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Example 31 with NumericalPropagatorBuilder

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

the class BatchLSEstimatorTest method testWrappedException.

@Test
public void testWrappedException() 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 range measurements
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new RangeMeasurementCreator(context), 1.0, 3.0, 300.0);
    // create orbit estimator
    final BatchLSEstimator estimator = new BatchLSEstimator(new LevenbergMarquardtOptimizer(), propagatorBuilder);
    for (final ObservedMeasurement<?> range : measurements) {
        estimator.addMeasurement(range);
    }
    estimator.setParametersConvergenceThreshold(1.0e-2);
    estimator.setMaxIterations(10);
    estimator.setMaxEvaluations(20);
    estimator.setObserver(new BatchLSObserver() {

        /**
         * {@inheritDoc}
         */
        @Override
        public void evaluationPerformed(int iterationsCount, int evaluationscount, Orbit[] orbits, ParameterDriversList estimatedOrbitalParameters, ParameterDriversList estimatedPropagatorParameters, ParameterDriversList estimatedMeasurementsParameters, EstimationsProvider evaluationsProvider, Evaluation lspEvaluation) throws DummyException {
            throw new DummyException();
        }
    });
    try {
        EstimationTestUtils.checkFit(context, estimator, 3, 4, 0.0, 1.5e-6, 0.0, 3.2e-6, 0.0, 3.8e-7, 0.0, 1.5e-10);
        Assert.fail("an exception should have been thrown");
    } catch (DummyException de) {
    // expected
    }
}
Also used : Context(org.orekit.estimation.Context) Evaluation(org.hipparchus.optim.nonlinear.vector.leastsquares.LeastSquaresProblem.Evaluation) Orbit(org.orekit.orbits.Orbit) CartesianOrbit(org.orekit.orbits.CartesianOrbit) KeplerianOrbit(org.orekit.orbits.KeplerianOrbit) LevenbergMarquardtOptimizer(org.hipparchus.optim.nonlinear.vector.leastsquares.LevenbergMarquardtOptimizer) ParameterDriversList(org.orekit.utils.ParameterDriversList) NumericalPropagatorBuilder(org.orekit.propagation.conversion.NumericalPropagatorBuilder) BoundedPropagator(org.orekit.propagation.BoundedPropagator) Propagator(org.orekit.propagation.Propagator) RangeMeasurementCreator(org.orekit.estimation.measurements.RangeMeasurementCreator) InterSatellitesRangeMeasurementCreator(org.orekit.estimation.measurements.InterSatellitesRangeMeasurementCreator) ObservedMeasurement(org.orekit.estimation.measurements.ObservedMeasurement) EstimationsProvider(org.orekit.estimation.measurements.EstimationsProvider) Test(org.junit.Test)

Example 32 with NumericalPropagatorBuilder

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

the class RangeAnalyticTest method genericTestStateDerivatives.

/**
 * Generic test function for derivatives with respect to state
 * @param isModifier Use of atmospheric modifiers
 * @param isFiniteDifferences Finite differences reference calculation if true, Range class otherwise
 * @param printResults Print the results ?
 * @throws OrekitException
 */
void genericTestStateDerivatives(final boolean isModifier, final boolean isFiniteDifferences, final boolean printResults, final double refErrorsPMedian, final double refErrorsPMean, final double refErrorsPMax, final double refErrorsVMedian, final double refErrorsVMean, final double refErrorsVMax) 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, 0.001);
    // Create perfect range measurements
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new RangeMeasurementCreator(context), 1.0, 3.0, 300.0);
    // Lists for results' storage - Used only for derivatives with respect to state
    // "final" value to be seen by "handleStep" function of the propagator
    final List<Double> errorsP = new ArrayList<Double>();
    final List<Double> errorsV = new ArrayList<Double>();
    // Set master mode
    // Use a lambda function to implement "handleStep" function
    propagator.setMasterMode((OrekitStepInterpolator interpolator, boolean isLast) -> {
        for (final ObservedMeasurement<?> measurement : measurements) {
            // Play test if the measurement date is between interpolator previous and current date
            if ((measurement.getDate().durationFrom(interpolator.getPreviousState().getDate()) > 0.) && (measurement.getDate().durationFrom(interpolator.getCurrentState().getDate()) <= 0.)) {
                // Add modifiers if test implies it
                final RangeTroposphericDelayModifier modifier = new RangeTroposphericDelayModifier(SaastamoinenModel.getStandardModel());
                if (isModifier) {
                    ((Range) measurement).addModifier(modifier);
                }
                // We intentionally propagate to a date which is close to the
                // real spacecraft state but is *not* the accurate date, by
                // compensating only part of the downlink delay. This is done
                // in order to validate the partial derivatives with respect
                // to velocity. If we had chosen the proper state date, the
                // range would have depended only on the current position but
                // not on the current velocity.
                final double meanDelay = measurement.getObservedValue()[0] / Constants.SPEED_OF_LIGHT;
                final AbsoluteDate date = measurement.getDate().shiftedBy(-0.75 * meanDelay);
                final SpacecraftState state = interpolator.getInterpolatedState(date);
                final EstimatedMeasurement<Range> range = new RangeAnalytic((Range) measurement).theoreticalEvaluationAnalytic(0, 0, state);
                if (isModifier) {
                    modifier.modify(range);
                }
                final double[][] jacobian = range.getStateDerivatives(0);
                // Jacobian reference value
                final double[][] jacobianRef;
                if (isFiniteDifferences) {
                    // Compute a reference value using finite differences
                    jacobianRef = Differentiation.differentiate(new StateFunction() {

