INCLUDES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
+#include <cstdlib>
+#include <cstring>
+
#include "FGLGear.h"
+#include "input_output/FGPropertyManager.h"
+#include "models/FGGroundReactions.h"
+#include "math/FGTable.h"
+
+using namespace std;
namespace JSBSim {
GLOBAL DATA
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-static const char *IdSrc = "$Id$";
+static const char *IdSrc = "$Id: FGLGear.cpp,v 1.100 2012/04/01 17:05:51 bcoconni Exp $";
static const char *IdHdr = ID_LGEAR;
// Body To Structural (body frame is rotated 180 deg about Y and lengths are given in
// ft instead of inches)
const FGMatrix33 FGLGear::Tb2s(-1./inchtoft, 0., 0., 0., 1./inchtoft, 0., 0., 0., -1./inchtoft);
+const FGMatrix33 FGLGear::Ts2b(-inchtoft, 0., 0., 0., inchtoft, 0., 0., 0., -inchtoft);
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-FGLGear::FGLGear(Element* el, FGFDMExec* fdmex, int number) :
+FGLGear::FGLGear(Element* el, FGFDMExec* fdmex, int number, const struct Inputs& inputs) :
FGForce(fdmex),
- GearNumber(number)
+ in(inputs),
+ GearNumber(number),
+ SteerAngle(0.0),
+ Castered(false),
+ StaticFriction(false)
{
- Element *force_table=0;
- Element *dampCoeff=0;
- Element *dampCoeffRebound=0;
- string force_type="";
-
kSpring = bDamp = bDampRebound = dynamicFCoeff = staticFCoeff = rollingFCoeff = maxSteerAngle = 0;
- sSteerType = sBrakeGroup = sSteerType = "";
- isRetractable = 0;
+ isRetractable = false;
eDampType = dtLinear;
eDampTypeRebound = dtLinear;
name = el->GetAttributeValue("name");
- sContactType = el->GetAttributeValue("type");
+ string sContactType = el->GetAttributeValue("type");
if (sContactType == "BOGEY") {
eContactType = ctBOGEY;
} else if (sContactType == "STRUCTURE") {
eContactType = ctSTRUCTURE;
}
+ // Default values for structural contact points
+ if (eContactType == ctSTRUCTURE) {
+ kSpring = in.EmptyWeight;
+ bDamp = kSpring;
+ bDampRebound = kSpring * 10;
+ staticFCoeff = 1.0;
+ dynamicFCoeff = 1.0;
+ }
+
if (el->FindElement("spring_coeff"))
kSpring = el->FindElementValueAsNumberConvertTo("spring_coeff", "LBS/FT");
if (el->FindElement("damping_coeff")) {
- dampCoeff = el->FindElement("damping_coeff");
+ Element* dampCoeff = el->FindElement("damping_coeff");
if (dampCoeff->GetAttributeValue("type") == "SQUARE") {
eDampType = dtSquare;
bDamp = el->FindElementValueAsNumberConvertTo("damping_coeff", "LBS/FT2/SEC2");
}
if (el->FindElement("damping_coeff_rebound")) {
- dampCoeffRebound = el->FindElement("damping_coeff_rebound");
+ Element* dampCoeffRebound = el->FindElement("damping_coeff_rebound");
if (dampCoeffRebound->GetAttributeValue("type") == "SQUARE") {
eDampTypeRebound = dtSquare;
bDampRebound = el->FindElementValueAsNumberConvertTo("damping_coeff_rebound", "LBS/FT2/SEC2");
staticFCoeff = el->FindElementValueAsNumber("static_friction");
if (el->FindElement("rolling_friction"))
rollingFCoeff = el->FindElementValueAsNumber("rolling_friction");
- if (el->FindElement("max_steer"))
- maxSteerAngle = el->FindElementValueAsNumberConvertTo("max_steer", "DEG");
if (el->FindElement("retractable"))
isRetractable = ((unsigned int)el->FindElementValueAsNumber("retractable"))>0.0?true:false;
+ if (el->FindElement("max_steer"))
+ maxSteerAngle = el->FindElementValueAsNumberConvertTo("max_steer", "DEG");
+
+ if (maxSteerAngle == 360) {
+ eSteerType = stCaster;
+ Castered = true;
+ }
+ else if (maxSteerAngle == 0.0) {
+ eSteerType = stFixed;
+ }
+ else
+ eSteerType = stSteer;
+
+ GroundReactions = fdmex->GetGroundReactions();
+ PropertyManager = fdmex->GetPropertyManager();
+
ForceY_Table = 0;
- force_table = el->FindElement("table");
+ Element* force_table = el->FindElement("table");
while (force_table) {
- force_type = force_table->GetAttributeValue("type");
+ string force_type = force_table->GetAttributeValue("type");
if (force_type == "CORNERING_COEFF") {
- ForceY_Table = new FGTable(fdmex->GetPropertyManager(), force_table);
+ ForceY_Table = new FGTable(PropertyManager, force_table);
+ break;
} else {
cerr << "Undefined force table for " << name << " contact point" << endl;
}
force_table = el->FindNextElement("table");
}
- sBrakeGroup = el->FindElementValue("brake_group");
-
