DSSTNewtonianAttraction.java
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* 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
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.propagation.semianalytical.dsst.forces;
import java.util.Collections;
import java.util.List;
import org.hipparchus.Field;
import org.hipparchus.RealFieldElement;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.MathArrays;
import org.orekit.attitudes.AttitudeProvider;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitInternalError;
import org.orekit.orbits.EquinoctialOrbit;
import org.orekit.orbits.FieldEquinoctialOrbit;
import org.orekit.orbits.OrbitType;
import org.orekit.orbits.PositionAngle;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.PropagationType;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.events.EventDetector;
import org.orekit.propagation.events.FieldEventDetector;
import org.orekit.propagation.semianalytical.dsst.DSSTPropagator;
import org.orekit.propagation.semianalytical.dsst.utilities.AuxiliaryElements;
import org.orekit.propagation.semianalytical.dsst.utilities.FieldAuxiliaryElements;
import org.orekit.utils.ParameterDriver;
/** Force model for Newtonian central body attraction for the {@link DSSTPropagator DSST propagator}.
* @author Bryan Cazabonne
* @author Luc Maisonobe
* @since 10.0
*/
public class DSSTNewtonianAttraction implements DSSTForceModel {
/** Name of the single parameter of this model: the central attraction coefficient. */
public static final String CENTRAL_ATTRACTION_COEFFICIENT = "central attraction coefficient";
/** Central attraction scaling factor.
* <p>
* We use a power of 2 to avoid numeric noise introduction
* in the multiplications/divisions sequences.
* </p>
*/
private static final double MU_SCALE = FastMath.scalb(1.0, 32);
/** Driver for gravitational parameter. */
private final ParameterDriver gmParameterDriver;
/** Simple constructor.
* @param mu central attraction coefficient (m^3/s^2)
*/
public DSSTNewtonianAttraction(final double mu) {
try {
gmParameterDriver = new ParameterDriver(DSSTNewtonianAttraction.CENTRAL_ATTRACTION_COEFFICIENT,
mu, MU_SCALE,
0.0, Double.POSITIVE_INFINITY);
} catch (OrekitException oe) {
// this should never occur as valueChanged above never throws an exception
throw new OrekitInternalError(oe);
}
}
/** Get the central attraction coefficient μ.
* @return mu central attraction coefficient (m³/s²)
*/
public double getMu() {
return gmParameterDriver.getValue();
}
/** {@inheritDoc} */
@Override
public List<ShortPeriodTerms> initialize(final AuxiliaryElements auxiliaryElements,
final PropagationType type,
final double[] parameters) {
return Collections.emptyList();
}
/** {@inheritDoc} */
@Override
public <T extends RealFieldElement<T>> List<FieldShortPeriodTerms<T>> initialize(final FieldAuxiliaryElements<T> auxiliaryElements,
final PropagationType type,
final T[] parameters) {
return Collections.emptyList();
}
/** Performs initialization at each integration step for the current force model.
* <p>
* This method aims at being called before mean elements rates computation.
* </p>
* @param auxiliaryElements auxiliary elements related to the current orbit
* @param parameters values of the force model parameters
* @return new force model context
*/
private DSSTNewtonianAttractionContext initializeStep(final AuxiliaryElements auxiliaryElements, final double[] parameters) {
return new DSSTNewtonianAttractionContext(auxiliaryElements, parameters);
}
/** Performs initialization at each integration step for the current force model.
* <p>
* This method aims at being called before mean elements rates computation.
* </p>
* @param <T> type of the elements
* @param auxiliaryElements auxiliary elements related to the current orbit
* @param parameters values of the force model parameters
* @return new force model context
*/
private <T extends RealFieldElement<T>> FieldDSSTNewtonianAttractionContext<T> initializeStep(final FieldAuxiliaryElements<T> auxiliaryElements,
final T[] parameters) {
return new FieldDSSTNewtonianAttractionContext<>(auxiliaryElements, parameters);
}
/** {@inheritDoc} */
@Override
public double[] getMeanElementRate(final SpacecraftState state,
final AuxiliaryElements auxiliaryElements,
final double[] parameters) {
// Container for attributes
final DSSTNewtonianAttractionContext context = initializeStep(auxiliaryElements, parameters);
final double[] yDot = new double[7];
final EquinoctialOrbit orbit = (EquinoctialOrbit) OrbitType.EQUINOCTIAL.convertType(state.getOrbit());
orbit.addKeplerContribution(PositionAngle.MEAN, context.getGM(), yDot);
return yDot;
}
/** {@inheritDoc} */
@Override
public <T extends RealFieldElement<T>> T[] getMeanElementRate(final FieldSpacecraftState<T> state,
final FieldAuxiliaryElements<T> auxiliaryElements,
final T[] parameters) {
// Field for array building
final Field<T> field = state.getMu().getField();
// Container for attributes
final FieldDSSTNewtonianAttractionContext<T> context = initializeStep(auxiliaryElements, parameters);
final T[] yDot = MathArrays.buildArray(field, 7);
final FieldEquinoctialOrbit<T> orbit = (FieldEquinoctialOrbit<T>) OrbitType.EQUINOCTIAL.convertType(state.getOrbit());
orbit.addKeplerContribution(PositionAngle.MEAN, context.getGM(), yDot);
return yDot;
}
/** {@inheritDoc} */
@Override
public EventDetector[] getEventsDetectors() {
return null;
}
/** {@inheritDoc} */
@Override
public <T extends RealFieldElement<T>> FieldEventDetector<T>[] getFieldEventsDetectors(final Field<T> field) {
return null;
}
/** {@inheritDoc} */
@Override
public void registerAttitudeProvider(final AttitudeProvider provider) {
//nothing is done since this contribution is not sensitive to attitude
}
/** {@inheritDoc} */
@Override
public void updateShortPeriodTerms(final double[] parameters,
final SpacecraftState... meanStates) {
}
/** {@inheritDoc} */
@Override
@SuppressWarnings("unchecked")
public <T extends RealFieldElement<T>> void updateShortPeriodTerms(final T[] parameters,
final FieldSpacecraftState<T>... meanStates) {
}
/** {@inheritDoc} */
@Override
public ParameterDriver[] getParametersDrivers() {
return new ParameterDriver[] {
gmParameterDriver
};
}
}