                        public double[] value(final SpacecraftState state) throws OrekitException {
                            return measurement.estimate(0, 0, new SpacecraftState[] { state }).getEstimatedValue();
                        }
                    }, measurement.getDimension(), propagator.getAttitudeProvider(), OrbitType.CARTESIAN, PositionAngle.TRUE, 2.0, 3).value(state);
                } else {
                    // Compute a reference value using Range class function
                    jacobianRef = ((Range) measurement).theoreticalEvaluation(0, 0, new SpacecraftState[] { state }).getStateDerivatives(0);
                }
                // //Test: Test point by point with the debugger
                // if (!isFiniteDifferences && !isModifier) {
                // final EstimatedMeasurement<Range> test =
                // new RangeAnalytic((Range)measurement).theoreticalEvaluationValidation(0, 0, state);
                // }
                // //Test
                Assert.assertEquals(jacobianRef.length, jacobian.length);
                Assert.assertEquals(jacobianRef[0].length, jacobian[0].length);
                // Errors & relative errors on the jacobian
                double[][] dJacobian = new double[jacobian.length][jacobian[0].length];
                double[][] dJacobianRelative = new double[jacobian.length][jacobian[0].length];
                for (int i = 0; i < jacobian.length; ++i) {
                    for (int j = 0; j < jacobian[i].length; ++j) {
                        dJacobian[i][j] = jacobian[i][j] - jacobianRef[i][j];
                        dJacobianRelative[i][j] = FastMath.abs(dJacobian[i][j] / jacobianRef[i][j]);
                        if (j < 3) {
                            errorsP.add(dJacobianRelative[i][j]);
                        } else {
                            errorsV.add(dJacobianRelative[i][j]);
                        }
                    }
                }
                // Print values in console ?
                if (printResults) {
                    String stationName = ((Range) measurement).getStation().getBaseFrame().getName();
                    System.out.format(Locale.US, "%-15s  %-23s  %-23s  " + "%10.3e  %10.3e  %10.3e  " + "%10.3e  %10.3e  %10.3e  " + "%10.3e  %10.3e  %10.3e  " + "%10.3e  %10.3e  %10.3e%n", stationName, measurement.getDate(), date, dJacobian[0][0], dJacobian[0][1], dJacobian[0][2], dJacobian[0][3], dJacobian[0][4], dJacobian[0][5], dJacobianRelative[0][0], dJacobianRelative[0][1], dJacobianRelative[0][2], dJacobianRelative[0][3], dJacobianRelative[0][4], dJacobianRelative[0][5]);
                }
            }
        // End if measurement date between previous and current interpolator step
        }
    // End for loop on the measurements
    });
    // Print results on console ?
    if (printResults) {
        System.out.format(Locale.US, "%-15s  %-23s  %-23s  " + "%10s  %10s  %10s  " + "%10s  %10s  %10s  " + "%10s  %10s  %10s  " + "%10s  %10s  %10s%n", "Station", "Measurement Date", "State Date", "ΔdPx", "ΔdPy", "ΔdPz", "ΔdVx", "ΔdVy", "ΔdVz", "rel ΔdPx", "rel ΔdPy", "rel ΔdPz", "rel ΔdVx", "rel ΔdVy", "rel ΔdVz");
    }
    // Rewind the propagator to initial date
    propagator.propagate(context.initialOrbit.getDate());
    // Sort measurements chronologically
    measurements.sort(new ChronologicalComparator());
    // Propagate to final measurement's date
    propagator.propagate(measurements.get(measurements.size() - 1).getDate());
    // Convert lists to double[] and evaluate some statistics
    final double[] relErrorsP = errorsP.stream().mapToDouble(Double::doubleValue).toArray();
    final double[] relErrorsV = errorsV.stream().mapToDouble(Double::doubleValue).toArray();
    final double errorsPMedian = new Median().evaluate(relErrorsP);
    final double errorsPMean = new Mean().evaluate(relErrorsP);
    final double errorsPMax = new Max().evaluate(relErrorsP);
    final double errorsVMedian = new Median().evaluate(relErrorsV);
    final double errorsVMean = new Mean().evaluate(relErrorsV);
    final double errorsVMax = new Max().evaluate(relErrorsV);
    // Print the results on console ?
    if (printResults) {
        System.out.println();
        System.out.format(Locale.US, "Relative errors dR/dP -> Median: %6.3e / Mean: %6.3e / Max: %6.3e%n", errorsPMedian, errorsPMean, errorsPMax);
        System.out.format(Locale.US, "Relative errors dR/dV -> Median: %6.3e / Mean: %6.3e / Max: %6.3e%n", errorsVMedian, errorsVMean, errorsVMax);
    }
    // Reference comparison with Range class
    Assert.assertEquals(0.0, errorsPMedian, refErrorsPMedian);
    Assert.assertEquals(0.0, errorsPMean, refErrorsPMean);
    Assert.assertEquals(0.0, errorsPMax, refErrorsPMax);
    Assert.assertEquals(0.0, errorsVMedian, refErrorsVMedian);
    Assert.assertEquals(0.0, errorsVMean, refErrorsVMean);
    Assert.assertEquals(0.0, errorsVMax, refErrorsVMax);
}
Also used : Mean(org.hipparchus.stat.descriptive.moment.Mean) Max(org.hipparchus.stat.descriptive.rank.Max) ArrayList(java.util.ArrayList) Median(org.hipparchus.stat.descriptive.rank.Median) AbsoluteDate(org.orekit.time.AbsoluteDate) SpacecraftState(org.orekit.propagation.SpacecraftState) Propagator(org.orekit.propagation.Propagator) OrekitException(org.orekit.errors.OrekitException) Context(org.orekit.estimation.Context) RangeTroposphericDelayModifier(org.orekit.estimation.measurements.modifiers.RangeTroposphericDelayModifier) OrekitStepInterpolator(org.orekit.propagation.sampling.OrekitStepInterpolator) NumericalPropagatorBuilder(org.orekit.propagation.conversion.NumericalPropagatorBuilder) StateFunction(org.orekit.utils.StateFunction) ChronologicalComparator(org.orekit.time.ChronologicalComparator)

