SequenceOfAttitudes 4.5.1 : Différence entre versions
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Version actuelle en date du 17 août 2020 à 08:30
public class SequenceOfAttitudeLaws { public static void main(String[] args) throws PatriusException, IOException, URISyntaxException { // Patrius Dataset initialization (needed for example to get the UTC time PatriusDataset.addResourcesFromPatriusDataset() ; // Recovery of the UTC time scale using a "factory" (not to duplicate such unique object) final TimeScale TUC = TimeScalesFactory.getUTC(); // Date of the orbit given in UTC time scale) final AbsoluteDate iniDate = new AbsoluteDate("2010-01-01T12:00:00.000", TUC); // Getting the frame with wich will defined the orbit parameters // As for time scale, we will use also a "factory". final Frame GCRF = FramesFactory.getGCRF(); // Initial orbit final double sma = 7200.e+3; final double exc = 0.01; final double inc = FastMath.toRadians(98.); final double pa = FastMath.toRadians(0.); final double raan = FastMath.toRadians(90.); final double anm = FastMath.toRadians(0.); final double MU = Constants.WGS84_EARTH_MU; final KeplerianParameters par = new KeplerianParameters(sma, exc, inc, pa, raan, anm, PositionAngle.MEAN, MU); final Orbit iniOrbit = new KeplerianOrbit(par, GCRF, iniDate); // Using the Meeus model for the Sun. final CelestialBody sun = new MeeusSun(); final double sunRadius = Constants.SUN_RADIUS; // Definition of the Earth ellipsoid for later atmospheric density computation final Frame ITRF = FramesFactory.getITRF(); final double earthRadius = Constants.WGS84_EARTH_EQUATORIAL_RADIUS; final GeometricBodyShape earth = new ExtendedOneAxisEllipsoid(earthRadius, Constants.WGS84_EARTH_FLATTENING, ITRF, "EARTH"); // Initializing attitude sequence final AttitudesSequence seqAtt = new AttitudesSequence(); // Building a first attitude law (Sun pointing) final Vector3D firstAxis = new Vector3D(1., 0., 0.); final Vector3D secondAxis = new Vector3D(0., 1., 0.); final AttitudeLaw sunPointingLaw = new SunPointing(sun, firstAxis, secondAxis, sun); // Building a second attitude law (LVLH) final AttitudeLaw lvlhLaw = new LofOffset(LOFType.LVLH); // Events that will switch from a law to another final double maxCheck = 10.; final double threshold = 1.e-3; final EventDetector eventEntryEclipse = new EclipseDetector(sun, sunRadius, earth, earthRadius, 0, maxCheck, threshold, Action.RESET_STATE, Action.RESET_STATE); final EventDetector eventExitEclipse = new EclipseDetector(sun, sunRadius, earth, earthRadius, 0, maxCheck, threshold, Action.RESET_STATE, Action.RESET_STATE); //Adding switches seqAtt.addSwitchingCondition(lvlhLaw, eventEntryEclipse, true, false, sunPointingLaw); seqAtt.addSwitchingCondition(sunPointingLaw, eventExitEclipse, false, true, lvlhLaw); testByPropagation(iniOrbit, seqAtt, sun); } public static void testByPropagation ( final Orbit iniOrbit, final AttitudesSequence seqAtt, final CelestialBody sun ) throws PatriusException { // We create a spacecratftstate final SpacecraftState iniState = new SpacecraftState(iniOrbit); // Initialization of the Runge Kutta integrator with a 2 s step final double pasRk = 2.; final FirstOrderIntegrator integrator = new ClassicalRungeKuttaIntegrator(pasRk); // Initialization of the propagator final NumericalPropagator propagator = new NumericalPropagator(integrator); propagator.resetInitialState(iniState); // Forcing integration using cartesian equations propagator.setOrbitType(OrbitType.CARTESIAN); // Adding the attitude sequence propagator.setAttitudeProvider(seqAtt); seqAtt.registerSwitchEvents(propagator); // Loop every 10 mn ... final double step = 600.; final double epsilon = 1.e-12; for (int i = 1; i <= 20; i++) { AbsoluteDate date = iniOrbit.getDate().shiftedBy(i*step); final SpacecraftState state = propagator.propagate(date); // Attitude in LVLH final Attitude attLVLH = state.getAttitude(LOFType.LVLH); final double psiLVLH = attLVLH.getRotation().getAngles(RotationOrder.ZYX)[0]; final double tetaLVLH = attLVLH.getRotation().getAngles(RotationOrder.ZYX)[1]; // Attitude in GCRF final Attitude attGCRF = state.getAttitude(); final double psiGCRF = attGCRF.getRotation().getAngles(RotationOrder.ZYX)[0]; final double tetaGCRF = attGCRF.getRotation().getAngles(RotationOrder.ZYX)[1]; // Direction of the Sun from the cdg of the satellite final Vector3D sunPos = sun.getPVCoordinates(date, FramesFactory.getGCRF()).getPosition(); final Vector3D satPos = state.getPVCoordinates().getPosition(); final Rotation sunDir = new Rotation(Vector3D.PLUS_I, sunPos.subtract(satPos)); // Sun direction final double psiSun = sunDir.getAngles(RotationOrder.ZYX)[0]; final double tetaSun = sunDir.getAngles(RotationOrder.ZYX)[1]; if ( (FastMath.abs(psiLVLH) < epsilon) || (FastMath.abs(tetaLVLH) < epsilon) ) { System.out.println(date+" => LVLH mode"); } else { System.out.println(date+" => Sun pointing mode"); System.out.println(" Delta Psi = "+FastMath.toDegrees(psiSun-psiGCRF)+" deg"); System.out.println(" Delta Teta = "+FastMath.toDegrees(tetaSun-tetaGCRF)+" deg"); } } } }