namespace JSBSim {
-static const char *IdSrc = "$Id: FGPropagate.cpp,v 1.73 2010/11/18 12:38:06 jberndt Exp $";
+static const char *IdSrc = "$Id: FGPropagate.cpp,v 1.85 2011/04/03 19:24:58 jberndt Exp $";
static const char *IdHdr = ID_PROPAGATE;
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-FGPropagate::FGPropagate(FGFDMExec* fdmex) : FGModel(fdmex)
+FGPropagate::FGPropagate(FGFDMExec* fdmex)
+ : FGModel(fdmex),
+ LocalTerrainRadius(0),
+ SeaLevelRadius(0),
+ VehicleRadius(0)
{
Debug(0);
Name = "FGPropagate";
gravType = gtWGS84;
- vPQRdot.InitMatrix();
+ vPQRidot.InitMatrix();
vQtrndot = FGQuaternion(0,0,0);
- vUVWdot.InitMatrix();
+ vUVWidot.InitMatrix();
vInertialVelocity.InitMatrix();
- integrator_rotational_rate = eAdamsBashforth2;
- integrator_translational_rate = eTrapezoidal;
- integrator_rotational_position = eAdamsBashforth2;
- integrator_translational_position = eTrapezoidal;
+ /// These define the indices use to select the various integrators.
+ // eNone = 0, eRectEuler, eTrapezoidal, eAdamsBashforth2, eAdamsBashforth3, eAdamsBashforth4};
+
+ integrator_rotational_rate = eRectEuler;
+ integrator_translational_rate = eAdamsBashforth2;
+ integrator_rotational_position = eRectEuler;
+ integrator_translational_position = eAdamsBashforth3;
VState.dqPQRidot.resize(4, FGColumnVector3(0.0,0.0,0.0));
VState.dqUVWidot.resize(4, FGColumnVector3(0.0,0.0,0.0));
VState.vLocation.SetEllipse(FDMExec->GetInertial()->GetSemimajor(), FDMExec->GetInertial()->GetSemiminor());
vOmegaEarth = FGColumnVector3( 0.0, 0.0, FDMExec->GetInertial()->omega() ); // Earth rotation vector
- vPQRdot.InitMatrix();
+ vPQRidot.InitMatrix();
vQtrndot = FGQuaternion(0,0,0);
- vUVWdot.InitMatrix();
+ vUVWidot.InitMatrix();
vInertialVelocity.InitMatrix();
VState.dqPQRidot.resize(4, FGColumnVector3(0.0,0.0,0.0));
VState.vLocation.SetEarthPositionAngle(FDMExec->GetInertial()->GetEarthPositionAngle());
- Ti2ec = GetTi2ec(); // ECI to ECEF transform
- Tec2i = Ti2ec.Transposed(); // ECEF to ECI frame transform
+ Ti2ec = VState.vLocation.GetTi2ec(); // ECI to ECEF transform
+ Tec2i = Ti2ec.Transposed(); // ECEF to ECI frame transform
VState.vInertialPosition = Tec2i * VState.vLocation;
VehicleRadius = GetRadius();
double radInv = 1.0/VehicleRadius;
- // Refer to Stevens and Lewis, 1.5-14a, pg. 49.
- // This is the rotation rate of the "Local" frame, expressed in the local frame.
-
- FGColumnVector3 vOmegaLocal = FGColumnVector3(
- radInv*vVel(eEast),
- -radInv*vVel(eNorth),
- -radInv*vVel(eEast)*VState.vLocation.GetTanLatitude() );
-
// Set the angular velocities of the body frame relative to the ECEF frame,
- // expressed in the body frame. Effectively, this is:
- // w_b/e = w_b/l + w_l/e
+ // expressed in the body frame.