- if (maxSteerAngle == 360) sSteerType = "CASTERED";
- else if (maxSteerAngle == 0.0) sSteerType = "FIXED";
- else sSteerType = "STEERABLE";
-
Element* element = el->FindElement("location");
if (element) vXYZn = element->FindElementTripletConvertTo("IN");
else {cerr << "No location given for contact " << name << endl; exit(-1);}
element = el->FindElement("orientation");
if (element && (eContactType == ctBOGEY)) {
- vGearOrient = element->FindElementTripletConvertTo("RAD");
-
- double cp,sp,cr,sr,cy,sy;
-
- cp=cos(vGearOrient(ePitch)); sp=sin(vGearOrient(ePitch));
- cr=cos(vGearOrient(eRoll)); sr=sin(vGearOrient(eRoll));
- cy=cos(vGearOrient(eYaw)); sy=sin(vGearOrient(eYaw));
-
- mTGear(1,1) = cp*cy;
- mTGear(2,1) = cp*sy;
- mTGear(3,1) = -sp;
-
- mTGear(1,2) = sr*sp*cy - cr*sy;
- mTGear(2,2) = sr*sp*sy + cr*cy;
- mTGear(3,2) = sr*cp;
+ FGQuaternion quatFromEuler(element->FindElementTripletConvertTo("RAD"));
- mTGear(1,3) = cr*sp*cy + sr*sy;
- mTGear(2,3) = cr*sp*sy - sr*cy;
- mTGear(3,3) = cr*cp;
+ mTGear = quatFromEuler.GetT();
}
else {
mTGear(1,1) = 1.;
mTGear(3,3) = 1.;
}
+ string sBrakeGroup = el->FindElementValue("brake_group");
+
if (sBrakeGroup == "LEFT" ) eBrakeGrp = bgLeft;
else if (sBrakeGroup == "RIGHT" ) eBrakeGrp = bgRight;
else if (sBrakeGroup == "CENTER") eBrakeGrp = bgCenter;
- else if (sBrakeGroup == "NOSE" ) eBrakeGrp = bgNose;
- else if (sBrakeGroup == "TAIL" ) eBrakeGrp = bgTail;
+ else if (sBrakeGroup == "NOSE" ) eBrakeGrp = bgCenter; // Nose brake is not supported by FGFCS
+ else if (sBrakeGroup == "TAIL" ) eBrakeGrp = bgCenter; // Tail brake is not supported by FGFCS
else if (sBrakeGroup == "NONE" ) eBrakeGrp = bgNone;
- else if (sBrakeGroup.empty() ) {eBrakeGrp = bgNone;
- sBrakeGroup = "NONE (defaulted)";}
+ else if (sBrakeGroup.empty() ) eBrakeGrp = bgNone;
else {
cerr << "Improper braking group specification in config file: "
<< sBrakeGroup << " is undefined." << endl;
}
- if (sSteerType == "STEERABLE") eSteerType = stSteer;
- else if (sSteerType == "FIXED" ) eSteerType = stFixed;
- else if (sSteerType == "CASTERED" ) eSteerType = stCaster;
- else if (sSteerType.empty() ) {eSteerType = stFixed;
- sSteerType = "FIXED (defaulted)";}
- else {
- cerr << "Improper steering type specification in config file: "
- << sSteerType << " is undefined." << endl;
- }
-
- RFRV = 0.7; // Rolling force relaxation velocity, default value
- SFRV = 0.7; // Side force relaxation velocity, default value
-
- Element* relax_vel = el->FindElement("relaxation_velocity");
- if (relax_vel) {
- if (relax_vel->FindElement("rolling")) {
- RFRV = relax_vel->FindElementValueAsNumberConvertTo("rolling", "FT/SEC");
- }
- if (relax_vel->FindElement("side")) {
- SFRV = relax_vel->FindElementValueAsNumberConvertTo("side", "FT/SEC");
- }
- }
-
- State = fdmex->GetState();
- Aircraft = fdmex->GetAircraft();
- Propagate = fdmex->GetPropagate();
- Auxiliary = fdmex->GetAuxiliary();
- FCS = fdmex->GetFCS();
- MassBalance = fdmex->GetMassBalance();
-
- LongForceLagFilterCoeff = 1/State->Getdt(); // default longitudinal force filter coefficient
- LatForceLagFilterCoeff = 1/State->Getdt(); // default lateral force filter coefficient
-
- Element* force_lag_filter_elem = el->FindElement("force_lag_filter");
- if (force_lag_filter_elem) {
- if (force_lag_filter_elem->FindElement("rolling")) {
- LongForceLagFilterCoeff = force_lag_filter_elem->FindElementValueAsNumber("rolling");
- }
- if (force_lag_filter_elem->FindElement("side")) {
- LatForceLagFilterCoeff = force_lag_filter_elem->FindElementValueAsNumber("side");
- }
- }
-
- LongForceFilter = Filter(LongForceLagFilterCoeff, State->Getdt());
- LatForceFilter = Filter(LatForceLagFilterCoeff, State->Getdt());
-
- WheelSlipLagFilterCoeff = 1/State->Getdt();
-
- Element *wheel_slip_angle_lag_elem = el->FindElement("wheel_slip_filter");
- if (wheel_slip_angle_lag_elem) {
- WheelSlipLagFilterCoeff = wheel_slip_angle_lag_elem->GetDataAsNumber();
- }
-
- WheelSlipFilter = Filter(WheelSlipLagFilterCoeff, State->Getdt());
-
- GearUp = false;
- GearDown = true;
GearPos = 1.0;
useFCSGearPos = false;
- Servicable = true;
// Add some AI here to determine if gear is located properly according to its
// brake group type ??