Example 33 with NumericalPropagatorBuilder

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

the class RangeAnalyticTest method genericTestParameterDerivatives.

/**
 * Generic test function for derivatives with respect to parameters (station's position in station's topocentric frame)
 * @param isModifier Use of atmospheric modifiers
 * @param isFiniteDifferences Finite differences reference calculation if true, Range class otherwise
 * @param printResults Print the results ?
 * @throws OrekitException
 */
void genericTestParameterDerivatives(final boolean isModifier, final boolean isFiniteDifferences, final boolean printResults) 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, 0.001);
    // Create perfect range measurements
    for (final GroundStation station : context.stations) {
        station.getEastOffsetDriver().setSelected(true);
        station.getNorthOffsetDriver().setSelected(true);
        station.getZenithOffsetDriver().setSelected(true);
    }
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new RangeMeasurementCreator(context), 1.0, 3.0, 300.0);
    // List to store the results
    final List<Double> relErrorList = new ArrayList<Double>();
    // Set master mode
    // Use a lambda function to implement "handleStep" function
    propagator.setMasterMode((OrekitStepInterpolator interpolator, boolean isLast) -> {
        for (final ObservedMeasurement<?> measurement : measurements) {
            // Play test if the measurement date is between interpolator previous and current date
            if ((measurement.getDate().durationFrom(interpolator.getPreviousState().getDate()) > 0.) && (measurement.getDate().durationFrom(interpolator.getCurrentState().getDate()) <= 0.)) {
                // Add modifiers if test implies it
                final RangeTroposphericDelayModifier modifier = new RangeTroposphericDelayModifier(SaastamoinenModel.getStandardModel());
                if (isModifier) {
                    ((Range) measurement).addModifier(modifier);
                }
                // Parameter corresponding to station position offset
                final GroundStation stationParameter = ((Range) measurement).getStation();
                // We intentionally propagate to a date which is close to the
                // real spacecraft state but is *not* the accurate date, by
                // compensating only part of the downlink delay. This is done
                // in order to validate the partial derivatives with respect
                // to velocity. If we had chosen the proper state date, the
                // range would have depended only on the current position but
                // not on the current velocity.
                final double meanDelay = measurement.getObservedValue()[0] / Constants.SPEED_OF_LIGHT;
                final AbsoluteDate date = measurement.getDate().shiftedBy(-0.75 * meanDelay);
                final SpacecraftState state = interpolator.getInterpolatedState(date);
                final ParameterDriver[] drivers = new ParameterDriver[] { stationParameter.getEastOffsetDriver(), stationParameter.getNorthOffsetDriver(), stationParameter.getZenithOffsetDriver() };
                if (printResults) {
                    String stationName = ((Range) measurement).getStation().getBaseFrame().getName();
                    System.out.format(Locale.US, "%-15s  %-23s  %-23s  ", stationName, measurement.getDate(), date);
                }
                for (int i = 0; i < 3; ++i) {
                    final double[] gradient = measurement.estimate(0, 0, new SpacecraftState[] { state }).getParameterDerivatives(drivers[i]);