VState.vPQR = FGColumnVector3( FGIC->GetPRadpsIC(),
FGIC->GetQRadpsIC(),
- FGIC->GetRRadpsIC() ) + Tl2b*vOmegaLocal;
+ FGIC->GetRRadpsIC() );
VState.vPQRi = VState.vPQR + Ti2b * vOmegaEarth;
- VState.vPQRi_i = Tb2i * VState.vPQRi;
// Make an initial run and set past values
InitializeDerivatives();
CalculateUVWdot(); // Translational rate derivative
ResolveFrictionForces(dt); // Update rate derivatives with friction forces
CalculateQuatdot(); // Angular orientation derivative
- CalculateUVW(); // Translational position derivative (velocities are integrated in the inertial frame)
// Propagate rotational / translational velocity, angular /translational position, respectively.
- Integrate(VState.vPQRi_i, vPQRidot, VState.dqPQRidot, dt, integrator_rotational_rate); // ECI integration
+ Integrate(VState.vPQRi, vPQRidot, VState.dqPQRidot, dt, integrator_rotational_rate);
Integrate(VState.qAttitudeECI, vQtrndot, VState.dqQtrndot, dt, integrator_rotational_position);
Integrate(VState.vInertialPosition, VState.vInertialVelocity, VState.dqInertialVelocity, dt, integrator_translational_position);
Integrate(VState.vInertialVelocity, vUVWidot, VState.dqUVWidot, dt, integrator_translational_rate);
VState.vLocation.SetEarthPositionAngle(FDMExec->GetInertial()->GetEarthPositionAngle());
// 2. Update the Ti2ec and Tec2i transforms from the updated EPA
- Ti2ec = GetTi2ec(); // ECI to ECEF transform
- Tec2i = Ti2ec.Transposed(); // ECEF to ECI frame transform
+ Ti2ec = VState.vLocation.GetTi2ec(); // ECI to ECEF transform
+ Tec2i = Ti2ec.Transposed(); // ECEF to ECI frame transform
// 3. Update the location from the updated Ti2ec and inertial position
VState.vLocation = Ti2ec*VState.vInertialPosition;
// orientation quaternion and vLocation vector.
UpdateBodyMatrices();
+ CalculateUVW(); // Translational position derivative (velocities are integrated in the inertial frame)
+
// Set auxililary state variables
RecomputeLocalTerrainRadius();
VehicleRadius = GetRadius(); // Calculate current aircraft radius from center of planet
- VState.vPQRi = Ti2b * VState.vPQRi_i;
VState.vPQR = VState.vPQRi - Ti2b * vOmegaEarth;
VState.qAttitudeLocal = Tl2b.GetQuaternion();
// moments and the total inertial angular velocity expressed in the body
// frame.
- vPQRdot = Jinv*(vMoments - VState.vPQRi*(J*VState.vPQRi));
- vPQRidot = Tb2i * vPQRdot;
+ vPQRidot = Jinv*(vMoments - VState.vPQRi*(J*VState.vPQRi));
+ vPQRdot = vPQRidot - VState.vPQRi * (Ti2b * vOmegaEarth);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
}
}
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+// Evaluates the rates (translation or rotation) that the friction forces have
+// to resist to. This includes the external forces and moments as well as the
+// relative movement between the aircraft and the ground.
+// Erin Catto's paper (see ref [6]) only supports Euler integration scheme and
+// this algorithm has been adapted to handle the multistep algorithms that
+// JSBSim supports (i.e. Trapezoidal, Adams-Bashforth 2, 3 and 4). The capacity
+// to handle the multistep integration schemes adds some complexity but it
+// significantly helps stabilizing the friction forces.
