DSSTPropagatorBuilder.java

  1. /* Copyright 2002-2025 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.propagation.conversion;

  19. import org.orekit.attitudes.Attitude;
  20. import org.orekit.attitudes.AttitudeProvider;
  21. import org.orekit.attitudes.FrameAlignedProvider;
  22. import org.orekit.estimation.leastsquares.DSSTBatchLSModel;
  23. import org.orekit.estimation.leastsquares.ModelObserver;
  24. import org.orekit.estimation.measurements.ObservedMeasurement;
  25. import org.orekit.orbits.EquinoctialOrbit;
  26. import org.orekit.orbits.Orbit;
  27. import org.orekit.orbits.OrbitType;
  28. import org.orekit.orbits.PositionAngleType;
  29. import org.orekit.propagation.PropagationType;
  30. import org.orekit.propagation.Propagator;
  31. import org.orekit.propagation.SpacecraftState;
  32. import org.orekit.propagation.integration.AdditionalDerivativesProvider;
  33. import org.orekit.propagation.semianalytical.dsst.DSSTPropagator;
  34. import org.orekit.propagation.semianalytical.dsst.forces.DSSTForceModel;
  35. import org.orekit.propagation.semianalytical.dsst.forces.DSSTNewtonianAttraction;
  36. import org.orekit.utils.ParameterDriver;
  37. import org.orekit.utils.ParameterDriversList;

  39. import java.util.ArrayList;
  40. import java.util.Collections;
  41. import java.util.List;

  43. /** Builder for DSST propagator.
  44.  * @author Bryan Cazabonne
  45.  * @since 10.0
  46.  */
  47. public class DSSTPropagatorBuilder extends AbstractIntegratedPropagatorBuilder<DSSTPropagator> {

  49.     /** Force models used during the extrapolation of the orbit. */
  50.     private final List<DSSTForceModel> forceModels;

  52.     /** Type of the elements used to define the orbital state.*/
  53.     private PropagationType stateType;

  55.     /** Build a new instance.
  56.      * <p>
  57.      * The reference orbit is used as a model to {@link
  58.      * #createInitialOrbit() create initial orbit}. It defines the
  59.      * inertial frame, the central attraction coefficient, and is also used together
  60.      * with the {@code positionScale} to convert from the {@link
  61.      * ParameterDriver#setNormalizedValue(double) normalized} parameters used by the
  62.      * callers of this builder to the real orbital parameters.
  63.      * The default attitude provider is aligned with the orbit's inertial frame.
  64.      * </p>
  65.      *
  66.      * @param referenceOrbit reference orbit from which real orbits will be built
  67.      * @param builder first order integrator builder
  68.      * @param positionScale scaling factor used for orbital parameters normalization
  69.      * (typically set to the expected standard deviation of the position)
  70.      * @param propagationType type of the orbit used for the propagation (mean or osculating)
  71.      * @param stateType type of the elements used to define the orbital state (mean or osculating)
  72.      * @see #DSSTPropagatorBuilder(Orbit, ODEIntegratorBuilder, double, PropagationType,
  73.      * PropagationType, AttitudeProvider)
  74.      */
  75.     public DSSTPropagatorBuilder(final Orbit referenceOrbit,
  76.                                  final ODEIntegratorBuilder builder,
  77.                                  final double positionScale,
  78.                                  final PropagationType propagationType,
  79.                                  final PropagationType stateType) {
  80.         this(referenceOrbit, builder, positionScale, propagationType, stateType,
  81.              FrameAlignedProvider.of(referenceOrbit.getFrame()));
  82.     }

  84.     /** Build a new instance.
  85.      * <p>
  86.      * The reference orbit is used as a model to {@link
  87.      * #createInitialOrbit() create initial orbit}. It defines the
  88.      * inertial frame, the central attraction coefficient, and is also used together
  89.      * with the {@code positionScale} to convert from the {@link
  90.      * ParameterDriver#setNormalizedValue(double) normalized} parameters used by the
  91.      * callers of this builder to the real orbital parameters.
  92.      * </p>
  93.      * @param referenceOrbit reference orbit from which real orbits will be built
  94.      * @param builder first order integrator builder
  95.      * @param positionScale scaling factor used for orbital parameters normalization
  96.      * (typically set to the expected standard deviation of the position)
  97.      * @param propagationType type of the orbit used for the propagation (mean or osculating)
  98.      * @param stateType type of the elements used to define the orbital state (mean or osculating)
  99.      * @param attitudeProvider attitude law.
  100.      * @since 10.1
  101.      */
  102.     public DSSTPropagatorBuilder(final Orbit referenceOrbit,
  103.                                  final ODEIntegratorBuilder builder,
  104.                                  final double positionScale,
  105.                                  final PropagationType propagationType,
  106.                                  final PropagationType stateType,
  107.                                  final AttitudeProvider attitudeProvider) {
  108.         super(referenceOrbit, builder, PositionAngleType.MEAN, positionScale, propagationType, attitudeProvider, Propagator.DEFAULT_MASS);
  109.         this.forceModels       = new ArrayList<>();
  110.         this.stateType         = stateType;
  111.     }

  113.     /** Copy constructor.
  114.      * @param builder builder to copy from
  115.      */
  116.     private DSSTPropagatorBuilder(final DSSTPropagatorBuilder builder) {
  117.         this(builder.createInitialOrbit(), builder.getIntegratorBuilder(),
  118.              builder.getPositionScale(), builder.getPropagationType(),
  119.              builder.getStateType(), builder.getAttitudeProvider());
  120.     }

