Examples with ICGEMFormatReader org.orekit.forces.gravity.potential.ICGEMFormatReader used on opensource projects

Example 16 with ICGEMFormatReader

use of org.orekit.forces.gravity.potential.ICGEMFormatReader in project Orekit by CS-SI.

the class AttitudesSequenceTest method testResetDuringTransitionBackward.

@Test
public void testResetDuringTransitionBackward() throws OrekitException {
    // Initial state definition : date, orbit
    final AbsoluteDate initialDate = new AbsoluteDate(2004, 01, 01, 23, 30, 00.000, TimeScalesFactory.getUTC());
    final Vector3D position = new Vector3D(-6142438.668, 3492467.560, -25767.25680);
    final Vector3D velocity = new Vector3D(505.8479685, 942.7809215, 7435.922231);
    final Orbit initialOrbit = new KeplerianOrbit(new PVCoordinates(position, velocity), FramesFactory.getEME2000(), initialDate, Constants.EIGEN5C_EARTH_MU);
    final OneAxisEllipsoid earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS, Constants.WGS84_EARTH_FLATTENING, FramesFactory.getITRF(IERSConventions.IERS_2010, true));
    final TopocentricFrame volgograd = new TopocentricFrame(earth, new GeodeticPoint(FastMath.toRadians(48.7), FastMath.toRadians(44.5), 24.0), "Волгоград");
    final AttitudesSequence attitudesSequence = new AttitudesSequence();
    final double transitionTime = 250.0;
    final AttitudeProvider nadirPointing = new NadirPointing(initialOrbit.getFrame(), earth);
    final AttitudeProvider targetPointing = new TargetPointing(initialOrbit.getFrame(), volgograd.getPoint(), earth);
    final ElevationDetector eventDetector = new ElevationDetector(volgograd).withConstantElevation(FastMath.toRadians(5.0)).withHandler(new ContinueOnEvent<>());
    final List<AbsoluteDate> nadirToTarget = new ArrayList<>();
    attitudesSequence.addSwitchingCondition(nadirPointing, targetPointing, eventDetector, true, false, transitionTime, AngularDerivativesFilter.USE_RR, (previous, next, state) -> nadirToTarget.add(state.getDate()));
    final double[][] tolerance = NumericalPropagator.tolerances(10.0, initialOrbit, initialOrbit.getType());
    final AdaptiveStepsizeIntegrator integrator = new DormandPrince853Integrator(0.001, 300.0, tolerance[0], tolerance[1]);
    final NumericalPropagator propagator = new NumericalPropagator(integrator);
    GravityFieldFactory.addPotentialCoefficientsReader(new ICGEMFormatReader("g007_eigen_05c_coef", false));
    propagator.addForceModel(new HolmesFeatherstoneAttractionModel(earth.getBodyFrame(), GravityFieldFactory.getNormalizedProvider(8, 8)));
    propagator.setInitialState(new SpacecraftState(initialOrbit, nadirPointing.getAttitude(initialOrbit, initialOrbit.getDate(), initialOrbit.getFrame())));
    propagator.setAttitudeProvider(attitudesSequence);
    attitudesSequence.registerSwitchEvents(propagator);
    propagator.propagate(initialDate.shiftedBy(6000));
    // check that if we restart a backward propagation from an intermediate state
    // we properly get an interpolated attitude despite we missed the event trigger
    final AbsoluteDate midTransition = nadirToTarget.get(0).shiftedBy(0.5 * transitionTime);
    SpacecraftState state = propagator.propagate(midTransition.shiftedBy(+60), midTransition);
    Rotation nadirR = nadirPointing.getAttitude(state.getOrbit(), state.getDate(), state.getFrame()).getRotation();
    Rotation targetR = targetPointing.getAttitude(state.getOrbit(), state.getDate(), state.getFrame()).getRotation();
    final double reorientationAngle = Rotation.distance(nadirR, targetR);
    Assert.assertEquals(0.5 * reorientationAngle, Rotation.distance(state.getAttitude().getRotation(), targetR), 0.03 * reorientationAngle);
}

Example 17 with ICGEMFormatReader

use of org.orekit.forces.gravity.potential.ICGEMFormatReader in project Orekit by CS-SI.

the class AdapterPropagatorTest method testNonKeplerian.

