ApsideDetectionAdaptableIntervalFactory.java
/* Copyright 2022-2024 Romain Serra
* 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.events.intervals;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.MathUtils;
import org.orekit.orbits.KeplerianOrbit;
import org.orekit.orbits.Orbit;
import org.orekit.orbits.OrbitType;
import org.orekit.propagation.events.AdaptableInterval;
/**
* Factory class for {@link AdaptableInterval} suitable for apside detection on eccentric orbits.
* It requires {@link org.orekit.propagation.SpacecraftState} to be based on {@link Orbit} in order to work.
* @see org.orekit.propagation.events.AdaptableInterval
* @see org.orekit.propagation.events.ApsideDetector
* @see org.orekit.propagation.events.EventSlopeFilter
* @author Romain Serra
* @since 12.1
*/
public class ApsideDetectionAdaptableIntervalFactory {
/**
* Private constructor.
*/
private ApsideDetectionAdaptableIntervalFactory() {
// factory class
}
/**
* Method providing a candidate {@link AdaptableInterval} for arbitrary apside detection with forward propagation.
* It uses a Keplerian, eccentric approximation.
* @return adaptable interval for forward apside detection
*/
public static AdaptableInterval getForwardApsideDetectionAdaptableInterval() {
return state -> {
final Orbit orbit = state.getOrbit();
final KeplerianOrbit keplerianOrbit = convertOrbitIntoKeplerianOne(orbit);
final double meanMotion = keplerianOrbit.getKeplerianMeanMotion();
final double meanAnomaly = keplerianOrbit.getMeanAnomaly();
final double durationToNextPeriapsis = computeKeplerianDurationToNextPeriapsis(meanAnomaly, meanMotion);
final double durationToNextApoapsis = computeKeplerianDurationToNextApoapsis(meanAnomaly, meanMotion);
return FastMath.min(durationToNextPeriapsis, durationToNextApoapsis);
};
}
/**
* Method providing a candidate {@link AdaptableInterval} for arbitrary apside detection with backward propagation.
* It uses a Keplerian, eccentric approximation.
* @return adaptable interval for backward apside detection
*/
public static AdaptableInterval getBackwardApsideDetectionAdaptableInterval() {
return state -> {
final Orbit orbit = state.getOrbit();
final KeplerianOrbit keplerianOrbit = convertOrbitIntoKeplerianOne(orbit);
final double meanMotion = keplerianOrbit.getKeplerianMeanMotion();
final double meanAnomaly = keplerianOrbit.getMeanAnomaly();
final double durationFromPreviousPeriapsis = computeKeplerianDurationFromPreviousPeriapsis(meanAnomaly,
meanMotion);
final double durationFromPreviousApoapsis = computeKeplerianDurationFromPreviousApoapsis(meanAnomaly,
meanMotion);
return FastMath.min(durationFromPreviousApoapsis, durationFromPreviousPeriapsis);
};
}
/**
* Method providing a candidate {@link AdaptableInterval} for periapsis detection with forward propagation.
* It uses a Keplerian, eccentric approximation.
* @return adaptable interval for forward periaspsis detection
*/
public static AdaptableInterval getForwardPeriapsisDetectionAdaptableInterval() {
return state -> {
final Orbit orbit = state.getOrbit();
final KeplerianOrbit keplerianOrbit = convertOrbitIntoKeplerianOne(orbit);
final double meanMotion = keplerianOrbit.getKeplerianMeanMotion();
final double meanAnomaly = keplerianOrbit.getMeanAnomaly();
return computeKeplerianDurationToNextPeriapsis(meanAnomaly, meanMotion);
};
}
/**
* Method providing a candidate {@link AdaptableInterval} for periapsis detection with backward propagation.
* It uses a Keplerian, eccentric approximation.
* @return adaptable interval for backward periaspsis detection
*/
public static AdaptableInterval getBackwardPeriapsisDetectionAdaptableInterval() {
return state -> {
final Orbit orbit = state.getOrbit();
final KeplerianOrbit keplerianOrbit = convertOrbitIntoKeplerianOne(orbit);
final double meanMotion = keplerianOrbit.getKeplerianMeanMotion();
final double meanAnomaly = keplerianOrbit.getMeanAnomaly();
return computeKeplerianDurationFromPreviousPeriapsis(meanAnomaly, meanMotion);
};
}
/**
* Method providing a candidate {@link AdaptableInterval} for apoapsis detection with forward propagation.
