org.orekit.propagation.events

Class MagneticFieldDetector

java.lang.Object

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

org.orekit.propagation.events.MagneticFieldDetector

All Implemented Interfaces:

EventDetector

public class MagneticFieldDetector
extends AbstractDetector<MagneticFieldDetector>

Detector for South-Atlantic anomaly frontier crossing.

The detector is based on the value of the earth magnetic field at see level at the satellite latitude and longitude.

Author:

Romaric Her

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
MagneticFieldDetector(double maxCheck, double threshold, double limit, GeoMagneticFieldFactory.FieldModel type, OneAxisEllipsoid body, boolean seaLevel) Build a detector.
MagneticFieldDetector(double limit, GeoMagneticFieldFactory.FieldModel type, OneAxisEllipsoid body) Build a new detector.
MagneticFieldDetector(double limit, GeoMagneticFieldFactory.FieldModel type, OneAxisEllipsoid body, boolean seaLevel) Build a new detector.

Method Summary

Modifier and Type	Method and Description
protected MagneticFieldDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super MagneticFieldDetector> newHandler) Build a new instance.
double	g(SpacecraftState s) Compute the value of the detection function.
void	init(SpacecraftState s0, AbsoluteDate t) Initialize event handler at the start of a propagation.

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

eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, 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

MagneticFieldDetector

public MagneticFieldDetector(double limit,
                             GeoMagneticFieldFactory.FieldModel type,
                             OneAxisEllipsoid body)
                      throws OrekitIllegalArgumentException

Build a new detector.

The new instance uses default values for maximal checking interval (AbstractDetector.DEFAULT_MAXCHECK) and convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

Parameters:

limit - the threshold value of magnetic field at see level

type - the magnetic field model

body - the body

Throws:

OrekitIllegalArgumentException - if orbit type is OrbitType.CARTESIAN

MagneticFieldDetector

public MagneticFieldDetector(double limit,
                             GeoMagneticFieldFactory.FieldModel type,
                             OneAxisEllipsoid body,
                             boolean seaLevel)
                      throws OrekitIllegalArgumentException

Build a new detector.

The new instance uses default values for maximal checking interval (AbstractDetector.DEFAULT_MAXCHECK) and convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

Parameters:

limit - the threshold value of magnetic field at see level

type - the magnetic field model

body - the body

seaLevel - true if the magnetic field intensity is computed at the sea level, false if it is computed at satellite altitude

Throws:

OrekitIllegalArgumentException - if orbit type is OrbitType.CARTESIAN

MagneticFieldDetector

public MagneticFieldDetector(double maxCheck,
                             double threshold,
                             double limit,
                             GeoMagneticFieldFactory.FieldModel type,
                             OneAxisEllipsoid body,
                             boolean seaLevel)
                      throws OrekitIllegalArgumentException

Build a detector.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

limit - the threshold value of magnetic field at see level

type - the magnetic field model

body - the body

seaLevel - true if the magnetic field intensity is computed at the sea level, false if it is computed at satellite altitude

Throws:

OrekitIllegalArgumentException - if orbit type is OrbitType.CARTESIAN

Method Detail

create

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

Build a new instance.

Specified by:

create in class AbstractDetector<MagneticFieldDetector>

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

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)

Initialize event handler at the start of a propagation.

This method is called once at the start of the propagation. It may be used by the event handler to initialize some internal data if needed.

The default implementation does nothing

This implementation sets the direction of propagation and initializes the event handler. If a subclass overrides this method it should call super.init(s0, t).

Specified by:

init in interface EventDetector

Overrides:

init in class AbstractDetector<MagneticFieldDetector>

Parameters:

s0 - initial state

t - target time for the integration

g

public double g(SpacecraftState s)

Compute the value of the detection function.

The value is the angle difference between the spacecraft and the fixed angle to be crossed, with some sign tweaks to ensure continuity. These tweaks imply the increasing flag in events detection becomes irrelevant here! As an example, the angle always increase in a Keplerian orbit, but this g function will increase and decrease so it will cross the zero value once per orbit, in increasing and decreasing directions on alternate orbits..

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<MagneticFieldDetector>

Parameters:

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

Returns:

angle difference between the spacecraft and the fixed angle, with some sign tweaks to ensure continuity