fr.cnes.sirius.patrius.events.postprocessing

Class GenericCodingEventDetector

java.lang.Object

fr.cnes.sirius.patrius.events.postprocessing.GenericCodingEventDetector

All Implemented Interfaces:

EventDetector, CodingEventDetector, Serializable

public class GenericCodingEventDetector
extends Object
implements CodingEventDetector

This class represents an all-purpose implementation of the CodingEventDetector interface.
It works using the EventDetector provided in the constructor.

This detector is able to build a CodedEvent for a given date using the method buildCodedEvent.
You cannot set the CodedEvent comment through this implementation. Subclassing is permitted for the purpose of adding functionality.

It supports phenomena or not, depending on which constructor was used. When it does support phenomena, the user can know for a given input if the state is active using the method isStateActive.

Since:

1.1

Version:

$Id$

Author:

Pierre Cardoso, Tiziana Sabatini

See Also:

CodingEventDetector, 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 interface fr.cnes.sirius.patrius.events.EventDetector

DECREASING, INCREASING, INCREASING_DECREASING

Constructor Summary

Constructors

Constructor and Description
GenericCodingEventDetector(EventDetector eventDetectorIn, String increasingCodeIn, String decreasingCodeIn) Constructor for a GenericCodingEventDetector that does not support a Phenomenon.
GenericCodingEventDetector(EventDetector eventDetectorIn, String increasingCodeIn, String decreasingCodeIn, boolean increasingIsStartIn, String phenomenonCodeIn) Constructor for a GenericCodingEventDetector that supports a Phenomenon.
GenericCodingEventDetector(EventDetector eventDetectorIn, String increasingCodeIn, String decreasingCodeIn, boolean increasingIsStartIn, String phenomenonCodeIn, double delayIn, int occurrenceIn) Constructor for a GenericCodingEventDetector that supports a Phenomenon.
GenericCodingEventDetector(EventDetector eventDetectorIn, String increasingCodeIn, String decreasingCodeIn, double delayIn, int occurrenceIn) Constructor for a GenericCodingEventDetector that does not support a Phenomenon.

Method Summary

Modifier and Type	Method and Description
CodedEvent	buildCodedEvent(SpacecraftState s, boolean increasing) Build a CodedEvent instance appropriate for the provided SpacecraftState.
CodedEvent	buildDelayedCodedEvent(SpacecraftState s, boolean increasing) Build a delayed CodedEvent instance appropriate for the provided SpacecraftState.
CodedEvent	buildOccurrenceCodedEvent(SpacecraftState s, boolean increasing) Build a CodedEvent instance appropriate for the provided SpacecraftState.
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.
boolean	filterEvent(SpacecraftState state, boolean increasing, boolean forward) Filter last event: returns true if the last event is a false detection, false otherwise.
double	g(SpacecraftState s) Compute the value of the switching function.
String	getEventType() Gets a code indicating the type of event we want to log: DELAY when a delay is associated to the logged events with respect to the detected events, N_OCCURRENCE when we want to log the nth occurrence of the detected events, STANDARD when no delays and no occurrence numbers are taken into consideration.
double	getMaxCheckInterval() Get maximal time interval between switching function checks.
int	getMaxIterationCount() Get maximal number of iterations in the event time search.
String	getPhenomenonCode() If the implementation supports a Phenomenon, provides a code for the phenomenon associated to the event.
int	getSlopeSelection() Get the parameter in charge of the selection of detected events by the slope of the g-function.
double	getThreshold() Get the convergence threshold in the event time search.
void	init(SpacecraftState s0, AbsoluteDate t) Initialize event handler at the start of a propagation.
boolean	isStateActive(SpacecraftState state) Tells if the event state is "active" for the given input.
static SpacecraftState	logEventsOverTimeInterval(CodedEventsLogger eventsLogger, Propagator satProp, CodingEventDetector detector, AbsoluteDateInterval interval) Log detected events on a given time interval into the entered events logger.
boolean	positiveSignMeansActive() Get the sign of the g method that means "the phenomenon associated to the event is active".
SpacecraftState	resetState(SpacecraftState oldState) Reset the state (including additional states) prior to continue 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 java.lang.Object

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

Constructor Detail

GenericCodingEventDetector

public GenericCodingEventDetector(EventDetector eventDetectorIn,
                                  String increasingCodeIn,
                                  String decreasingCodeIn,
                                  boolean increasingIsStartIn,
                                  String phenomenonCodeIn)

Constructor for a GenericCodingEventDetector that supports a Phenomenon.
No delays and no occurrence numbers are associated to the events detected by this detector.

