return true;
163 if (FDMExec->Holding()) return false;
165 double ChildFDMWeight = 0.0;
166 for (int fdm=0; fdm<FDMExec->GetFDMCount(); fdm++) {
167 if (FDMExec->GetChildFDM(fdm)->mated) ChildFDMWeight += FDMExec->GetChildFDM(fdm)->exec->GetMassBalance()->GetWeight();
170 Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetTotalPointMassWeight()
171 + BuoyantForces->GetGasMass()*slugtolb + ChildFDMWeight;
173 Mass = lbtoslug*Weight;
177 vXYZcg = (Propulsion->GetTanksMoment() + EmptyWeight*vbaseXYZcg
178 + GetPointMassMoment()
179 + BuoyantForces->GetGasMassMoment()) / Weight;
181 // Track frame-by-frame delta CG, and move the EOM-tracked location
183 if (vLastXYZcg.Magnitude() == 0.0) vLastXYZcg = vXYZcg;
184 vDeltaXYZcg = vXYZcg - vLastXYZcg;
185 vDeltaXYZcgBody = StructuralToBody(vLastXYZcg) - StructuralToBody(vXYZcg);
187 Propagate->NudgeBodyLocation(vDeltaXYZcgBody);
189 // Calculate new total moments of inertia
191 // At first it is the base configuration inertia matrix ...
193 // ... with the additional term originating from the parallel axis theorem.
194 mJ += GetPointmassInertia( lbtoslug * EmptyWeight, vbaseXYZcg );
195 // Then add the contributions from the additional pointmasses.
196 mJ += CalculatePMInertias();
197 mJ += Propulsion->CalculateTankInertias();
198 mJ += BuoyantForces->GetGasMassInertia();
207 // Calculate inertia matrix inverse (ref. Stevens and Lewis, "Flight Control & Simulation")
209 k1 = (Iyy*Izz - Iyz*Iyz);
210 k2 = (Iyz*Ixz + Ixy*Izz);
211 k3 = (Ixy*Iyz + Iyy*Ixz);
213 denom = 1.0/(Ixx*k1 - Ixy*k2 - Ixz*k3 );
217 k4 = (Izz*Ixx - Ixz*Ixz)*denom;
218 k5 = (Ixy*Ixz + Iyz*Ixx)*denom;
219 k6 = (Ixx*Iyy - Ixy*Ixy)*denom;
221 mJinv.InitMatrix( k1, k2, k3,
230 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
232 void FGMassBalance::AddPointMass(Element* el)
234 Element* loc_element = el->FindElement("location");
235 string pointmass_name = el->GetAttributeValue("name");
237 cerr << "Pointmass " << pointmass_name << " has no location." << endl;
241 double w = el->FindElementValueAsNumberConvertTo("weight", "LBS");
242 FGColumnVector3 vXYZ = loc_element->FindElementTripletConvertTo("IN");
244 PointMasses.push_back(new PointMass(w, vXYZ));
245 PointMasses.back()->bind(PropertyManager, PointMasses.size()-1);
248 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
250 double FGMassBalance::GetTotalPointMassWeight(void)
252 double PM_total_weight = 0.0;
254 for (unsigned int i=0; i<PointMasses.size(); i++) {
255 PM_total_weight += PointMasses[i]->Weight;
257 return PM_total_weight;
260 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
262 FGColumnVector3& FGMassBalance::GetPointMassMoment(void)
264 PointMassCG.InitMatrix();
266 for (unsigned int i=0; i<PointMasses.size(); i++) {
267 PointMassCG += PointMasses[i]->Weight*PointMasses[i]->Location;
272 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
274 FGMatrix33& FGMassBalance::CalculatePMInertias(void)
278 size = PointMasses.size();
279 if (size == 0) return pmJ;
283 for (unsigned int i=0; i<size; i++)
284 pmJ += GetPointmassInertia( lbtoslug * PointMasses[i]->Weight, PointMasses[i]->Location );
289 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
291 FGColumnVector3 FGMassBalance::StructuralToBody(const FGColumnVector3& r) const
293 // Under the assumption that in the structural frame the:
295 // - X-axis is directed afterwards,
296 // - Y-axis is directed towards the right,
297 // - Z-axis is directed upwards,
299 // (as documented in http://jsbsim.sourceforge.net/JSBSimCoordinates.pdf)
300 // we have to subtract first the center of gravity of the plane which
301 // is also defined in the structural frame:
303 // FGColumnVector3 cgOff = r - vXYZcg;
305 // Next, we do a change of units:
307 // cgOff *= inchtoft;
309 // And then a 180 degree rotation is done about the Y axis so that the:
311 // - X-axis is directed forward,
312 // - Y-axis is directed towards the right,
313 // - Z-axis is directed downward.
