AbstractAnalyticalGradientConverter.java
- /* Copyright 2002-2022 CS GROUP
- * Licensed to CS GROUP (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.propagation.analytical;
- import java.util.ArrayList;
- import java.util.List;
- import org.hipparchus.analysis.differentiation.Gradient;
- import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
- import org.hipparchus.geometry.euclidean.threed.Vector3D;
- import org.orekit.attitudes.AttitudeProvider;
- import org.orekit.attitudes.FieldAttitude;
- import org.orekit.orbits.FieldCartesianOrbit;
- import org.orekit.orbits.FieldOrbit;
- import org.orekit.propagation.FieldSpacecraftState;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.propagation.integration.AbstractGradientConverter;
- import org.orekit.utils.FieldAngularCoordinates;
- import org.orekit.utils.FieldPVCoordinates;
- import org.orekit.utils.ParameterDriver;
- import org.orekit.utils.TimeStampedFieldAngularCoordinates;
- import org.orekit.utils.TimeStampedFieldPVCoordinates;
- /**
- * Converter for analytical orbit propagator.
- *
- * @author Bryan Cazabonne
- * @since 11.1
- */
- public abstract class AbstractAnalyticalGradientConverter extends AbstractGradientConverter {
- /** Attitude provider. */
- private final AttitudeProvider provider;
- /** States with various number of additional propagation parameters. */
- private final List<FieldSpacecraftState<Gradient>> gStates;
- /**
- * Constructor.
- * @param propagator analytical orbit propagator
- * @param mu central attraction coefficient
- * @param freeStateParameters number of free parameters
- */
- protected AbstractAnalyticalGradientConverter(final AbstractAnalyticalPropagator propagator,
- final double mu,
- final int freeStateParameters) {
- super(freeStateParameters);
- // Attitude provider
- this.provider = propagator.getAttitudeProvider();
- // Spacecraft state
- final SpacecraftState state = propagator.getInitialState();
- // Position always has derivatives
- final Vector3D pos = state.getPVCoordinates().getPosition();
- final FieldVector3D<Gradient> posG = new FieldVector3D<>(Gradient.variable(freeStateParameters, 0, pos.getX()),
- Gradient.variable(freeStateParameters, 1, pos.getY()),
- Gradient.variable(freeStateParameters, 2, pos.getZ()));
- // Velocity may have derivatives or not
- final Vector3D vel = state.getPVCoordinates().getVelocity();
- final FieldVector3D<Gradient> velG = new FieldVector3D<>(Gradient.variable(freeStateParameters, 3, vel.getX()),
- Gradient.variable(freeStateParameters, 4, vel.getY()),
- Gradient.variable(freeStateParameters, 5, vel.getZ()));
- // Acceleration never has derivatives
- final Vector3D acc = state.getPVCoordinates().getAcceleration();
- final FieldVector3D<Gradient> accG = new FieldVector3D<>(Gradient.constant(freeStateParameters, acc.getX()),
- Gradient.constant(freeStateParameters, acc.getY()),
- Gradient.constant(freeStateParameters, acc.getZ()));
- // Mass never has derivatives
- final Gradient gM = Gradient.constant(freeStateParameters, state.getMass());
- final Gradient gMu = Gradient.constant(freeStateParameters, mu);
- final FieldOrbit<Gradient> gOrbit =
- new FieldCartesianOrbit<>(new TimeStampedFieldPVCoordinates<>(state.getDate(), posG, velG, accG),
- state.getFrame(), gMu);
- // Attitude
- final FieldAttitude<Gradient> gAttitude = provider.getAttitude(gOrbit, gOrbit.getDate(), gOrbit.getFrame());
- // Initialize the list with the state having 0 force model parameters
- gStates = new ArrayList<>();
- gStates.add(new FieldSpacecraftState<>(gOrbit, gAttitude, gM));
- }
- /** Get the state with the number of parameters consistent with the propagation model.
- * @return state with the number of parameters consistent with the propagation model
- */
- public FieldSpacecraftState<Gradient> getState() {
- // Count the required number of parameters
- int nbParams = 0;
- for (final ParameterDriver driver : getParametersDrivers()) {
- if (driver.isSelected()) {
- ++nbParams;
- }
- }
- // Fill in intermediate slots
- while (gStates.size() < nbParams + 1) {
- gStates.add(null);
- }
- if (gStates.get(nbParams) == null) {
- // It is the first time we need this number of parameters
- // We need to create the state
- final int freeParameters = getFreeStateParameters() + nbParams;
- final FieldSpacecraftState<Gradient> s0 = gStates.get(0);
- // Orbit
- final FieldPVCoordinates<Gradient> pv0 = s0.getPVCoordinates();
- final FieldOrbit<Gradient> gOrbit =
- new FieldCartesianOrbit<>(new TimeStampedFieldPVCoordinates<>(s0.getDate().toAbsoluteDate(),
- extend(pv0.getPosition(), freeParameters),
- extend(pv0.getVelocity(), freeParameters),
- extend(pv0.getAcceleration(), freeParameters)),
- s0.getFrame(),
- extend(s0.getMu(), freeParameters));
- // Attitude
- final FieldAngularCoordinates<Gradient> ac0 = s0.getAttitude().getOrientation();
- final FieldAttitude<Gradient> gAttitude =
- new FieldAttitude<>(s0.getAttitude().getReferenceFrame(),
- new TimeStampedFieldAngularCoordinates<>(gOrbit.getDate(),
- extend(ac0.getRotation(), freeParameters),
- extend(ac0.getRotationRate(), freeParameters),
- extend(ac0.getRotationAcceleration(), freeParameters)));
- // Mass
- final Gradient gM = extend(s0.getMass(), freeParameters);
- gStates.set(nbParams, new FieldSpacecraftState<>(gOrbit, gAttitude, gM));
- }
- return gStates.get(nbParams);
- }
- /** Get the model parameters.
- * @param state state as returned by {@link #getState()}
- * @return the model parameters
- */
- public Gradient[] getParameters(final FieldSpacecraftState<Gradient> state) {
- final int freeParameters = state.getMass().getFreeParameters();
- final List<ParameterDriver> drivers = getParametersDrivers();
- final Gradient[] parameters = new Gradient[drivers.size()];
- int index = getFreeStateParameters();
- int i = 0;
- for (ParameterDriver driver : drivers) {
- parameters[i++] = driver.isSelected() ?
- Gradient.variable(freeParameters, index++, driver.getValue()) :
- Gradient.constant(freeParameters, driver.getValue());
- }
- return parameters;
- }
- /**
- * Get the parameter drivers related to the analytical propagation model.
- * @return a list of parameter drivers
- */
- public abstract List<ParameterDriver> getParametersDrivers();
- /**
- * Get the converted analytical orbit propagator.
- * @param state state as returned by {@link #getState()}
- * @param parameters model parameters as returned by {@link #getParameters(FieldSpacecraftState)}
- * @return the converted analytical orbit propagator
- */
- public abstract FieldAbstractAnalyticalPropagator<Gradient> getPropagator(FieldSpacecraftState<Gradient> state,
- Gradient[] parameters);
- }