org.orekit.propagation.events
Class ExtremaElevationDetector

java.lang.Object
  org.orekit.propagation.events.AbstractDetector
      org.orekit.propagation.events.ExtremaElevationDetector

All Implemented Interfaces:

Serializable, EventDetector

public class ExtremaElevationDetector
extends AbstractDetector

Detects the time when the spacecraft reaches the elevation extrema in a given topocentric frame. The local minimum or maximum is chosen through a constructor parameter, with values MIN, MAX and MIN_MAX for both.

The default implementation behaviour is to stop propagation when the minimum/maximum elevation is reached. This can be changed by using provided constructors.

Since:

1.2

Version:

$Id: ExtremaElevationDetector.java 17582 2017-05-10 12:58:16Z bignon $

Author:

Thomas Trapier

See Also:

EventDetector, Serialized Form

Concurrency :

not thread-safe

Concurrency comment :

the link to the tree of frames makes this class not thread-safe

Nested Class Summary

Nested classes/interfaces inherited from interface org.orekit.propagation.events.EventDetector

EventDetector.Action

Field Summary

static int	MAX Flag for local maximum elevation detection.
static int	MIN Flag for local minimum elevation detection.
static int	MIN_MAX Flag for both local minimum and maximum elevation detection.

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

DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Fields inherited from interface org.orekit.propagation.events.EventDetector

DECREASING, INCREASING, INCREASING_DECREASING

Constructor Summary

ExtremaElevationDetector(TopocentricFrame topoFrame, int extremumType, double maxCheck)
Constructor for a min and max elevation detector.

ExtremaElevationDetector(TopocentricFrame topoFrame, int extremumType, double maxCheck, double threshold)
Constructor for a min or max elevation detector.

ExtremaElevationDetector(TopocentricFrame topoFrame, int extremumType, double maxCheck, double threshold, EventDetector.Action action)
Constructor for a min or max elevation detector.

ExtremaElevationDetector(TopocentricFrame topoFrame, int extremumType, double maxCheck, double threshold, EventDetector.Action action, boolean remove)
Constructor for a min or max elevation detector.

Method Summary

EventDetector.Action	eventOccurred(SpacecraftState s, boolean increasing, boolean forward) Handle an extrema distance event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function.
TopocentricFrame	getTopocentricFrame()
void	init(SpacecraftState s0, AbsoluteDate t) Initialize event handler at the start of a propagation.
boolean	shouldBeRemoved() This method is called after EventDetector.eventOccurred(org.orekit.propagation.SpacecraftState, boolean, boolean) has been triggered.

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

getMaxCheckInterval, getMaxIterationCount, getSlopeSelection, getThreshold, resetState

Methods inherited from class java.lang.Object

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

Field Detail

MIN

public static final int MIN

Flag for local minimum elevation detection.

See Also:

Constant Field Values

MAX

public static final int MAX

Flag for local maximum elevation detection.

See Also:

Constant Field Values

MIN_MAX

public static final int MIN_MAX

Flag for both local minimum and maximum elevation detection.

See Also:

Constant Field Values

Constructor Detail

ExtremaElevationDetector

public ExtremaElevationDetector(TopocentricFrame topoFrame,
                                int extremumType,
                                double maxCheck)

Constructor for a min and max elevation detector.

This constructor takes default value for convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

The maximal interval between elevation checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

Parameters:

topoFrame - topocentric frame in which elevation should be evaluated

extremumType - MIN for minimal elevation detection, MAX for maximal elevation detection or MIN_MAX for both shortest and farthest elevation detection

maxCheck - maximal checking interval (s)

ExtremaElevationDetector

public ExtremaElevationDetector(TopocentricFrame topoFrame,
                                int extremumType,
                                double maxCheck,
                                double threshold)

Constructor for a min or max elevation detector.

The maximal interval between elevation checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

The default implementation behavior is to stop propagation when the expected extremum is reached.

Parameters:

topoFrame - topocentric frame in which elevation should be evaluated

extremumType - MIN for minimal elevation detection, MAX for maximal elevation detection or MIN_MAX for both shortest and farthest elevation detection

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

ExtremaElevationDetector

public ExtremaElevationDetector(TopocentricFrame topoFrame,
                                int extremumType,
                                double maxCheck,
                                double threshold,
                                EventDetector.Action action)

Constructor for a min or max elevation detector.

The maximal interval between elevation checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

Parameters:

topoFrame - topocentric frame in which elevation should be evaluated

extremumType - MIN for minimal elevation detection, MAX for maximal elevation detection or MIN_MAX for both shortest and farthest elevation detection

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

action - action performed at extrema elevation detection

ExtremaElevationDetector

public ExtremaElevationDetector(TopocentricFrame topoFrame,
                                int extremumType,
                                double maxCheck,
                                double threshold,
                                EventDetector.Action action,
                                boolean remove)

Constructor for a min or max elevation detector.

The maximal interval between elevation checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

Parameters:

topoFrame - topocentric frame in which elevation should be evaluated

extremumType - MIN for minimal elevation detection, MAX for maximal elevation detection or MIN_MAX for both shortest and farthest elevation detection

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

action - action performed at extrema elevation detection

remove - true if detector should be removed at extrema elevation detection

Since:

3.1

Method Detail

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)

Description copied from class: AbstractDetector

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.

Specified by:

init in interface EventDetector

Overrides:

init in class AbstractDetector

Parameters:

s0 - initial state

t - target time for the integration

eventOccurred

public EventDetector.Action eventOccurred(SpacecraftState s,
                                          boolean increasing,
                                          boolean forward)
                                   throws OrekitException

Handle an extrema distance event and choose what to do next.

Specified by:

eventOccurred in interface EventDetector

Specified by:

eventOccurred in class AbstractDetector

Parameters:

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

increasing - if true, the value of the switching function increases when times increases around event

forward - if true, the integration variable (time) increases during integration.

Returns:

the action performed when the expected extrema elevation is reached

Throws:

OrekitException - if some specific error occurs

shouldBeRemoved

public boolean shouldBeRemoved()

This method is called after EventDetector.eventOccurred(org.orekit.propagation.SpacecraftState, boolean, boolean) has been triggered. It returns true if the current detector should be removed after first event detection. WARNING: this method can be called only once a event has been triggered. Before, the value is not available.

Specified by:

shouldBeRemoved in interface EventDetector

Specified by:

shouldBeRemoved in class AbstractDetector

Returns:

true if the current detector should be removed after first event detection

g

public double g(SpacecraftState s)
         throws OrekitException

Description copied from class: AbstractDetector

Compute the value of the switching function. This function must be continuous (at least in its roots neighborhood), as the integrator will need to find its roots to locate the events.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector

Parameters:

s - the current state information: date, kinematics, attitude for forces and events computation, mass provider, and additional states

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs

getTopocentricFrame

public TopocentricFrame getTopocentricFrame()

Returns:

the Topocentric frame in which elevation should be evaluated.