+
+void FGPropagate::EvaluateRateToResistTo(FGColumnVector3& vdot,
+ const FGColumnVector3& Val,
+ const FGColumnVector3& ValDot,
+ const FGColumnVector3& LocalTerrainVal,
+ deque <FGColumnVector3>& dqValDot,
+ const double dt,
+ const eIntegrateType integration_type)
+{
+ switch(integration_type) {
+ case eAdamsBashforth4:
+ vdot = ValDot + Ti2b * (-59.*dqValDot[0]+37.*dqValDot[1]-9.*dqValDot[2])/55.;
+ if (dt > 0.) // Zeroes out the relative movement between aircraft and ground
+ vdot += 24.*(Val - Tec2b * LocalTerrainVal) / (55.*dt);
+ break;
+ case eAdamsBashforth3:
+ vdot = ValDot + Ti2b * (-16.*dqValDot[0]+5.*dqValDot[1])/23.;
+ if (dt > 0.) // Zeroes out the relative movement between aircraft and ground
+ vdot += 12.*(Val - Tec2b * LocalTerrainVal) / (23.*dt);
+ break;
+ case eAdamsBashforth2:
+ vdot = ValDot - Ti2b * dqValDot[0]/3.;
+ if (dt > 0.) // Zeroes out the relative movement between aircraft and ground
+ vdot += 2.*(Val - Tec2b * LocalTerrainVal) / (3.*dt);
+ break;
+ case eTrapezoidal:
+ vdot = ValDot + Ti2b * dqValDot[0];
+ if (dt > 0.) // Zeroes out the relative movement between aircraft and ground
+ vdot += 2.*(Val - Tec2b * LocalTerrainVal) / dt;
+ break;
+ case eRectEuler:
+ vdot = ValDot;
+ if (dt > 0.) // Zeroes out the relative movement between aircraft and ground
+ vdot += (Val - Tec2b * LocalTerrainVal) / dt;
+ break;
+ case eNone:
+ break;
+ }
+}
+
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
// Resolves the contact forces just before integrating the EOM.
// This routine is using Lagrange multipliers and the projected Gauss-Seidel
const double invMass = 1.0 / FDMExec->GetMassBalance()->GetMass();
const FGMatrix33& Jinv = FDMExec->GetMassBalance()->GetJinv();
vector <FGColumnVector3> JacF, JacM;
+ vector<double> lambda, lambdaMin, lambdaMax;
FGColumnVector3 vdot, wdot;
FGColumnVector3 Fc, Mc;
- int n = 0, i;
+ int n = 0;
// Compiles data from the ground reactions to build up the jacobian matrix
for (MultiplierIterator it=MultiplierIterator(FDMExec->GetGroundReactions()); *it; ++it, n++) {
JacF.push_back((*it)->ForceJacobian);
JacM.push_back((*it)->MomentJacobian);
+ lambda.push_back((*it)->value);
+ lambdaMax.push_back((*it)->Max);
+ lambdaMin.push_back((*it)->Min);
}
// If no gears are in contact with the ground then return
if (!n) return;
vector<double> a(n*n); // Will contain J*M^-1*J^T
- vector<double> eta(n);
- vector<double> lambda(n);
- vector<double> lambdaMin(n);
- vector<double> lambdaMax(n);
-
- // Initializes the Lagrange multipliers
- i = 0;
- for (MultiplierIterator it=MultiplierIterator(FDMExec->GetGroundReactions()); *it; ++it, i++) {
- lambda[i] = (*it)->value;
- lambdaMax[i] = (*it)->Max;
- lambdaMin[i] = (*it)->Min;
- }
-
- vdot = vUVWdot;
- wdot = vPQRdot;
-
- if (dt > 0.) {
- // Instruct the algorithm to zero out the relative movement between the
- // aircraft and the ground.
- vdot += (VState.vUVW - Tec2b * LocalTerrainVelocity) / dt;
- wdot += (VState.vPQR - Tec2b * LocalTerrainAngularVelocity) / dt;
- }
+ vector<double> rhs(n);
// Assemble the linear system of equations
- for (i=0; i < n; i++) {
+ for (int i=0; i < n; i++) {
for (int j=0; j < i; j++)
a[i*n+j] = a[j*n+i]; // Takes advantage of the symmetry of J^T*M^-1*J
for (int j=i; j < n; j++)
a[i*n+j] = DotProduct(JacF[i],invMass*JacF[j])+DotProduct(JacM[i],Jinv*JacM[j]);
}
+ // Assemble the RHS member
+
+ // Translation
+ EvaluateRateToResistTo(vdot, VState.vUVW, vUVWdot, LocalTerrainVelocity,
+ VState.dqUVWidot, dt, integrator_translational_rate);
+
+ // Rotation
+ EvaluateRateToResistTo(wdot, VState.vPQR, vPQRdot, LocalTerrainAngularVelocity,
+ VState.dqPQRidot, dt, integrator_rotational_rate);
+
// Prepare the linear system for the Gauss-Seidel algorithm :
- // divide every line of 'a' and eta by a[i,i]. This is in order to save
- // a division computation at each iteration of Gauss-Seidel.