MaximumStrutForce = MaximumStrutTravel = 0.0;
SinkRate = GroundSpeed = 0.0;
- vWhlBodyVec = MassBalance->StructuralToBody(vXYZn);
- vLocalGear = Propagate->GetTb2l() * vWhlBodyVec;
vWhlVelVec.InitMatrix();
compressLength = 0.0;
compressSpeed = 0.0;
- brakePct = 0.0;
maxCompLen = 0.0;
WheelSlip = 0.0;
- TirePressureNorm = 1.0;
// Set Pacejka terms
Peak = staticFCoeff;
Curvature = 1.03;
+ // Initialize Lagrange multipliers
+ memset(LMultiplier, 0, sizeof(LMultiplier));
+
Debug(0);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-FGColumnVector3& FGLGear::GetBodyForces(void)
+const FGColumnVector3& FGLGear::GetBodyForces(void)
{
- double t = fdmex->GetState()->Getsim_time();
- dT = State->Getdt()*fdmex->GetGroundReactions()->GetRate();
+ double gearPos = 1.0;
+ double t = fdmex->GetSimTime();
vFn.InitMatrix();
- if (isRetractable) ComputeRetractionState();
+ if (isRetractable) gearPos = GetGearUnitPos();
- if (GearDown) {
- double verticalZProj = 0.;
+ if (gearPos > 0.99) { // Gear DOWN
+ FGColumnVector3 normal, terrainVel, dummy;
+ FGLocation gearLoc, contact;
+ FGColumnVector3 vWhlBodyVec = Ts2b * (vXYZn - in.vXYZcg);
- vWhlBodyVec = MassBalance->StructuralToBody(vXYZn); // Get wheel in body frame
- vLocalGear = Propagate->GetTb2l() * vWhlBodyVec; // Get local frame wheel location
+ vLocalGear = in.Tb2l * vWhlBodyVec; // Get local frame wheel location
+ gearLoc = in.Location.LocalToLocation(vLocalGear);
- gearLoc = Propagate->GetLocation().LocalToLocation(vLocalGear);
- // Compute the height of the theoretical location of the wheel (if strut is not compressed) with
- // respect to the ground level
- double height = fdmex->GetGroundCallback()->GetAGLevel(t, gearLoc, contact, normal, cvel);
- vGroundNormal = -1. * Propagate->GetTec2b() * normal;
-
- // The height returned above is the AGL and is expressed in the Z direction of the local
- // coordinate frame. We now need to transform this height in actual compression of the strut (BOGEY)
- // of in the normal direction to the ground (STRUCTURE)
- switch (eContactType) {
- case ctBOGEY:
- verticalZProj = (Propagate->GetTb2l()*mTGear*FGColumnVector3(0.,0.,1.))(eZ);
- compressLength = verticalZProj > 0.0 ? -height / verticalZProj : 0.0;
- break;
- case ctSTRUCTURE:
- verticalZProj = (Propagate->GetTec2l()*normal)(eZ);
- compressLength = fabs(verticalZProj) > 0.0 ? -height / verticalZProj : 0.0;
- break;
- }
-
- if (compressLength > 0.00) {
+ // Compute the height of the theoretical location of the wheel (if strut is
+ // not compressed) with respect to the ground level
+ double height = gearLoc.GetContactPoint(t, contact, normal, terrainVel, dummy);
+ if (height < 0.0) {
WOW = true;
+ vGroundNormal = in.Tec2b * normal;
+
+ // The height returned by GetGroundCallback() is the AGL and is expressed
+ // in the Z direction of the local coordinate frame. We now need to transform
+ // this height in actual compression of the strut (BOGEY) or in the normal
+ // direction to the ground (STRUCTURE)
+ double normalZ = (in.Tec2l*normal)(eZ);
+ double LGearProj = -(mTGear.Transposed() * vGroundNormal)(eZ);
+ FGColumnVector3 vWhlDisplVec;
+
+ // The following equations use the vector to the tire contact patch
+ // including the strut compression.
+ switch(eContactType) {
+ case ctBOGEY:
+ compressLength = LGearProj > 0.0 ? height * normalZ / LGearProj : 0.0;
+ vWhlDisplVec = mTGear * FGColumnVector3(0., 0., -compressLength);
+ break;
+ case ctSTRUCTURE:
+ compressLength = height * normalZ / DotProduct(normal, normal);
+ vWhlDisplVec = compressLength * vGroundNormal;
+ break;
+ }
- // [The next equation should really use the vector to the contact patch of
- // the tire including the strut compression and not the original vWhlBodyVec.]
