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 bixx = biyy = bizz = bixy = bixz = biyz = 0.0;
100 if (el->FindElement("ixx"))
101 bixx = el->FindElementValueAsNumberConvertTo("ixx", "SLUG*FT2");
102 if (el->FindElement("iyy"))
103 biyy = el->FindElementValueAsNumberConvertTo("iyy", "SLUG*FT2");
104 if (el->FindElement("izz"))
105 bizz = el->FindElementValueAsNumberConvertTo("izz", "SLUG*FT2");
106 if (el->FindElement("ixy"))
107 bixy = el->FindElementValueAsNumberConvertTo("ixy", "SLUG*FT2");
108 if (el->FindElement("ixz"))
109 bixz = el->FindElementValueAsNumberConvertTo("ixz", "SLUG*FT2");
110 if (el->FindElement("iyz"))
111 biyz = el->FindElementValueAsNumberConvertTo("iyz", "SLUG*FT2");
112 SetAircraftBaseInertias(FGMatrix33( bixx, -bixy, bixz,
114 bixz, -biyz, bizz ));
115 EmptyWeight = el->FindElementValueAsNumberConvertTo("emptywt", "LBS");
117 element = el->FindElement("location");
119 element_name = element->GetAttributeValue("name");
120 if (element_name == "CG") vbaseXYZcg = element->FindElementTripletConvertTo("IN");
121 element = el->FindNextElement("location");
124 // Find all POINTMASS elements that descend from this METRICS branch of the
127 element = el->FindElement("pointmass");
129 AddPointMass(element);
130 element = el->FindNextElement("pointmass");
137 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
139 bool FGMassBalance::Run(void)
141 double denom, k1, k2, k3, k4, k5, k6;
142 double Ixx, Iyy, Izz, Ixy, Ixz, Iyz;
144 if (FGModel::Run()) return true;
145 if (FDMExec->Holding()) return false;
147 Weight = EmptyWeight + Propulsion->GetTanksWeight() + GetPointMassWeight()
148 + BuoyantForces->GetGasMass()*slugtolb;
150 Mass = lbtoslug*Weight;
154 vXYZcg = (Propulsion->GetTanksMoment() + EmptyWeight*vbaseXYZcg
155 + GetPointMassMoment()
156 + BuoyantForces->GetGasMassMoment()) / Weight;
158 // Calculate new total moments of inertia
160 // At first it is the base configuration inertia matrix ...
162 // ... with the additional term originating from the parallel axis theorem.
163 mJ += GetPointmassInertia( lbtoslug * EmptyWeight, vbaseXYZcg );
164 // Then add the contributions from the additional pointmasses.
165 mJ += CalculatePMInertias();
166 mJ += Propulsion->CalculateTankInertias();
167 mJ += BuoyantForces->GetGasMassInertia();
176 // Calculate inertia matrix inverse (ref. Stevens and Lewis, "Flight Control & Simulation")
178 k1 = (Iyy*Izz - Iyz*Iyz);
179 k2 = (Iyz*Ixz + Ixy*Izz);
180 k3 = (Ixy*Iyz + Iyy*Ixz);
182 denom = 1.0/(Ixx*k1 - Ixy*k2 - Ixz*k3 );
186 k4 = (Izz*Ixx - Ixz*Ixz)*denom;
187 k5 = (Ixy*Ixz + Iyz*Ixx)*denom;
188 k6 = (Ixx*Iyy - Ixy*Ixy)*denom;
190 mJinv.InitMatrix( k1, k2, k3,
199 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
201 void FGMassBalance::AddPointMass(Element* el)
205 Element* loc_element = el->FindElement("location");
206 string pointmass_name = el->GetAttributeValue("name");
208 cerr << "Pointmass " << pointmass_name << " has no location." << endl;
212 double w = el->FindElementValueAsNumberConvertTo("weight", "LBS");
213 FGColumnVector3 vXYZ = loc_element->FindElementTripletConvertTo("IN");
214 PointMasses.push_back(new PointMass(w, vXYZ));
216 int num = PointMasses.size()-1;
218 snprintf(tmp, 80, "inertia/pointmass-weight-lbs[%u]", num);
219 PropertyManager->Tie( tmp, this, num, &FGMassBalance::GetPointMassWeight,
220 &FGMassBalance::SetPointMassWeight);
223 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
225 double FGMassBalance::GetPointMassWeight(void)
227 double PM_total_weight = 0.0;
229 for (unsigned int i=0; i<PointMasses.size(); i++) {
230 PM_total_weight += PointMasses[i]->Weight;
232 return PM_total_weight;
235 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
237 FGColumnVector3& FGMassBalance::GetPointMassMoment(void)
239 PointMassCG.InitMatrix();
241 for (unsigned int i=0; i<PointMasses.size(); i++) {
242 PointMassCG += PointMasses[i]->Weight*PointMasses[i]->Location;
247 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
249 FGMatrix33& FGMassBalance::CalculatePMInertias(void)
253 size = PointMasses.size();
254 if (size == 0) return pmJ;
258 for (unsigned int i=0; i<size; i++)
259 pmJ += GetPointmassInertia( lbtoslug * PointMasses[i]->Weight, PointMasses[i]->Location );
264 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
266 FGColumnVector3 FGMassBalance::StructuralToBody(const FGColumnVector3& r) const
268 // Under the assumption that in the structural frame the:
270 // - X-axis is directed afterwards,
271 // - Y-axis is directed towards the right,
272 // - Z-axis is directed upwards,
274 // (as documented in http://jsbsim.sourceforge.net/JSBSimCoordinates.pdf)
275 // we have to subtract first the center of gravity of the plane which
276 // is also defined in the structural frame:
278 // FGColumnVector3 cgOff = r - vXYZcg;
280 // Next, we do a change of units:
282 // cgOff *= inchtoft;
284 // And then a 180 degree rotation is done about the Y axis so that the:
286 // - X-axis is directed forward,
287 // - Y-axis is directed towards the right,
288 // - Z-axis is directed downward.