* It uses a Keplerian, eccentric approximation.
* @return adaptable interval for forward apoapsis detection
*/
public static AdaptableInterval getForwardApoapsisDetectionAdaptableInterval() {
return state -> {
final Orbit orbit = state.getOrbit();
final KeplerianOrbit keplerianOrbit = convertOrbitIntoKeplerianOne(orbit);
final double meanMotion = keplerianOrbit.getKeplerianMeanMotion();
final double meanAnomaly = keplerianOrbit.getMeanAnomaly();
return computeKeplerianDurationToNextApoapsis(meanAnomaly, meanMotion);
};
}
/**
* Method providing a candidate {@link AdaptableInterval} for apoapsis detection with backward propagation.
* It uses a Keplerian, eccentric approximation.
* @return adaptable interval for backward apoapsis detection
*/
public static AdaptableInterval getBackwardApoapsisDetectionAdaptableInterval() {
return state -> {
final Orbit orbit = state.getOrbit();
final KeplerianOrbit keplerianOrbit = convertOrbitIntoKeplerianOne(orbit);
final double meanMotion = keplerianOrbit.getKeplerianMeanMotion();
final double meanAnomaly = keplerianOrbit.getMeanAnomaly();
return computeKeplerianDurationFromPreviousApoapsis(meanAnomaly, meanMotion);
};
}
/**
* Convert a generic {@link Orbit} into a {@link KeplerianOrbit}.
* @param orbit orbit to convert
* @return Keplerian orbit
*/
private static KeplerianOrbit convertOrbitIntoKeplerianOne(final Orbit orbit) {
return (KeplerianOrbit) OrbitType.KEPLERIAN.convertType(orbit);
}
/**
* Method computing time to go until next periapsis, assuming Keplerian motion.
* @param meanAnomaly mean anomaly
* @param meanMotion Keplerian mean motion
* @return duration to next periapsis
*/
private static double computeKeplerianDurationToNextPeriapsis(final double meanAnomaly,
final double meanMotion) {
final double normalizedMeanAnomaly = MathUtils.normalizeAngle(meanAnomaly, FastMath.PI);
return (MathUtils.TWO_PI - normalizedMeanAnomaly) / meanMotion;
}
/**
* Method computing time elapsed since last periapsis, assuming Keplerian motion.
* @param meanAnomaly mean anomaly
* @param meanMotion Keplerian mean motion
* @return duration elapsed since last periapsis
*/
public static double computeKeplerianDurationFromPreviousPeriapsis(final double meanAnomaly,
final double meanMotion) {
final double normalizedMeanAnomaly = MathUtils.normalizeAngle(meanAnomaly, FastMath.PI);
return normalizedMeanAnomaly / meanMotion;
}
/**
* Method computing time to go until next apoapsis, assuming Keplerian motion.
* @param meanAnomaly mean anomaly
* @param meanMotion Keplerian mean motion
* @return duration to next apoapsis
*/
private static double computeKeplerianDurationToNextApoapsis(final double meanAnomaly,
final double meanMotion) {
final double normalizedMeanAnomaly = MathUtils.normalizeAngle(meanAnomaly, MathUtils.TWO_PI);
return (MathUtils.TWO_PI + FastMath.PI - normalizedMeanAnomaly) / meanMotion;
}
/**
* Method computing time elapsed since last apoapsis, assuming Keplerian motion.
* @param meanAnomaly mean anomaly
* @param meanMotion Keplerian mean motion
* @return duration elapsed since last apoapsis
*/
public static double computeKeplerianDurationFromPreviousApoapsis(final double meanAnomaly,
final double meanMotion) {
final double normalizedMeanAnomaly = MathUtils.normalizeAngle(meanAnomaly, MathUtils.TWO_PI);
return (normalizedMeanAnomaly - FastMath.PI) / meanMotion;
}
}