-
- FGColumnVector3 vWhlDisplVec = mTGear * FGColumnVector3(0., 0., compressLength);
- FGColumnVector3 vWhlContactVec = vWhlBodyVec - vWhlDisplVec;
- vActingXYZn = vXYZn - Tb2s * vWhlDisplVec;
- FGColumnVector3 vBodyWhlVel = Propagate->GetPQR() * vWhlContactVec;
- vBodyWhlVel += Propagate->GetUVW() - Propagate->GetTec2b() * cvel;
+ FGColumnVector3 vWhlContactVec = vWhlBodyVec + vWhlDisplVec;
+ vActingXYZn = vXYZn + Tb2s * vWhlDisplVec;
+ FGColumnVector3 vBodyWhlVel = in.PQR * vWhlContactVec;
+ vBodyWhlVel += in.UVW - in.Tec2b * terrainVel;
vWhlVelVec = mTGear.Transposed() * vBodyWhlVel;
InitializeReporting();
ComputeSteeringAngle();
- ComputeGroundCoordSys();
+ ComputeGroundFrame();
- vLocalWhlVel = Transform().Transposed() * vBodyWhlVel;
+ vGroundWhlVel = mT.Transposed() * vBodyWhlVel;
- switch (eContactType) {
- case ctBOGEY:
- // Compression speed along the strut
- compressSpeed = -vWhlVelVec(eZ);
- case ctSTRUCTURE:
- // Compression speed along the ground normal
- compressSpeed = -vLocalWhlVel(eX);
+ if (fdmex->GetTrimStatus())
+ compressSpeed = 0.0; // Steady state is sought during trimming
+ else {
+ compressSpeed = -vGroundWhlVel(eZ);
+ if (eContactType == ctBOGEY)
+ compressSpeed /= LGearProj;
}
ComputeVerticalStrutForce();
- // Compute the forces in the wheel ground plane.
+ // Compute the friction coefficients in the wheel ground plane.
if (eContactType == ctBOGEY) {
ComputeSlipAngle();
ComputeBrakeForceCoefficient();
ComputeSideForceCoefficient();
- double sign = vLocalWhlVel(eY)>0?1.0:(vLocalWhlVel(eY)<0?-1.0:0.0);
- vFn(eY) = - ((1.0 - TirePressureNorm) * 30 + vFn(eX) * BrakeFCoeff) * sign;
- vFn(eZ) = vFn(eX) * FCoeff;
- }
- else if (eContactType == ctSTRUCTURE) {
- FGColumnVector3 vSlipVec = vLocalWhlVel;
- vSlipVec(eX) = 0.;
- vSlipVec.Normalize();
- vFn -= staticFCoeff * vFn(eX) * vSlipVec;
}
- // Lag and attenuate the XY-plane forces dependent on velocity. This code
- // uses a lag filter, C/(s + C) where "C" is the filter coefficient. When
- // "C" is chosen at the frame rate (in Hz), the jittering is significantly
- // reduced. This is because the jitter is present *at* the execution rate.
- // If a coefficient is set to something equal to or less than zero, the
- // filter is bypassed.
-
- if (LongForceLagFilterCoeff > 0) vFn(eY) = LongForceFilter.execute(vFn(eY));
- if (LatForceLagFilterCoeff > 0) vFn(eZ) = LatForceFilter.execute(vFn(eZ));
-
- if ((fabs(vLocalWhlVel(eY)) <= RFRV) && RFRV > 0) vFn(eY) *= fabs(vLocalWhlVel(eY))/RFRV;
- if ((fabs(vLocalWhlVel(eZ)) <= SFRV) && SFRV > 0) vFn(eZ) *= fabs(vLocalWhlVel(eZ))/SFRV;
-
- // End section for attenuating gear jitter
+ // Prepare the Jacobians and the Lagrange multipliers for later friction
+ // forces calculations.
+ ComputeJacobian(vWhlContactVec);
} else { // Gear is NOT compressed
WOW = false;
compressLength = 0.0;
compressSpeed = 0.0;
+ WheelSlip = 0.0;
+ StrutForce = 0.0;
+
+ LMultiplier[ftRoll].value = 0.0;
+ LMultiplier[ftSide].value = 0.0;
+ LMultiplier[ftDynamic].value = 0.0;
// Let wheel spin down slowly
- vWhlVelVec(eX) -= 13.0*dT;
+ vWhlVelVec(eX) -= 13.0 * in.TotalDeltaT;
if (vWhlVelVec(eX) < 0.0) vWhlVelVec(eX) = 0.0;
// Return to neutral position between 1.0 and 0.8 gear pos.
- SteerAngle *= max(GetGearUnitPos()-0.8, 0.0)/0.2;
+ SteerAngle *= max(gearPos-0.8, 0.0)/0.2;
ResetReporting();
}
}
+ else if (gearPos < 0.01) { // Gear UP
+ WOW = false;
+ vWhlVelVec.InitMatrix();
+ }
- ReportTakeoffOrLanding();
+ if (!fdmex->GetTrimStatus()) {
+ ReportTakeoffOrLanding();
- // Require both WOW and LastWOW to be true before checking crash conditions
- // to allow the WOW flag to be used in terminating a scripted run.
- if (WOW && lastWOW) CrashDetect();
+ // Require both WOW and LastWOW to be true before checking crash conditions
+ // to allow the WOW flag to be used in terminating a scripted run.
+ if (WOW && lastWOW) CrashDetect();
- lastWOW = WOW;
+ lastWOW = WOW;
+ }
return FGForce::GetBodyForces();
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
// Build a local "ground" coordinate system defined by
-// eX : normal to the ground
-// eY : projection of the rolling direction on the ground
-// eZ : projection of the sliping direction on the ground
-
-void FGLGear::ComputeGroundCoordSys(void)
-{
- // Euler angles are built up to create a local frame to describe the forces
- // applied to the gear by the ground. Here pitch, yaw and roll do not have
- // any physical meaning. It is just a convenient notation.
- // First, "pitch" and "yaw" are determined in order to align eX with the
- // ground normal.
