AbstractMeasurement.java

  1. /* Copyright 2002-2024 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.estimation.measurements;

  19. import java.util.ArrayList;
  20. import java.util.Collections;
  21. import java.util.List;

  23. import org.hipparchus.CalculusFieldElement;
  24. import org.hipparchus.analysis.differentiation.Gradient;
  25. import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
  26. import org.hipparchus.geometry.euclidean.threed.Vector3D;
  27. import org.hipparchus.util.FastMath;
  28. import org.orekit.annotation.DefaultDataContext;
  29. import org.orekit.frames.Frame;
  30. import org.orekit.frames.FramesFactory;
  31. import org.orekit.propagation.SpacecraftState;
  32. import org.orekit.time.AbsoluteDate;
  33. import org.orekit.time.FieldAbsoluteDate;
  34. import org.orekit.utils.Constants;
  35. import org.orekit.utils.FieldPVCoordinatesProvider;
  36. import org.orekit.utils.PVCoordinatesProvider;
  37. import org.orekit.utils.ParameterDriver;
  38. import org.orekit.utils.FieldShiftingPVCoordinatesProvider;
  39. import org.orekit.utils.ShiftingPVCoordinatesProvider;
  40. import org.orekit.utils.TimeStampedFieldPVCoordinates;
  41. import org.orekit.utils.TimeStampedPVCoordinates;

  43. /** Abstract class handling measurements boilerplate.
  44.  * @param <T> the type of the measurement
  45.  * @author Luc Maisonobe
  46.  * @since 8.0
  47.  */
  48. public abstract class AbstractMeasurement<T extends ObservedMeasurement<T>> implements ObservedMeasurement<T> {

  50.     /** List of the supported parameters. */
  51.     private final List<ParameterDriver> supportedParameters;

  53.     /** Satellites related to this measurement.
  54.      * @since 9.3
  55.      */
  56.     private final List<ObservableSatellite> satellites;

  58.     /** Date of the measurement. */
  59.     private final AbsoluteDate date;

  61.     /** Observed value. */
  62.     private final double[] observed;

  64.     /** Theoretical standard deviation. */
  65.     private final double[] sigma;

  67.     /** Base weight. */
  68.     private final double[] baseWeight;

  70.     /** Modifiers that apply to the measurement.*/
  71.     private final List<EstimationModifier<T>> modifiers;

  73.     /** Enabling status. */
  74.     private boolean enabled;

  76.     /** Simple constructor for mono-dimensional measurements.
  77.      * <p>
  78.      * At construction, a measurement is enabled.
  79.      * </p>
  80.      * @param date date of the measurement
  81.      * @param observed observed value
  82.      * @param sigma theoretical standard deviation
  83.      * @param baseWeight base weight
  84.      * @param satellites satellites related to this measurement
  85.      * @since 9.3
  86.      */
  87.     protected AbstractMeasurement(final AbsoluteDate date, final double observed,
  88.                                   final double sigma, final double baseWeight,
  89.                                   final List<ObservableSatellite> satellites) {

  91.         this.supportedParameters = new ArrayList<ParameterDriver>();

  93.         this.date       = date;
  94.         this.observed   = new double[] {
  95.             observed
  96.         };
  97.         this.sigma      = new double[] {
  98.             sigma
  99.         };
  100.         this.baseWeight = new double[] {
  101.             baseWeight
  102.         };

  104.         this.satellites = satellites;

  106.         this.modifiers = new ArrayList<EstimationModifier<T>>();
  107.         setEnabled(true);

  109.     }

  111.     /** Simple constructor, for multi-dimensional measurements.
  112.      * <p>
  113.      * At construction, a measurement is enabled.
  114.      * </p>
  115.      * @param date date of the measurement
  116.      * @param observed observed value
  117.      * @param sigma theoretical standard deviation
  118.      * @param baseWeight base weight
  119.      * @param satellites satellites related to this measurement
  120.      * @since 9.3
  121.      */
  122.     protected AbstractMeasurement(final AbsoluteDate date, final double[] observed,
  123.                                   final double[] sigma, final double[] baseWeight,
  124.                                   final List<ObservableSatellite> satellites) {
  125.         this.supportedParameters = new ArrayList<ParameterDriver>();

