1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
6 Purpose: Integrates the rotational 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 rotational EOM.
33 --------------------------------------------------------------------------------
36 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
37 COMMENTS, REFERENCES, and NOTES
38 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 [1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
40 Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate
42 [2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
44 [3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
45 NASA-Ames", NASA CR-2497, January 1975
46 [4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
47 Wiley & Sons, 1979 ISBN 0-471-03032-5
48 [5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
49 1982 ISBN 0-471-08936-2
51 The order of rotations used in this class corresponds to a 3-2-1 sequence,
52 or Y-P-R, or Z-Y-X, if you prefer.
54 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
58 #include "FGRotation.h"
59 #include "FGAtmosphere.h"
61 #include "FGFDMExec.h"
63 #include "FGAircraft.h"
64 #include "FGMassBalance.h"
65 #include "FGTranslation.h"
66 #include "FGPosition.h"
67 #include "FGAuxiliary.h"
70 static const char *IdSrc = "$Id$";
71 static const char *IdHdr = ID_ROTATION;
73 extern short debug_lvl;
75 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
77 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
80 FGRotation::FGRotation(FGFDMExec* fdmex) : FGModel(fdmex),
92 if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
95 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
97 FGRotation::~FGRotation()
99 if (debug_lvl & 2) cout << "Destroyed: FGRotation" << endl;
102 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
104 bool FGRotation::Run(void)
109 if (!FGModel::Run()) {
112 L2 = vMoments(eL) + Ixz*vPQR(eP)*vPQR(eQ) - (Izz-Iyy)*vPQR(eR)*vPQR(eQ);
113 N1 = vMoments(eN) - (Iyy-Ixx)*vPQR(eP)*vPQR(eQ) - Ixz*vPQR(eR)*vPQR(eQ);
115 vPQRdot(eP) = (L2*Izz - N1*Ixz) / (Ixx*Izz - Ixz*Ixz);
116 vPQRdot(eQ) = (vMoments(eM) - (Ixx-Izz)*vPQR(eP)*vPQR(eR) - Ixz*(vPQR(eP)*vPQR(eP) - vPQR(eR)*vPQR(eR)))/Iyy;
117 vPQRdot(eR) = (N1*Ixx + L2*Ixz) / (Ixx*Izz - Ixz*Ixz);
119 vPQR += dt*rate*(vlastPQRdot + vPQRdot)/2.0;
121 State->IntegrateQuat(vPQR, rate);
122 State->CalcMatrices();
123 vEuler = State->CalcEuler();
125 cTht = cos(vEuler(eTht)); sTht = sin(vEuler(eTht));
126 cPhi = cos(vEuler(ePhi)); sPhi = sin(vEuler(ePhi));
127 cPsi = cos(vEuler(ePsi)); sPsi = sin(vEuler(ePsi));
129 vEulerRates(eTht) = vPQR(2)*cPhi - vPQR(3)*sPhi;
131 tTheta = sTht/cTht; // what's cheaper: / or tan() ?
132 vEulerRates(ePhi) = vPQR(1) + (vPQR(2)*sPhi + vPQR(3)*cPhi)*tTheta;
133 vEulerRates(ePsi) = (vPQR(2)*sPhi + vPQR(3)*cPhi)/cTht;
136 vlastPQRdot = vPQRdot;
138 if (debug_lvl > 1) Debug();
146 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
148 void FGRotation::GetState(void)
151 vMoments = Aircraft->GetMoments();
153 Ixx = MassBalance->GetIxx();
154 Iyy = MassBalance->GetIyy();
155 Izz = MassBalance->GetIzz();
156 Ixz = MassBalance->GetIxz();
159 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
161 void FGRotation::Debug(void)
163 if (debug_lvl & 16) { // Sanity check variables
164 if (fabs(vPQR(eP)) > 100)
165 cout << "FGRotation::P (Roll Rate) out of bounds: " << vPQR(eP) << endl;
166 if (fabs(vPQR(eQ)) > 100)
167 cout << "FGRotation::Q (Pitch Rate) out of bounds: " << vPQR(eQ) << endl;
168 if (fabs(vPQR(eR)) > 100)
169 cout << "FGRotation::R (Yaw Rate) out of bounds: " << vPQR(eR) << endl;