- if (vGroundNormal(eZ) < -1.0)
- vOrient(ePitch) = 0.5*M_PI;
- else if (1.0 < vGroundNormal(eZ))
- vOrient(ePitch) = -0.5*M_PI;
- else
- vOrient(ePitch) = asin(-vGroundNormal(eZ));
-
- if (fabs(vOrient(ePitch)) == 0.5*M_PI)
- vOrient(eYaw) = 0.;
- else
- vOrient(eYaw) = atan2(vGroundNormal(eY), vGroundNormal(eX));
-
- vOrient(eRoll) = 0.;
- UpdateCustomTransformMatrix();
+// eX : projection of the rolling direction on the ground
+// eY : projection of the sliping direction on the ground
+// eZ : normal to the ground
- if (eContactType == ctBOGEY) {
- // In the case of a bogey, the third angle "roll" is used to align the axis eY and eZ
- // to the rolling and sliping direction respectively.
- FGColumnVector3 updatedRollingAxis = Transform().Transposed() * mTGear
- * FGColumnVector3(-sin(SteerAngle), cos(SteerAngle), 0.);
-
- vOrient(eRoll) = atan2(updatedRollingAxis(eY), -updatedRollingAxis(eZ));
- UpdateCustomTransformMatrix();
- }
-}
-
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-void FGLGear::ComputeRetractionState(void)
+void FGLGear::ComputeGroundFrame(void)
{
- double gearPos = GetGearUnitPos();
- if (gearPos < 0.01) {
- GearUp = true;
- WOW = false;
- GearDown = false;
- vWhlVelVec.InitMatrix();
- } else if (gearPos > 0.99) {
- GearDown = true;
- GearUp = false;
- } else {
- GearUp = false;
- GearDown = false;
- }
+ FGColumnVector3 roll = mTGear * FGColumnVector3(cos(SteerAngle), sin(SteerAngle), 0.);
+ FGColumnVector3 side = vGroundNormal * roll;
+
+ roll -= DotProduct(roll, vGroundNormal) * vGroundNormal;
+ roll.Normalize();
+ side.Normalize();
+
+ mT(eX,eX) = roll(eX);
+ mT(eY,eX) = roll(eY);
+ mT(eZ,eX) = roll(eZ);
+ mT(eX,eY) = side(eX);
+ mT(eY,eY) = side(eY);
+ mT(eZ,eY) = side(eZ);
+ mT(eX,eZ) = vGroundNormal(eX);
+ mT(eY,eZ) = vGroundNormal(eY);
+ mT(eZ,eZ) = vGroundNormal(eZ);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+// Calculate tire slip angle.
void FGLGear::ComputeSlipAngle(void)
{
- // Calculate tire slip angle.
- WheelSlip = -atan2(vLocalWhlVel(eZ), fabs(vLocalWhlVel(eY)))*radtodeg;
-
- // Filter the wheel slip angle
- if (WheelSlipLagFilterCoeff > 0) WheelSlip = WheelSlipFilter.execute(WheelSlip);
+// Check that the speed is non-null otherwise use the current angle
+ if (vGroundWhlVel.Magnitude(eX,eY) > 1E-3)
+ WheelSlip = -atan2(vGroundWhlVel(eY), fabs(vGroundWhlVel(eX)))*radtodeg;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
{
switch (eSteerType) {
case stSteer:
- SteerAngle = degtorad * FCS->GetSteerPosDeg(GearNumber);
+ SteerAngle = degtorad * in.SteerPosDeg[GearNumber];
break;
case stFixed:
SteerAngle = 0.0;
break;
case stCaster:
- SteerAngle = atan2(vWhlVelVec(eY), fabs(vWhlVelVec(eX)));
+ if (!Castered)
+ SteerAngle = degtorad * in.SteerPosDeg[GearNumber];
+ else {
+ // Check that the speed is non-null otherwise use the current angle
+ if (vWhlVelVec.Magnitude(eX,eY) > 0.1)
+ SteerAngle = atan2(vWhlVelVec(eY), fabs(vWhlVelVec(eX)));
+ }
break;
default:
cerr << "Improper steering type membership detected for this gear." << endl;
void FGLGear::ResetReporting(void)
{
- if (Propagate->GetDistanceAGL() > 200.0) {
+ if (in.DistanceAGL > 200.0) {
FirstContact = false;
StartedGroundRun = false;
LandingReported = false;
if (!FirstContact) {
FirstContact = true;
SinkRate = compressSpeed;
- GroundSpeed = Propagate->GetVel().Magnitude();
+ GroundSpeed = in.Vground;
TakeoffReported = false;
}
// If the takeoff run is starting, initialize.