                    Assert.assertEquals(1, measurement.getDimension());
                    Assert.assertEquals(1, gradient.length);
                    // Compute a reference value using analytical formulas
                    final EstimatedMeasurement<Range> rangeAnalytic = new RangeAnalytic((Range) measurement).theoreticalEvaluationAnalytic(0, 0, state);
                    if (isModifier) {
                        modifier.modify(rangeAnalytic);
                    }
                    final double ref = rangeAnalytic.getParameterDerivatives(drivers[i])[0];
                    if (printResults) {
                        System.out.format(Locale.US, "%10.3e  %10.3e  ", gradient[0] - ref, FastMath.abs((gradient[0] - ref) / ref));
                    }
                    final double relError = FastMath.abs((ref - gradient[0]) / ref);
                    relErrorList.add(relError);
                // Assert.assertEquals(ref, gradient[0], 6.1e-5 * FastMath.abs(ref));
                }
                if (printResults) {
                    System.out.format(Locale.US, "%n");
                }
            }
        // End if measurement date between previous and current interpolator step
        }
    // End for loop on the measurements
    });
    // Rewind the propagator to initial date
    propagator.propagate(context.initialOrbit.getDate());
    // Sort measurements chronologically
    measurements.sort(new ChronologicalComparator());
    // Print results ? Header
    if (printResults) {
        System.out.format(Locale.US, "%-15s  %-23s  %-23s  " + "%10s  %10s  %10s  " + "%10s  %10s  %10s%n", "Station", "Measurement Date", "State Date", "ΔdQx", "rel ΔdQx", "ΔdQy", "rel ΔdQy", "ΔdQz", "rel ΔdQz");
    }
    // Propagate to final measurement's date
    propagator.propagate(measurements.get(measurements.size() - 1).getDate());
    // Convert error list to double[]
    final double[] relErrors = relErrorList.stream().mapToDouble(Double::doubleValue).toArray();
    // Compute statistics
    final double relErrorsMedian = new Median().evaluate(relErrors);
    final double relErrorsMean = new Mean().evaluate(relErrors);
    final double relErrorsMax = new Max().evaluate(relErrors);
    // Print the results on console ?
    if (printResults) {
        System.out.println();
        System.out.format(Locale.US, "Relative errors dR/dQ -> Median: %6.3e / Mean: %6.3e / Max: %6.3e%n", relErrorsMedian, relErrorsMean, relErrorsMax);
    }
    // Assert the results / max values depend on the test
    double refErrorsMedian, refErrorsMean, refErrorsMax;
    // Analytic references
    refErrorsMedian = 1.55e-06;
    refErrorsMean = 3.64e-06;
    refErrorsMax = 6.1e-05;
    Assert.assertEquals(0.0, relErrorsMedian, refErrorsMedian);
    Assert.assertEquals(0.0, relErrorsMean, refErrorsMean);
    Assert.assertEquals(0.0, relErrorsMax, refErrorsMax);
}
Also used : Mean(org.hipparchus.stat.descriptive.moment.Mean) Max(org.hipparchus.stat.descriptive.rank.Max) ArrayList(java.util.ArrayList) Median(org.hipparchus.stat.descriptive.rank.Median) AbsoluteDate(org.orekit.time.AbsoluteDate) SpacecraftState(org.orekit.propagation.SpacecraftState) Propagator(org.orekit.propagation.Propagator) Context(org.orekit.estimation.Context) ParameterDriver(org.orekit.utils.ParameterDriver) RangeTroposphericDelayModifier(org.orekit.estimation.measurements.modifiers.RangeTroposphericDelayModifier) OrekitStepInterpolator(org.orekit.propagation.sampling.OrekitStepInterpolator) NumericalPropagatorBuilder(org.orekit.propagation.conversion.NumericalPropagatorBuilder) ChronologicalComparator(org.orekit.time.ChronologicalComparator)

