DSSTDSConverter.java
/* Copyright 2002-2019 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (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
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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;
import java.util.ArrayList;
import java.util.List;
import org.hipparchus.analysis.differentiation.DSFactory;
import org.hipparchus.analysis.differentiation.DerivativeStructure;
import org.orekit.attitudes.AttitudeProvider;
import org.orekit.attitudes.FieldAttitude;
import org.orekit.orbits.FieldEquinoctialOrbit;
import org.orekit.orbits.FieldOrbit;
import org.orekit.orbits.PositionAngle;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.integration.AbstractDSConverter;
import org.orekit.propagation.semianalytical.dsst.forces.DSSTForceModel;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.FieldAngularCoordinates;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.TimeStampedFieldAngularCoordinates;
/** Converter for states and parameters arrays.
* @author Luc Maisonobe
* @author Bryan Cazabonne
* @since 10.0
*/
class DSSTDSConverter extends AbstractDSConverter {
/** Fixed dimension of the state. */
private static final int FREE_STATE_PARAMETERS = 6;
/** States with various number of additional parameters for force models. */
private final List<FieldSpacecraftState<DerivativeStructure>> dsStates;
/** Simple constructor.
* @param state regular state
* @param provider provider to use if attitude needs to be recomputed
*/
DSSTDSConverter(final SpacecraftState state, final AttitudeProvider provider) {
super(FREE_STATE_PARAMETERS);
// prepare derivation variables
final DSFactory factory = new DSFactory(FREE_STATE_PARAMETERS, 1);
// equinoctial parameters always has derivatives
final DerivativeStructure sma = factory.variable(0, state.getA());
final DerivativeStructure ex = factory.variable(1, state.getEquinoctialEx());
final DerivativeStructure ey = factory.variable(2, state.getEquinoctialEy());
final DerivativeStructure hx = factory.variable(3, state.getHx());
final DerivativeStructure hy = factory.variable(4, state.getHy());
final DerivativeStructure l = factory.variable(5, state.getLM());
final DerivativeStructure dsMu = factory.constant(state.getMu());
// date
final AbsoluteDate date = state.getDate();
final FieldAbsoluteDate<DerivativeStructure> dateField = new FieldAbsoluteDate<>(sma.getField(), date);
// mass never has derivatives
final DerivativeStructure dsM = factory.constant(state.getMass());
final FieldOrbit<DerivativeStructure> dsOrbit =
new FieldEquinoctialOrbit<>(sma, ex, ey, hx, hy, l,
PositionAngle.MEAN,
state.getFrame(),
dateField,
dsMu);
final FieldAttitude<DerivativeStructure> dsAttitude;
// compute attitude partial derivatives
dsAttitude = provider.getAttitude(dsOrbit, dsOrbit.getDate(), dsOrbit.getFrame());
// initialize the list with the state having 0 force model parameters
dsStates = new ArrayList<>();
dsStates.add(new FieldSpacecraftState<>(dsOrbit, dsAttitude, dsM));
}
/** Get the state with the number of parameters consistent with force model.
* @param forceModel force model
* @return state with the number of parameters consistent with force model
*/
public FieldSpacecraftState<DerivativeStructure> getState(final DSSTForceModel forceModel) {
// count the required number of parameters
int nbParams = 0;
for (final ParameterDriver driver : forceModel.getParametersDrivers()) {
if (driver.isSelected()) {
++nbParams;
}
}
// fill in intermediate slots
while (dsStates.size() < nbParams + 1) {
dsStates.add(null);
}
if (dsStates.get(nbParams) == null) {
// it is the first time we need this number of parameters
// we need to create the state
final DSFactory factory = new DSFactory(FREE_STATE_PARAMETERS + nbParams, 1);
final FieldSpacecraftState<DerivativeStructure> s0 = dsStates.get(0);
final FieldAbsoluteDate<DerivativeStructure> date = new FieldAbsoluteDate<>(extend(s0.getA(), factory).getField(),
s0.getDate().toAbsoluteDate());
// orbit
final FieldOrbit<DerivativeStructure> dsOrbit =
new FieldEquinoctialOrbit<>(extend(s0.getA(), factory),
extend(s0.getEquinoctialEx(), factory),
extend(s0.getEquinoctialEy(), factory),
extend(s0.getHx(), factory),
extend(s0.getHy(), factory),
extend(s0.getLM(), factory),
PositionAngle.MEAN,
s0.getFrame(), date,
extend(s0.getMu(), factory));
// attitude
final FieldAngularCoordinates<DerivativeStructure> ac0 = s0.getAttitude().getOrientation();
final FieldAttitude<DerivativeStructure> dsAttitude =
new FieldAttitude<>(s0.getAttitude().getReferenceFrame(),
new TimeStampedFieldAngularCoordinates<>(dsOrbit.getDate(),
extend(ac0.getRotation(), factory),
extend(ac0.getRotationRate(), factory),
extend(ac0.getRotationAcceleration(), factory)));
// mass
final DerivativeStructure dsM = extend(s0.getMass(), factory);
dsStates.set(nbParams, new FieldSpacecraftState<>(dsOrbit, dsAttitude, dsM));
}
return dsStates.get(nbParams);
}
/** Get the force model parameters.
* @param state state as returned by {@link #getState(DSSTForceModel)}
* @param forceModel force model associated with the parameters
* @return force model parameters
* @since 9.0
*/
public DerivativeStructure[] getParameters(final FieldSpacecraftState<DerivativeStructure> state,
final DSSTForceModel forceModel) {
final DSFactory factory = state.getA().getFactory();
final ParameterDriver[] drivers = forceModel.getParametersDrivers();
final DerivativeStructure[] parameters = new DerivativeStructure[drivers.length];
int index = FREE_STATE_PARAMETERS;
for (int i = 0; i < drivers.length; ++i) {
parameters[i] = drivers[i].isSelected() ?
factory.variable(index++, drivers[i].getValue()) :
factory.constant(drivers[i].getValue());
}
return parameters;
}
}