- if ((Propagate->GetVel().Magnitude() > 0.1) &&
- (FCS->GetBrake(bgLeft) == 0) &&
- (FCS->GetBrake(bgRight) == 0) &&
- (FCS->GetThrottlePos(0) > 0.90) && !StartedGroundRun)
+ if ((in.Vground > 0.1) &&
+ (in.BrakePos[bgLeft] == 0) &&
+ (in.BrakePos[bgRight] == 0) &&
+ (in.TakeoffThrottle && !StartedGroundRun))
{
TakeoffDistanceTraveled = 0;
TakeoffDistanceTraveled50ft = 0;
void FGLGear::ReportTakeoffOrLanding(void)
{
- double deltaT = State->Getdt()*fdmex->GetGroundReactions()->GetRate();
-
if (FirstContact)
- LandingDistanceTraveled += Auxiliary->GetVground()*deltaT;
+ LandingDistanceTraveled += in.Vground * in.TotalDeltaT;
if (StartedGroundRun) {
- TakeoffDistanceTraveled50ft += Auxiliary->GetVground()*deltaT;
- if (WOW) TakeoffDistanceTraveled += Auxiliary->GetVground()*deltaT;
+ TakeoffDistanceTraveled50ft += in.Vground * in.TotalDeltaT;
+ if (WOW) TakeoffDistanceTraveled += in.Vground * in.TotalDeltaT;
}
if ( ReportEnable
- && Auxiliary->GetVground() <= 0.05
+ && in.Vground <= 0.05
&& !LandingReported
- && fdmex->GetGroundReactions()->GetWOW())
+ && in.WOW)
{
if (debug_lvl > 0) Report(erLand);
}
if ( ReportEnable
&& !TakeoffReported
- && (Propagate->GetDistanceAGL() - vLocalGear(eZ)) > 50.0
- && !fdmex->GetGroundReactions()->GetWOW())
+ && (in.DistanceAGL - vLocalGear(eZ)) > 50.0
+ && !in.WOW)
{
if (debug_lvl > 0) Report(erTakeoff);
}
if ( (compressLength > 500.0 ||
vFn.Magnitude() > 100000000.0 ||
GetMoments().Magnitude() > 5000000000.0 ||
- SinkRate > 1.4666*30 ) && !State->IntegrationSuspended())
+ SinkRate > 1.4666*30 ) && !fdmex->IntegrationSuspended())
{
PutMessage("Crash Detected: Simulation FREEZE.");
- State->SuspendIntegration();
+ fdmex->SuspendIntegration();
}
}
void FGLGear::ComputeBrakeForceCoefficient(void)
{
- switch (eBrakeGrp) {
- case bgLeft:
- BrakeFCoeff = ( rollingFCoeff*(1.0 - FCS->GetBrake(bgLeft)) +
- staticFCoeff*FCS->GetBrake(bgLeft) );
- break;
- case bgRight:
- BrakeFCoeff = ( rollingFCoeff*(1.0 - FCS->GetBrake(bgRight)) +
- staticFCoeff*FCS->GetBrake(bgRight) );
- break;
- case bgCenter:
- BrakeFCoeff = ( rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
- staticFCoeff*FCS->GetBrake(bgCenter) );
- break;
- case bgNose:
- BrakeFCoeff = ( rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
- staticFCoeff*FCS->GetBrake(bgCenter) );
- break;
- case bgTail:
- BrakeFCoeff = ( rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
- staticFCoeff*FCS->GetBrake(bgCenter) );
- break;
- case bgNone:
- BrakeFCoeff = rollingFCoeff;
- break;
- default:
- cerr << "Improper brake group membership detected for this gear." << endl;
- break;
- }
+ BrakeFCoeff = rollingFCoeff;
+
+ if (eBrakeGrp != bgNone)
+ BrakeFCoeff += in.BrakePos[eBrakeGrp] * (staticFCoeff - rollingFCoeff);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if (compressSpeed >= 0.0) {
- if (eDampType == dtLinear) dampForce = -compressSpeed * bDamp;
- else dampForce = -compressSpeed * compressSpeed * bDamp;
+ if (eDampType == dtLinear)
+ dampForce = -compressSpeed * bDamp;
+ else
+ dampForce = -compressSpeed * compressSpeed * bDamp;
} else {
switch (eContactType) {
case ctBOGEY:
// Project back the strut force in the local coordinate frame of the ground
- vFn(eX) = StrutForce / (mTGear.Transposed()*vGroundNormal)(eZ);
+ vFn(eZ) = StrutForce / (mTGear.Transposed()*vGroundNormal)(eZ);
break;
case ctSTRUCTURE:
- vFn(eX) = -StrutForce;
+ vFn(eZ) = -StrutForce;
break;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-double FGLGear::GetGearUnitPos(void)
+double FGLGear::GetGearUnitPos(void) const
{
// hack to provide backward compatibility to gear/gear-pos-norm property
- if( useFCSGearPos || FCS->GetGearPos() != 1.0 ) {
+ if( useFCSGearPos || in.FCSGearPos != 1.0 ) {
useFCSGearPos = true;
- return FCS->GetGearPos();
+ return in.FCSGearPos;
}
return GearPos;
}
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+// Compute the jacobian entries for the friction forces resolution later
+// in FGPropagate
+
+void FGLGear::ComputeJacobian(const FGColumnVector3& vWhlContactVec)
+{
+ // When the point of contact is moving, dynamic friction is used
+ // This type of friction is limited to ctSTRUCTURE elements because their
+ // friction coefficient is the same in every directions
+ if ((eContactType == ctSTRUCTURE) && (vGroundWhlVel.Magnitude(eX,eY) > 1E-3)) {
+
+ FGColumnVector3 velocityDirection = vGroundWhlVel;
+
+ StaticFriction = false;
+
+ velocityDirection(eZ) = 0.;
+ velocityDirection.Normalize();
+
+ LMultiplier[ftDynamic].ForceJacobian = mT * velocityDirection;
+ LMultiplier[ftDynamic].MomentJacobian = vWhlContactVec * LMultiplier[ftDynamic].ForceJacobian;
+ LMultiplier[ftDynamic].Max = 0.;
+ LMultiplier[ftDynamic].Min = -fabs(dynamicFCoeff * vFn(eZ));
+
+ // The Lagrange multiplier value obtained from the previous iteration is kept
+ // This is supposed to accelerate the convergence of the projected Gauss-Seidel
+ // algorithm. The code just below is to make sure that the initial value
+ // is consistent with the current friction coefficient and normal reaction.