- for (i=0; i < n; i++) {
+ // 1. Compute the right hand side member 'rhs'
+ // 2. Divide every line of 'a' and 'rhs' by a[i,i]. This is in order to save
+ // a division computation at each iteration of Gauss-Seidel.
+ for (int i=0; i < n; i++) {
double d = 1.0 / a[i*n+i];
- eta[i] = -(DotProduct(JacF[i],vdot)+DotProduct(JacM[i],wdot))*d;
+ rhs[i] = -(DotProduct(JacF[i],vdot)+DotProduct(JacM[i],wdot))*d;
for (int j=0; j < n; j++)
a[i*n+j] *= d;
}
for (int iter=0; iter < 50; iter++) {
double norm = 0.;
- for (i=0; i < n; i++) {
+ for (int i=0; i < n; i++) {
double lambda0 = lambda[i];
- double dlambda = eta[i];
+ double dlambda = rhs[i];
for (int j=0; j < n; j++)
dlambda -= a[i*n+j]*lambda[j];
Fc.InitMatrix();
Mc.InitMatrix();
- for (i=0; i< n; i++) {
+ for (int i=0; i< n; i++) {
Fc += lambda[i]*JacF[i];
Mc += lambda[i]*JacM[i];
}
vUVWdot += invMass * Fc;
vUVWidot += invMass * Tb2i * Fc;
vPQRdot += Jinv * Mc;
- vPQRidot += Tb2i* Jinv * Mc;
+ vPQRidot += Jinv * Mc;
// Save the value of the Lagrange multipliers to accelerate the convergence
// of the Gauss-Seidel algorithm at next iteration.
- i = 0;
+ int i = 0;
for (MultiplierIterator it=MultiplierIterator(FDMExec->GetGroundReactions()); *it; ++it)
(*it)->value = lambda[i++];
void FGPropagate::UpdateLocationMatrices(void)
{
- Tl2ec = GetTl2ec(); // local to ECEF transform
- Tec2l = Tl2ec.Transposed(); // ECEF to local frame transform
- Ti2l = GetTi2l();
- Tl2i = Ti2l.Transposed();
+ Tl2ec = VState.vLocation.GetTl2ec(); // local to ECEF transform
+ Tec2l = Tl2ec.Transposed(); // ECEF to local frame transform
+ Ti2l = VState.vLocation.GetTi2l(); // ECI to local frame transform
+ Tl2i = Ti2l.Transposed(); // local to ECI transform
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGPropagate::UpdateBodyMatrices(void)
{
- Ti2b = GetTi2b(); // ECI to body frame transform
- Tb2i = Ti2b.Transposed(); // body to ECI frame transform
- Tl2b = Ti2b*Tl2i; // local to body frame transform
- Tb2l = Tl2b.Transposed(); // body to local frame transform
- Tec2b = Tl2b * Tec2l; // ECEF to body frame transform
- Tb2ec = Tec2b.Transposed(); // body to ECEF frame tranform
+ Ti2b = VState.qAttitudeECI.GetT(); // ECI to body frame transform
+ Tb2i = Ti2b.Transposed(); // body to ECI frame transform
+ Tl2b = Ti2b*Tl2i; // local to body frame transform
+ Tb2l = Tl2b.Transposed(); // body to local frame transform
+ Tec2b = Tl2b * Tec2l; // ECEF to body frame transform
+ Tb2ec = Tec2b.Transposed(); // body to ECEF frame tranform
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGPropagate::SetInertialVelocity(FGColumnVector3 Vi) {
VState.vInertialVelocity = Vi;
CalculateUVW();
- vVel = GetTb2l() * VState.vUVW;
+ vVel = Tb2l * VState.vUVW;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGPropagate::SetInertialRates(FGColumnVector3 vRates) {
- VState.vPQRi_i = vRates;
- VState.vPQRi = Ti2b * VState.vPQRi_i;
+ VState.vPQRi = Ti2b * vRates;
VState.vPQR = VState.vPQRi - Ti2b * vOmegaEarth;
}
VState.dqQtrndot.clear();
for (int i=0; i<4; i++) {
VState.dqPQRidot.push_front(vPQRidot);
- VState.dqUVWidot.push_front(vUVWdot);
+ VState.dqUVWidot.push_front(vUVWidot);
VState.dqInertialVelocity.push_front(VState.vInertialVelocity);
VState.dqQtrndot.push_front(vQtrndot);
}
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-//Todo: when should this be called - when should the new EPA be used to
-// calculate the transformation matrix, so that the matrix is not a step
-// ahead of the sim and the associated calculations?
