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);
72 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
74 FGMassBalance::~FGMassBalance()
76 for (unsigned int i=0; i<PointMasses.size(); i++) delete PointMasses[i];
82 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
84 bool FGMassBalance::InitModel(void)
86 if (!FGModel::InitModel()) return false;
91 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
93 bool FGMassBalance::Load(Element* el)
96 string element_name = "";
97 double bixx, biyy, bizz, bixy, bixz, biyz;
99 FGModel::Load(el); // Perform base class Load.
101 bixx = biyy = bizz = bixy = bixz = biyz = 0.0;
102 if (el->FindElement("ixx"))
103 bixx = el->FindElementValueAsNumberConvertTo("ixx", "SLUG*FT2");
104 if (el->FindElement("iyy"))
105 biyy = el->FindElementValueAsNumberConvertTo("iyy", "SLUG*FT2");
106 if (el->FindElement("izz"))
107 bizz = el->FindElementValueAsNumberConvertTo("izz", "SLUG*FT2");
108 if (el->FindElement("ixy"))
109 bixy = el->FindElementValueAsNumberConvertTo("ixy", "SLUG*FT2");
110 if (el->FindElement("ixz"))
111 bixz = el->FindElementValueAsNumberConvertTo("ixz", "SLUG*FT2");
112 if (el->FindElement("iyz"))
113 biyz = el->FindElementValueAsNumberConvertTo("iyz", "SLUG*FT2");
114 SetAircraftBaseInertias(FGMatrix33( bixx, -bixy, bixz,
116 bixz, -biyz, bizz ));
117 EmptyWeight = el->FindElementValueAsNumberConvertTo("emptywt", "LBS");
119 element = el->FindElement("location");
121 element_name = element->GetAttributeValue("name");
122 if (element_name == "CG") vbaseXYZcg = element->FindElementTripletConvertTo("IN");
123 element = el->FindNextElement("location");
126 // Find all POINTMASS elements that descend from this METRICS branch of the
129 element = el->FindElement("pointmass");
131 AddPointMass(element);
132 element = el->FindNextElement("pointmass");
135 double ChildFDMWeight = 0.0;
136 for (int fdm=0; fdm<FDMExec->GetFDMCount(); fdm++) {
137 if (FDMExec->GetChildFDM(fdm)->mated) ChildFDMWeight += FDMExec->GetChildFDM(fdm)->exec->GetMassBalance()->GetWeight();
140 Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetTotalPointMassWeight()
141 + BuoyantForces->GetGasMass()*slugtolb + ChildFDMWeight;
143 Mass = lbtoslug*Weight;
149 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
151 bool FGMassBalance::Run(void)
153 double denom, k1, k2, k3, k4, k5, k6;
154 double Ixx, Iyy, Izz, Ixy, Ixz, Iyz;
156 if (FGModel::Run()) return true;
157 if (FDMExec->Holding()) return false;
159 double ChildFDMWeight = 0.0;
160 for (int fdm=0; fdm<FDMExec->GetFDMCount(); fdm++) {
161 if (FDMExec->GetChildFDM(fdm)->mated) ChildFDMWeight += FDMExec->GetChildFDM(fdm)->exec->GetMassBalance()->GetWeight();
164 Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetTotalPointMassWeight()
165 + BuoyantForces->GetGasMass()*slugtolb + ChildFDMWeight;
167 Mass = lbtoslug*Weight;
171 vXYZcg = (Propulsion->GetTanksMoment() + EmptyWeight*vbaseXYZcg
172 + GetPointMassMoment()
173 + BuoyantForces->GetGasMassMoment()) / Weight;
175 // Calculate new total moments of inertia
177 // At first it is the base configuration inertia matrix ...
179 // ... with the additional term originating from the parallel axis theorem.
180 mJ += GetPointmassInertia( lbtoslug * EmptyWeight, vbaseXYZcg );
181 // Then add the contributions from the additional pointmasses.
182 mJ += CalculatePMInertias();
183 mJ += Propulsion->CalculateTankInertias();
184 mJ += BuoyantForces->GetGasMassInertia();
193 // Calculate inertia matrix inverse (ref. Stevens and Lewis, "Flight Control & Simulation")
195 k1 = (Iyy*Izz - Iyz*Iyz);
196 k2 = (Iyz*Ixz + Ixy*Izz);
197 k3 = (Ixy*Iyz + Iyy*Ixz);
199 denom = 1.0/(Ixx*k1 - Ixy*k2 - Ixz*k3 );
203 k4 = (Izz*Ixx - Ixz*Ixz)*denom;
204 k5 = (Ixy*Ixz + Iyz*Ixx)*denom;
205 k6 = (Ixx*Iyy - Ixy*Ixy)*denom;
207 mJinv.InitMatrix( k1, k2, k3,
216 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
218 void FGMassBalance::AddPointMass(Element* el)
220 Element* loc_element = el->FindElement("location");
221 string pointmass_name = el->GetAttributeValue("name");
223 cerr << "Pointmass " << pointmass_name << " has no location." << endl;
227 double w = el->FindElementValueAsNumberConvertTo("weight", "LBS");
228 FGColumnVector3 vXYZ = loc_element->FindElementTripletConvertTo("IN");
230 PointMasses.push_back(new PointMass(w, vXYZ));
231 PointMasses.back()->bind(PropertyManager, PointMasses.size()-1);
234 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
236 double FGMassBalance::GetTotalPointMassWeight(void)
238 double PM_total_weight = 0.0;
240 for (unsigned int i=0; i<PointMasses.size(); i++) {
241 PM_total_weight += PointMasses[i]->Weight;
243 return PM_total_weight;
246 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
248 FGColumnVector3& FGMassBalance::GetPointMassMoment(void)
250 PointMassCG.InitMatrix();
252 for (unsigned int i=0; i<PointMasses.size(); i++) {
253 PointMassCG += PointMasses[i]->Weight*PointMasses[i]->Location;
258 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
260 FGMatrix33& FGMassBalance::CalculatePMInertias(void)
264 size = PointMasses.size();
265 if (size == 0) return pmJ;
269 for (unsigned int i=0; i<size; i++)
270 pmJ += GetPointmassInertia( lbtoslug * PointMasses[i]->Weight, PointMasses[i]->Location );
275 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
277 FGColumnVector3 FGMassBalance::StructuralToBody(const FGColumnVector3& r) const
279 // Under the assumption that in the structural frame the:
281 // - X-axis is directed afterwards,
282 // - Y-axis is directed towards the right,
283 // - Z-axis is directed upwards,
285 // (as documented in http://jsbsim.sourceforge.net/JSBSimCoordinates.pdf)
286 // we have to subtract first the center of gravity of the plane which
287 // is also defined in the structural frame:
289 // FGColumnVector3 cgOff = r - vXYZcg;
291 // Next, we do a change of units:
293 // cgOff *= inchtoft;
295 // And then a 180 degree rotation is done about the Y axis so that the:
297 // - X-axis is directed forward,
298 // - Y-axis is directed towards the right,
299 // - Z-axis is directed downward.
