Examples with Context org.orekit.estimation.Context used on opensource projects

Example 26 with Context

use of org.orekit.estimation.Context in project Orekit by CS-SI.

the class IodGibbsTest method testGibbs2.

@Test
public void testGibbs2() throws OrekitException {
    // test extracted from "Fundamentals of astrodynamics & applications", D. Vallado, 3rd ed, chap Initial Orbit Determination, Exple 7-3, p457
    // extraction of the context.
    final Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
    final double mu = context.initialOrbit.getMu();
    // initialisation
    final IodGibbs gibbs = new IodGibbs(mu);
    // Observation  vector (EME2000)
    final Vector3D posR1 = new Vector3D(0.0, 0.0, 6378137.0);
    final Vector3D posR2 = new Vector3D(0.0, -4464696.0, -5102509.0);
    final Vector3D posR3 = new Vector3D(0.0, 5740323.0, 3189068);
    // epoch corresponding to the observation vector
    AbsoluteDate dateRef = new AbsoluteDate(2000, 01, 01, 0, 0, 0, TimeScalesFactory.getUTC());
    AbsoluteDate date2 = dateRef.shiftedBy(76.48);
    AbsoluteDate date3 = dateRef.shiftedBy(153.04);
    // Reference result (cf. Vallado)
    final Vector3D velR2 = new Vector3D(0.0, 5531.148, -5191.806);
    // Gibbs IOD
    final KeplerianOrbit orbit = gibbs.estimate(FramesFactory.getEME2000(), posR1, dateRef, posR2, date2, posR3, date3);
    // test
    Assert.assertEquals(0.0, orbit.getPVCoordinates().getVelocity().getNorm() - velR2.getNorm(), 1e-3);
}

Example 27 with Context

use of org.orekit.estimation.Context in project Orekit by CS-SI.

the class IodGibbsTest method testGibbs3.

@Test
public void testGibbs3() throws OrekitException {
    // test extracted from "Fundamentals of astrodynamics & applications", D. Vallado, 3rd ed, chap Initial Orbit Determination, Exple 7-4, p463
    // Remark: the test value in Vallado is performed with an Herrick-Gibbs methods but results are very close with Gibbs method.
    // extraction of context
    final Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
    final double mu = context.initialOrbit.getMu();
    // Initialisation
    final IodGibbs gibbs = new IodGibbs(mu);
    // Observations vector (EME2000)
    final Vector3D posR1 = new Vector3D(3419855.64, 6019826.02, 2784600.22);
    final Vector3D posR2 = new Vector3D(2935911.95, 6326183.24, 2660595.84);
    final Vector3D posR3 = new Vector3D(2434952.02, 6597386.74, 2521523.11);
    // epoch corresponding to the observation vector
    AbsoluteDate dateRef = new AbsoluteDate(2000, 01, 01, 0, 0, 0, TimeScalesFactory.getUTC());
    AbsoluteDate date2 = dateRef.shiftedBy(76.48);
    AbsoluteDate date3 = dateRef.shiftedBy(153.04);
    // Reference result
    final Vector3D velR2 = new Vector3D(-6441.632, 3777.625, -1720.582);
    // Gibbs IOD
    final KeplerianOrbit orbit = gibbs.estimate(FramesFactory.getEME2000(), posR1, dateRef, posR2, date2, posR3, date3);
    // test for the norm of the velocity
    Assert.assertEquals(0.0, orbit.getPVCoordinates().getVelocity().getNorm() - velR2.getNorm(), 1e-3);
}

Example 28 with Context

use of org.orekit.estimation.Context in project Orekit by CS-SI.

the class IodGoodingTest method testGooding.

