BetaAngleDetector.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.geometry.euclidean.threed.Vector3D;
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.SpacecraftState;
import org.orekit.propagation.events.handlers.EventHandler;
import org.orekit.propagation.events.handlers.StopOnEvent;
import org.orekit.utils.PVCoordinatesProvider;
import org.orekit.utils.TimeStampedPVCoordinates;
/** 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(SpacecraftState)} 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(EventHandler)} after construction.</p>
* @see org.orekit.propagation.Propagator#addEventDetector(EventDetector)
* @author Joe Reed
* @since 12.1
*/
public class BetaAngleDetector extends AbstractDetector<BetaAngleDetector> {
/** Beta angle crossing threshold. */
private final double betaAngleThreshold;
/** Coordinate provider for the celestial body. */
private final PVCoordinatesProvider 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 BetaAngleDetector(final double betaAngleThreshold) {
this(betaAngleThreshold, CelestialBodyFactory.getSun(), FramesFactory.getGCRF());
}
/** Class constructor.
* @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 BetaAngleDetector(final double betaAngleThreshold, final PVCoordinatesProvider celestialBodyProvider,
final Frame inertialFrame) {
this(AdaptableInterval.of(DEFAULT_MAXCHECK), DEFAULT_THRESHOLD, DEFAULT_MAX_ITER, new StopOnEvent(),
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 BetaAngleDetector(final AdaptableInterval maxCheck, final double threshold,
final int maxIter, final EventHandler handler,
final double betaAngleThreshold, final PVCoordinatesProvider 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 PVCoordinatesProvider 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 double 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 BetaAngleDetector withCelestialProvider(final PVCoordinatesProvider newProvider) {
return new BetaAngleDetector(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 (radians)
* @return the new detector instance
*/
public BetaAngleDetector withBetaThreshold(final double newBetaAngleThreshold) {
return new BetaAngleDetector(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 BetaAngleDetector withInertialFrame(final Frame newFrame) {
return new BetaAngleDetector(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(),
getHandler(), getBetaAngleThreshold(), getCelestialBodyProvider(), newFrame);
}
/** {@inheritDoc} */
@Override
public double g(final SpacecraftState s) {
final double beta = calculateBetaAngle(s, celestialBodyProvider, inertialFrame);
return betaAngleThreshold - 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
* @return the beta angle (radians)
*/
public static double calculateBetaAngle(final SpacecraftState state,
final PVCoordinatesProvider 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
* @return the beta angle (radians)
*/
public static double calculateBetaAngle(final SpacecraftState state,
final PVCoordinatesProvider celestialBodyProvider, final Frame frame) {
final Vector3D celestialP = celestialBodyProvider.getPosition(state.getDate(), frame);
final TimeStampedPVCoordinates pv = state.getPVCoordinates(frame);
return MathUtils.SEMI_PI - Vector3D.angle(celestialP, pv.getMomentum());
}
/** {@inheritDoc} */
@Override
protected BetaAngleDetector create(final AdaptableInterval newMaxCheck, final double newThreshold,
final int newMaxIter, final EventHandler newHandler) {
return new BetaAngleDetector(newMaxCheck, newThreshold, newMaxIter, newHandler,
getBetaAngleThreshold(), getCelestialBodyProvider(), getInertialFrame());
}
}