301 // This is needed because the structural and body frames are 180 degrees apart.
303 return FGColumnVector3(inchtoft*(vXYZcg(1)-r(1)),
304 inchtoft*(r(2)-vXYZcg(2)),
305 inchtoft*(vXYZcg(3)-r(3)));
308 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
310 void FGMassBalance::bind(void)
312 typedef double (FGMassBalance::*PMF)(int) const;
313 PropertyManager->Tie("inertia/mass-slugs", this,
314 &FGMassBalance::GetMass);
315 PropertyManager->Tie("inertia/weight-lbs", this,
316 &FGMassBalance::GetWeight);
317 PropertyManager->Tie("inertia/empty-weight-lbs", this,
318 &FGMassBalance::GetWeight, &FGMassBalance::SetEmptyWeight);
319 PropertyManager->Tie("inertia/cg-x-in", this,1,
320 (PMF)&FGMassBalance::GetXYZcg);
321 PropertyManager->Tie("inertia/cg-y-in", this,2,
322 (PMF)&FGMassBalance::GetXYZcg);
323 PropertyManager->Tie("inertia/cg-z-in", this,3,
324 (PMF)&FGMassBalance::GetXYZcg);
327 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
328 // The bitmasked value choices are as follows:
329 // unset: In this case (the default) JSBSim would only print
330 // out the normally expected messages, essentially echoing
331 // the config files as they are read. If the environment
332 // variable is not set, debug_lvl is set to 1 internally
333 // 0: This requests JSBSim not to output any messages
335 // 1: This value explicity requests the normal JSBSim
337 // 2: This value asks for a message to be printed out when
338 // a class is instantiated
339 // 4: When this value is set, a message is displayed when a
340 // FGModel object executes its Run() method
341 // 8: When this value is set, various runtime state variables
342 // are printed out periodically
343 // 16: When set various parameters are sanity checked and
344 // a message is printed out when they go out of bounds
346 void FGMassBalance::Debug(int from)
348 if (debug_lvl <= 0) return;
350 if (debug_lvl & 1) { // Standard console startup message output
351 if (from == 2) { // Loading
352 cout << endl << " Mass and Balance:" << endl;
353 cout << " baseIxx: " << baseJ(1,1) << " slug-ft2" << endl;
354 cout << " baseIyy: " << baseJ(2,2) << " slug-ft2" << endl;
355 cout << " baseIzz: " << baseJ(3,3) << " slug-ft2" << endl;
356 cout << " baseIxy: " << baseJ(1,2) << " slug-ft2" << endl;
357 cout << " baseIxz: " << baseJ(1,3) << " slug-ft2" << endl;
358 cout << " baseIyz: " << baseJ(2,3) << " slug-ft2" << endl;
359 cout << " EmptyWeight: " << EmptyWeight << " lbm" << endl;
360 cout << " CG (x, y, z): " << vbaseXYZcg << endl;
361 // ToDo: Need to add point mass outputs here
362 for (unsigned int i=0; i<PointMasses.size(); i++) {
363 cout << " Point Mass Object: " << PointMasses[i]->Weight << " lbs. at "
364 << "X, Y, Z (in.): " << PointMasses[i]->Location(eX) << " "
365 << PointMasses[i]->Location(eY) << " "
366 << PointMasses[i]->Location(eZ) << endl;
370 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
371 if (from == 0) cout << "Instantiated: FGMassBalance" << endl;
372 if (from == 1) cout << "Destroyed: FGMassBalance" << endl;
374 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
376 if (debug_lvl & 8 ) { // Runtime state variables
378 if (debug_lvl & 16) { // Sanity checking
380 if (EmptyWeight <= 0.0 || EmptyWeight > 1e9)
381 cout << "MassBalance::EmptyWeight out of bounds: " << EmptyWeight << endl;
382 if (Weight <= 0.0 || Weight > 1e9)
383 cout << "MassBalance::Weight out of bounds: " << Weight << endl;
384 if (Mass <= 0.0 || Mass > 1e9)
385 cout << "MassBalance::Mass out of bounds: " << Mass << endl;
388 if (debug_lvl & 64) {
389 if (from == 0) { // Constructor
390 cout << IdSrc << endl;
391 cout << IdHdr << endl;