DSSTForceModel.java
/* Copyright 2002-2023 CS GROUP
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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
* (the "License"); you may not use this file except in compliance with
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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.List;
import java.util.stream.Stream;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.hipparchus.util.MathArrays;
import org.orekit.attitudes.AttitudeProvider;
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.EventDetectorsProvider;
import org.orekit.propagation.events.FieldEventDetector;
import org.orekit.propagation.integration.AbstractGradientConverter;
import org.orekit.propagation.semianalytical.dsst.utilities.AuxiliaryElements;
import org.orekit.propagation.semianalytical.dsst.utilities.FieldAuxiliaryElements;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParameterDriversProvider;
import org.orekit.utils.TimeSpanMap.Span;
/** This interface represents a force modifying spacecraft motion for a {@link
* org.orekit.propagation.semianalytical.dsst.DSSTPropagator DSSTPropagator}.
* <p>
* Objects implementing this interface are intended to be added to a {@link
* org.orekit.propagation.semianalytical.dsst.DSSTPropagator DSST propagator}
* before the propagation is started.
* </p>
* <p>
* The propagator will call at the very beginning of a propagation the {@link
* #initializeShortPeriodTerms(AuxiliaryElements, PropagationType, double[])} method allowing
* preliminary computation such as truncation if needed.
* </p>
* <p>
* Then the propagator will call at each step:
* <ol>
* <li>the {@link #getMeanElementRate(SpacecraftState, AuxiliaryElements, double[])} method.
* The force model instance will extract all the state data needed to compute
* the mean element rates that contribute to the mean state derivative.</li>
* <li>the {@link #updateShortPeriodTerms(double[], SpacecraftState...)} method,
* if osculating parameters are desired, on a sample of points within the
* last step.</li>
* </ol>
*
* @author Romain Di Constanzo
* @author Pascal Parraud
*/
public interface DSSTForceModel extends ParameterDriversProvider, EventDetectorsProvider {
/**
* Initialize the force model at the start of propagation.
* <p> The default implementation of this method does nothing.</p>
*
* @param initialState spacecraft state at the start of propagation.
* @param target date of propagation. Not equal to {@code initialState.getDate()}.
* @since 11.0
*/
default void init(SpacecraftState initialState, AbsoluteDate target) {
}
/**
* Initialize the force model at the start of propagation.
* <p> The default implementation of this method does nothing.</p>
*
* @param initialState spacecraft state at the start of propagation.
* @param target date of propagation. Not equal to {@code initialState.getDate()}.
* @param <T> type of the elements
* @since 11.1
*/
default <T extends CalculusFieldElement<T>> void init(FieldSpacecraftState<T> initialState, FieldAbsoluteDate<T> target) {
init(initialState.toSpacecraftState(), target.toAbsoluteDate());
}
/** {@inheritDoc}.*/
@Override
default Stream<EventDetector> getEventDetectors() {
return getEventDetectors(getParametersDrivers());
}
/** {@inheritDoc}.*/
@Override
default <T extends CalculusFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventDetectors(Field<T> field) {
return getFieldEventDetectors(field, getParametersDrivers());
}
/** Performs initialization prior to propagation for the current force model.
* <p>
* This method aims at being called at the very beginning of a propagation.
* </p>
* @param auxiliaryElements auxiliary elements related to the current orbit
* @param type type of the elements used during the propagation
* @param parameters values of the force model parameters for specific date
* (1 value only per parameter driver) obtained for example by calling
* {@link #getParameters(AbsoluteDate)} on force model.
* @return a list of objects that will hold short period terms (the objects
* are also retained by the force model, which will update them during propagation)
*/
List<ShortPeriodTerms> initializeShortPeriodTerms(AuxiliaryElements auxiliaryElements,
PropagationType type, double[] parameters);
/** Performs initialization prior to propagation for the current force model.
* <p>
* This method aims at being called at the very beginning of a propagation.
* </p>
* @param <T> type of the elements
* @param auxiliaryElements auxiliary elements related to the current orbit
* @param type type of the elements used during the propagation
* @param parameters values of the force model parameters for specific date
* (1 value only per parameter driver) obtained for example by calling
* {@link #getParameters(AbsoluteDate)} on force model or
* {@link AbstractGradientConverter#getParametersAtStateDate(FieldSpacecraftState, ParameterDriversProvider)}
* on gradient converter.
* @return a list of objects that will hold short period terms (the objects
* are also retained by the force model, which will update them during propagation)
*/
<T extends CalculusFieldElement<T>> List<FieldShortPeriodTerms<T>> initializeShortPeriodTerms(FieldAuxiliaryElements<T> auxiliaryElements,
PropagationType type, T[] parameters);
/** Extract the proper parameter drivers' values from the array in input of the
* {@link #updateShortPeriodTerms(double[], SpacecraftState...) updateShortPeriodTerms} method.
* Parameters are filtered given an input date.
