AbstractPropagatorBuilder.java

  1. /* Copyright 2002-2017 CS Systèmes d'Information
  2.  * Licensed to CS Systèmes d'Information (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.propagation.conversion;

  19. import org.hipparchus.exception.LocalizedCoreFormats;
  20. import org.hipparchus.util.FastMath;
  21. import org.orekit.errors.OrekitException;
  22. import org.orekit.errors.OrekitIllegalArgumentException;
  23. import org.orekit.forces.gravity.NewtonianAttraction;
  24. import org.orekit.frames.Frame;
  25. import org.orekit.orbits.Orbit;
  26. import org.orekit.orbits.OrbitType;
  27. import org.orekit.orbits.PositionAngle;
  28. import org.orekit.time.AbsoluteDate;
  29. import org.orekit.utils.ParameterDriver;
  30. import org.orekit.utils.ParameterDriversList;
  31. import org.orekit.utils.ParameterDriversList.DelegatingDriver;
  32. import org.orekit.utils.ParameterObserver;

  34. /** Base class for propagator builders.
  35.  * @author Pascal Parraud
  36.  * @since 7.1
  37.  */
  38. public abstract class AbstractPropagatorBuilder implements PropagatorBuilder {

  40.     /** Central attraction scaling factor.
  41.      * <p>
  42.      * We use a power of 2 to avoid numeric noise introduction
  43.      * in the multiplications/divisions sequences.
  44.      * </p>
  45.      */
  46.     private static final double MU_SCALE = FastMath.scalb(1.0, 32);

  48.     /** Date of the initial orbit. */
  49.     private final AbsoluteDate initialOrbitDate;

  51.     /** Frame in which the orbit is propagated. */
  52.     private final Frame frame;

  54.     /** Central attraction coefficient (m³/s²). */
  55.     private double mu;

  57.     /** Drivers for orbital parameters. */
  58.     private final ParameterDriversList orbitalDrivers;

  60.     /** List of the supported parameters. */
  61.     private ParameterDriversList propagationDrivers;

  63.     /** Orbit type to use. */
  64.     private final OrbitType orbitType;

  66.     /** Position angle type to use. */
  67.     private final PositionAngle positionAngle;

  69.     /** Build a new instance.
  70.      * <p>
  71.      * The template orbit is used as a model to {@link
  72.      * #createInitialOrbit() create initial orbit}. It defines the
  73.      * inertial frame, the central attraction coefficient, the orbit type, and is also
  74.      * used together with the {@code positionScale} to convert from the {@link
  75.      * ParameterDriver#setNormalizedValue(double) normalized} parameters used by the
  76.      * callers of this builder to the real orbital parameters.
  77.      * </p>
  78.      * <p>
  79.      * By default, all the {@link #getOrbitalParametersDrivers() orbital parameters drivers}
  80.      * are selected, which means that if the builder is used for orbit determination or
  81.      * propagator conversion, all orbital parameters will be estimated. If only a subset
  82.      * of the orbital parameters must be estimated, caller must retrieve the orbital
  83.      * parameters by calling {@link #getOrbitalParametersDrivers()} and then call
  84.      * {@link ParameterDriver#setSelected(boolean) setSelected(false)}.
  85.      * </p>
  86.      * @param templateOrbit reference orbit from which real orbits will be built
  87.      * @param positionAngle position angle type to use
  88.      * @param positionScale scaling factor used for orbital parameters normalization
  89.      * (typically set to the expected standard deviation of the position)
  90.      * @param addDriverForCentralAttraction if true, a {@link ParameterDriver} should
  91.      * be set up for central attraction coefficient
  92.      * @exception OrekitException if parameters drivers cannot be scaled
  93.      * @since 8.0
  94.      */
  95.     protected AbstractPropagatorBuilder(final Orbit templateOrbit, final PositionAngle positionAngle,
  96.                                         final double positionScale, final boolean addDriverForCentralAttraction)
  97.         throws OrekitException {

  99.         this.initialOrbitDate    = templateOrbit.getDate();
  100.         this.frame               = templateOrbit.getFrame();
  101.         this.mu                  = templateOrbit.getMu();
  102.         this.propagationDrivers  = new ParameterDriversList();
  103.         this.orbitType           = templateOrbit.getType();
  104.         this.positionAngle       = positionAngle;
  105.         this.orbitalDrivers      = orbitType.getDrivers(positionScale, templateOrbit, positionAngle);
  106.         for (final DelegatingDriver driver : orbitalDrivers.getDrivers()) {
  107.             driver.setSelected(true);
  108.         }

  110.         if (addDriverForCentralAttraction) {
  111.             final ParameterDriver muDriver = new ParameterDriver(NewtonianAttraction.CENTRAL_ATTRACTION_COEFFICIENT,
  112.                                                                  mu, MU_SCALE, 0, Double.POSITIVE_INFINITY);
  113.             muDriver.addObserver(new ParameterObserver() {
  114.                 /** {@inheridDoc} */
  115.                 @Override
  116.                 public void valueChanged(final double previousValue, final ParameterDriver driver) {
  117.                     AbstractPropagatorBuilder.this.mu = driver.getValue();
  118.                 }
  119.             });
  120.             propagationDrivers.add(muDriver);
  121.         }

