146 lines
4.5 KiB
C++
146 lines
4.5 KiB
C++
/*******************************************************************************
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Module: FGPosition.cpp
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Author: Jon S. Berndt
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Date started: 01/05/99
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Purpose: Integrate the EOM to determine instantaneous position
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Called by: FGFDMExec
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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
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the terms of the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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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
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the world wide web at http://www.gnu.org.
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FUNCTIONAL DESCRIPTION
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--------------------------------------------------------------------------------
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This class encapsulates the integration of rates and accelerations to get the
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current position of the aircraft.
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HISTORY
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--------------------------------------------------------------------------------
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01/05/99 JSB Created
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********************************************************************************
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COMMENTS, REFERENCES, and NOTES
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********************************************************************************
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[1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
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Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate
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School, January 1994
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[2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
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JSC 12960, July 1977
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[3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
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NASA-Ames", NASA CR-2497, January 1975
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[4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
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Wiley & Sons, 1979 ISBN 0-471-03032-5
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[5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
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1982 ISBN 0-471-08936-2
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********************************************************************************
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INCLUDES
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*******************************************************************************/
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#ifdef FGFS
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# include <simgear/compiler.h>
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# ifdef FG_HAVE_STD_INCLUDES
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# include <cmath>
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# else
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# include <math.h>
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# endif
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#else
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# include <cmath>
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#endif
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#include "FGPosition.h"
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#include "FGAtmosphere.h"
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#include "FGState.h"
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#include "FGFDMExec.h"
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#include "FGFCS.h"
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#include "FGAircraft.h"
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#include "FGTranslation.h"
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#include "FGRotation.h"
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#include "FGAuxiliary.h"
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#include "FGOutput.h"
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/*******************************************************************************
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************************************ CODE **************************************
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*******************************************************************************/
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FGPosition::FGPosition(FGFDMExec* fdmex) : FGModel(fdmex),
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vUVW(3),
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vVel(3)
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{
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Name = "FGPosition";
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LongitudeDot = LatitudeDot = RadiusDot = 0.0;
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lastLongitudeDot = lastLatitudeDot = lastRadiusDot = 0.0;
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Longitude = Latitude = 0.0;
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h = 0.0;
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}
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/******************************************************************************/
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FGPosition::~FGPosition(void)
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{
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}
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/******************************************************************************/
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bool FGPosition:: Run(void)
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{
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float cosLat;
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if (!FGModel::Run()) {
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GetState();
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vVel = State->GetTl2b()*vUVW;
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cosLat = cos(Latitude);
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if (cosLat != 0) LongitudeDot = vVel(eEast) / (Radius * cosLat);
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LatitudeDot = vVel(eNorth) * invRadius;
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RadiusDot = -vVel(eDown);
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Longitude += 0.5*dt*rate*(LongitudeDot + lastLongitudeDot);
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Latitude += 0.5*dt*rate*(LatitudeDot + lastLatitudeDot);
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Radius += 0.5*dt*rate*(RadiusDot + lastRadiusDot);
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h = Radius - EARTHRAD;
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lastLatitudeDot = LatitudeDot;
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lastLongitudeDot = LongitudeDot;
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lastRadiusDot = RadiusDot;
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return false;
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} else {
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return true;
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}
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}
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/******************************************************************************/
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void FGPosition::GetState(void)
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{
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dt = State->Getdt();
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vUVW = Translation->GetUVW();
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invMass = 1.0 / Aircraft->GetMass();
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invRadius = 1.0 / (h + EARTHRAD);
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Radius = h + EARTHRAD;
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}
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