Example 34 with NumericalPropagatorBuilder

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

the class RangeRateTest method testParameterDerivativesOneWay.

@Test
public void testParameterDerivativesOneWay() 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, 0.001);
    // create perfect range rate measurements
    for (final GroundStation station : context.stations) {
        station.getEastOffsetDriver().setSelected(true);
        station.getNorthOffsetDriver().setSelected(true);
        station.getZenithOffsetDriver().setSelected(true);
    }
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new RangeRateMeasurementCreator(context, false), 1.0, 3.0, 300.0);
    propagator.setSlaveMode();
    double maxRelativeError = 0;
    for (final ObservedMeasurement<?> measurement : measurements) {
        // parameter corresponding to station position offset
        final GroundStation stationParameter = ((RangeRate) measurement).getStation();
        // We intentionally propagate to a date which is close to the
        // real spacecraft state but is *not* the accurate date, by
        // compensating only part of the downlink delay. This is done
        // in order to validate the partial derivatives with respect
        // to velocity. If we had chosen the proper state date, the
        // range would have depended only on the current position but
        // not on the current velocity.
        final double meanDelay = measurement.getObservedValue()[0] / Constants.SPEED_OF_LIGHT;
        final AbsoluteDate date = measurement.getDate().shiftedBy(-0.75 * meanDelay);
        final SpacecraftState state = propagator.propagate(date);
        final ParameterDriver[] drivers = new ParameterDriver[] { stationParameter.getEastOffsetDriver(), stationParameter.getNorthOffsetDriver(), stationParameter.getZenithOffsetDriver() };
        for (int i = 0; i < 3; ++i) {
            final double[] gradient = measurement.estimate(0, 0, new SpacecraftState[] { state }).getParameterDerivatives(drivers[i]);
            Assert.assertEquals(1, measurement.getDimension());
            Assert.assertEquals(1, gradient.length);
            final ParameterFunction dMkdP = Differentiation.differentiate(new ParameterFunction() {

                /**
                 * {@inheritDoc}
                 */
                @Override
                public double value(final ParameterDriver parameterDriver) throws OrekitException {
                    return measurement.estimate(0, 0, new SpacecraftState[] { state }).getEstimatedValue()[0];
                }
            }, drivers[i], 3, 20.0);
            final double ref = dMkdP.value(drivers[i]);
            maxRelativeError = FastMath.max(maxRelativeError, FastMath.abs((ref - gradient[0]) / ref));
        }
    }
    Assert.assertEquals(0, maxRelativeError, 1.2e-6);
}
Also used : Context(org.orekit.estimation.Context) ParameterDriver(org.orekit.utils.ParameterDriver) AbsoluteDate(org.orekit.time.AbsoluteDate) SpacecraftState(org.orekit.propagation.SpacecraftState) NumericalPropagatorBuilder(org.orekit.propagation.conversion.NumericalPropagatorBuilder) ParameterFunction(org.orekit.utils.ParameterFunction) Propagator(org.orekit.propagation.Propagator) OrekitException(org.orekit.errors.OrekitException) Test(org.junit.Test)

Example 35 with NumericalPropagatorBuilder

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

the class RangeRateTest method testParameterDerivativesTwoWays.