  123.     }

  125.     /** {@inheritDoc} */
  126.     public OrbitType getOrbitType() {
  127.         return orbitType;
  128.     }

  130.     /** {@inheritDoc} */
  131.     public PositionAngle getPositionAngle() {
  132.         return positionAngle;
  133.     }

  135.     /** {@inheritDoc} */
  136.     public AbsoluteDate getInitialOrbitDate() {
  137.         return initialOrbitDate;
  138.     }

  140.     /** {@inheritDoc} */
  141.     public Frame getFrame() {
  142.         return frame;
  143.     }

  145.     /** {@inheritDoc} */
  146.     public ParameterDriversList getOrbitalParametersDrivers() {
  147.         return orbitalDrivers;
  148.     }

  150.     /** {@inheritDoc} */
  151.     public ParameterDriversList getPropagationParametersDrivers() {
  152.         return propagationDrivers;
  153.     }

  155.     /** Get the number of selected parameters.
  156.      * @return number of selected parameters
  157.      */
  158.     private int getNbSelected() {

  160.         int count = 0;

  162.         // count orbital parameters
  163.         for (final ParameterDriver driver : orbitalDrivers.getDrivers()) {
  164.             if (driver.isSelected()) {
  165.                 ++count;
  166.             }
  167.         }

  169.         // count propagation parameters
  170.         for (final ParameterDriver driver : propagationDrivers.getDrivers()) {
  171.             if (driver.isSelected()) {
  172.                 ++count;
  173.             }
  174.         }

  176.         return count;

  178.     }

  180.     /** {@inheritDoc} */
  181.     public double[] getSelectedNormalizedParameters() {

  183.         // allocate array
  184.         final double[] selected = new double[getNbSelected()];

  186.         // fill data
  187.         int index = 0;
  188.         for (final ParameterDriver driver : orbitalDrivers.getDrivers()) {
  189.             if (driver.isSelected()) {
  190.                 selected[index++] = driver.getNormalizedValue();
  191.             }
  192.         }
  193.         for (final ParameterDriver driver : propagationDrivers.getDrivers()) {
  194.             if (driver.isSelected()) {
  195.                 selected[index++] = driver.getNormalizedValue();
  196.             }
  197.         }

  199.         return selected;

  201.     }

  203.     /** Build an initial orbit using the current selected parameters.
  204.      * <p>
  205.      * This method is a stripped down version of {@link #buildPropagator(double[])}
  206.      * that only builds the initial orbit and not the full propagator.
  207.      * </p>
  208.      * @return an initial orbit
  209.      * @since 8.0
  210.      */
  211.     protected Orbit createInitialOrbit() {
  212.         final double[] unNormalized = new double[orbitalDrivers.getNbParams()];
  213.         for (int i = 0; i < unNormalized.length; ++i) {
  214.             unNormalized[i] = orbitalDrivers.getDrivers().get(i).getValue();
  215.         }
  216.         return getOrbitType().mapArrayToOrbit(unNormalized, null, positionAngle, initialOrbitDate, mu, frame);
  217.     }

  219.     /** Set the selected parameters.
  220.      * @param normalizedParameters normalized values for the selected parameters
  221.      * @exception OrekitException if some parameter cannot be set to the specified value
  222.      * @exception OrekitIllegalArgumentException if the number of parameters is not the
  223.      * number of selected parameters (adding orbits and models parameters)
  224.      */
  225.     protected void setParameters(final double[] normalizedParameters)
  226.         throws OrekitException, OrekitIllegalArgumentException {


  229.         if (normalizedParameters.length != getNbSelected()) {
  230.             throw new OrekitIllegalArgumentException(LocalizedCoreFormats.DIMENSIONS_MISMATCH,
  231.                                                      normalizedParameters.length,
  232.                                                      getNbSelected());
  233.         }

  235.         int index = 0;

  237.         // manage orbital parameters
  238.         for (final ParameterDriver driver : orbitalDrivers.getDrivers()) {
  239.             if (driver.isSelected()) {
  240.                 driver.setNormalizedValue(normalizedParameters[index++]);
  241.             }
  242.         }

  244.         // manage propagation parameters
  245.         for (final ParameterDriver driver : propagationDrivers.getDrivers()) {
  246.             if (driver.isSelected()) {
  247.                 driver.setNormalizedValue(normalizedParameters[index++]);
  248.             }
  249.         }

  251.     }

  253.     /** Add a supported parameter.
  254.      * @param driver driver for the parameter
  255.      * @exception OrekitException if the name is already supported
  256.      */
  257.     protected void addSupportedParameter(final ParameterDriver driver)
  258.         throws OrekitException {
  259.         propagationDrivers.add(driver);
  260.         propagationDrivers.sort();
  261.     }

  263. }
Created with JaCoCo 0.7.9.201702052155