Examples with KeplerianPropagator org.orekit.propagation.analytical.KeplerianPropagator used on opensource projects

Example 21 with KeplerianPropagator

use of org.orekit.propagation.analytical.KeplerianPropagator in project Orekit by CS-SI.

the class TabulatedLofOffsetTest method testYawCompensation.

@Test
public void testYawCompensation() throws OrekitException {
    // create a sample from Yaw compensation law
    final LOFType type = LOFType.VNC;
    final List<TimeStampedAngularCoordinates> sample = new ArrayList<TimeStampedAngularCoordinates>();
    final AttitudeProvider yawCompensLaw = new YawCompensation(orbit.getFrame(), new NadirPointing(orbit.getFrame(), earth));
    final Propagator originalPropagator = new KeplerianPropagator(orbit);
    originalPropagator.setAttitudeProvider(yawCompensLaw);
    originalPropagator.setMasterMode(1.0, new OrekitFixedStepHandler() {

        public void handleStep(final SpacecraftState currentState, final boolean isLast) throws OrekitException {
            Rotation offsetAtt = currentState.getAttitude().getRotation();
            LofOffset aligned = new LofOffset(currentState.getFrame(), type);
            Rotation alignedAtt = aligned.getAttitude(currentState.getOrbit(), currentState.getDate(), currentState.getFrame()).getRotation();
            Rotation offsetProper = offsetAtt.compose(alignedAtt.revert(), RotationConvention.VECTOR_OPERATOR);
            sample.add(new TimeStampedAngularCoordinates(currentState.getDate(), offsetProper, Vector3D.ZERO, Vector3D.ZERO));
        }
    });
    originalPropagator.propagate(orbit.getDate().shiftedBy(2000));
    originalPropagator.setSlaveMode();
    // use the sample and compare it to original
    final AttitudeProvider tabulated = new TabulatedLofOffset(orbit.getFrame(), type, sample, 6, AngularDerivativesFilter.USE_RR);
    final Propagator rebuildingPropagator = new KeplerianPropagator(orbit);
    rebuildingPropagator.setAttitudeProvider(tabulated);
    rebuildingPropagator.setMasterMode(0.3, new OrekitFixedStepHandler() {

        public void handleStep(final SpacecraftState currentState, final boolean isLast) throws OrekitException {
            final SpacecraftState rebuilt = originalPropagator.propagate(currentState.getDate());
            final Rotation r1 = currentState.getAttitude().getRotation();
            final Rotation r2 = rebuilt.getAttitude().getRotation();
            Assert.assertEquals(0.0, Rotation.distance(r1, r2), 7.0e-6);
            checkField(Decimal64Field.getInstance(), tabulated, currentState.getOrbit(), currentState.getDate(), currentState.getFrame());
        }
    });
    rebuildingPropagator.propagate(orbit.getDate().shiftedBy(50), orbit.getDate().shiftedBy(1950));
}

Example 22 with KeplerianPropagator

use of org.orekit.propagation.analytical.KeplerianPropagator in project Orekit by CS-SI.

the class TargetPointingTest method testSpin.