@Test
public void testGooding() throws OrekitException {
    final Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
    final double mu = context.initialOrbit.getMu();
    final Frame frame = context.initialOrbit.getFrame();
    final NumericalPropagatorBuilder propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true, 1.0e-6, 60.0, 0.001);
    // create perfect range measurements
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new PVMeasurementCreator(), 0.0, 1.0, 60.0);
    // measurement data 1
    final int idMeasure1 = 0;
    final AbsoluteDate date1 = measurements.get(idMeasure1).getDate();
    final Vector3D stapos1 = Vector3D.ZERO;
    /*context.stations.get(0)  // FIXME we need to access the station of the measurement
                                    .getBaseFrame()
                                    .getPVCoordinates(date1, frame)
                                    .getPosition();*/
    final Vector3D position1 = new Vector3D(measurements.get(idMeasure1).getObservedValue()[0], measurements.get(idMeasure1).getObservedValue()[1], measurements.get(idMeasure1).getObservedValue()[2]);
    final double r1 = position1.getNorm();
    final Vector3D lineOfSight1 = position1.normalize();
    // measurement data 2
    final int idMeasure2 = 20;
    final AbsoluteDate date2 = measurements.get(idMeasure2).getDate();
    final Vector3D stapos2 = Vector3D.ZERO;
    /*context.stations.get(0)  // FIXME we need to access the station of the measurement
                        .getBaseFrame()
                        .getPVCoordinates(date2, frame)
                        .getPosition();*/
    final Vector3D position2 = new Vector3D(measurements.get(idMeasure2).getObservedValue()[0], measurements.get(idMeasure2).getObservedValue()[1], measurements.get(idMeasure2).getObservedValue()[2]);
    final Vector3D lineOfSight2 = position2.normalize();
    // measurement data 3
    final int idMeasure3 = 40;
    final AbsoluteDate date3 = measurements.get(idMeasure3).getDate();
    final Vector3D stapos3 = Vector3D.ZERO;
    /*context.stations.get(0)  // FIXME we need to access the station of the measurement
                        .getBaseFrame()
                        .getPVCoordinates(date3, frame)
                        .getPosition();*/
    final Vector3D position3 = new Vector3D(measurements.get(idMeasure3).getObservedValue()[0], measurements.get(idMeasure3).getObservedValue()[1], measurements.get(idMeasure3).getObservedValue()[2]);
    final double r3 = position3.getNorm();
    final Vector3D lineOfSight3 = position3.normalize();
    // instantiate the IOD method
    final IodGooding iod = new IodGooding(frame, mu);
    // the problem is very sensitive, and unless one can provide the exact
    // initial range estimate, the estimate may be far off the truth...
    final KeplerianOrbit orbit = iod.estimate(stapos1, stapos2, stapos3, lineOfSight1, date1, lineOfSight2, date2, lineOfSight3, date3, r1 * 1.0, r3 * 1.0);
    Assert.assertEquals(orbit.getA(), context.initialOrbit.getA(), 1.0e-6 * context.initialOrbit.getA());
    Assert.assertEquals(orbit.getE(), context.initialOrbit.getE(), 1.0e-6 * context.initialOrbit.getE());
    Assert.assertEquals(orbit.getI(), context.initialOrbit.getI(), 1.0e-6 * context.initialOrbit.getI());
    Assert.assertEquals(13127847.99808, iod.getRange1(), 1.0e-3);
    Assert.assertEquals(13375711.51931, iod.getRange2(), 1.0e-3);
    Assert.assertEquals(13950296.64852, iod.getRange3(), 1.0e-3);
}

Example 29 with Context

use of org.orekit.estimation.Context in project Orekit by CS-SI.

the class BatchLSEstimatorTest method testMultiSatWithParameters.

