FieldBetaAngleDetector.java
/* Copyright 2002-2024 Joseph Reed
* 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.
* Joseph Reed 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.events;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.ode.events.Action;
import org.hipparchus.util.MathUtils;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.bodies.CelestialBodyFactory;
import org.orekit.frames.Frame;
import org.orekit.frames.FramesFactory;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.events.handlers.FieldEventHandler;
import org.orekit.propagation.events.handlers.FieldStopOnEvent;
import org.orekit.utils.FieldPVCoordinatesProvider;
import org.orekit.utils.TimeStampedFieldPVCoordinates;
/** Finder for beta angle crossing events.
* <p>Locate events when the beta angle (the angle between the orbit plane and the celestial body)
* crosses a threshold. The {@link #g(FieldSpacecraftState)} function is negative when the beta angle
* is above the threshold and positive when the beta angle is below the threshold.</p>
* <p>The inertial frame provided must have it's origin centered at the satellite's orbit plane. The
* beta angle is computed as the angle between the celestial body's position in this frame with the
* satellite's orbital momentum vector.</p>
* <p>The default implementation behavior is to {@link Action#STOP stop}
* propagation at the first event date occurrence. This can be changed by calling
* {@link #withHandler(FieldEventHandler)} after construction.</p>
* @see org.orekit.propagation.Propagator#addEventDetector(EventDetector)
* @param <T> The field type
* @author Joe Reed
* @since 12.1
*/
public class FieldBetaAngleDetector<T extends CalculusFieldElement<T>> extends FieldAbstractDetector<FieldBetaAngleDetector<T>, T> {
/** Beta angle crossing threshold. */
private final T betaAngleThreshold;
/** Coordinate provider for the celestial body. */
private final FieldPVCoordinatesProvider<T> celestialBodyProvider;
/** Inertial frame in which beta angle is calculated. */
private final Frame inertialFrame;
/**Solar beta angle constructor.
* <p>This method uses the default data context, assigns the sun as the celestial
* body and uses GCRF as the inertial frame.</p>
* @param betaAngleThreshold beta angle threshold (radians)
*/
@DefaultDataContext
public FieldBetaAngleDetector(final T betaAngleThreshold) {
this(betaAngleThreshold.getField(), betaAngleThreshold,
CelestialBodyFactory.getSun().toFieldPVCoordinatesProvider(betaAngleThreshold.getField()),
FramesFactory.getGCRF());
}
/** Class constructor.
* @param field the field instance
* @param betaAngleThreshold beta angle threshold (radians)
* @param celestialBodyProvider coordinate provider for the celestial provider
* @param inertialFrame inertial frame in which to compute the beta angle
*/
public FieldBetaAngleDetector(final Field<T> field, final T betaAngleThreshold,
final FieldPVCoordinatesProvider<T> celestialBodyProvider,
final Frame inertialFrame) {
this(FieldAdaptableInterval.of(DEFAULT_MAXCHECK), field.getZero().newInstance(DEFAULT_THRESHOLD), DEFAULT_MAX_ITER,
new FieldStopOnEvent<>(), betaAngleThreshold, celestialBodyProvider, inertialFrame);
}
/** Protected constructor with full parameters.
* <p>This constructor is not public as users are expected to use the builder
* API with the various {@code withXxx()} methods to set up the instance
* in a readable manner without using a huge amount of parameters.</p>
* @param maxCheck maximum checking interval
* @param threshold convergence threshold (s)
* @param maxIter maximum number of iterations in the event time search
* @param handler event handler to call at event occurrences
* @param betaAngleThreshold beta angle threshold (radians)
* @param celestialBodyProvider coordinate provider for the celestial provider
* @param inertialFrame inertial frame in which to compute the beta angle
*/
protected FieldBetaAngleDetector(final FieldAdaptableInterval<T> maxCheck, final T threshold,
final int maxIter, final FieldEventHandler<T> handler,
final T betaAngleThreshold, final FieldPVCoordinatesProvider<T> celestialBodyProvider,
final Frame inertialFrame) {
super(maxCheck, threshold, maxIter, handler);
this.betaAngleThreshold = betaAngleThreshold;
this.celestialBodyProvider = celestialBodyProvider;
this.inertialFrame = inertialFrame;
}
/** Coordinate provider for the celestial body.
