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

Example 66 with Context

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

the class PVTest method testStateDerivatives.

@Test
public void testStateDerivatives() 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 PVMeasurementCreator(), 1.0, 3.0, 300.0);
    propagator.setSlaveMode();
    double[] errorsP = new double[3 * 6 * measurements.size()];
    double[] errorsV = new double[3 * 6 * measurements.size()];
    int indexP = 0;
    int indexV = 0;
    for (final ObservedMeasurement<?> measurement : measurements) {
        final AbsoluteDate date = measurement.getDate();
        final SpacecraftState state = propagator.propagate(date);
        final double[][] jacobian = measurement.estimate(0, 0, new SpacecraftState[] { state }).getStateDerivatives(0);
        // compute a reference value using finite differences
        final double[][] finiteDifferencesJacobian = 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, 1.0, 3).value(state);
        Assert.assertEquals(finiteDifferencesJacobian.length, jacobian.length);
        Assert.assertEquals(finiteDifferencesJacobian[0].length, jacobian[0].length);
        for (int i = 0; i < jacobian.length; ++i) {
            for (int j = 0; j < jacobian[i].length; ++j) {
                final double relativeError = FastMath.abs((finiteDifferencesJacobian[i][j] - jacobian[i][j]) / finiteDifferencesJacobian[i][j]);
                if (j < 3) {
                    errorsP[indexP++] = relativeError;
                } else {
                    errorsV[indexV++] = relativeError;
                }
            }
        }
    }
    // median errors
    Assert.assertEquals(0.0, new Median().evaluate(errorsP), 2.1e-10);
    Assert.assertEquals(0.0, new Median().evaluate(errorsV), 2.1e-10);
}

Example 67 with Context

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

the class RangeAnalyticTest method genericTestValues.

/**
 * Generic test function for values of the range
 * @param printResults Print the results ?
 * @throws OrekitException
 */
void genericTestValues(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
    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> absoluteErrors = new ArrayList<Double>();
    final List<Double> relativeErrors = 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.)) {
                // 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);
                // Values of the RangeAnalytic & errors
                final double RangeObserved = measurement.getObservedValue()[0];
                final double RangeEstimated = new RangeAnalytic((Range) measurement).theoreticalEvaluationAnalytic(0, 0, state).getEstimatedValue()[0];
                final double absoluteError = RangeEstimated - RangeObserved;
                absoluteErrors.add(absoluteError);
                relativeErrors.add(FastMath.abs(absoluteError) / FastMath.abs(RangeObserved));
                // Print results on console ?
                if (printResults) {
                    final AbsoluteDate measurementDate = measurement.getDate();
                    String stationName = ((Range) measurement).getStation().getBaseFrame().getName();
                    System.out.format(Locale.US, "%-15s  %-23s  %-23s  %19.6f  %19.6f  %13.6e  %13.6e%n", stationName, measurementDate, date, RangeObserved, RangeEstimated, FastMath.abs(RangeEstimated - RangeObserved), FastMath.abs((RangeEstimated - RangeObserved) / RangeObserved));
                }
            }
        // End if measurement date between previous and current interpolator step
        }
    // End for loop on the measurements
    });
    // Print results on console ? Header
    if (printResults) {
        System.out.format(Locale.US, "%-15s  %-23s  %-23s  %19s  %19s  %13s  %13s%n", "Station", "Measurement Date", "State Date", "Range observed [m]", "Range estimated [m]", "ΔRange [m]", "rel ΔRange");
    }
    // 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 array
    final double[] absErrors = absoluteErrors.stream().mapToDouble(Double::doubleValue).toArray();
    final double[] relErrors = relativeErrors.stream().mapToDouble(Double::doubleValue).toArray();
    // Statistics' assertion
    final double absErrorsMedian = new Median().evaluate(absErrors);
    final double absErrorsMin = new Min().evaluate(absErrors);
    final double absErrorsMax = new Max().evaluate(absErrors);
    final double relErrorsMedian = new Median().evaluate(relErrors);
    final double relErrorsMax = new Max().evaluate(relErrors);
    // Print the results on console ? Final results
    if (printResults) {
        System.out.println();
        System.out.println("Absolute errors median: " + absErrorsMedian);
        System.out.println("Absolute errors min   : " + absErrorsMin);
        System.out.println("Absolute errors max   : " + absErrorsMax);
        System.out.println("Relative errors median: " + relErrorsMedian);
        System.out.println("Relative errors max   : " + relErrorsMax);
    }
    Assert.assertEquals(0.0, absErrorsMedian, 3.8e-08);
    Assert.assertEquals(0.0, absErrorsMin, 2.0e-07);
    Assert.assertEquals(0.0, absErrorsMax, 2.3e-07);
    Assert.assertEquals(0.0, relErrorsMedian, 6.5e-15);
    Assert.assertEquals(0.0, relErrorsMax, 2.4e-14);
}

Example 68 with Context

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

the class RangeRateTest method testStateDerivativesWithModifier.