@Test
public void testSpin() throws OrekitException {
    Frame itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true);
    // Elliptic earth shape
    OneAxisEllipsoid earthShape = new OneAxisEllipsoid(6378136.460, 1 / 298.257222101, itrf);
    // Create target pointing attitude provider
    GeodeticPoint geoTarget = new GeodeticPoint(FastMath.toRadians(43.36), FastMath.toRadians(1.26), 600.);
    AttitudeProvider law = new TargetPointing(FramesFactory.getEME2000(), geoTarget, earthShape);
    KeplerianOrbit orbit = new KeplerianOrbit(7178000.0, 1.e-4, FastMath.toRadians(50.), FastMath.toRadians(10.), FastMath.toRadians(20.), FastMath.toRadians(30.), PositionAngle.MEAN, FramesFactory.getEME2000(), date, 3.986004415e14);
    Propagator propagator = new KeplerianPropagator(orbit, law);
    double h = 0.01;
    SpacecraftState sMinus = propagator.propagate(date.shiftedBy(-h));
    SpacecraftState s0 = propagator.propagate(date);
    SpacecraftState sPlus = propagator.propagate(date.shiftedBy(h));
    // check spin is consistent with attitude evolution
    double errorAngleMinus = Rotation.distance(sMinus.shiftedBy(h).getAttitude().getRotation(), s0.getAttitude().getRotation());
    double evolutionAngleMinus = Rotation.distance(sMinus.getAttitude().getRotation(), s0.getAttitude().getRotation());
    Assert.assertEquals(0.0, errorAngleMinus, 1.0e-5 * evolutionAngleMinus);
    double errorAnglePlus = Rotation.distance(s0.getAttitude().getRotation(), sPlus.shiftedBy(-h).getAttitude().getRotation());
    double evolutionAnglePlus = Rotation.distance(s0.getAttitude().getRotation(), sPlus.getAttitude().getRotation());
    Assert.assertEquals(0.0, errorAnglePlus, 1.0e-5 * evolutionAnglePlus);
    Vector3D spin0 = s0.getAttitude().getSpin();
    Vector3D reference = AngularCoordinates.estimateRate(sMinus.getAttitude().getRotation(), sPlus.getAttitude().getRotation(), 2 * h);
    Assert.assertEquals(0.0, spin0.subtract(reference).getNorm(), 1.1e-10);
}

Example 23 with KeplerianPropagator

use of org.orekit.propagation.analytical.KeplerianPropagator in project Orekit by CS-SI.

the class YawSteeringTest method testSpin.

@Test
public void testSpin() throws OrekitException {
    NadirPointing nadirLaw = new NadirPointing(circOrbit.getFrame(), earthShape);
    // Target pointing attitude provider with yaw compensation
    AttitudeProvider law = new YawSteering(circOrbit.getFrame(), nadirLaw, CelestialBodyFactory.getSun(), Vector3D.MINUS_I);
    KeplerianOrbit orbit = new KeplerianOrbit(7178000.0, 1.e-4, FastMath.toRadians(50.), FastMath.toRadians(10.), FastMath.toRadians(20.), FastMath.toRadians(30.), PositionAngle.MEAN, FramesFactory.getEME2000(), date.shiftedBy(-300.0), 3.986004415e14);
    Propagator propagator = new KeplerianPropagator(orbit, law);
    double h = 0.01;
    SpacecraftState sMinus = propagator.propagate(date.shiftedBy(-h));
    SpacecraftState s0 = propagator.propagate(date);
    SpacecraftState sPlus = propagator.propagate(date.shiftedBy(h));
    // check spin is consistent with attitude evolution
    double errorAngleMinus = Rotation.distance(sMinus.shiftedBy(h).getAttitude().getRotation(), s0.getAttitude().getRotation());
    double evolutionAngleMinus = Rotation.distance(sMinus.getAttitude().getRotation(), s0.getAttitude().getRotation());
    Assert.assertEquals(0.0, errorAngleMinus, 1.0e-9 * evolutionAngleMinus);
    double errorAnglePlus = Rotation.distance(s0.getAttitude().getRotation(), sPlus.shiftedBy(-h).getAttitude().getRotation());
    double evolutionAnglePlus = Rotation.distance(s0.getAttitude().getRotation(), sPlus.getAttitude().getRotation());
    Assert.assertEquals(0.0, errorAnglePlus, 1.0e-9 * evolutionAnglePlus);
    Vector3D spin0 = s0.getAttitude().getSpin();
    Vector3D reference = AngularCoordinates.estimateRate(sMinus.getAttitude().getRotation(), sPlus.getAttitude().getRotation(), 2 * h);
    Assert.assertTrue(spin0.getNorm() > 1.0e-3);
    Assert.assertEquals(0.0, spin0.subtract(reference).getNorm(), 5.0e-13);
}

Example 24 with KeplerianPropagator

use of org.orekit.propagation.analytical.KeplerianPropagator in project Orekit by CS-SI.

the class TabulatedProviderTest method createSample.