  127.         this.date       = date;
  128.         this.observed   = observed.clone();
  129.         this.sigma      = sigma.clone();
  130.         this.baseWeight = baseWeight.clone();

  132.         this.satellites = satellites;

  134.         this.modifiers = new ArrayList<EstimationModifier<T>>();
  135.         setEnabled(true);

  137.     }

  139.     /** Add a parameter driver.
  140.      * @param driver parameter driver to add
  141.      * @since 9.3
  142.      */
  143.     protected void addParameterDriver(final ParameterDriver driver) {
  144.         supportedParameters.add(driver);
  145.     }

  147.     /** {@inheritDoc} */
  148.     @Override
  149.     public List<ParameterDriver> getParametersDrivers() {
  150.         return Collections.unmodifiableList(supportedParameters);
  151.     }

  153.     /** {@inheritDoc} */
  154.     @Override
  155.     public void setEnabled(final boolean enabled) {
  156.         this.enabled = enabled;
  157.     }

  159.     /** {@inheritDoc} */
  160.     @Override
  161.     public boolean isEnabled() {
  162.         return enabled;
  163.     }

  165.     /** {@inheritDoc} */
  166.     @Override
  167.     public int getDimension() {
  168.         return observed.length;
  169.     }

  171.     /** {@inheritDoc} */
  172.     @Override
  173.     public double[] getTheoreticalStandardDeviation() {
  174.         return sigma.clone();
  175.     }

  177.     /** {@inheritDoc} */
  178.     @Override
  179.     public double[] getBaseWeight() {
  180.         return baseWeight.clone();
  181.     }

  183.     /** {@inheritDoc} */
  184.     @Override
  185.     public List<ObservableSatellite> getSatellites() {
  186.         return satellites;
  187.     }

  189.     /** Estimate the theoretical value without derivatives.
  190.      * <p>
  191.      * The theoretical value does not have <em>any</em> modifiers applied.
  192.      * </p>
  193.      * @param iteration iteration number
  194.      * @param evaluation evaluation number
  195.      * @param states orbital states at measurement date
  196.      * @return theoretical value
  197.      * @see #estimate(int, int, SpacecraftState[])
  198.      * @since 12.0
  199.      */
  200.     protected abstract EstimatedMeasurementBase<T> theoreticalEvaluationWithoutDerivatives(int iteration, int evaluation,
  201.                                                                                            SpacecraftState[] states);

  203.     /** Estimate the theoretical value.
  204.      * <p>
  205.      * The theoretical value does not have <em>any</em> modifiers applied.
  206.      * </p>
  207.      * @param iteration iteration number
  208.      * @param evaluation evaluation number
  209.      * @param states orbital states at measurement date
  210.      * @return theoretical value
  211.      * @see #estimate(int, int, SpacecraftState[])
  212.      */
  213.     protected abstract EstimatedMeasurement<T> theoreticalEvaluation(int iteration, int evaluation, SpacecraftState[] states);

  215.     /** {@inheritDoc} */
  216.     @Override
  217.     public EstimatedMeasurementBase<T> estimateWithoutDerivatives(final int iteration, final int evaluation, final SpacecraftState[] states) {

  219.         // compute the theoretical value
  220.         final EstimatedMeasurementBase<T> estimation = theoreticalEvaluationWithoutDerivatives(iteration, evaluation, states);

  222.         // apply the modifiers
  223.         for (final EstimationModifier<T> modifier : modifiers) {
  224.             modifier.modifyWithoutDerivatives(estimation);
  225.         }

  227.         return estimation;

  229.     }

  231.     /** {@inheritDoc} */
  232.     @Override
  233.     public EstimatedMeasurement<T> estimate(final int iteration, final int evaluation, final SpacecraftState[] states) {

  235.         // compute the theoretical value
  236.         final EstimatedMeasurement<T> estimation = theoreticalEvaluation(iteration, evaluation, states);

  238.         // apply the modifiers
  239.         for (final EstimationModifier<T> modifier : modifiers) {
  240.             modifier.modify(estimation);
  241.         }

  243.         return estimation;

  245.     }

  247.     /** {@inheritDoc} */
  248.     @Override
  249.     public AbsoluteDate getDate() {
  250.         return date;
  251.     }

