Package org.orekit.propagation.events

Class FieldLongitudeCrossingDetector<T extends CalculusFieldElement<T>>

java.lang.Object

org.orekit.propagation.events.FieldAbstractDetector<FieldLongitudeCrossingDetector<T>,T>

org.orekit.propagation.events.FieldLongitudeCrossingDetector<T>

Type Parameters:

T - type of the field elements

All Implemented Interfaces:

FieldEventDetector<T>

public class FieldLongitudeCrossingDetector<T extends CalculusFieldElement<T>>
extends FieldAbstractDetector<FieldLongitudeCrossingDetector<T>,T>

Detector for geographic longitude crossing.

This detector identifies when a spacecraft crosses a fixed longitude with respect to a central body.

Since:

12.0

Author:

Alberto Ferrero

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Modifier	Constructor	Description
	FieldLongitudeCrossingDetector(Field<T> field, OneAxisEllipsoid body, double longitude)	Build a new detector.
protected	FieldLongitudeCrossingDetector(FieldAdaptableInterval<T> maxCheck, T threshold, int maxIter, FieldEventHandler<T> handler, OneAxisEllipsoid body, double longitude)	Protected constructor with full parameters.
	FieldLongitudeCrossingDetector(T maxCheck, T threshold, OneAxisEllipsoid body, double longitude)	Build a detector.

Method Summary

Modifier and Type	Method	Description
protected FieldLongitudeCrossingDetector<T>	create(FieldAdaptableInterval<T> newMaxCheck, T newThreshold, int newMaxIter, FieldEventHandler<T> newHandler)	Build a new instance.
T	g(FieldSpacecraftState<T> s)	Compute the value of the detection function.
OneAxisEllipsoid	getBody()	Get the body on which the geographic zone is defined.
double	getLongitude()	Get the fixed longitude to be crossed (radians).
void	init(FieldSpacecraftState<T> s0, FieldAbsoluteDate<T> t)	Initialize event handler at the start of a propagation.

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

getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, isForward, withHandler, withMaxCheck, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Constructor Detail

FieldLongitudeCrossingDetector

public FieldLongitudeCrossingDetector(Field<T> field,
                                      OneAxisEllipsoid body,
                                      double longitude)

Build a new detector.

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

Parameters:

field - the type of numbers to use.

body - body on which the longitude is defined

longitude - longitude to be crossed

FieldLongitudeCrossingDetector

public FieldLongitudeCrossingDetector(T maxCheck,
                                      T threshold,
                                      OneAxisEllipsoid body,
                                      double longitude)

Build a detector.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

body - body on which the longitude is defined

longitude - longitude to be crossed

FieldLongitudeCrossingDetector

protected FieldLongitudeCrossingDetector(FieldAdaptableInterval<T> maxCheck,
                                         T threshold,
                                         int maxIter,
                                         FieldEventHandler<T> handler,
                                         OneAxisEllipsoid body,
                                         double longitude)

Protected constructor with full parameters.

This constructor is not public as users are expected to use the builder API with the various withXxx() methods to set up the instance in a readable manner without using a huge amount of parameters.

Parameters:

maxCheck - maximum checking interval

threshold - convergence threshold (s)

maxIter - maximum number of iterations in the event time search

handler - event handler to call at event occurrences

body - body on which the longitude is defined

longitude - longitude to be crossed

Method Detail

create

protected FieldLongitudeCrossingDetector<T> create(FieldAdaptableInterval<T> newMaxCheck,
                                                   T newThreshold,
                                                   int newMaxIter,
                                                   FieldEventHandler<T> newHandler)

Build a new instance.

Specified by:

create in class FieldAbstractDetector<FieldLongitudeCrossingDetector<T extends CalculusFieldElement<T>>,T extends CalculusFieldElement<T>>

Parameters:

newMaxCheck - maximum checking interval

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

getBody

public OneAxisEllipsoid getBody()

Get the body on which the geographic zone is defined.

Returns:

body on which the geographic zone is defined

getLongitude

public double getLongitude()

Get the fixed longitude to be crossed (radians).

Returns:

fixed longitude to be crossed (radians)

init

public void init(FieldSpacecraftState<T> s0,
                 FieldAbsoluteDate<T> 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

Specified by:

init in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Overrides:

init in class FieldAbstractDetector<FieldLongitudeCrossingDetector<T extends CalculusFieldElement<T>>,T extends CalculusFieldElement<T>>

Parameters:

s0 - initial state

t - target time for the integration

g

public T g(FieldSpacecraftState<T> s)

Compute the value of the detection function.

The value is the longitude difference between the spacecraft and the fixed longitude 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 longitude of a prograde spacecraft will always increase, 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. If eastwards and westwards crossing have to be distinguished, the velocity direction has to be checked instead of looking at the increasing flag.

Specified by:

g in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Specified by:

g in class FieldAbstractDetector<FieldLongitudeCrossingDetector<T extends CalculusFieldElement<T>>,T extends CalculusFieldElement<T>>

Parameters:

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

Returns:

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