Examples with CircularOrbit org.orekit.orbits.CircularOrbit used on opensource projects

Example 41 with CircularOrbit

use of org.orekit.orbits.CircularOrbit in project Orekit by CS-SI.

the class YawSteeringTest method setUp.

@Before
public void setUp() {
    try {
        Utils.setDataRoot("regular-data");
        // Computation date
        date = new AbsoluteDate(new DateComponents(1970, 04, 07), TimeComponents.H00, TimeScalesFactory.getUTC());
        // Body mu
        final double mu = 3.9860047e14;
        // Reference frame = ITRF
        itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true);
        // Satellite position
        circOrbit = new CircularOrbit(7178000.0, 0.5e-4, -0.5e-4, FastMath.toRadians(50.), FastMath.toRadians(270.), FastMath.toRadians(5.300), PositionAngle.MEAN, FramesFactory.getEME2000(), date, mu);
        // Elliptic earth shape
        earthShape = new OneAxisEllipsoid(6378136.460, 1 / 298.257222101, itrf);
    } catch (OrekitException oe) {
        Assert.fail(oe.getMessage());
    }
}

Example 42 with CircularOrbit

use of org.orekit.orbits.CircularOrbit in project Orekit by CS-SI.

the class LofOffsetPointingTest method testMiss.

@Test
public void testMiss() throws OrekitException {
    final CircularOrbit circ = new CircularOrbit(7178000.0, 0.5e-4, -0.5e-4, FastMath.toRadians(0.), FastMath.toRadians(270.), FastMath.toRadians(5.300), PositionAngle.MEAN, FramesFactory.getEME2000(), date, mu);
    final LofOffset upsideDown = new LofOffset(circ.getFrame(), LOFType.VVLH, RotationOrder.XYX, FastMath.PI, 0, 0);
    final LofOffsetPointing pointing = new LofOffsetPointing(circ.getFrame(), earthSpheric, upsideDown, Vector3D.PLUS_K);
    try {
        pointing.getTargetPV(circ, date, circ.getFrame());
        Assert.fail("an exception should have been thrown");
    } catch (OrekitException oe) {
        Assert.assertEquals(OrekitMessages.ATTITUDE_POINTING_LAW_DOES_NOT_POINT_TO_GROUND, oe.getSpecifier());
    }
}

Example 43 with CircularOrbit

use of org.orekit.orbits.CircularOrbit in project Orekit by CS-SI.

the class AttitudeTest method testInterpolation.