/**
 * A modified version of the previous test with a selection of propagation drivers to estimate
 *  One common (µ)
 *  Some specifics for each satellite (Cr and Ca)
 *
 * @throws OrekitException
 */
@Test
public void testMultiSatWithParameters() throws OrekitException {
    // Test: Set the propagator drivers to estimate for each satellite
    final boolean muEstimated = true;
    final boolean crEstimated1 = true;
    final boolean caEstimated1 = true;
    final boolean crEstimated2 = true;
    final boolean caEstimated2 = false;
    // Builder sat 1
    final Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
    final NumericalPropagatorBuilder propagatorBuilder1 = context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true, 1.0e-6, 60.0, 1.0, Force.POTENTIAL, Force.SOLAR_RADIATION_PRESSURE);
    // Adding selection of parameters
    String satName = "sat 1";
    for (DelegatingDriver driver : propagatorBuilder1.getPropagationParametersDrivers().getDrivers()) {
        if (driver.getName().equals("central attraction coefficient")) {
            driver.setSelected(muEstimated);
        }
        if (driver.getName().equals(RadiationSensitive.REFLECTION_COEFFICIENT)) {
            driver.setName(driver.getName() + " " + satName);
            driver.setSelected(crEstimated1);
        }
        if (driver.getName().equals(RadiationSensitive.ABSORPTION_COEFFICIENT)) {
            driver.setName(driver.getName() + " " + satName);
            driver.setSelected(caEstimated1);
        }
    }
    // Builder for sat 2
    final Context context2 = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
    final NumericalPropagatorBuilder propagatorBuilder2 = context2.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true, 1.0e-6, 60.0, 1.0, Force.POTENTIAL, Force.SOLAR_RADIATION_PRESSURE);
    // Adding selection of parameters
    satName = "sat 2";
    for (ParameterDriver driver : propagatorBuilder2.getPropagationParametersDrivers().getDrivers()) {
        if (driver.getName().equals("central attraction coefficient")) {
            driver.setSelected(muEstimated);
        }
        if (driver.getName().equals(RadiationSensitive.REFLECTION_COEFFICIENT)) {
            driver.setName(driver.getName() + " " + satName);
            driver.setSelected(crEstimated2);
        }
        if (driver.getName().equals(RadiationSensitive.ABSORPTION_COEFFICIENT)) {
            driver.setName(driver.getName() + " " + satName);
            driver.setSelected(caEstimated2);
        }
    }
    // Create perfect inter-satellites range measurements
    final TimeStampedPVCoordinates original = context.initialOrbit.getPVCoordinates();
    final Orbit closeOrbit = new CartesianOrbit(new TimeStampedPVCoordinates(context.initialOrbit.getDate(), original.getPosition().add(new Vector3D(1000, 2000, 3000)), original.getVelocity().add(new Vector3D(-0.03, 0.01, 0.02))), context.initialOrbit.getFrame(), context.initialOrbit.getMu());
    final Propagator closePropagator = EstimationTestUtils.createPropagator(closeOrbit, propagatorBuilder2);
    closePropagator.setEphemerisMode();
    closePropagator.propagate(context.initialOrbit.getDate().shiftedBy(3.5 * closeOrbit.getKeplerianPeriod()));
    final BoundedPropagator ephemeris = closePropagator.getGeneratedEphemeris();
    Propagator propagator1 = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder1);
    final List<ObservedMeasurement<?>> r12 = EstimationTestUtils.createMeasurements(propagator1, new InterSatellitesRangeMeasurementCreator(ephemeris), 1.0, 3.0, 300.0);
    // create perfect range measurements for first satellite
    propagator1 = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder1);
    final List<ObservedMeasurement<?>> r1 = EstimationTestUtils.createMeasurements(propagator1, new RangeMeasurementCreator(context), 1.0, 3.0, 300.0);
    // create orbit estimator
    final BatchLSEstimator estimator = new BatchLSEstimator(new LevenbergMarquardtOptimizer(), propagatorBuilder1, propagatorBuilder2);
    for (final ObservedMeasurement<?> interSat : r12) {
        estimator.addMeasurement(interSat);
    }
    for (final ObservedMeasurement<?> range : r1) {
        estimator.addMeasurement(range);
    }
    estimator.setParametersConvergenceThreshold(1.0e-2);
    estimator.setMaxIterations(10);
    estimator.setMaxEvaluations(20);
    estimator.setObserver(new BatchLSObserver() {

        int lastIter = 0;

        int lastEval = 0;