  122.     /** {@inheritDoc}. */
  123.     @Override
  124.     public DSSTPropagatorBuilder clone() {
  125.         // Call to super clone() method to avoid warning
  126.         final DSSTPropagatorBuilder clonedBuilder = (DSSTPropagatorBuilder) super.clone();

  128.         // Use copy constructor to unlink orbital drivers
  129.         final DSSTPropagatorBuilder copyBuilder = new DSSTPropagatorBuilder(clonedBuilder);

  131.         // Update mass and force models
  132.         copyBuilder.setMass(getMass());
  133.         for (DSSTForceModel model : forceModels) {
  134.             copyBuilder.addForceModel(model);
  135.         }
  136.         return copyBuilder;

  138.     }

  140.     /** Get the type of the elements used to define the orbital state (mean or osculating).
  141.      * @return the type of the elements used to define the orbital state
  142.      */
  143.     public PropagationType getStateType() {
  144.         return stateType;
  145.     }

  147.     /** Get the list of all force models.
  148.      * @return the list of all force models
  149.      */
  150.     public List<DSSTForceModel> getAllForceModels()
  151.     {
  152.         return Collections.unmodifiableList(forceModels);
  153.     }

  155.     /** Add a force model to the global perturbation model.
  156.      * <p>If this method is not called at all, the integrated orbit will follow
  157.      * a Keplerian evolution only.</p>
  158.      * @param model perturbing {@link DSSTForceModel} to add
  159.      */
  160.     public void addForceModel(final DSSTForceModel model) {
  161.         if (model instanceof DSSTNewtonianAttraction) {
  162.             // we want to add the central attraction force model
  163.             if (hasNewtonianAttraction()) {
  164.                 // there is already a central attraction model, replace it
  165.                 forceModels.set(forceModels.size() - 1, model);
  166.             } else {
  167.                 // there are no central attraction model yet, add it at the end of the list
  168.                 forceModels.add(model);
  169.             }
  170.         } else {
  171.             // we want to add a perturbing force model
  172.             if (hasNewtonianAttraction()) {
  173.                 // insert the new force model before Newtonian attraction,
  174.                 // which should always be the last one in the list
  175.                 forceModels.add(forceModels.size() - 1, model);
  176.             } else {
  177.                 // we only have perturbing force models up to now, just append at the end of the list
  178.                 forceModels.add(model);
  179.             }
  180.         }

  182.         addSupportedParameters(model.getParametersDrivers());
  183.     }

  185.     /** Reset the orbit in the propagator builder.
  186.      * @param newOrbit newOrbit New orbit to set in the propagator builder
  187.      * @param orbitType orbit type (MEAN or OSCULATING)
  188.      */
  189.     public void resetOrbit(final Orbit newOrbit, final PropagationType orbitType) {
  190.         this.stateType = orbitType;
  191.         super.resetOrbit(newOrbit);
  192.     }

  194.     /** {@inheritDoc} */
  195.     public DSSTPropagator buildPropagator(final double[] normalizedParameters) {

  197.         setParameters(normalizedParameters);
  198.         final EquinoctialOrbit orbit    = (EquinoctialOrbit) OrbitType.EQUINOCTIAL.convertType(createInitialOrbit());
  199.         final Attitude         attitude = getAttitudeProvider().getAttitude(orbit, orbit.getDate(), getFrame());
  200.         final SpacecraftState  state    = new SpacecraftState(orbit, attitude).withMass(getMass());

  202.         final DSSTPropagator propagator = new DSSTPropagator(
  203.                 getIntegratorBuilder().buildIntegrator(orbit, OrbitType.EQUINOCTIAL, PositionAngleType.MEAN),
  204.                 getPropagationType(), getAttitudeProvider());

  206.         // Configure force models
  207.         if (!hasNewtonianAttraction()) {
  208.             // There are no central attraction model yet, add it at the end of the list
  209.             addForceModel(new DSSTNewtonianAttraction(orbit.getMu()));
  210.         }
  211.         for (DSSTForceModel model : forceModels) {
  212.             propagator.addForceModel(model);
  213.         }

  215.         propagator.setInitialState(state, stateType);

  217.         // Add additional derivatives providers to the propagator
  218.         for (AdditionalDerivativesProvider provider: getAdditionalDerivativesProviders()) {
  219.             propagator.addAdditionalDerivativesProvider(provider);
  220.         }

  222.         return propagator;

  224.     }

  226.     /** {@inheritDoc} */
  227.     @Override
  228.     public DSSTBatchLSModel buildLeastSquaresModel(final PropagatorBuilder[] builders,
  229.                                                    final List<ObservedMeasurement<?>> measurements,
  230.                                                    final ParameterDriversList estimatedMeasurementsParameters,
  231.                                                    final ModelObserver observer) {
  232.         return new DSSTBatchLSModel(builders,
  233.                                     measurements,
  234.                                     estimatedMeasurementsParameters,
  235.                                     observer,
  236.                                     getPropagationType());
  237.     }

  239.     /** Check if Newtonian attraction force model is available.
  240.      * <p>
  241.      * Newtonian attraction is always the last force model in the list.
  242.      * </p>
  243.      * @return true if Newtonian attraction force model is available
  244.      */
  245.     private boolean hasNewtonianAttraction() {
  246.         final int last = forceModels.size() - 1;
  247.         return last >= 0 && forceModels.get(last) instanceof DSSTNewtonianAttraction;
  248.     }

  250. }
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