use of org.orekit.propagation.Propagator 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);
}
use of org.orekit.propagation.Propagator 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);
}
use of org.orekit.propagation.Propagator 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);
}
use of org.orekit.propagation.Propagator in project Orekit by CS-SI.
the class RangeRateTest method testStateDerivativesOneWay.
@Test
public void testStateDerivativesOneWay() 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);
for (final ObservedMeasurement<?> m : measurements) {
Assert.assertFalse(((RangeRate) m).isTwoWay());
}
propagator.setSlaveMode();
double maxRelativeError = 0;
for (final ObservedMeasurement<?> measurement : measurements) {
// 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(2, 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, 1.6e-8);
}
use of org.orekit.propagation.Propagator in project Orekit by CS-SI.
the class RangeTest 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 Range & errors
final double RangeObserved = measurement.getObservedValue()[0];
final EstimatedMeasurement<?> estimated = measurement.estimate(0, 0, new SpacecraftState[] { state });
final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
Assert.assertEquals(3, participants.length);
Assert.assertEquals(0.5 * Constants.SPEED_OF_LIGHT * participants[2].getDate().durationFrom(participants[0].getDate()), estimated.getEstimatedValue()[0], 2.0e-8);
// the real state used for estimation is adjusted according to downlink delay
double adjustment = state.getDate().durationFrom(estimated.getStates()[0].getDate());
Assert.assertTrue(adjustment > 0.006);
Assert.assertTrue(adjustment < 0.010);
final double RangeEstimated = estimated.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, 4.9e-8);
Assert.assertEquals(0.0, absErrorsMin, 2.2e-7);
Assert.assertEquals(0.0, absErrorsMax, 2.1e-7);
Assert.assertEquals(0.0, relErrorsMedian, 1.0e-14);
Assert.assertEquals(0.0, relErrorsMax, 2.6e-14);
}
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