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flightgear/src/FDM/JSBSim/FGTranslation.cpp

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/*******************************************************************************
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Module: FGTranslation.cpp
Author: Jon Berndt
Date started: 12/02/98
Purpose: Integrates the translational EOM
Called by: FDMExec
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------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
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This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
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This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
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You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA.
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Further information about the GNU General Public License can also be found on
the world wide web at http://www.gnu.org.
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FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------
This class integrates the translational EOM.
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HISTORY
--------------------------------------------------------------------------------
12/02/98 JSB Created
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7/23/99 TP Added data member and modified Run and PutState to calcuate
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Mach number
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********************************************************************************
COMMENTS, REFERENCES, and NOTES
********************************************************************************
[1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate
School, January 1994
[2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
JSC 12960, July 1977
[3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
NASA-Ames", NASA CR-2497, January 1975
[4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
Wiley & Sons, 1979 ISBN 0-471-03032-5
[5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
1982 ISBN 0-471-08936-2
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The order of rotations used in this class corresponds to a 3-2-1 sequence,
or Y-P-R, or Z-Y-X, if you prefer.
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********************************************************************************
INCLUDES
*******************************************************************************/
#include "FGTranslation.h"
#include "FGRotation.h"
#include "FGAtmosphere.h"
#include "FGState.h"
#include "FGFDMExec.h"
#include "FGFCS.h"
#include "FGAircraft.h"
#include "FGPosition.h"
#include "FGAuxiliary.h"
#include "FGOutput.h"
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/*******************************************************************************
************************************ CODE **************************************
*******************************************************************************/
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FGTranslation::FGTranslation(FGFDMExec* fdmex) : FGModel(fdmex),
vUVW(3),
vWindUVW(3),
vUVWdot(3),
vNcg(3),
vPQR(3),
vForces(3),
vEuler(3)
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{
Name = "FGTranslation";
qbar = 0;
Vt = 0.0;
Mach = 0.0;
alpha = beta = 0.0;
rho = 0.002378;
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}
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/******************************************************************************/
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FGTranslation::~FGTranslation(void) {}
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/******************************************************************************/
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bool FGTranslation::Run(void) {
static FGColumnVector vlastUVWdot(3);
static FGMatrix mVel(3,3);
if (!FGModel::Run()) {
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GetState();
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mVel(1,1) = 0.0;
mVel(1,2) = -vUVW(eW);
mVel(1,3) = vUVW(eV);
mVel(2,1) = vUVW(eW);
mVel(2,2) = 0.0;
mVel(2,3) = -vUVW(eU);
mVel(3,1) = -vUVW(eV);
mVel(3,2) = vUVW(eU);
mVel(3,3) = 0.0;
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vUVWdot = mVel*vPQR + vForces/Mass;
vNcg=vUVWdot*INVGRAVITY;
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vUVW += 0.5*dt*rate*(vlastUVWdot + vUVWdot) + vWindUVW;
Vt = vUVW.Magnitude();
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if (vUVW(eW) != 0.0)
alpha = vUVW(eU)*vUVW(eU) > 0.0 ? atan2(vUVW(eW), vUVW(eU)) : 0.0;
if (vUVW(eV) != 0.0)
beta = vUVW(eU)*vUVW(eU)+vUVW(eW)*vUVW(eW) > 0.0 ? atan2(vUVW(eV),
sqrt(vUVW(eU)*vUVW(eU) + vUVW(eW)*vUVW(eW))) : 0.0;
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qbar = 0.5*rho*Vt*Vt;
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Mach = Vt / State->Geta();
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vlastUVWdot = vUVWdot;
} else {}
return false;
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}
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/******************************************************************************/
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void FGTranslation::GetState(void) {
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dt = State->Getdt();
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vPQR = Rotation->GetPQR();
vForces = Aircraft->GetForces();
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Mass = Aircraft->GetMass();
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rho = Atmosphere->GetDensity();
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vEuler = Rotation->GetEuler();
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vWindUVW = Atmosphere->GetWindUVW();
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}