  253.     /** {@inheritDoc} */
  254.     @Override
  255.     public double[] getObservedValue() {
  256.         return observed.clone();
  257.     }

  259.     /** {@inheritDoc} */
  260.     @Override
  261.     public void addModifier(final EstimationModifier<T> modifier) {

  263.         // combine the measurement parameters and the modifier parameters
  264.         supportedParameters.addAll(modifier.getParametersDrivers());

  266.         modifiers.add(modifier);

  268.     }

  270.     /** {@inheritDoc} */
  271.     @Override
  272.     public List<EstimationModifier<T>> getModifiers() {
  273.         return Collections.unmodifiableList(modifiers);
  274.     }

  276.     /** Compute propagation delay on a link leg (typically downlink or uplink).
  277.      * @param adjustableEmitterPV position/velocity of emitter that may be adjusted
  278.      * @param receiverPosition fixed position of receiver at {@code signalArrivalDate},
  279.      * in the same frame as {@code adjustableEmitterPV}
  280.      * @param signalArrivalDate date at which the signal arrives to receiver
  281.      * @return <em>positive</em> delay between signal emission and signal reception dates
  282.      * @deprecated as of 12.1, replaced by either {@link #signalTimeOfFlight(TimeStampedPVCoordinates,
  283.      * Vector3D, AbsoluteDate, Frame)} or {@link #signalTimeOfFlight(PVCoordinatesProvider, AbsoluteDate,
  284.      * Vector3D, AbsoluteDate, Frame)}
  285.      */
  286.     @Deprecated
  287.     @DefaultDataContext
  288.     public static double signalTimeOfFlight(final TimeStampedPVCoordinates adjustableEmitterPV,
  289.                                             final Vector3D receiverPosition,
  290.                                             final AbsoluteDate signalArrivalDate) {
  291.         return signalTimeOfFlight(adjustableEmitterPV, receiverPosition, signalArrivalDate,
  292.                                   FramesFactory.getGCRF());
  293.     }

  295.     /** Compute propagation delay on a link leg (typically downlink or uplink).
  296.      * @param adjustableEmitterPV position/velocity of emitter that may be adjusted
  297.      * @param receiverPosition fixed position of receiver at {@code signalArrivalDate}
  298.      * @param receiverFrame frame in which both {@code adjustableEmitterPV} and
  299.      *                      {@code receiver receiverPosition} are defined
  300.      * @param signalArrivalDate date at which the signal arrives to receiver
  301.      * @return <em>positive</em> delay between signal emission and signal reception dates
  302.      * @since 12.1
  303.      */
  304.     public static double signalTimeOfFlight(final TimeStampedPVCoordinates adjustableEmitterPV,
  305.                                             final Vector3D receiverPosition,
  306.                                             final AbsoluteDate signalArrivalDate,
  307.                                             final Frame receiverFrame) {
  308.         return signalTimeOfFlight(new ShiftingPVCoordinatesProvider(adjustableEmitterPV,
  309.                                                                     receiverFrame),
  310.                                   adjustableEmitterPV.getDate(),
  311.                                   receiverPosition, signalArrivalDate,
  312.                                   receiverFrame);
  313.     }

  315.     /** Compute propagation delay on a link leg (typically downlink or uplink).
  316.      * @param adjustableEmitter position/velocity provider of emitter
  317.      * @param approxEmissionDate approximate emission date
  318.      * @param receiverPosition fixed position of receiver at {@code signalArrivalDate}
  319.      * @param signalArrivalDate date at which the signal arrives to receiver
  320.      * @param receiverFrame frame in which receiver is defined
  321.      * @return <em>positive</em> delay between signal emission and signal reception dates
  322.      * @since 12.1
  323.      */
  324.     public static double signalTimeOfFlight(final PVCoordinatesProvider adjustableEmitter,
  325.                                             final AbsoluteDate approxEmissionDate,
  326.                                             final Vector3D receiverPosition,
  327.                                             final AbsoluteDate signalArrivalDate,
  328.                                             final Frame receiverFrame) {

  330.         // initialize emission date search loop assuming the state is already correct
  331.         // this will be true for all but the first orbit determination iteration,
  332.         // and even for the first iteration the loop will converge very fast
  333.         final double offset = signalArrivalDate.durationFrom(approxEmissionDate);
  334.         double delay = offset;

