1 /*******************************************************************************
6 Purpose: Encapsulates the landing gear elements
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 --------------------------------------------------------------------------------
32 --------------------------------------------------------------------------------
35 ********************************************************************************
37 *******************************************************************************/
42 static const char *IdSrc = "$Header$";
43 static const char *IdHdr = ID_LGEAR;
45 /*******************************************************************************
46 ************************************ CODE **************************************
47 *******************************************************************************/
50 FGLGear::FGLGear(FGConfigFile* AC_cfg, FGFDMExec* fdmex) : vXYZ(3),
56 *AC_cfg >> tmp >> name >> vXYZ(1) >> vXYZ(2) >> vXYZ(3)
57 >> kSpring >> bDamp>> dynamicFCoeff >> staticFCoeff
58 >> SteerType >> BrakeType >> GroupMember >> maxSteerAngle;
60 cout << " Name: " << name << endl;
61 cout << " Location: " << vXYZ << endl;
62 cout << " Spring Constant: " << kSpring << endl;
63 cout << " Damping Constant: " << bDamp << endl;
64 cout << " Dynamic Friction: " << dynamicFCoeff << endl;
65 cout << " Static Friction: " << staticFCoeff << endl;
66 cout << " Brake Type: " << BrakeType << endl;
67 cout << " Grouping: " << GroupMember << endl;
68 cout << " Steering Type: " << SteerType << endl;
69 cout << " Max Steer Angle: " << maxSteerAngle << endl;
71 State = Exec->GetState();
72 Aircraft = Exec->GetAircraft();
73 Position = Exec->GetPosition();
74 Rotation = Exec->GetRotation();
80 DistanceTraveled = 0.0;
81 MaximumStrutForce = MaximumStrutTravel = 0.0;
85 /******************************************************************************/
87 FGLGear::~FGLGear(void)
89 cout << "Destructing Landing Gear ..." << endl;
92 /******************************************************************************/
94 FGColumnVector FGLGear::Force(void)
96 FGColumnVector vForce(3);
97 FGColumnVector vLocalForce(3);
98 FGColumnVector vLocalGear(3); // Vector: CG to this wheel (Local)
99 FGColumnVector vWhlVelVec(3); // Velocity of this wheel (Local)
101 vWhlBodyVec = (vXYZ - Aircraft->GetXYZcg()) / 12.0;
102 vWhlBodyVec(eX) = -vWhlBodyVec(eX);
103 vWhlBodyVec(eZ) = -vWhlBodyVec(eZ);
105 vLocalGear = State->GetTb2l() * vWhlBodyVec;
107 compressLength = vLocalGear(eZ) - Position->GetDistanceAGL();
109 if (compressLength > 0.00) {
112 vWhlVelVec = State->GetTb2l() * (Rotation->GetPQR() * vWhlBodyVec);
113 vWhlVelVec += Position->GetVel();
115 compressSpeed = vWhlVelVec(eZ);
119 SinkRate = compressSpeed;
120 GroundSpeed = Position->GetVel().Magnitude();
123 // The following code normalizes the wheel velocity vector, reverses it, and zeroes out
124 // the z component of the velocity. The question is, should the Z axis velocity be zeroed
125 // out first before the normalization takes place or not? Subsequent to that, the Wheel
126 // Velocity vector now points as a unit vector backwards and parallel to the wheel
127 // velocity vector. It acts AT the wheel.
129 vWhlVelVec = -1.0 * vWhlVelVec.Normalize();
130 vWhlVelVec(eZ) = 0.00;
132 // the following needs work regarding friction coefficients and braking and steering
134 vLocalForce(eZ) = min(-compressLength * kSpring - compressSpeed * bDamp, (float)0.0);
135 vLocalForce(eX) = fabs(vLocalForce(eZ) * staticFCoeff) * vWhlVelVec(eX);
136 vLocalForce(eY) = fabs(vLocalForce(eZ) * staticFCoeff) * vWhlVelVec(eY);
138 MaximumStrutForce = max(MaximumStrutForce, fabs(vLocalForce(eZ)));
139 MaximumStrutTravel = max(MaximumStrutTravel, fabs(compressLength));
141 vForce = State->GetTl2b() * vLocalForce ;
142 vMoment = vWhlBodyVec * vForce;
148 if (Position->GetDistanceAGL() > 200.0) {
149 FirstContact = false;
151 DistanceTraveled = 0.0;
152 MaximumStrutForce = MaximumStrutTravel = 0.0;
156 vMoment.InitMatrix();
160 DistanceTraveled += Position->GetVel().Magnitude()*State->Getdt()*Aircraft->GetRate();
163 if (ReportEnable && Position->GetVel().Magnitude() <= 0.05 && !Reported) {
169 /******************************************************************************/
171 void FGLGear::Report(void)
173 cout << endl << "Touchdown report for " << name << endl;
174 cout << " Sink rate at contact: " << SinkRate << " fps, "
175 << SinkRate*0.3408 << " mps" << endl;
176 cout << " Contact ground speed: " << GroundSpeed*.5925 << " knots, "
177 << GroundSpeed*0.3408 << " mps" << endl;
178 cout << " Maximum contact force: " << MaximumStrutForce << " lbs, "
179 << MaximumStrutForce*4.448 << " Newtons" << endl;
180 cout << " Maximum strut travel: " << MaximumStrutTravel*12.0 << " inches, "
181 << MaximumStrutTravel*30.48 << " cm" << endl;
182 cout << " Distance traveled: " << DistanceTraveled << " ft, "
183 << DistanceTraveled*0.3408 << " meters" << endl;