1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 Module: FGTranslation.cpp
6 Purpose: Integrates the translational EOM
9 ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
11 This program is free software; you can redistribute it and/or modify it under
12 the terms of the GNU General Public License as published by the Free Software
13 Foundation; either version 2 of the License, or (at your option) any later
16 This program is distributed in the hope that it will be useful, but WITHOUT
17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
18 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
21 You should have received a copy of the GNU General Public License along with
22 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
23 Place - Suite 330, Boston, MA 02111-1307, USA.
25 Further information about the GNU General Public License can also be found on
26 the world wide web at http://www.gnu.org.
28 FUNCTIONAL DESCRIPTION
29 --------------------------------------------------------------------------------
30 This class integrates the translational EOM.
33 --------------------------------------------------------------------------------
35 7/23/99 TP Added data member and modified Run and PutState to calcuate
38 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 COMMENTS, REFERENCES, and NOTES
40 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
41 [1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
42 Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate
44 [2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
46 [3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
47 NASA-Ames", NASA CR-2497, January 1975
48 [4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
49 Wiley & Sons, 1979 ISBN 0-471-03032-5
50 [5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
51 1982 ISBN 0-471-08936-2
53 The order of rotations used in this class corresponds to a 3-2-1 sequence,
54 or Y-P-R, or Z-Y-X, if you prefer.
56 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
58 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
60 #include "FGTranslation.h"
61 #include "FGRotation.h"
62 #include "FGAtmosphere.h"
64 #include "FGFDMExec.h"
66 #include "FGMassBalance.h"
67 #include "FGAircraft.h"
68 #include "FGPosition.h"
69 #include "FGAuxiliary.h"
72 static const char *IdSrc = "$Id$";
73 static const char *IdHdr = ID_TRANSLATION;
75 extern short debug_lvl;
77 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
79 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
82 FGTranslation::FGTranslation(FGFDMExec* fdmex) : FGModel(fdmex),
92 Name = "FGTranslation";
100 if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
103 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
105 FGTranslation::~FGTranslation()
107 if (debug_lvl & 2) cout << "Destroyed: FGTranslation" << endl;
110 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
112 bool FGTranslation::Run(void) {
114 if (!FGModel::Run()) {
119 mVel(1,2) = -vUVW(eW);
120 mVel(1,3) = vUVW(eV);
121 mVel(2,1) = vUVW(eW);
123 mVel(2,3) = -vUVW(eU);
124 mVel(3,1) = -vUVW(eV);
125 mVel(3,2) = vUVW(eU);
128 vUVWdot = mVel*vPQR + vForces/Mass;
130 vNcg = vUVWdot*INVGRAVITY;
132 vUVW += 0.5*dt*rate*(vlastUVWdot + vUVWdot);
134 Vt = vUVW.Magnitude();
137 alpha = vUVW(eU)*vUVW(eU) > 0.0 ? atan2(vUVW(eW), vUVW(eU)) : 0.0;
139 beta = vUVW(eU)*vUVW(eU)+vUVW(eW)*vUVW(eW) > 0.0 ? atan2(vUVW(eV),
140 sqrt(vUVW(eU)*vUVW(eU) + vUVW(eW)*vUVW(eW))) : 0.0;
142 // stolen, quite shamelessly, from LaRCsim
143 float mUW = (vUVW(eU)*vUVW(eU) + vUVW(eW)*vUVW(eW));
146 signU = vUVW(eU)/fabs(vUVW(eU));
148 if ( (mUW == 0.0) || (Vt == 0.0) ) {
152 adot = (vUVW(eU)*vUVWdot(eW) - vUVW(eW)*vUVWdot(eU))/mUW;
153 bdot = (signU*mUW*vUVWdot(eV) - vUVW(eV)*(vUVW(eU)*vUVWdot(eU)
154 + vUVW(eW)*vUVWdot(eW)))/(Vt*Vt*sqrt(mUW));
157 qbar = 0.5*rho*Vt*Vt;
158 Mach = Vt / State->Geta();
160 vlastUVWdot = vUVWdot;
162 if (debug_lvl > 1) Debug();
170 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
172 void FGTranslation::GetState(void) {
175 vPQR = Rotation->GetPQR();
176 vForces = Aircraft->GetForces();
178 Mass = MassBalance->GetMass();
179 rho = Atmosphere->GetDensity();
181 vEuler = Rotation->GetEuler();
184 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
186 void FGTranslation::Debug(void)
188 if (debug_lvl & 16) { // Sanity check variables
189 if (fabs(vUVW(eU)) > 1e6)
190 cout << "FGTranslation::U velocity out of bounds: " << vUVW(eU) << endl;
191 if (fabs(vUVW(eV)) > 1e6)
192 cout << "FGTranslation::V velocity out of bounds: " << vUVW(eV) << endl;
193 if (fabs(vUVW(eW)) > 1e6)
194 cout << "FGTranslation::W velocity out of bounds: " << vUVW(eW) << endl;
195 if (fabs(vUVWdot(eU)) > 1e4)
196 cout << "FGTranslation::U acceleration out of bounds: " << vUVWdot(eU) << endl;
197 if (fabs(vUVWdot(eV)) > 1e4)
198 cout << "FGTranslation::V acceleration out of bounds: " << vUVWdot(eV) << endl;
199 if (fabs(vUVWdot(eW)) > 1e4)
200 cout << "FGTranslation::W acceleration out of bounds: " << vUVWdot(eW) << endl;
201 if (Mach > 100 || Mach < 0.00)
202 cout << "FGTranslation::Mach is out of bounds: " << Mach << endl;
203 if (qbar > 1e6 || qbar < 0.00)
204 cout << "FGTranslation::qbar is out of bounds: " << qbar << endl;