fr.cnes.sirius.patrius.events.detectors

Class CombinedPhenomenaDetector

java.lang.Object

fr.cnes.sirius.patrius.events.AbstractDetector

fr.cnes.sirius.patrius.events.detectors.CombinedPhenomenaDetector

All Implemented Interfaces:

EventDetector, Serializable

public class CombinedPhenomenaDetector
extends AbstractDetector

This class finds the events resulting from the combination of two phenomena. Combinations of phenomena can be done using the following boolean operators:

• AND : combined events are detected only both phenomena associated to event1 and event2 are active (i.e. an event is detected if event1 is triggered and phenomenon associated to event2 is active, or vice-versa);
• OR : combined events are detected if at least one of the phenomena associated to event1 and event2 is active (i.e. an event is detected if event1 or event2 are triggered);
  

The default implementation behaviour is to continue propagation when combined phnomena are detected. This can be changed by using one of the provided constructors.

Since:

1.1

Version:

$Id$

Author:

Julie Anton, Tiziana Sabatini

See Also:

EventDetector, Propagator.addEventDetector(EventDetector), Serialized Form

Concurrency :

not thread-safe or thread-hostile

Concurrency comment :

As of now, existing Orekit EventDetector implementations are either not thread-safe or thread-hostile, so this class also is. But this class could probably become conditionally thread-safe; the main thread safety condition would then be that the included EventDetector should be thread-safe.

Nested Class Summary

Nested classes/interfaces inherited from interface fr.cnes.sirius.patrius.events.EventDetector

EventDetector.Action

Field Summary

Fields inherited from class fr.cnes.sirius.patrius.events.AbstractDetector

actionAtEntry, actionAtExit, DEFAULT_MAXCHECK, DEFAULT_MAXITER, DEFAULT_THRESHOLD, removeAtEntry, removeAtExit, shouldBeRemovedFlag

Fields inherited from interface fr.cnes.sirius.patrius.events.EventDetector

DECREASING, INCREASING, INCREASING_DECREASING

Constructor Summary

Constructors

Constructor and Description
CombinedPhenomenaDetector(EventDetector d1, boolean d1IncreasingIsStart, EventDetector d2, boolean d2IncreasingIsStart, boolean togetherIn) Constructor for the detector of the combination of two phenomena.
CombinedPhenomenaDetector(EventDetector d1, boolean d1IncreasingIsStart, EventDetector d2, boolean d2IncreasingIsStart, boolean togetherIn, EventDetector.Action action) Constructor for the detector of the combination of two phenomena.

Method Summary

Modifier and Type	Method and Description
EventDetector	copy() A copy of the detector.
EventDetector.Action	eventOccurred(SpacecraftState s, boolean increasing, boolean forward) Handle an event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function for a combination (AND or OR) of two phenomena. After computing the switching function of each detector and, if necessary, changing its sign to apply a general convention (g>0 if the phenomenon associated to an event is active), it returns one between the two g functions, according to the boolean operator.
EventDetector	getDetector1() Returns first detector.
EventDetector	getDetector2() Returns second detector.
void	init(SpacecraftState s0, AbsoluteDate t) Initialize event handler at the start of a propagation.
boolean	shouldBeRemoved() This method is called after EventDetector.eventOccurred(fr.cnes.sirius.patrius.propagation.SpacecraftState, boolean, boolean) has been triggered.

Methods inherited from class fr.cnes.sirius.patrius.events.AbstractDetector

filterEvent, getActionAtEntry, getActionAtExit, getMaxCheckInterval, getMaxIterationCount, getSlopeSelection, getThreshold, isRemoveAtEntry, isRemoveAtExit, logEventsOverTimeInterval, resetState, setMaxCheckInterval, setMaxIter

Methods inherited from class java.lang.Object

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

Constructor Detail

CombinedPhenomenaDetector

public CombinedPhenomenaDetector(EventDetector d1,
                                 boolean d1IncreasingIsStart,
                                 EventDetector d2,
                                 boolean d2IncreasingIsStart,
                                 boolean togetherIn)

Constructor for the detector of the combination of two phenomena.

Parameters:

d1 - the first EventDetector

d1IncreasingIsStart - true if increasing of the g function of the the first EventDetector represents the "beginning" of the associated phenomenon

d2 - the second EventDetector

d2IncreasingIsStart - true if increasing of the g function of the the second EventDetector represents the "beginning" of the associated phenomenon

togetherIn - true if AND, false if OR

CombinedPhenomenaDetector

public CombinedPhenomenaDetector(EventDetector d1,
                                 boolean d1IncreasingIsStart,
                                 EventDetector d2,
                                 boolean d2IncreasingIsStart,
                                 boolean togetherIn,
                                 EventDetector.Action action)

Constructor for the detector of the combination of two phenomena.

Parameters:

d1 - the first EventDetector

d1IncreasingIsStart - true if increasing of the g function of the the first EventDetector represents the "beginning" of the associated phenomenon

d2 - the second EventDetector

d2IncreasingIsStart - true if increasing of the g function of the the second EventDetector represents the "beginning" of the associated phenomenon

togetherIn - true if AND, false if OR

action - action performed at combined Phenomena detection

Method Detail

g

public final double g(SpacecraftState s)
               throws PatriusException

Compute the value of the switching function for a combination (AND or OR) of two phenomena.
After computing the switching function of each detector and, if necessary, changing its sign to apply a general convention (g>0 if the phenomenon associated to an event is active), it returns one between the two g functions, according to the boolean operator.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector

Parameters:

s - the SpacecraftState that contains the current state information

Returns:

value of the switching function

Throws:

PatriusException - if some specific error occurs

eventOccurred

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

Handle an event and choose what to do next.

Specified by:

eventOccurred in interface EventDetector

Overrides:

eventOccurred in class AbstractDetector

Parameters:

s - the SpacecraftState that contains the current state information

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 combined philomena is reached

Throws:

PatriusException - if some specific error occurs

shouldBeRemoved

public boolean shouldBeRemoved()

This method is called after EventDetector.eventOccurred(fr.cnes.sirius.patrius.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

Overrides:

shouldBeRemoved in class AbstractDetector

Returns:

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

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)
          throws PatriusException

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

Throws:

PatriusException - thrown if initialization failed

getDetector1

public EventDetector getDetector1()

Returns first detector.

Returns:

EventDetector 1

getDetector2

public EventDetector getDetector2()

Returns second detector.

Returns:

EventDetector 2

copy

public EventDetector copy()

A copy of the detector. By default copy is deep. If not, detector javadoc will specify which attribute is not fully copied. In that case, the attribute reference is passed.

Returns:

a copy of the detector.