private List<TimeStampedAngularCoordinates> createSample(double samplingRate, AttitudeProvider referenceProvider) throws OrekitException {
    // reference propagator, using a yaw compensation law
    final KeplerianPropagator referencePropagator = new KeplerianPropagator(circOrbit);
    referencePropagator.setAttitudeProvider(referenceProvider);
    // create sample
    final List<TimeStampedAngularCoordinates> sample = new ArrayList<TimeStampedAngularCoordinates>();
    referencePropagator.setMasterMode(samplingRate, new OrekitFixedStepHandler() {

        public void handleStep(SpacecraftState currentState, boolean isLast) {
            sample.add(currentState.getAttitude().getOrientation());
        }
    });
    referencePropagator.propagate(circOrbit.getDate().shiftedBy(2 * circOrbit.getKeplerianPeriod()));
    return sample;
}

Example 25 with KeplerianPropagator

use of org.orekit.propagation.analytical.KeplerianPropagator in project Orekit by CS-SI.

the class YawCompensationTest method testCompensMinMax.

/**
 * Test that maximum yaw compensation is at ascending/descending node,
 * and minimum yaw compensation is at maximum latitude.
 */
@Test
public void testCompensMinMax() throws OrekitException {
    // Attitude laws
    // **************
    // Target pointing attitude provider over satellite nadir at date, without yaw compensation
    NadirPointing nadirLaw = new NadirPointing(circOrbit.getFrame(), earthShape);
    // Target pointing attitude provider with yaw compensation
    YawCompensation yawCompensLaw = new YawCompensation(circOrbit.getFrame(), nadirLaw);
    // Extrapolation over one orbital period (sec)
    double duration = circOrbit.getKeplerianPeriod();
    KeplerianPropagator extrapolator = new KeplerianPropagator(circOrbit);
    // Extrapolation initializations
    // extrapolation duration in seconds
    double delta_t = 15.0;
    // extrapolation start date
    AbsoluteDate extrapDate = date;
    // Min initialization
    double yawMin = 1.e+12;
    double latMin = 0.;
    while (extrapDate.durationFrom(date) < duration) {
        extrapDate = extrapDate.shiftedBy(delta_t);
        // Extrapolated orbit state at date
        Orbit extrapOrbit = extrapolator.propagate(extrapDate).getOrbit();
        PVCoordinates extrapPvSatEME2000 = extrapOrbit.getPVCoordinates();
        // Satellite latitude at date
        double extrapLat = earthShape.transform(extrapPvSatEME2000.getPosition(), FramesFactory.getEME2000(), extrapDate).getLatitude();
        // Compute yaw compensation angle -- rotations composition
        double yawAngle = yawCompensLaw.getYawAngle(extrapOrbit, extrapDate, extrapOrbit.getFrame());
        // Update minimum yaw compensation angle
        if (FastMath.abs(yawAngle) <= yawMin) {
            yawMin = FastMath.abs(yawAngle);
            latMin = extrapLat;
        }
        // 1/ Check yaw values around ascending node (max yaw)
        if ((FastMath.abs(extrapLat) < FastMath.toRadians(2.)) && (extrapPvSatEME2000.getVelocity().getZ() >= 0.)) {
            Assert.assertEquals(-3.206, FastMath.toDegrees(yawAngle), 0.003);
        }
        // 2/ Check yaw values around maximum positive latitude (min yaw)
        if (extrapLat > FastMath.toRadians(50.15)) {
            Assert.assertEquals(0, FastMath.toDegrees(yawAngle), 0.15);
        }
        // 3/ Check yaw values around descending node (max yaw)
        if ((FastMath.abs(extrapLat) < FastMath.toRadians(2.)) && (extrapPvSatEME2000.getVelocity().getZ() <= 0.)) {
            Assert.assertEquals(3.206, FastMath.toDegrees(yawAngle), 0.003);
        }
        // 4/ Check yaw values around maximum negative latitude (min yaw)
        if (extrapLat < FastMath.toRadians(-50.15)) {
            Assert.assertEquals(0, FastMath.toDegrees(yawAngle), 0.15);
        }
    }
    // 5/ Check that minimum yaw compensation value is around maximum latitude
    Assert.assertEquals(0.0, FastMath.toDegrees(yawMin), 0.004);
    Assert.assertEquals(50.0, FastMath.toDegrees(latMin), 0.22);
}