        /**
         * {@inheritDoc}
         */
        @Override
        public void evaluationPerformed(int iterationsCount, int evaluationscount, Orbit[] orbits, ParameterDriversList estimatedOrbitalParameters, ParameterDriversList estimatedPropagatorParameters, ParameterDriversList estimatedMeasurementsParameters, EstimationsProvider evaluationsProvider, Evaluation lspEvaluation) throws OrekitException {
            if (iterationsCount == lastIter) {
                Assert.assertEquals(lastEval + 1, evaluationscount);
            } else {
                Assert.assertEquals(lastIter + 1, iterationsCount);
            }
            lastIter = iterationsCount;
            lastEval = evaluationscount;
            AbsoluteDate previous = AbsoluteDate.PAST_INFINITY;
            for (int i = 0; i < evaluationsProvider.getNumber(); ++i) {
                AbsoluteDate current = evaluationsProvider.getEstimatedMeasurement(i).getDate();
                Assert.assertTrue(current.compareTo(previous) >= 0);
                previous = current;
            }
        }
    });
    List<DelegatingDriver> parameters = estimator.getOrbitalParametersDrivers(true).getDrivers();
    ParameterDriver a0Driver = parameters.get(0);
    Assert.assertEquals("a[0]", a0Driver.getName());
    a0Driver.setValue(a0Driver.getValue() + 1.2);
    a0Driver.setReferenceDate(AbsoluteDate.GALILEO_EPOCH);
    ParameterDriver a1Driver = parameters.get(6);
    Assert.assertEquals("a[1]", a1Driver.getName());
    a1Driver.setValue(a1Driver.getValue() - 5.4);
    a1Driver.setReferenceDate(AbsoluteDate.GALILEO_EPOCH);
    final Orbit before = new KeplerianOrbit(parameters.get(6).getValue(), parameters.get(7).getValue(), parameters.get(8).getValue(), parameters.get(9).getValue(), parameters.get(10).getValue(), parameters.get(11).getValue(), PositionAngle.TRUE, closeOrbit.getFrame(), closeOrbit.getDate(), closeOrbit.getMu());
    Assert.assertEquals(4.7246, Vector3D.distance(closeOrbit.getPVCoordinates().getPosition(), before.getPVCoordinates().getPosition()), 1.0e-3);
    Assert.assertEquals(0.0010514, Vector3D.distance(closeOrbit.getPVCoordinates().getVelocity(), before.getPVCoordinates().getVelocity()), 1.0e-6);
    EstimationTestUtils.checkFit(context, estimator, 4, 5, 0.0, 6.0e-06, 0.0, 1.7e-05, 0.0, 4.4e-07, 0.0, 1.7e-10);
    final Orbit determined = new KeplerianOrbit(parameters.get(6).getValue(), parameters.get(7).getValue(), parameters.get(8).getValue(), parameters.get(9).getValue(), parameters.get(10).getValue(), parameters.get(11).getValue(), PositionAngle.TRUE, closeOrbit.getFrame(), closeOrbit.getDate(), closeOrbit.getMu());
    Assert.assertEquals(0.0, Vector3D.distance(closeOrbit.getPVCoordinates().getPosition(), determined.getPVCoordinates().getPosition()), 5.8e-6);
    Assert.assertEquals(0.0, Vector3D.distance(closeOrbit.getPVCoordinates().getVelocity(), determined.getPVCoordinates().getVelocity()), 3.5e-9);
    // got a default one
    for (final ParameterDriver driver : estimator.getOrbitalParametersDrivers(true).getDrivers()) {
        if (driver.getName().startsWith("a[")) {
            // user-specified reference date
            Assert.assertEquals(0, driver.getReferenceDate().durationFrom(AbsoluteDate.GALILEO_EPOCH), 1.0e-15);
        } else {
            // default reference date
            Assert.assertEquals(0, driver.getReferenceDate().durationFrom(propagatorBuilder1.getInitialOrbitDate()), 1.0e-15);
        }
    }
}

Example 30 with Context

use of org.orekit.estimation.Context in project Orekit by CS-SI.

the class BatchLSEstimatorTest method testKeplerPVBackward.

/**
 * Test PV measurements generation and backward propagation in least-square orbit determination.
 */
@Test
public void testKeplerPVBackward() throws OrekitException {
    Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
    final NumericalPropagatorBuilder propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true, 1.0e-6, 60.0, 1.0);
    // create perfect PV measurements
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new PVMeasurementCreator(), 0.0, -1.0, 300.0);
    // create orbit estimator
    final BatchLSEstimator estimator = new BatchLSEstimator(new LevenbergMarquardtOptimizer(), propagatorBuilder);
    for (final ObservedMeasurement<?> measurement : measurements) {
        estimator.addMeasurement(measurement);
    }
    estimator.setParametersConvergenceThreshold(1.0e-2);
    estimator.setMaxIterations(10);
    estimator.setMaxEvaluations(20);
    EstimationTestUtils.checkFit(context, estimator, 1, 2, 0.0, 8.3e-9, 0.0, 5.3e-8, 0.0, 5.6e-9, 0.0, 1.6e-12);
    RealMatrix normalizedCovariances = estimator.getOptimum().getCovariances(1.0e-10);
    RealMatrix physicalCovariances = estimator.getPhysicalCovariances(1.0e-10);
    Assert.assertEquals(6, normalizedCovariances.getRowDimension());
    Assert.assertEquals(6, normalizedCovariances.getColumnDimension());
    Assert.assertEquals(6, physicalCovariances.getRowDimension());
    Assert.assertEquals(6, physicalCovariances.getColumnDimension());
    Assert.assertEquals(0.00258, physicalCovariances.getEntry(0, 0), 1.0e-5);
}