org.orekit.propagation.events

Class ApsideDetector

java.lang.Object

org.orekit.propagation.events.AbstractDetector<ApsideDetector>

org.orekit.propagation.events.ApsideDetector

All Implemented Interfaces:

EventDetector

public class ApsideDetector
extends AbstractDetector<ApsideDetector>

Finder for apside crossing events.

This class finds apside crossing events (i.e. apogee or perigee crossing).

The default implementation behavior is to continue propagation at apogee crossing and to stop propagation at perigee crossing. This can be changed by calling AbstractDetector.withHandler(EventHandler) after construction.

Beware that apside detection will fail for almost circular orbits. If for example an apside detector is used to trigger an ImpulseManeuver and the maneuver change the orbit shape to circular, then the detector may completely fail just after the maneuver has been performed!

Author:

Luc Maisonobe

See Also:

Propagator.addEventDetector(EventDetector)

Field Summary

Fields inherited from class org.orekit.propagation.events.AbstractDetector

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
ApsideDetector(double threshold, Orbit orbit) Build a new instance.
ApsideDetector(Orbit orbit) Build a new instance.

Method Summary

Modifier and Type	Method and Description
protected ApsideDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super ApsideDetector> newHandler) Build a new instance.
double	g(SpacecraftState s) Compute the value of the switching function.

Methods inherited from class org.orekit.propagation.events.AbstractDetector

eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, init, isForward, resetState, withHandler, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ApsideDetector

public ApsideDetector(Orbit orbit)

Build a new instance.

The orbit is used only to set an upper bound for the max check interval to period/3 and to set the convergence threshold according to orbit size

Parameters:

orbit - initial orbit

ApsideDetector

public ApsideDetector(double threshold,
                      Orbit orbit)

Build a new instance.

The orbit is used only to set an upper bound for the max check interval to period/3

Parameters:

threshold - convergence threshold (s)

orbit - initial orbit

Method Detail

create

protected ApsideDetector create(double newMaxCheck,
                                double newThreshold,
                                int newMaxIter,
                                EventHandler<? super ApsideDetector> newHandler)

Build a new instance.

Specified by:

create in class AbstractDetector<ApsideDetector>

Parameters:

newMaxCheck - maximum checking interval (s)

newThreshold - convergence threshold (s)

newMaxIter - maximum number of iterations in the event time search

newHandler - event handler to call at event occurrences

Returns:

a new instance of the appropriate sub-type

g

public double g(SpacecraftState s)

Compute the value of the switching function. This function computes the dot product of the 2 vectors : position.velocity.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<ApsideDetector>

Parameters:

s - the current state information: date, kinematics, attitude

Returns:

value of the switching function