Examples with Propagator org.orekit.propagation.Propagator used on opensource projects

Example 86 with Propagator

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

the class SpinStabilizedTest method testSpin.

@Test
public void testSpin() throws OrekitException {
    AbsoluteDate date = new AbsoluteDate(new DateComponents(1970, 01, 01), new TimeComponents(3, 25, 45.6789), TimeScalesFactory.getUTC());
    double rate = 2.0 * FastMath.PI / (12 * 60);
    AttitudeProvider law = new SpinStabilized(new InertialProvider(Rotation.IDENTITY), date, Vector3D.PLUS_K, rate);
    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 = 10.0;
    SpacecraftState sMinus = propagator.propagate(date.shiftedBy(-h));
    SpacecraftState s0 = propagator.propagate(date);
    SpacecraftState sPlus = propagator.propagate(date.shiftedBy(h));
    Vector3D spin0 = s0.getAttitude().getSpin();
    // 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.assertTrue(errorAngleMinus <= 1.0e-6 * evolutionAngleMinus);
    double errorAnglePlus = Rotation.distance(s0.getAttitude().getRotation(), sPlus.shiftedBy(-h).getAttitude().getRotation());
    double evolutionAnglePlus = Rotation.distance(s0.getAttitude().getRotation(), sPlus.getAttitude().getRotation());
    Assert.assertTrue(errorAnglePlus <= 1.0e-6 * evolutionAnglePlus);
    // compute spin axis using finite differences
    Rotation rM = sMinus.getAttitude().getRotation();
    Rotation rP = sPlus.getAttitude().getRotation();
    Vector3D reference = AngularCoordinates.estimateRate(rM, rP, 2 * h);
    Assert.assertEquals(2 * FastMath.PI / reference.getNorm(), 2 * FastMath.PI / spin0.getNorm(), 0.05);
    Assert.assertEquals(0.0, FastMath.toDegrees(Vector3D.angle(reference, spin0)), 1.0e-10);
    Assert.assertEquals(0.0, FastMath.toDegrees(Vector3D.angle(Vector3D.PLUS_K, spin0)), 1.0e-10);
}

Example 87 with Propagator

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

the class TabulatedLofOffsetTest method testSerialization.

@Test
public void testSerialization() throws OrekitException, IOException, ClassNotFoundException {
    // 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(10.0, 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 generate an ephemeris
    final AttitudeProvider tabulated = new TabulatedLofOffset(orbit.getFrame(), type, sample, 6, AngularDerivativesFilter.USE_RR);
    final Propagator rebuildingPropagator = new KeplerianPropagator(orbit);
    rebuildingPropagator.setAttitudeProvider(tabulated);
    rebuildingPropagator.setEphemerisMode();
    rebuildingPropagator.propagate(orbit.getDate().shiftedBy(5));
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bos);
    oos.writeObject(rebuildingPropagator.getGeneratedEphemeris());
    // even despite we propagated only 5 seconds, the attitude sample is huge
    Assert.assertTrue(bos.size() > 17000);
    Assert.assertTrue(bos.size() < 18000);
    ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
    ObjectInputStream ois = new ObjectInputStream(bis);
    TabulatedLofOffset deserialized = (TabulatedLofOffset) ((BoundedPropagator) ois.readObject()).getAttitudeProvider();
    Assert.assertEquals(sample.size(), deserialized.getTable().size());
}

Example 88 with Propagator

use of org.orekit.propagation.Propagator 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 89 with Propagator

use of org.orekit.propagation.Propagator 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 90 with Propagator

use of org.orekit.propagation.Propagator 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);
}