@Test
public void testInterpolation() throws OrekitException {
    Utils.setDataRoot("regular-data");
    final double ehMu = 3.9860047e14;
    final double ae = 6.378137e6;
    final double c20 = -1.08263e-3;
    final double c30 = 2.54e-6;
    final double c40 = 1.62e-6;
    final double c50 = 2.3e-7;
    final double c60 = -5.5e-7;
    final AbsoluteDate date = AbsoluteDate.J2000_EPOCH.shiftedBy(584.);
    final Vector3D position = new Vector3D(3220103., 69623., 6449822.);
    final Vector3D velocity = new Vector3D(6414.7, -2006., -3180.);
    final CircularOrbit initialOrbit = new CircularOrbit(new PVCoordinates(position, velocity), FramesFactory.getEME2000(), date, ehMu);
    EcksteinHechlerPropagator propagator = new EcksteinHechlerPropagator(initialOrbit, ae, ehMu, c20, c30, c40, c50, c60);
    OneAxisEllipsoid earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS, Constants.WGS84_EARTH_FLATTENING, FramesFactory.getITRF(IERSConventions.IERS_2010, true));
    propagator.setAttitudeProvider(new BodyCenterPointing(initialOrbit.getFrame(), earth));
    final Attitude initialAttitude = propagator.propagate(initialOrbit.getDate()).getAttitude();
    // set up a 5 points sample
    List<Attitude> sample = new ArrayList<Attitude>();
    for (double dt = 0; dt < 251.0; dt += 60.0) {
        sample.add(propagator.propagate(date.shiftedBy(dt)).getAttitude());
    }
    // well inside the sample, interpolation should be better than quadratic shift
    double maxShiftAngleError = 0;
    double maxInterpolationAngleError = 0;
    double maxShiftRateError = 0;
    double maxInterpolationRateError = 0;
    for (double dt = 0; dt < 240.0; dt += 1.0) {
        AbsoluteDate t = initialOrbit.getDate().shiftedBy(dt);
        Attitude propagated = propagator.propagate(t).getAttitude();
        double shiftAngleError = Rotation.distance(propagated.getRotation(), initialAttitude.shiftedBy(dt).getRotation());
        double interpolationAngleError = Rotation.distance(propagated.getRotation(), initialAttitude.interpolate(t, sample).getRotation());
        double shiftRateError = Vector3D.distance(propagated.getSpin(), initialAttitude.shiftedBy(dt).getSpin());
        double interpolationRateError = Vector3D.distance(propagated.getSpin(), initialAttitude.interpolate(t, sample).getSpin());
        maxShiftAngleError = FastMath.max(maxShiftAngleError, shiftAngleError);
        maxInterpolationAngleError = FastMath.max(maxInterpolationAngleError, interpolationAngleError);
        maxShiftRateError = FastMath.max(maxShiftRateError, shiftRateError);
        maxInterpolationRateError = FastMath.max(maxInterpolationRateError, interpolationRateError);
    }
    Assert.assertTrue(maxShiftAngleError > 4.0e-6);
    Assert.assertTrue(maxInterpolationAngleError < 1.5e-13);
    Assert.assertTrue(maxShiftRateError > 6.0e-8);
    Assert.assertTrue(maxInterpolationRateError < 2.5e-14);
    // past sample end, interpolation error should increase, but still be far better than quadratic shift
    maxShiftAngleError = 0;
    maxInterpolationAngleError = 0;
    maxShiftRateError = 0;
    maxInterpolationRateError = 0;
    for (double dt = 250.0; dt < 300.0; dt += 1.0) {
        AbsoluteDate t = initialOrbit.getDate().shiftedBy(dt);
        Attitude propagated = propagator.propagate(t).getAttitude();
        double shiftAngleError = Rotation.distance(propagated.getRotation(), initialAttitude.shiftedBy(dt).getRotation());
        double interpolationAngleError = Rotation.distance(propagated.getRotation(), initialAttitude.interpolate(t, sample).getRotation());
        double shiftRateError = Vector3D.distance(propagated.getSpin(), initialAttitude.shiftedBy(dt).getSpin());
        double interpolationRateError = Vector3D.distance(propagated.getSpin(), initialAttitude.interpolate(t, sample).getSpin());
        maxShiftAngleError = FastMath.max(maxShiftAngleError, shiftAngleError);
        maxInterpolationAngleError = FastMath.max(maxInterpolationAngleError, interpolationAngleError);
        maxShiftRateError = FastMath.max(maxShiftRateError, shiftRateError);
        maxInterpolationRateError = FastMath.max(maxInterpolationRateError, interpolationRateError);
    }
    Assert.assertTrue(maxShiftAngleError > 9.0e-6);
    Assert.assertTrue(maxInterpolationAngleError < 6.0e-11);
    Assert.assertTrue(maxShiftRateError > 9.0e-8);
    Assert.assertTrue(maxInterpolationRateError < 4.0e-12);
}

Example 44 with CircularOrbit

use of org.orekit.orbits.CircularOrbit in project Orekit by CS-SI.

the class BodyCenterPointingTest method testQDot.