* @param parameters the input parameters array containing all span values of all drivers
* from which the parameter values at date date wants to be extracted
* @param date the date
* @return the parameters given the date
*/
default double[] extractParameters(final double[] parameters, final AbsoluteDate date) {
// Find out the indexes of the parameters in the whole array of parameters
final List<ParameterDriver> allParameters = getParametersDrivers();
final double[] outParameters = new double[allParameters.size()];
int index = 0;
int paramIndex = 0;
for (int i = 0; i < allParameters.size(); i++) {
final ParameterDriver driver = allParameters.get(i);
final String driverNameforDate = driver.getNameSpan(date);
// Loop on the spans
for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
// Add all the parameter drivers of the span
if (span.getData().equals(driverNameforDate)) {
outParameters[index++] = parameters[paramIndex];
}
paramIndex++;
}
}
return outParameters;
}
/** Extract the proper parameter drivers' values from the array in input of the
* {@link #updateShortPeriodTerms(CalculusFieldElement[], FieldSpacecraftState...)
* updateShortPeriodTerms} method. Parameters are filtered given an input date.
* @param parameters the input parameters array containing all span values of all drivers
* from which the parameter values at date date wants to be extracted
* @param date the date
* @param <T> extends CalculusFieldElement
* @return the parameters given the date
*/
default <T extends CalculusFieldElement<T>> T[] extractParameters(final T[] parameters,
final FieldAbsoluteDate<T> date) {
// Find out the indexes of the parameters in the whole array of parameters
final List<ParameterDriver> allParameters = getParametersDrivers();
final T[] outParameters = MathArrays.buildArray(date.getField(), allParameters.size());
int index = 0;
int paramIndex = 0;
for (int i = 0; i < allParameters.size(); i++) {
final ParameterDriver driver = allParameters.get(i);
final String driverNameforDate = driver.getNameSpan(date.toAbsoluteDate());
// Loop on the spans
for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
// Add all the parameter drivers of the span
if (span.getData().equals(driverNameforDate)) {
outParameters[index++] = parameters[paramIndex];
}
++paramIndex;
}
}
return outParameters;
}
/** Computes the mean equinoctial elements rates da<sub>i</sub> / dt.
*
* @param state current state information: date, kinematics, attitude
* @param auxiliaryElements auxiliary elements related to the current orbit
* @param parameters values of the force model parameters at state date (only 1 span for
* each parameter driver) obtained for example by calling {@link #getParameters(AbsoluteDate)}
* on force model.
* @return the mean element rates dai/dt
*/
double[] getMeanElementRate(SpacecraftState state,
AuxiliaryElements auxiliaryElements, double[] parameters);
/** Computes the mean equinoctial elements rates da<sub>i</sub> / dt.
*
* @param <T> type of the elements
* @param state current state information: date, kinematics, attitude
* @param auxiliaryElements auxiliary elements related to the current orbit
* @param parameters values of the force model parameters at state date (only 1 span for
* each parameter driver) obtained for example by calling {@link #getParameters(Field, FieldAbsoluteDate)}
* on force model or
* {@link AbstractGradientConverter#getParametersAtStateDate(FieldSpacecraftState, ParameterDriversProvider)}
* on gradient converter.
* @return the mean element rates dai/dt
*/
<T extends CalculusFieldElement<T>> T[] getMeanElementRate(FieldSpacecraftState<T> state,
FieldAuxiliaryElements<T> auxiliaryElements, T[] parameters);
/** Register an attitude provider.
* <p>
* Register an attitude provider that can be used by the force model.
* </p>
* @param provider the {@link AttitudeProvider}
*/
void registerAttitudeProvider(AttitudeProvider provider);
/** Update the short period terms.
* <p>
* The {@link ShortPeriodTerms short period terms} that will be updated
* are the ones that were returned during the call to {@link
* #initializeShortPeriodTerms(AuxiliaryElements, PropagationType, double[])}.
* </p>
* @param parameters values of the force model parameters (all span values for each parameters)
* obtained for example by calling
* {@link #getParametersAllValues()}
* on force model. The extract parameter method {@link #extractParameters(double[], AbsoluteDate)} is called in
* the method to select the right parameter corresponding to the mean state date.
* @param meanStates mean states information: date, kinematics, attitude
*/
void updateShortPeriodTerms(double[] parameters, SpacecraftState... meanStates);
/** Update the short period terms.
* <p>
* The {@link ShortPeriodTerms short period terms} that will be updated
* are the ones that were returned during the call to {@link
* #initializeShortPeriodTerms(AuxiliaryElements, PropagationType, double[])}.
* </p>
* @param <T> type of the elements
* @param parameters values of the force model parameters (all span values for each parameters)
* obtained for example by calling {@link #getParametersAllValues(Field)} on force model or
* {@link AbstractGradientConverter#getParameters(FieldSpacecraftState, ParameterDriversProvider)}
* on gradient converter. The extract parameter method
* {@link #extractParameters(CalculusFieldElement[], FieldAbsoluteDate)} is called in
* the method to select the right parameter.
* @param meanStates mean states information: date, kinematics, attitude
*/
@SuppressWarnings("unchecked")
<T extends CalculusFieldElement<T>> void updateShortPeriodTerms(T[] parameters, FieldSpacecraftState<T>... meanStates);
}