  336.         // search signal transit date, computing the signal travel in inertial frame
  337.         final double cReciprocal = 1.0 / Constants.SPEED_OF_LIGHT;
  338.         double delta;
  339.         int count = 0;
  340.         do {
  341.             final double previous   = delay;
  342.             final Vector3D transitP = adjustableEmitter.getPosition(approxEmissionDate.shiftedBy(offset - delay),
  343.                                                                     receiverFrame);
  344.             delay                   = receiverPosition.distance(transitP) * cReciprocal;
  345.             delta                   = FastMath.abs(delay - previous);
  346.         } while (count++ < 10 && delta >= 2 * FastMath.ulp(delay));

  348.         return delay;

  350.     }

  352.     /** Compute propagation delay on a link leg (typically downlink or uplink).
  353.      * @param adjustableEmitterPV position/velocity of emitter that may be adjusted
  354.      * @param receiverPosition fixed position of receiver at {@code signalArrivalDate},
  355.      * in the same frame as {@code adjustableEmitterPV}
  356.      * @param signalArrivalDate date at which the signal arrives to receiver
  357.      * @return <em>positive</em> delay between signal emission and signal reception dates
  358.      * @param <T> the type of the components
  359.      * @deprecated as of 12.1, replaced by either {@link #signalTimeOfFlight(TimeStampedFieldPVCoordinates,
  360.      * FieldVector3D, FieldAbsoluteDate, Frame)} or {@link #signalTimeOfFlight(FieldPVCoordinatesProvider,
  361.      * FieldAbsoluteDate, FieldVector3D, FieldAbsoluteDate, Frame)}
  362.      */
  363.     @Deprecated
  364.     @DefaultDataContext
  365.     public static <T extends CalculusFieldElement<T>> T signalTimeOfFlight(final TimeStampedFieldPVCoordinates<T> adjustableEmitterPV,
  366.                                                                            final FieldVector3D<T> receiverPosition,
  367.                                                                            final FieldAbsoluteDate<T> signalArrivalDate) {
  368.         return signalTimeOfFlight(adjustableEmitterPV, receiverPosition, signalArrivalDate,
  369.                                   FramesFactory.getGCRF());
  370.     }

  372.     /** Compute propagation delay on a link leg (typically downlink or uplink).
  373.      * @param adjustableEmitterPV position/velocity of emitter that may be adjusted
  374.      * @param receiverPosition fixed position of receiver at {@code signalArrivalDate},
  375.      * in the same frame as {@code adjustableEmitterPV}
  376.      * @param signalArrivalDate date at which the signal arrives to receiver
  377.      * @return <em>positive</em> delay between signal emission and signal reception dates
  378.      * @param receiverFrame frame in which receiver is defined
  379.      * @param <T> the type of the components
  380.      * @since 12.1
  381.      */
  382.     public static <T extends CalculusFieldElement<T>> T signalTimeOfFlight(final TimeStampedFieldPVCoordinates<T> adjustableEmitterPV,
  383.                                                                            final FieldVector3D<T> receiverPosition,
  384.                                                                            final FieldAbsoluteDate<T> signalArrivalDate,
  385.                                                                            final Frame receiverFrame) {
  386.         return signalTimeOfFlight(new FieldShiftingPVCoordinatesProvider<>(adjustableEmitterPV,
  387.                                                                            receiverFrame),
  388.                                   adjustableEmitterPV.getDate(),
  389.                                   receiverPosition, signalArrivalDate,
  390.                                   receiverFrame);
  391.     }

  393.     /** Compute propagation delay on a link leg (typically downlink or uplink).
  394.      * @param adjustableEmitter position/velocity provider of emitter
  395.      * @param approxEmissionDate approximate emission date
  396.      * @param receiverPosition fixed position of receiver at {@code signalArrivalDate},
  397.      * in the same frame as {@code adjustableEmitterPV}
  398.      * @param signalArrivalDate date at which the signal arrives to receiver
  399.      * @param receiverFrame frame in which receiver is defined
  400.      * @return <em>positive</em> delay between signal emission and signal reception dates
  401.      * @param <T> the type of the components
  402.      * @since 12.1
  403.      */
  404.     public static <T extends CalculusFieldElement<T>> T signalTimeOfFlight(final FieldPVCoordinatesProvider<T> adjustableEmitter,
  405.                                                                            final FieldAbsoluteDate<T> approxEmissionDate,
  406.                                                                            final FieldVector3D<T> receiverPosition,
  407.                                                                            final FieldAbsoluteDate<T> signalArrivalDate,
  408.                                                                            final Frame receiverFrame) {