@Test
public void testStateDerivativesWithModifier() 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
    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) {
        final RangeRateTroposphericDelayModifier modifier = new RangeRateTroposphericDelayModifier(SaastamoinenModel.getStandardModel(), true);
        ((RangeRate) measurement).addModifier(modifier);
        // 
        // final AbsoluteDate date = measurement.getDate();
        // measurement.getObservedValue()[0] / Constants.SPEED_OF_LIGHT;
        final double meanDelay = 1;
        final AbsoluteDate date = measurement.getDate().shiftedBy(-0.75 * meanDelay);
        final SpacecraftState state = propagator.propagate(date);
        final double[][] jacobian = measurement.estimate(0, 0, new SpacecraftState[] { state }).getStateDerivatives(0);
        final double[][] finiteDifferencesJacobian = Differentiation.differentiate(new StateFunction() {

            public double[] value(final SpacecraftState state) throws OrekitException {
                return measurement.estimate(0, 0, new SpacecraftState[] { state }).getEstimatedValue();
            }
        }, 1, propagator.getAttitudeProvider(), OrbitType.CARTESIAN, PositionAngle.TRUE, 15.0, 3).value(state);
        Assert.assertEquals(finiteDifferencesJacobian.length, jacobian.length);
        Assert.assertEquals(finiteDifferencesJacobian[0].length, jacobian[0].length);
        for (int i = 0; i < jacobian.length; ++i) {
            for (int j = 0; j < jacobian[i].length; ++j) {
                // check the values returned by getStateDerivatives() are correct
                maxRelativeError = FastMath.max(maxRelativeError, FastMath.abs((finiteDifferencesJacobian[i][j] - jacobian[i][j]) / finiteDifferencesJacobian[i][j]));
            }
        }
    }
    Assert.assertEquals(0, maxRelativeError, 1.5e-7);
}

Example 69 with Context

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

the class RangeRateTest method testParameterDerivativesWithModifier.

@Test
public void testParameterDerivativesWithModifier() 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) {
        final RangeRateTroposphericDelayModifier modifier = new RangeRateTroposphericDelayModifier(SaastamoinenModel.getStandardModel(), true);
        ((RangeRate) measurement).addModifier(modifier);
        // 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);
}

Example 70 with Context

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

the class RangeRateTest method testStateDerivativesTwoWays.

@Test
public void testStateDerivativesTwoWays() 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
    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);
    for (final ObservedMeasurement<?> m : measurements) {
        Assert.assertTrue(((RangeRate) m).isTwoWay());
    }
    propagator.setSlaveMode();
    double maxRelativeError = 0;
    for (final ObservedMeasurement<?> measurement : measurements) {
        // 
        // final AbsoluteDate date = measurement.getDate();
        // measurement.getObservedValue()[0] / Constants.SPEED_OF_LIGHT;
        final double meanDelay = 1;
        final AbsoluteDate date = measurement.getDate().shiftedBy(-0.75 * meanDelay);
        final SpacecraftState state = propagator.propagate(date);
        final EstimatedMeasurement<?> estimated = measurement.estimate(0, 0, new SpacecraftState[] { state });
        Assert.assertEquals(3, estimated.getParticipants().length);
        final double[][] jacobian = estimated.getStateDerivatives(0);
        final double[][] finiteDifferencesJacobian = Differentiation.differentiate(new StateFunction() {

            public double[] value(final SpacecraftState state) throws OrekitException {
                return measurement.estimate(0, 0, new SpacecraftState[] { state }).getEstimatedValue();
            }
        }, 1, propagator.getAttitudeProvider(), OrbitType.CARTESIAN, PositionAngle.TRUE, 15.0, 3).value(state);
        Assert.assertEquals(finiteDifferencesJacobian.length, jacobian.length);
        Assert.assertEquals(finiteDifferencesJacobian[0].length, jacobian[0].length);
        for (int i = 0; i < jacobian.length; ++i) {
            for (int j = 0; j < jacobian[i].length; ++j) {
                // check the values returned by getStateDerivatives() are correct
                maxRelativeError = FastMath.max(maxRelativeError, FastMath.abs((finiteDifferencesJacobian[i][j] - jacobian[i][j]) / finiteDifferencesJacobian[i][j]));
            }
        }
    }
    Assert.assertEquals(0, maxRelativeError, 2.6e-5);
}