290 // This is needed because the structural and body frames are 180 degrees apart.
292 return FGColumnVector3(inchtoft*(vXYZcg(1)-r(1)),
293 inchtoft*(r(2)-vXYZcg(2)),
294 inchtoft*(vXYZcg(3)-r(3)));
297 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
299 void FGMassBalance::bind(void)
301 typedef double (FGMassBalance::*PMF)(int) const;
302 PropertyManager->Tie("inertia/mass-slugs", this,
303 &FGMassBalance::GetMass);
304 PropertyManager->Tie("inertia/weight-lbs", this,
305 &FGMassBalance::GetWeight);
306 PropertyManager->Tie("inertia/empty-weight-lbs", this,
307 &FGMassBalance::GetWeight, &FGMassBalance::SetEmptyWeight);
308 PropertyManager->Tie("inertia/cg-x-in", this,1,
309 (PMF)&FGMassBalance::GetXYZcg);
310 PropertyManager->Tie("inertia/cg-y-in", this,2,
311 (PMF)&FGMassBalance::GetXYZcg);
312 PropertyManager->Tie("inertia/cg-z-in", this,3,
313 (PMF)&FGMassBalance::GetXYZcg);
316 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
317 // The bitmasked value choices are as follows:
318 // unset: In this case (the default) JSBSim would only print
319 // out the normally expected messages, essentially echoing
320 // the config files as they are read. If the environment
321 // variable is not set, debug_lvl is set to 1 internally
322 // 0: This requests JSBSim not to output any messages
324 // 1: This value explicity requests the normal JSBSim
326 // 2: This value asks for a message to be printed out when
327 // a class is instantiated
328 // 4: When this value is set, a message is displayed when a
329 // FGModel object executes its Run() method
330 // 8: When this value is set, various runtime state variables
331 // are printed out periodically
332 // 16: When set various parameters are sanity checked and
333 // a message is printed out when they go out of bounds
335 void FGMassBalance::Debug(int from)
337 if (debug_lvl <= 0) return;
339 if (debug_lvl & 1) { // Standard console startup message output
340 if (from == 2) { // Loading
341 cout << endl << " Mass and Balance:" << endl;
342 cout << " baseIxx: " << baseJ(1,1) << " slug-ft2" << endl;
343 cout << " baseIyy: " << baseJ(2,2) << " slug-ft2" << endl;
344 cout << " baseIzz: " << baseJ(3,3) << " slug-ft2" << endl;
345 cout << " baseIxy: " << baseJ(1,2) << " slug-ft2" << endl;
346 cout << " baseIxz: " << baseJ(1,3) << " slug-ft2" << endl;
347 cout << " baseIyz: " << baseJ(2,3) << " slug-ft2" << endl;
348 cout << " EmptyWeight: " << EmptyWeight << " lbm" << endl;
349 cout << " CG (x, y, z): " << vbaseXYZcg << endl;
350 // ToDo: Need to add point mass outputs here
351 for (unsigned int i=0; i<PointMasses.size(); i++) {
352 cout << " Point Mass Object: " << PointMasses[i]->Weight << " lbs. at "
353 << "X, Y, Z (in.): " << PointMasses[i]->Location(eX) << " "
354 << PointMasses[i]->Location(eY) << " "
355 << PointMasses[i]->Location(eZ) << endl;
359 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
360 if (from == 0) cout << "Instantiated: FGMassBalance" << endl;
361 if (from == 1) cout << "Destroyed: FGMassBalance" << endl;
363 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
365 if (debug_lvl & 8 ) { // Runtime state variables
367 if (debug_lvl & 16) { // Sanity checking
369 if (EmptyWeight <= 0.0 || EmptyWeight > 1e9)
370 cout << "MassBalance::EmptyWeight out of bounds: " << EmptyWeight << endl;
371 if (Weight <= 0.0 || Weight > 1e9)
372 cout << "MassBalance::Weight out of bounds: " << Weight << endl;
373 if (Mass <= 0.0 || Mass > 1e9)
374 cout << "MassBalance::Mass out of bounds: " << Mass << endl;
377 if (debug_lvl & 64) {
378 if (from == 0) { // Constructor
379 cout << IdSrc << endl;
380 cout << IdHdr << endl;