315 // This is needed because the structural and body frames are 180 degrees apart.
317 return FGColumnVector3(inchtoft*(vXYZcg(1)-r(1)),
318 inchtoft*(r(2)-vXYZcg(2)),
319 inchtoft*(vXYZcg(3)-r(3)));
322 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
324 void FGMassBalance::bind(void)
326 typedef double (FGMassBalance::*PMF)(int) const;
327 PropertyManager->Tie("inertia/mass-slugs", this,
328 &FGMassBalance::GetMass);
329 PropertyManager->Tie("inertia/weight-lbs", this,
330 &FGMassBalance::GetWeight);
331 PropertyManager->Tie("inertia/empty-weight-lbs", this,
332 &FGMassBalance::GetWeight, &FGMassBalance::SetEmptyWeight);
333 PropertyManager->Tie("inertia/cg-x-in", this,1,
334 (PMF)&FGMassBalance::GetXYZcg);
335 PropertyManager->Tie("inertia/cg-y-in", this,2,
336 (PMF)&FGMassBalance::GetXYZcg);
337 PropertyManager->Tie("inertia/cg-z-in", this,3,
338 (PMF)&FGMassBalance::GetXYZcg);
341 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
342 // The bitmasked value choices are as follows:
343 // unset: In this case (the default) JSBSim would only print
344 // out the normally expected messages, essentially echoing
345 // the config files as they are read. If the environment
346 // variable is not set, debug_lvl is set to 1 internally
347 // 0: This requests JSBSim not to output any messages
349 // 1: This value explicity requests the normal JSBSim
351 // 2: This value asks for a message to be printed out when
352 // a class is instantiated
353 // 4: When this value is set, a message is displayed when a
354 // FGModel object executes its Run() method
355 // 8: When this value is set, various runtime state variables
356 // are printed out periodically
357 // 16: When set various parameters are sanity checked and
358 // a message is printed out when they go out of bounds
360 void FGMassBalance::Debug(int from)
362 if (debug_lvl <= 0) return;
364 if (debug_lvl & 1) { // Standard console startup message output
365 if (from == 2) { // Loading
366 cout << endl << " Mass and Balance:" << endl;
367 cout << " baseIxx: " << baseJ(1,1) << " slug-ft2" << endl;
368 cout << " baseIyy: " << baseJ(2,2) << " slug-ft2" << endl;
369 cout << " baseIzz: " << baseJ(3,3) << " slug-ft2" << endl;
370 cout << " baseIxy: " << baseJ(1,2) << " slug-ft2" << endl;
371 cout << " baseIxz: " << baseJ(1,3) << " slug-ft2" << endl;
372 cout << " baseIyz: " << baseJ(2,3) << " slug-ft2" << endl;
373 cout << " EmptyWeight: " << EmptyWeight << " lbm" << endl;
374 cout << " CG (x, y, z): " << vbaseXYZcg << endl;
375 // ToDo: Need to add point mass outputs here
376 for (unsigned int i=0; i<PointMasses.size(); i++) {
377 cout << " Point Mass Object: " << PointMasses[i]->Weight << " lbs. at "
378 << "X, Y, Z (in.): " << PointMasses[i]->Location(eX) << " "
379 << PointMasses[i]->Location(eY) << " "
380 << PointMasses[i]->Location(eZ) << endl;
384 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
385 if (from == 0) cout << "Instantiated: FGMassBalance" << endl;
386 if (from == 1) cout << "Destroyed: FGMassBalance" << endl;
388 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
390 if (debug_lvl & 8 ) { // Runtime state variables
392 if (debug_lvl & 16) { // Sanity checking
394 if (EmptyWeight <= 0.0 || EmptyWeight > 1e9)
395 cout << "MassBalance::EmptyWeight out of bounds: " << EmptyWeight << endl;
396 if (Weight <= 0.0 || Weight > 1e9)
397 cout << "MassBalance::Weight out of bounds: " << Weight << endl;
398 if (Mass <= 0.0 || Mass > 1e9)
399 cout << "MassBalance::Mass out of bounds: " << Mass << endl;
402 if (debug_lvl & 64) {
403 if (from == 0) { // Constructor
404 cout << IdSrc << endl;
405 cout << IdHdr << endl;