+ LMultiplier[ftDynamic].value = Constrain(LMultiplier[ftDynamic].Min, LMultiplier[ftDynamic].value, LMultiplier[ftDynamic].Max);
+
+ GroundReactions->RegisterLagrangeMultiplier(&LMultiplier[ftDynamic]);
+ }
+ else {
+ // Static friction is used for ctSTRUCTURE when the contact point is not moving.
+ // It is always used for ctBOGEY elements because the friction coefficients
+ // of a tyre depend on the direction of the movement (roll & side directions).
+ // This cannot be handled properly by the so-called "dynamic friction".
+ StaticFriction = true;
+
+ LMultiplier[ftRoll].ForceJacobian = mT * FGColumnVector3(1.,0.,0.);
+ LMultiplier[ftSide].ForceJacobian = mT * FGColumnVector3(0.,1.,0.);
+ LMultiplier[ftRoll].MomentJacobian = vWhlContactVec * LMultiplier[ftRoll].ForceJacobian;
+ LMultiplier[ftSide].MomentJacobian = vWhlContactVec * LMultiplier[ftSide].ForceJacobian;
+
+ switch(eContactType) {
+ case ctBOGEY:
+ LMultiplier[ftRoll].Max = fabs(BrakeFCoeff * vFn(eZ));
+ LMultiplier[ftSide].Max = fabs(FCoeff * vFn(eZ));
+ break;
+ case ctSTRUCTURE:
+ LMultiplier[ftRoll].Max = fabs(staticFCoeff * vFn(eZ));
+ LMultiplier[ftSide].Max = LMultiplier[ftRoll].Max;
+ break;
+ }
+
+ LMultiplier[ftRoll].Min = -LMultiplier[ftRoll].Max;
+ LMultiplier[ftSide].Min = -LMultiplier[ftSide].Max;
+
+ // The Lagrange multiplier value obtained from the previous iteration is kept
+ // This is supposed to accelerate the convergence of the projected Gauss-Seidel
+ // algorithm. The code just below is to make sure that the initial value
+ // is consistent with the current friction coefficient and normal reaction.
+ LMultiplier[ftRoll].value = Constrain(LMultiplier[ftRoll].Min, LMultiplier[ftRoll].value, LMultiplier[ftRoll].Max);
+ LMultiplier[ftSide].value = Constrain(LMultiplier[ftSide].Min, LMultiplier[ftSide].value, LMultiplier[ftSide].Max);
+
+ GroundReactions->RegisterLagrangeMultiplier(&LMultiplier[ftRoll]);
+ GroundReactions->RegisterLagrangeMultiplier(&LMultiplier[ftSide]);
+ }
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+// This routine is called after the Lagrange multiplier has been computed in
+// the FGAccelerations class. The friction forces of the landing gear are then
+// updated accordingly.
+void FGLGear::UpdateForces(void)
+{
+ if (StaticFriction) {
+ vFn(eX) = LMultiplier[ftRoll].value;
+ vFn(eY) = LMultiplier[ftSide].value;
+ }
+ else {
+ FGColumnVector3 forceDir = mT.Transposed() * LMultiplier[ftDynamic].ForceJacobian;
+ vFn(eX) = LMultiplier[ftDynamic].value * forceDir(eX);
+ vFn(eY) = LMultiplier[ftDynamic].value * forceDir(eY);
+ }
+}
+
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGLGear::bind(void)
{
string property_name;
string base_property_name;
- base_property_name = CreateIndexedPropertyName("gear/unit", GearNumber);
+
+ switch(eContactType) {
+ case ctBOGEY:
+ base_property_name = CreateIndexedPropertyName("gear/unit", GearNumber);
+ break;
+ case ctSTRUCTURE:
+ base_property_name = CreateIndexedPropertyName("contact/unit", GearNumber);
+ break;
+ default:
+ return;
+ }
+
+ property_name = base_property_name + "/WOW";
+ PropertyManager->Tie( property_name.c_str(), &WOW );
+ property_name = base_property_name + "/z-position";
+ PropertyManager->Tie( property_name.c_str(), (FGForce*)this,
+ &FGForce::GetLocationZ, &FGForce::SetLocationZ);
+ property_name = base_property_name + "/compression-ft";
+ PropertyManager->Tie( property_name.c_str(), &compressLength );
+ property_name = base_property_name + "/static_friction_coeff";
+ PropertyManager->Tie( property_name.c_str(), &staticFCoeff );
+ property_name = base_property_name + "/dynamic_friction_coeff";
+ PropertyManager->Tie( property_name.c_str(), &dynamicFCoeff );
+
if (eContactType == ctBOGEY) {
property_name = base_property_name + "/slip-angle-deg";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &WheelSlip );
- property_name = base_property_name + "/WOW";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &WOW );
+ PropertyManager->Tie( property_name.c_str(), &WheelSlip );
property_name = base_property_name + "/wheel-speed-fps";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), (FGLGear*)this,
+ PropertyManager->Tie( property_name.c_str(), (FGLGear*)this,
&FGLGear::GetWheelRollVel);
- property_name = base_property_name + "/z-position";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), (FGForce*)this,
