org.orekit.propagation.events

Class AlignmentDetector

java.lang.Object

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

org.orekit.propagation.events.AlignmentDetector

All Implemented Interfaces:

Serializable, EventDetector

public class AlignmentDetector
extends AbstractDetector<AlignmentDetector>

Finder for satellite/body alignment events in orbital plane.

This class finds alignment events.

Alignment means the conjunction, with some threshold angle, between the satellite position and the projection in the orbital plane of some body position.

The default handler behavior is to stop propagation when alignment is reached. This can be changed by calling AbstractDetector.withHandler(EventHandler) after construction.

Author:

Pascal Parraud

See Also:

Propagator.addEventDetector(EventDetector), Serialized Form

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
AlignmentDetector(double threshold, Orbit orbit, PVCoordinatesProvider body, double alignAngle) Build a new alignment detector.
AlignmentDetector(Orbit orbit, PVCoordinatesProvider body, double alignAngle) Build a new alignment detector.

Method Summary

Modifier and Type	Method and Description
protected AlignmentDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super AlignmentDetector> newHandler) Build a new instance.
double	g(SpacecraftState s) Compute the value of the switching function.
double	getAlignAngle() Get the alignment angle (rad).
PVCoordinatesProvider	getPVCoordinatesProvider() Get the body to align.

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

AlignmentDetector

public AlignmentDetector(Orbit orbit,
                         PVCoordinatesProvider body,
                         double alignAngle)

Build a new alignment detector.

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

body - the body to align

alignAngle - the alignment angle (rad)

AlignmentDetector

public AlignmentDetector(double threshold,
                         Orbit orbit,
                         PVCoordinatesProvider body,
                         double alignAngle)

Build a new alignment detector.

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

body - the body to align

alignAngle - the alignment angle (rad)

Method Detail

create

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

Build a new instance.

Specified by:

create in class AbstractDetector<AlignmentDetector>

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

getPVCoordinatesProvider

public PVCoordinatesProvider getPVCoordinatesProvider()

Get the body to align.

Returns:

the body to align

getAlignAngle

public double getAlignAngle()

Get the alignment angle (rad).

Returns:

the alignment angle

g

public double g(SpacecraftState s)
         throws OrekitException

Compute the value of the switching function. This function measures the difference between the alignment angle and the angle between the satellite position and the body position projection in the orbital plane.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<AlignmentDetector>

Parameters:

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

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs