1
0
Fork 0
flightgear/src/FDM/JSBSim/FGLGear.cpp
2000-10-02 23:07:30 +00:00

174 lines
5.9 KiB
C++

/*******************************************************************************
Module: FGLGear.cpp
Author: Jon S. Berndt
Date started: 11/18/99
Purpose: Encapsulates the landing gear elements
Called by: FGAircraft
------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
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.
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.
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.
Further information about the GNU General Public License can also be found on
the world wide web at http://www.gnu.org.
FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------
HISTORY
--------------------------------------------------------------------------------
11/18/99 JSB Created
********************************************************************************
INCLUDES
*******************************************************************************/
#include "FGLGear.h"
#include <algorithm>
/*******************************************************************************
************************************ CODE **************************************
*******************************************************************************/
FGLGear::FGLGear(FGConfigFile* AC_cfg, FGFDMExec* fdmex) : vXYZ(3),
vMoment(3),
vWhlBodyVec(3),
Exec(fdmex)
{
string tmp;
*AC_cfg >> tmp >> name >> vXYZ(1) >> vXYZ(2) >> vXYZ(3)
>> kSpring >> bDamp >> statFCoeff >> brakeCoeff;
cout << " Name: " << name << endl;
cout << " Location: " << vXYZ << endl;
cout << " Spring Constant: " << kSpring << endl;
cout << " Damping Constant: " << bDamp << endl;
cout << " Rolling Resistance: " << statFCoeff << endl;
cout << " Braking Coeff: " << brakeCoeff << endl;
State = Exec->GetState();
Aircraft = Exec->GetAircraft();
Position = Exec->GetPosition();
Rotation = Exec->GetRotation();
WOW = false;
ReportEnable=true;
FirstContact = false;
Reported = false;
DistanceTraveled = 0.0;
MaximumStrutForce = MaximumStrutTravel = 0.0;
}
/******************************************************************************/
FGLGear::~FGLGear(void)
{
}
/******************************************************************************/
FGColumnVector FGLGear::Force(void)
{
FGColumnVector vForce(3);
FGColumnVector vLocalForce(3);
FGColumnVector vLocalGear(3); // Vector: CG to this wheel (Local)
FGColumnVector vWhlVelVec(3); // Velocity of this wheel (Local)
vWhlBodyVec = (vXYZ - Aircraft->GetXYZcg()) / 12.0;
vWhlBodyVec(eX) = -vWhlBodyVec(eX);
vWhlBodyVec(eZ) = -vWhlBodyVec(eZ);
vLocalGear = State->GetTb2l() * vWhlBodyVec;
compressLength = vLocalGear(eZ) - Position->GetDistanceAGL();
if (compressLength > 0.00) {
WOW = true;
vWhlVelVec = State->GetTb2l() * (Rotation->GetPQR() * vWhlBodyVec);
vWhlVelVec += Position->GetVel();
compressSpeed = vWhlVelVec(eZ);
if (!FirstContact) {
FirstContact = true;
SinkRate = compressSpeed;
GroundSpeed = Position->GetVel().Magnitude();
}
vWhlVelVec = -1.0 * vWhlVelVec.Normalize();
vWhlVelVec(eZ) = 0.00;
vLocalForce(eZ) = min(-compressLength * kSpring - compressSpeed * bDamp, (float)0.0);
vLocalForce(eX) = fabs(vLocalForce(eZ) * statFCoeff) * vWhlVelVec(eX);
vLocalForce(eY) = fabs(vLocalForce(eZ) * statFCoeff) * vWhlVelVec(eY);
MaximumStrutForce = max(MaximumStrutForce, fabs(vLocalForce(eZ)));
MaximumStrutTravel = max(MaximumStrutTravel, fabs(compressLength));
vForce = State->GetTl2b() * vLocalForce ;
vMoment = vWhlBodyVec * vForce;
cout << " Force: " << vForce << endl;
cout << " Moment: " << vMoment << endl;
} else {
WOW = false;
if (Position->GetDistanceAGL() > 200.0) {
FirstContact = false;
Reported = false;
DistanceTraveled = 0.0;
MaximumStrutForce = MaximumStrutTravel = 0.0;
}
vForce.InitMatrix();
vMoment.InitMatrix();
}
if (FirstContact) {
DistanceTraveled += Position->GetVel().Magnitude()*State->Getdt()*Aircraft->GetRate();
}
if (ReportEnable && Position->GetVel().Magnitude() <= 0.05 && !Reported) {
Report();
}
return vForce;
}
/******************************************************************************/
void FGLGear::Report(void)
{
cout << endl << "Touchdown report for " << name << endl;
cout << " Sink rate at contact: " << SinkRate << " fps, "
<< SinkRate*0.3408 << " mps" << endl;
cout << " Contact ground speed: " << GroundSpeed*.5925 << " knots, "
<< GroundSpeed*0.3408 << " mps" << endl;
cout << " Maximum contact force: " << MaximumStrutForce << " lbs, "
<< MaximumStrutForce*4.448 << " Newtons" << endl;
cout << " Maximum strut travel: " << MaximumStrutTravel*12.0 << " inches, "
<< MaximumStrutTravel*30.48 << " cm" << endl;
cout << " Distance traveled: " << DistanceTraveled << " ft, "
<< DistanceTraveled*0.3408 << " meters" << endl;
Reported = true;
}