@Test
public void testQDot() throws OrekitException {
    Utils.setDataRoot("regular-data");
    final double ehMu = 3.9860047e14;
    final double ae = 6.378137e6;
    final double c20 = -1.08263e-3;
    final double c30 = 2.54e-6;
    final double c40 = 1.62e-6;
    final double c50 = 2.3e-7;
    final double c60 = -5.5e-7;
    final AbsoluteDate date = AbsoluteDate.J2000_EPOCH.shiftedBy(584.);
    final Vector3D position = new Vector3D(3220103., 69623., 6449822.);
    final Vector3D velocity = new Vector3D(6414.7, -2006., -3180.);
    final CircularOrbit initialOrbit = new CircularOrbit(new PVCoordinates(position, velocity), FramesFactory.getEME2000(), date, ehMu);
    EcksteinHechlerPropagator propagator = new EcksteinHechlerPropagator(initialOrbit, ae, ehMu, c20, c30, c40, c50, c60);
    propagator.setAttitudeProvider(earthCenterAttitudeLaw);
    List<WeightedObservedPoint> w0 = new ArrayList<WeightedObservedPoint>();
    List<WeightedObservedPoint> w1 = new ArrayList<WeightedObservedPoint>();
    List<WeightedObservedPoint> w2 = new ArrayList<WeightedObservedPoint>();
    List<WeightedObservedPoint> w3 = new ArrayList<WeightedObservedPoint>();
    for (double dt = -1; dt < 1; dt += 0.01) {
        Rotation rP = propagator.propagate(date.shiftedBy(dt)).getAttitude().getRotation();
        w0.add(new WeightedObservedPoint(1, dt, rP.getQ0()));
        w1.add(new WeightedObservedPoint(1, dt, rP.getQ1()));
        w2.add(new WeightedObservedPoint(1, dt, rP.getQ2()));
        w3.add(new WeightedObservedPoint(1, dt, rP.getQ3()));
    }
    double q0DotRef = PolynomialCurveFitter.create(2).fit(w0)[1];
    double q1DotRef = PolynomialCurveFitter.create(2).fit(w1)[1];
    double q2DotRef = PolynomialCurveFitter.create(2).fit(w2)[1];
    double q3DotRef = PolynomialCurveFitter.create(2).fit(w3)[1];
    Attitude a0 = propagator.propagate(date).getAttitude();
    double q0 = a0.getRotation().getQ0();
    double q1 = a0.getRotation().getQ1();
    double q2 = a0.getRotation().getQ2();
    double q3 = a0.getRotation().getQ3();
    double oX = a0.getSpin().getX();
    double oY = a0.getSpin().getY();
    double oZ = a0.getSpin().getZ();
    // first time-derivatives of the quaternion
    double q0Dot = 0.5 * MathArrays.linearCombination(-q1, oX, -q2, oY, -q3, oZ);
    double q1Dot = 0.5 * MathArrays.linearCombination(q0, oX, -q3, oY, q2, oZ);
    double q2Dot = 0.5 * MathArrays.linearCombination(q3, oX, q0, oY, -q1, oZ);
    double q3Dot = 0.5 * MathArrays.linearCombination(-q2, oX, q1, oY, q0, oZ);
    Assert.assertEquals(q0DotRef, q0Dot, 5.0e-9);
    Assert.assertEquals(q1DotRef, q1Dot, 5.0e-9);
    Assert.assertEquals(q2DotRef, q2Dot, 5.0e-9);
    Assert.assertEquals(q3DotRef, q3Dot, 5.0e-9);
}

Example 45 with CircularOrbit

use of org.orekit.orbits.CircularOrbit in project Orekit by CS-SI.

the class BodyCenterPointingTest method testSpin.

@Test
public void testSpin() throws OrekitException {
    Utils.setDataRoot("regular-data");
    final double ehMu = 3.9860047e14;
    final double ae = 6.378137e6;
    final double c20 = -1.08263e-3;
    final double c30 = 2.54e-6;
    final double c40 = 1.62e-6;
    final double c50 = 2.3e-7;
    final double c60 = -5.5e-7;
    final AbsoluteDate date = AbsoluteDate.J2000_EPOCH.shiftedBy(584.);
    final Vector3D position = new Vector3D(3220103., 69623., 6449822.);
    final Vector3D velocity = new Vector3D(6414.7, -2006., -3180.);
    final CircularOrbit initialOrbit = new CircularOrbit(new PVCoordinates(position, velocity), FramesFactory.getEME2000(), date, ehMu);
    EcksteinHechlerPropagator propagator = new EcksteinHechlerPropagator(initialOrbit, ae, ehMu, c20, c30, c40, c50, c60);
    propagator.setAttitudeProvider(earthCenterAttitudeLaw);
    double h = 0.01;
    SpacecraftState s0 = propagator.propagate(date);
    SpacecraftState sMinus = propagator.propagate(date.shiftedBy(-h));
    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-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.assertEquals(0.0, errorAnglePlus, 1.0e-6 * 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(), 1.0e-13);
}