-const FGMatrix33& FGPropagate::GetTi2ec(void)
-{
- return VState.vLocation.GetTi2ec();
-}
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-const FGMatrix33& FGPropagate::GetTec2i(void)
+double FGPropagate::GetDistanceAGL(void) const
{
- return VState.vLocation.GetTec2i();
+ return VState.vLocation.GetRadius() - LocalTerrainRadius;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-void FGPropagate::SetAltitudeASL(double altASL)
+void FGPropagate::SetVState(const VehicleState& vstate)
{
- VState.vLocation.SetRadius( altASL + SeaLevelRadius );
-}
-
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ VState.vLocation = vstate.vLocation;
+ VState.vLocation.SetEarthPositionAngle(FDMExec->GetInertial()->GetEarthPositionAngle());
+ Ti2ec = VState.vLocation.GetTi2ec(); // useless ?
+ Tec2i = Ti2ec.Transposed();
+ UpdateLocationMatrices();
+ SetInertialOrientation(vstate.qAttitudeECI);
+ RecomputeLocalTerrainRadius();
+ VehicleRadius = GetRadius();
+ VState.vUVW = vstate.vUVW;
+ vVel = Tb2l * VState.vUVW;
+ VState.vPQR = vstate.vPQR;
+ VState.vPQRi = VState.vPQR + Ti2b * vOmegaEarth;
+ VState.vInertialPosition = vstate.vInertialPosition;
-double FGPropagate::GetLocalTerrainRadius(void) const
-{
- return LocalTerrainRadius;
+ InitializeDerivatives();
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-double FGPropagate::GetDistanceAGL(void) const
+void FGPropagate::UpdateVehicleState(void)
{
- return VState.vLocation.GetRadius() - LocalTerrainRadius;
+ RecomputeLocalTerrainRadius();
+ VehicleRadius = GetRadius();
+ VState.vInertialPosition = Tec2i * VState.vLocation;
+ UpdateLocationMatrices();
+ UpdateBodyMatrices();
+ vVel = Tb2l * VState.vUVW;
+ VState.qAttitudeLocal = Tl2b.GetQuaternion();
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-void FGPropagate::SetDistanceAGL(double tt)
+void FGPropagate::SetLocation(const FGLocation& l)
{
- VState.vLocation.SetRadius( tt + LocalTerrainRadius );
+ VState.vLocation = l;
+ VState.vLocation.SetEarthPositionAngle(FDMExec->GetInertial()->GetEarthPositionAngle());
+ Ti2ec = VState.vLocation.GetTi2ec(); // useless ?
+ Tec2i = Ti2ec.Transposed();
+ UpdateVehicleState();
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
cout << endl << " " << underon
<< "Velocity" << underoff << endl;
cout << " ECI: " << VState.vInertialVelocity.Dump(", ") << " (x,y,z in ft/s)" << endl;
- cout << " ECEF: " << (GetTb2ec() * VState.vUVW).Dump(", ") << " (x,y,z in ft/s)" << endl;
+ cout << " ECEF: " << (Tb2ec * VState.vUVW).Dump(", ") << " (x,y,z in ft/s)" << endl;
cout << " Local: " << GetVel() << " (n,e,d in ft/sec)" << endl;
cout << " Body: " << GetUVW() << " (u,v,w in ft/sec)" << endl;
projects / flightgear.git / blobdiff