@Test
public void testParameterDerivativesTwoWays() 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, 0.001);
    // create perfect range rate measurements
    for (final GroundStation station : context.stations) {
        station.getEastOffsetDriver().setSelected(true);
        station.getNorthOffsetDriver().setSelected(true);
        station.getZenithOffsetDriver().setSelected(true);
    }
    final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
    final List<ObservedMeasurement<?>> measurements = EstimationTestUtils.createMeasurements(propagator, new RangeRateMeasurementCreator(context, true), 1.0, 3.0, 300.0);
    propagator.setSlaveMode();
    double maxRelativeError = 0;
    for (final ObservedMeasurement<?> measurement : measurements) {
        // parameter corresponding to station position offset
        final GroundStation stationParameter = ((RangeRate) measurement).getStation();
        // We intentionally propagate to a date which is close to the
        // real spacecraft state but is *not* the accurate date, by
        // compensating only part of the downlink delay. This is done
        // in order to validate the partial derivatives with respect
        // to velocity. If we had chosen the proper state date, the
        // range would have depended only on the current position but
        // not on the current velocity.
        final double meanDelay = measurement.getObservedValue()[0] / Constants.SPEED_OF_LIGHT;
        final AbsoluteDate date = measurement.getDate().shiftedBy(-0.75 * meanDelay);
        final SpacecraftState state = propagator.propagate(date);
        final ParameterDriver[] drivers = new ParameterDriver[] { stationParameter.getEastOffsetDriver(), stationParameter.getNorthOffsetDriver(), stationParameter.getZenithOffsetDriver() };
        for (int i = 0; i < 3; ++i) {
            final double[] gradient = measurement.estimate(0, 0, new SpacecraftState[] { state }).getParameterDerivatives(drivers[i]);
            Assert.assertEquals(1, measurement.getDimension());
            Assert.assertEquals(1, gradient.length);
            final ParameterFunction dMkdP = Differentiation.differentiate(new ParameterFunction() {

                /**
                 * {@inheritDoc}
                 */
                @Override
                public double value(final ParameterDriver parameterDriver) throws OrekitException {
                    return measurement.estimate(0, 0, new SpacecraftState[] { state }).getEstimatedValue()[0];
                }
            }, drivers[i], 3, 20.0);
            final double ref = dMkdP.value(drivers[i]);
            maxRelativeError = FastMath.max(maxRelativeError, FastMath.abs((ref - gradient[0]) / ref));
        }
    }
    Assert.assertEquals(0, maxRelativeError, 5.2e-5);
}
Also used : Context(org.orekit.estimation.Context) ParameterDriver(org.orekit.utils.ParameterDriver) AbsoluteDate(org.orekit.time.AbsoluteDate) SpacecraftState(org.orekit.propagation.SpacecraftState) NumericalPropagatorBuilder(org.orekit.propagation.conversion.NumericalPropagatorBuilder) ParameterFunction(org.orekit.utils.ParameterFunction) Propagator(org.orekit.propagation.Propagator) OrekitException(org.orekit.errors.OrekitException) Test(org.junit.Test)

Aggregations

NumericalPropagatorBuilder (org.orekit.propagation.conversion.NumericalPropagatorBuilder)76 Context (org.orekit.estimation.Context)67 Propagator (org.orekit.propagation.Propagator)67 Test (org.junit.Test)54 ObservedMeasurement (org.orekit.estimation.measurements.ObservedMeasurement)44 AbsoluteDate (org.orekit.time.AbsoluteDate)44 SpacecraftState (org.orekit.propagation.SpacecraftState)36 ParameterDriver (org.orekit.utils.ParameterDriver)27 Vector3D (org.hipparchus.geometry.euclidean.threed.Vector3D)26 Orbit (org.orekit.orbits.Orbit)23 ParameterDriversList (org.orekit.utils.ParameterDriversList)22 ArrayList (java.util.ArrayList)21 OrekitException (org.orekit.errors.OrekitException)18 Median (org.hipparchus.stat.descriptive.rank.Median)17 RangeMeasurementCreator (org.orekit.estimation.measurements.RangeMeasurementCreator)17 CartesianOrbit (org.orekit.orbits.CartesianOrbit)15 Max (org.hipparchus.stat.descriptive.rank.Max)14 RealMatrix (org.hipparchus.linear.RealMatrix)13 LevenbergMarquardtOptimizer (org.hipparchus.optim.nonlinear.vector.leastsquares.LevenbergMarquardtOptimizer)13 KeplerianOrbit (org.orekit.orbits.KeplerianOrbit)13