@Test
public void testNonKeplerian() throws OrekitException, ParseException, IOException {
    Orbit leo = new CircularOrbit(7204319.233600575, 4.434564637450575E-4, 0.0011736728299091088, 1.7211611441767323, 5.5552084166959474, 24950.321259193086, PositionAngle.TRUE, FramesFactory.getEME2000(), new AbsoluteDate(new DateComponents(2003, 9, 16), new TimeComponents(23, 11, 20.264), TimeScalesFactory.getUTC()), Constants.EIGEN5C_EARTH_MU);
    double mass = 4093.0;
    AbsoluteDate t0 = new AbsoluteDate(new DateComponents(2003, 9, 16), new TimeComponents(23, 14, 40.264), TimeScalesFactory.getUTC());
    Vector3D dV = new Vector3D(0.0, 3.0, 0.0);
    double f = 40.0;
    double isp = 300.0;
    double vExhaust = Constants.G0_STANDARD_GRAVITY * isp;
    double dt = -(mass * vExhaust / f) * FastMath.expm1(-dV.getNorm() / vExhaust);
    // setup a specific coefficient file for gravity potential as it will also
    // try to read a corrupted one otherwise
    GravityFieldFactory.addPotentialCoefficientsReader(new ICGEMFormatReader("g007_eigen_05c_coef", false));
    NormalizedSphericalHarmonicsProvider gravityField = GravityFieldFactory.getNormalizedProvider(8, 8);
    BoundedPropagator withoutManeuver = getEphemeris(leo, mass, 10, new LofOffset(leo.getFrame(), LOFType.VNC), t0, Vector3D.ZERO, f, isp, true, true, gravityField);
    BoundedPropagator withManeuver = getEphemeris(leo, mass, 10, new LofOffset(leo.getFrame(), LOFType.VNC), t0, dV, f, isp, true, true, gravityField);
    // we set up a model that reverts the maneuvers
    AdapterPropagator adapterPropagator = new AdapterPropagator(withManeuver);
    SpacecraftState state0 = adapterPropagator.propagate(t0);
    AdapterPropagator.DifferentialEffect directEffect = new SmallManeuverAnalyticalModel(state0, dV.negate(), isp);
    AdapterPropagator.DifferentialEffect derivedEffect = new J2DifferentialEffect(state0, directEffect, false, GravityFieldFactory.getUnnormalizedProvider(gravityField));
    adapterPropagator.addEffect(directEffect);
    adapterPropagator.addEffect(derivedEffect);
    adapterPropagator.addAdditionalStateProvider(new AdditionalStateProvider() {

        public String getName() {
            return "dummy 3";
        }

        public double[] getAdditionalState(SpacecraftState state) {
            return new double[3];
        }
    });
    // the adapted propagators do not manage the additional states from the reference,
    // they simply forward them
    Assert.assertFalse(adapterPropagator.isAdditionalStateManaged("dummy 1"));
    Assert.assertFalse(adapterPropagator.isAdditionalStateManaged("dummy 2"));
    Assert.assertTrue(adapterPropagator.isAdditionalStateManaged("dummy 3"));
    double maxDelta = 0;
    double maxNominal = 0;
    for (AbsoluteDate t = t0.shiftedBy(0.5 * dt); t.compareTo(withoutManeuver.getMaxDate()) < 0; t = t.shiftedBy(600.0)) {
        PVCoordinates pvWithout = withoutManeuver.getPVCoordinates(t, leo.getFrame());
        PVCoordinates pvWith = withManeuver.getPVCoordinates(t, leo.getFrame());
        PVCoordinates pvReverted = adapterPropagator.getPVCoordinates(t, leo.getFrame());
        double nominal = new PVCoordinates(pvWithout, pvWith).getPosition().getNorm();
        double revertError = new PVCoordinates(pvWithout, pvReverted).getPosition().getNorm();
        maxDelta = FastMath.max(maxDelta, revertError);
        maxNominal = FastMath.max(maxNominal, nominal);
        Assert.assertEquals(2, adapterPropagator.propagate(t).getAdditionalState("dummy 1").length);
        Assert.assertEquals(1, adapterPropagator.propagate(t).getAdditionalState("dummy 2").length);
        Assert.assertEquals(3, adapterPropagator.propagate(t).getAdditionalState("dummy 3").length);
    }
    Assert.assertTrue(maxDelta < 120);
    Assert.assertTrue(maxNominal > 2800);
}

Example 18 with ICGEMFormatReader

use of org.orekit.forces.gravity.potential.ICGEMFormatReader in project Orekit by CS-SI.

the class SecularAndHarmonicTest method setUp.

@Before
public void setUp() throws OrekitException {
    Utils.setDataRoot("regular-data:potential");
    GravityFieldFactory.addPotentialCoefficientsReader(new ICGEMFormatReader("eigen-6s-truncated", false));
    utc = TimeScalesFactory.getUTC();
    gravityField = GravityFieldFactory.getNormalizedProvider(8, 8);
    earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS, Constants.WGS84_EARTH_FLATTENING, FramesFactory.getGTOD(IERSConventions.IERS_2010, true));
    TimeScale ut1 = TimeScalesFactory.getUT1(IERSConventions.IERS_2010, true);
    gmst = IERSConventions.IERS_2010.getGMSTFunction(ut1);
}