IntegratedEphemeris.java
/* Copyright 2002-2020 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.integration;
import java.util.List;
import java.util.Map;
import org.hipparchus.ode.DenseOutputModel;
import org.hipparchus.ode.ODEStateAndDerivative;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.frames.Frame;
import org.orekit.orbits.Orbit;
import org.orekit.propagation.AdditionalStateProvider;
import org.orekit.propagation.BoundedPropagator;
import org.orekit.propagation.PropagationType;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.analytical.AbstractAnalyticalPropagator;
import org.orekit.time.AbsoluteDate;
import org.orekit.utils.TimeStampedPVCoordinates;
/** This class stores sequentially generated orbital parameters for
* later retrieval.
*
* <p>
* Instances of this class are built and then must be fed with the results
* provided by {@link org.orekit.propagation.Propagator Propagator} objects
* configured in {@link org.orekit.propagation.Propagator#setEphemerisMode()
* ephemeris generation mode}. Once propagation is o, random access to any
* intermediate state of the orbit throughout the propagation range is possible.
* </p>
* <p>
* A typical use case is for numerically integrated orbits, which can be used by
* algorithms that need to wander around according to their own algorithm without
* cumbersome tight links with the integrator.
* </p>
* <p>
* As this class implements the {@link org.orekit.propagation.Propagator Propagator}
* interface, it can itself be used in batch mode to build another instance of the
* same type. This is however not recommended since it would be a waste of resources.
* </p>
* <p>
* Note that this class stores all intermediate states along with interpolation
* models, so it may be memory intensive.
* </p>
*
* @see org.orekit.propagation.numerical.NumericalPropagator
* @author Mathieu Roméro
* @author Luc Maisonobe
* @author Véronique Pommier-Maurussane
*/
public class IntegratedEphemeris
extends AbstractAnalyticalPropagator implements BoundedPropagator {
/** Event detection requires evaluating the state slightly before / past an event. */
private static final double EXTRAPOLATION_TOLERANCE = 1.0;
/** Mapper between raw double components and spacecraft state. */
private final StateMapper mapper;
/** Type of orbit to output (mean or osculating).
* <p>
* This is used only in the case of semianalitical propagators where there is a clear separation between
* mean and short periodic elements. It is ignored by the Numerical propagator.
* </p>
*/
private PropagationType type;
/** Start date of the integration (can be min or max). */
private final AbsoluteDate startDate;
/** First date of the range. */
private final AbsoluteDate minDate;
/** Last date of the range. */
private final AbsoluteDate maxDate;
/** Underlying raw mathematical model. */
private DenseOutputModel model;
/** Unmanaged additional states that must be simply copied. */
private final Map<String, double[]> unmanaged;
/** Creates a new instance of IntegratedEphemeris.
* @param startDate Start date of the integration (can be minDate or maxDate)
* @param minDate first date of the range
* @param maxDate last date of the range
* @param mapper mapper between raw double components and spacecraft state
* @param type type of orbit to output (mean or osculating)
* @param model underlying raw mathematical model
* @param unmanaged unmanaged additional states that must be simply copied
* @param providers providers for pre-integrated states
* @param equations names of additional equations
*/
public IntegratedEphemeris(final AbsoluteDate startDate,
final AbsoluteDate minDate, final AbsoluteDate maxDate,
final StateMapper mapper, final PropagationType type,
final DenseOutputModel model,
final Map<String, double[]> unmanaged,
final List<AdditionalStateProvider> providers,
final String[] equations) {
super(mapper.getAttitudeProvider());
this.startDate = startDate;
this.minDate = minDate;
this.maxDate = maxDate;
this.mapper = mapper;
this.type = type;
this.model = model;
this.unmanaged = unmanaged;
// set up the pre-integrated providers
for (final AdditionalStateProvider provider : providers) {
addAdditionalStateProvider(provider);
}
// set up providers to map the final elements of the model array to additional states
for (int i = 0; i < equations.length; ++i) {
addAdditionalStateProvider(new LocalProvider(equations[i], i));
}
}
/** Interpolate the model at some date.
* @param date desired interpolation date
* @return state interpolated at date
*/
private ODEStateAndDerivative getInterpolatedState(final AbsoluteDate date) {
// compare using double precision instead of AbsoluteDate.compareTo(...)
// because time is expressed as a double when searching for events
if (date.compareTo(minDate.shiftedBy(-EXTRAPOLATION_TOLERANCE)) < 0 ||
date.compareTo(maxDate.shiftedBy(EXTRAPOLATION_TOLERANCE)) > 0 ) {
// date is outside of supported range
throw new OrekitException(OrekitMessages.OUT_OF_RANGE_EPHEMERIDES_DATE,
date, minDate, maxDate);
}
return model.getInterpolatedState(date.durationFrom(startDate));
}
/** {@inheritDoc} */
@Override
protected SpacecraftState basicPropagate(final AbsoluteDate date) {
final ODEStateAndDerivative os = getInterpolatedState(date);
SpacecraftState state = mapper.mapArrayToState(mapper.mapDoubleToDate(os.getTime(), date),
os.getPrimaryState(), os.getPrimaryDerivative(),
type);
for (Map.Entry<String, double[]> initial : unmanaged.entrySet()) {
state = state.addAdditionalState(initial.getKey(), initial.getValue());
}
return state;
}
/** {@inheritDoc} */
protected Orbit propagateOrbit(final AbsoluteDate date) {
return basicPropagate(date).getOrbit();
}
/** {@inheritDoc} */
protected double getMass(final AbsoluteDate date) {
return basicPropagate(date).getMass();
}
/** {@inheritDoc} */
public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate date, final Frame frame) {
return propagate(date).getPVCoordinates(frame);
}
/** Get the first date of the range.
* @return the first date of the range
*/
public AbsoluteDate getMinDate() {
return minDate;
}
/** Get the last date of the range.
* @return the last date of the range
*/
public AbsoluteDate getMaxDate() {
return maxDate;
}
@Override
public Frame getFrame() {
return this.mapper.getFrame();
}
/** {@inheritDoc} */
public void resetInitialState(final SpacecraftState state) {
throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
}
/** {@inheritDoc} */
protected void resetIntermediateState(final SpacecraftState state, final boolean forward) {
throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
}
/** {@inheritDoc} */
public SpacecraftState getInitialState() {
return updateAdditionalStates(basicPropagate(getMinDate()));
}
/** Local provider for additional state data. */
private class LocalProvider implements AdditionalStateProvider {
/** Name of the additional state. */
private final String name;
/** Index of the additional state. */
private final int index;
/** Simple constructor.
* @param name name of the additional state
* @param index index of the additional state
*/
LocalProvider(final String name, final int index) {
this.name = name;
this.index = index;
}
/** {@inheritDoc} */
public String getName() {
return name;
}
/** {@inheritDoc} */
public double[] getAdditionalState(final SpacecraftState state) {
// extract the part of the interpolated array corresponding to the additional state
return getInterpolatedState(state.getDate()).getSecondaryState(index + 1);
}
}
}