* @return celestial body's coordinate provider
*/
public FieldPVCoordinatesProvider<T> getCelestialBodyProvider() {
return this.celestialBodyProvider;
}
/** The inertial frame in which beta angle is computed.
* @return the inertial frame
*/
public Frame getInertialFrame() {
return this.inertialFrame;
}
/** The beta angle threshold (radians).
* @return the beta angle threshold (radians)
*/
public T getBetaAngleThreshold() {
return this.betaAngleThreshold;
}
/** Create a new instance with the provided coordinate provider.
* <p>This method does not change the current instance.</p>
* @param newProvider the new coordinate provider
* @return the new detector instance
*/
public FieldBetaAngleDetector<T> withCelestialProvider(final FieldPVCoordinatesProvider<T> newProvider) {
return new FieldBetaAngleDetector<>(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(),
getHandler(), getBetaAngleThreshold(), newProvider, getInertialFrame());
}
/** Create a new instance with the provided beta angle threshold.
* <p>This method does not change the current instance.</p>
* @param newBetaAngleThreshold the beta angle threshold
* @return the new detector instance
*/
public FieldBetaAngleDetector<T> withBetaThreshold(final T newBetaAngleThreshold) {
return new FieldBetaAngleDetector<>(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(),
getHandler(), newBetaAngleThreshold, getCelestialBodyProvider(), getInertialFrame());
}
/** Create a new instance with the provided inertial frame.
* <p>This method does not change the current instance.</p>
* @param newFrame the inertial frame
* @return the new detector instance
*/
public FieldBetaAngleDetector<T> withInertialFrame(final Frame newFrame) {
return new FieldBetaAngleDetector<>(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(),
getHandler(), getBetaAngleThreshold(), getCelestialBodyProvider(), newFrame);
}
/** {@inheritDoc} */
@Override
public T g(final FieldSpacecraftState<T> s) {
final T beta = calculateBetaAngle(s, celestialBodyProvider, inertialFrame);
return betaAngleThreshold.subtract(beta);
}
/**Calculate the beta angle between the orbit plane and the celestial body.
* <p>This method computes the beta angle using the frame from the spacecraft state.</p>
* @param state spacecraft state
* @param celestialBodyProvider celestial body coordinate provider
* @param <T> The field type
* @return the beta angle (radians)
*/
public static <T extends CalculusFieldElement<T>> T calculateBetaAngle(final FieldSpacecraftState<T> state,
final FieldPVCoordinatesProvider<T> celestialBodyProvider) {
return calculateBetaAngle(state, celestialBodyProvider, state.getFrame());
}
/**Calculate the beta angle between the orbit plane and the celestial body.
* @param state spacecraft state
* @param celestialBodyProvider celestial body coordinate provider
* @param frame inertial frame in which beta angle will be computed
* @param <T> The field type
* @return the beta angle (radians)
*/
public static <T extends CalculusFieldElement<T>> T calculateBetaAngle(final FieldSpacecraftState<T> state,
final FieldPVCoordinatesProvider<T> celestialBodyProvider, final Frame frame) {
final FieldVector3D<T> celestialP = celestialBodyProvider.getPosition(state.getDate(), frame);
final TimeStampedFieldPVCoordinates<T> pv = state.getPVCoordinates(frame);
return FieldVector3D.angle(celestialP, pv.getMomentum()).negate().add(MathUtils.SEMI_PI);
}
/** {@inheritDoc} */
@Override
protected FieldBetaAngleDetector<T> create(final FieldAdaptableInterval<T> newMaxCheck, final T newThreshold,
final int newMaxIter, final FieldEventHandler<T> newHandler) {
return new FieldBetaAngleDetector<>(newMaxCheck, newThreshold, newMaxIter, newHandler,
getBetaAngleThreshold(), getCelestialBodyProvider(), getInertialFrame());
}
}