- &FGForce::GetLocationZ, &FGForce::SetLocationZ);
- property_name = base_property_name + "/compression-ft";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &compressLength );
property_name = base_property_name + "/side_friction_coeff";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &FCoeff );
-
- property_name = base_property_name + "/static_friction_coeff";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &staticFCoeff );
+ PropertyManager->Tie( property_name.c_str(), &FCoeff );
+ property_name = base_property_name + "/rolling_friction_coeff";
+ PropertyManager->Tie( property_name.c_str(), &rollingFCoeff );
if (eSteerType == stCaster) {
- property_name = base_property_name + "/steering-angle-rad";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &SteerAngle );
+ property_name = base_property_name + "/steering-angle-deg";
+ PropertyManager->Tie( property_name.c_str(), this, &FGLGear::GetSteerAngleDeg );
+ property_name = base_property_name + "/castered";
+ PropertyManager->Tie( property_name.c_str(), &Castered);
}
}
if( isRetractable ) {
property_name = base_property_name + "/pos-norm";
- fdmex->GetPropertyManager()->Tie( property_name.c_str(), &GearPos );
+ PropertyManager->Tie( property_name.c_str(), &GearPos );
}
}
switch(repType) {
case erLand:
cout << endl << "Touchdown report for " << name << " (WOW at time: "
- << fdmex->GetState()->Getsim_time() << " seconds)" << endl;
+ << fdmex->GetSimTime() << " seconds)" << endl;
cout << " Sink rate at contact: " << SinkRate << " fps, "
<< SinkRate*0.3048 << " mps" << endl;
cout << " Contact ground speed: " << GroundSpeed*.5925 << " knots, "
break;
case erTakeoff:
cout << endl << "Takeoff report for " << name << " (Liftoff at time: "
- << fdmex->GetState()->Getsim_time() << " seconds)" << endl;
+ << fdmex->GetSimTime() << " seconds)" << endl;
cout << " Distance traveled: " << TakeoffDistanceTraveled
<< " ft, " << TakeoffDistanceTraveled*0.3048 << " meters" << endl;
cout << " Distance traveled (over 50'): " << TakeoffDistanceTraveled50ft
<< " ft, " << TakeoffDistanceTraveled50ft*0.3048 << " meters" << endl;
- cout << " [Altitude (ASL): " << fdmex->GetPropagate()->GetAltitudeASL() << " ft. / "
- << fdmex->GetPropagate()->GetAltitudeASLmeters() << " m | Temperature: "
- << fdmex->GetAtmosphere()->GetTemperature() - 459.67 << " F / "
- << RankineToCelsius(fdmex->GetAtmosphere()->GetTemperature()) << " C]" << endl;
- cout << " [Velocity (KCAS): " << fdmex->GetAuxiliary()->GetVcalibratedKTS() << "]" << endl;
+ cout << " [Altitude (ASL): " << in.DistanceASL << " ft. / "
+ << in.DistanceASL*FGJSBBase::fttom << " m | Temperature: "
+ << in.Temperature - 459.67 << " F / "
+ << RankineToCelsius(in.Temperature) << " C]" << endl;
+ cout << " [Velocity (KCAS): " << in.VcalibratedKts << "]" << endl;
TakeoffReported = true;
break;
case erNone:
void FGLGear::Debug(int from)
{
+ static const char* sSteerType[] = {"STEERABLE", "FIXED", "CASTERED" };
+ static const char* sBrakeGroup[] = {"NONE", "LEFT", "RIGHT", "CENTER", "NOSE", "TAIL"};
+ static const char* sContactType[] = {"BOGEY", "STRUCTURE" };
+
if (debug_lvl <= 0) return;
if (debug_lvl & 1) { // Standard console startup message output
if (from == 0) { // Constructor - loading and initialization
- cout << " " << sContactType << " " << name << endl;
+ cout << " " << sContactType[eContactType] << " " << name << endl;
cout << " Location: " << vXYZn << endl;
cout << " Spring Constant: " << kSpring << endl;
if (eDampTypeRebound == dtLinear)
cout << " Rebound Damping Constant: " << bDampRebound << " (linear)" << endl;
- else
+ else
cout << " Rebound Damping Constant: " << bDampRebound << " (square law)" << endl;
cout << " Dynamic Friction: " << dynamicFCoeff << endl;
cout << " Static Friction: " << staticFCoeff << endl;
if (eContactType == ctBOGEY) {
cout << " Rolling Friction: " << rollingFCoeff << endl;
- cout << " Steering Type: " << sSteerType << endl;
- cout << " Grouping: " << sBrakeGroup << endl;
+ cout << " Steering Type: " << sSteerType[eSteerType] << endl;
+ cout << " Grouping: " << sBrakeGroup[eBrakeGrp] << endl;
cout << " Max Steer Angle: " << maxSteerAngle << endl;
cout << " Retractable: " << isRetractable << endl;
- cout << " Relaxation Velocities:" << endl;
- cout << " Rolling: " << RFRV << endl;
- cout << " Side: " << SFRV << endl;
}
}
}
}
} // namespace JSBSim
-
projects / flightgear.git / blobdiff