ProfileThrustPropulsionModel.java
/* Copyright 2002-2024 Luc Maisonobe
* 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.forces.maneuvers.propulsion;
import java.lang.reflect.Array;
import java.util.Collections;
import java.util.List;
import java.util.stream.Stream;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.ode.events.Action;
import org.hipparchus.util.FastMath;
import org.orekit.forces.maneuvers.Control3DVectorCostType;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.events.DateDetector;
import org.orekit.propagation.events.EventDetector;
import org.orekit.propagation.events.FieldDateDetector;
import org.orekit.propagation.events.FieldEventDetector;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.time.FieldTimeStamped;
import org.orekit.utils.Constants;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.TimeSpanMap;
/** Thrust propulsion model based on segmented profile.
* @author Luc Maisonobe
* @since 12.0
*/
public class ProfileThrustPropulsionModel implements ThrustPropulsionModel {
/** Accuracy of switching events datation (s). */
private static final double DATATION_ACCURACY = 1.0e-10;
/** Thrust profile. */
private final TimeSpanMap<PolynomialThrustSegment> profile;
/** Specific impulse. */
private final double isp;
/** Name of the maneuver. */
private final String name;
/** Type of norm linking thrust vector to mass flow rate. */
private final Control3DVectorCostType control3DVectorCostType;
/** Generic constructor.
* @param profile thrust profile (N)
* @param isp specific impulse (s)
* @param control3DVectorCostType control vector's cost type
* @param name name of the maneuver
*/
public ProfileThrustPropulsionModel(final TimeSpanMap<PolynomialThrustSegment> profile, final double isp,
final Control3DVectorCostType control3DVectorCostType, final String name) {
this.name = name;
this.isp = isp;
this.profile = profile;
this.control3DVectorCostType = control3DVectorCostType;
}
/** {@inheritDoc} */
@Override
public String getName() {
return name;
}
/** {@inheritDoc} */
@Override
public Control3DVectorCostType getControl3DVectorCostType() {
return control3DVectorCostType;
}
/** {@inheritDoc} */
@Override
public Vector3D getThrustVector(final SpacecraftState s) {
final PolynomialThrustSegment active = profile.get(s.getDate());
return active == null ? Vector3D.ZERO : active.getThrustVector(s.getDate());
}
/** {@inheritDoc} */
@Override
public double getFlowRate(final SpacecraftState s) {
return -control3DVectorCostType.evaluate(getThrustVector(s)) / (Constants.G0_STANDARD_GRAVITY * isp);
}
/** {@inheritDoc}
* <p>
* Here the thrust vector does not depend on parameters
* </p>
*/
@Override
public Vector3D getThrustVector(final SpacecraftState s, final double[] parameters) {
return getThrustVector(s);
}
/** {@inheritDoc}
* <p>
* Here the flow rate does not depend on parameters
* </p>
*/
public double getFlowRate(final SpacecraftState s, final double[] parameters) {
return getFlowRate(s);
}
/** {@inheritDoc}
* <p>
* Here the thrust vector does not depend on parameters
* </p>
*/
public <T extends CalculusFieldElement<T>> FieldVector3D<T> getThrustVector(final FieldSpacecraftState<T> s,
final T[] parameters) {
final PolynomialThrustSegment active = profile.get(s.getDate().toAbsoluteDate());
return active == null ? FieldVector3D.getZero(s.getDate().getField()) : active.getThrustVector(s.getDate());
}
/** {@inheritDoc}
* <p>
* Here the flow rate does not depend on parameters
* </p>
*/
public <T extends CalculusFieldElement<T>> T getFlowRate(final FieldSpacecraftState<T> s, final T[] parameters) {
return control3DVectorCostType.evaluate(getThrustVector(s, parameters)).divide(-Constants.G0_STANDARD_GRAVITY * isp);
}
/** {@inheritDoc}.
* <p>
* The single detector returned triggers {@link org.hipparchus.ode.events.Action#RESET_DERIVATIVES} events
* at every {@link PolynomialThrustSegment thrust segments} boundaries.
* </p>
*/
@Override
public Stream<EventDetector> getEventDetectors() {
final double shortest = shortestSegmentDuration();
final DateDetector detector = new DateDetector().
withMaxCheck(0.5 * shortest).
withMinGap(0.5 * shortest).
withThreshold(DATATION_ACCURACY).
withHandler((state, det, increasing) -> Action.RESET_DERIVATIVES);
for (TimeSpanMap.Transition<PolynomialThrustSegment> transition = profile.getFirstTransition();
transition != null;
transition = transition.next()) {
detector.addEventDate(transition.getDate());
}
return Stream.of(detector);
}
/** {@inheritDoc}.
* <p>
* The single detector returned triggers {@link org.hipparchus.ode.events.Action#RESET_DERIVATIVES} events
* at every {@link PolynomialThrustSegment thrust segments} boundaries.
* </p>
*/
@Override
public <T extends CalculusFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventDetectors(final Field<T> field) {
final double shortest = shortestSegmentDuration();
@SuppressWarnings("unchecked")
final FieldDateDetector<T> detector = new FieldDateDetector<>(field,
(FieldTimeStamped<T>[]) Array.newInstance(FieldTimeStamped.class, 0)).
withMaxCheck(0.5 * shortest).
withMinGap(0.5 * shortest).
withThreshold(field.getZero().newInstance(DATATION_ACCURACY)).
withHandler((state, det, increasing) -> Action.RESET_DERIVATIVES);
for (TimeSpanMap.Transition<PolynomialThrustSegment> transition = profile.getFirstTransition();
transition != null;
transition = transition.next()) {
detector.addEventDate(new FieldAbsoluteDate<>(field, transition.getDate()));
}
return Stream.of(detector);
}
/** Compute the duration of the shortest segment.
* @return duration of the shortest segment
*/
private double shortestSegmentDuration() {
double shortest = Double.POSITIVE_INFINITY;
for (TimeSpanMap.Span<PolynomialThrustSegment> span = profile.getFirstSpan();
span != null;
span = span.next()) {
shortest = FastMath.min(shortest, span.getEnd().durationFrom(span.getStart()));
}
return shortest;
}
@Override
public List<ParameterDriver> getParametersDrivers() {
return Collections.emptyList();
}
}