  410.         // Initialize emission date search loop assuming the emitter PV is almost correct
  411.         // this will be true for all but the first orbit determination iteration,
  412.         // and even for the first iteration the loop will converge extremely fast
  413.         final T offset = signalArrivalDate.durationFrom(approxEmissionDate);
  414.         T delay = offset;

  416.         // search signal transit date, computing the signal travel in the frame shared by emitter and receiver
  417.         final double cReciprocal = 1.0 / Constants.SPEED_OF_LIGHT;
  418.         double delta;
  419.         int count = 0;
  420.         do {
  421.             final double previous           = delay.getReal();
  422.             final FieldVector3D<T> transitP = adjustableEmitter.getPosition(approxEmissionDate.shiftedBy(offset.subtract(delay)),
  423.                                                                             receiverFrame);
  424.             delay                           = receiverPosition.distance(transitP).multiply(cReciprocal);
  425.             delta                           = FastMath.abs(delay.getReal() - previous);
  426.         } while (count++ < 10 && delta >= 2 * FastMath.ulp(delay.getReal()));

  428.         return delay;

  430.     }

  432.     /** Get Cartesian coordinates as derivatives.
  433.      * <p>
  434.      * The position will correspond to variables {@code firstDerivative},
  435.      * {@code firstDerivative + 1} and {@code firstDerivative + 2}.
  436.      * The velocity will correspond to variables {@code firstDerivative + 3},
  437.      * {@code firstDerivative + 4} and {@code firstDerivative + 5}.
  438.      * The acceleration will correspond to constants.
  439.      * </p>
  440.      * @param state state of the satellite considered
  441.      * @param firstDerivative index of the first derivative
  442.      * @param freeParameters total number of free parameters in the gradient
  443.      * @return Cartesian coordinates as derivatives
  444.      * @since 10.2
  445.      */
  446.     public static TimeStampedFieldPVCoordinates<Gradient> getCoordinates(final SpacecraftState state,
  447.                                                                          final int firstDerivative,
  448.                                                                          final int freeParameters) {

  450.         // Position of the satellite expressed as a gradient
  451.         // The components of the position are the 3 first derivative parameters
  452.         final Vector3D p = state.getPosition();
  453.         final FieldVector3D<Gradient> pDS =
  454.                         new FieldVector3D<>(Gradient.variable(freeParameters, firstDerivative + 0, p.getX()),
  455.                                             Gradient.variable(freeParameters, firstDerivative + 1, p.getY()),
  456.                                             Gradient.variable(freeParameters, firstDerivative + 2, p.getZ()));

  458.         // Velocity of the satellite expressed as a gradient
  459.         // The components of the velocity are the 3 second derivative parameters
  460.         final Vector3D v = state.getPVCoordinates().getVelocity();
  461.         final FieldVector3D<Gradient> vDS =
  462.                         new FieldVector3D<>(Gradient.variable(freeParameters, firstDerivative + 3, v.getX()),
  463.                                             Gradient.variable(freeParameters, firstDerivative + 4, v.getY()),
  464.                                             Gradient.variable(freeParameters, firstDerivative + 5, v.getZ()));

  466.         // Acceleration of the satellite
  467.         // The components of the acceleration are not derivative parameters
  468.         final Vector3D a = state.getPVCoordinates().getAcceleration();
  469.         final FieldVector3D<Gradient> aDS =
  470.                         new FieldVector3D<>(Gradient.constant(freeParameters, a.getX()),
  471.                                             Gradient.constant(freeParameters, a.getY()),
  472.                                             Gradient.constant(freeParameters, a.getZ()));

  474.         return new TimeStampedFieldPVCoordinates<>(state.getDate(), pDS, vDS, aDS);

  476.     }

  478. }
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