Parameters:

eventDetectorIn - the EventDetector of the current event

increasingCodeIn - code identifying the "increasing" event

decreasingCodeIn - code identifying the "decreasing" event

increasingIsStartIn - true if increasing of the g function represents the "beginning" of the associated phenomenon

phenomenonCodeIn - code identifying the phenomenon associated to the event

See Also:

CodingEventDetector, EventDetector, Phenomenon

GenericCodingEventDetector

public GenericCodingEventDetector(EventDetector eventDetectorIn,
                                  String increasingCodeIn,
                                  String decreasingCodeIn,
                                  boolean increasingIsStartIn,
                                  String phenomenonCodeIn,
                                  double delayIn,
                                  int occurrenceIn)

Constructor for a GenericCodingEventDetector that supports a Phenomenon.
A delay and/or an occurrence number can be associated to the events detected by this detector.
When a delay is added to the detected events, two kinds of events will be coded:
- the original events, with their original codes;
- the delayed events, whose codes will be "DELAYED_" followed by the original code.

Parameters:

eventDetectorIn - the EventDetector of the current event

increasingCodeIn - code identifying the "increasing" event

decreasingCodeIn - code identifying the "decreasing" event

increasingIsStartIn - true if increasing of the g function represents the "beginning" of the associated phenomenon

phenomenonCodeIn - code identifying the phenomenon associated to the event

delayIn - the delay of the output events with respect to the events detected during propagation; if it is set to zero, no delay will be added to the events

occurrenceIn - the occurrence number of the output event (only the nth event will be detected); if it is set to zero, all events will be detected

See Also:

CodingEventDetector, EventDetector, Phenomenon

GenericCodingEventDetector

public GenericCodingEventDetector(EventDetector eventDetectorIn,
                                  String increasingCodeIn,
                                  String decreasingCodeIn)

Constructor for a GenericCodingEventDetector that does not support a Phenomenon. No delays and no occurrence numbers are associated to the events detected by this detector.

Parameters:

eventDetectorIn - the EventDetector of the current event

increasingCodeIn - code identifying the "increasing" event

decreasingCodeIn - code identifying the "decreasing" event

See Also:

CodingEventDetector, EventDetector

GenericCodingEventDetector

public GenericCodingEventDetector(EventDetector eventDetectorIn,
                                  String increasingCodeIn,
                                  String decreasingCodeIn,
                                  double delayIn,
                                  int occurrenceIn)

Constructor for a GenericCodingEventDetector that does not support a Phenomenon.
When a delay is added to the detected events, two kinds of events will be coded:
- the original events, with their original codes;
- the delayed events, whose codes will be "DELAYED_" followed by the original code.

Parameters:

eventDetectorIn - the EventDetector of the current event

increasingCodeIn - code identifying the "increasing" event

decreasingCodeIn - code identifying the "decreasing" event

delayIn - the delay of the output events with respect to the events detected during propagation; if it is set to zero, no delay will be added to the events

occurrenceIn - the occurrence number of the output event (only the nth event will be detected); if it is set to zero, all events will be detected

See Also:

CodingEventDetector, EventDetector

Method Detail

g

public final double g(SpacecraftState s)
               throws PatriusException

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

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:

PatriusException - if some specific error occurs

eventOccurred

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

Handle an event and choose what to do next.

The scheduling between this method and the PatriusStepHandler method handleStep() is to call this method first and handleStep afterwards. This scheduling allows the propagator to pass true as the isLast parameter to the step handler to make it aware the step will be the last one if this method returns EventDetector.Action.STOP. As the interpolator may be used to navigate back throughout the last step (as OrekitStepNormalizer does for example), user code called by this method and user code called by step handlers may experience apparently out of order values of the independent time variable. As an example, if the same user object implements both this EventDetector interface and the OrekitFixedStepHandler interface, a forward integration may call its eventOccurred method with a state at 2000-01-01T00:00:10 first and call its handleStep method with a state at 2000-01-01T00:00:09 afterwards. Such out of order calls are limited to the size of the integration step for variable step handlers and to the size of the fixed step for fixed step handlers.

Specified by:

eventOccurred in interface EventDetector

Parameters:

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

increasing - if true, the value of the switching function increases when times increases around event (note that increase is measured with respect to physical time, not with respect to propagation which may go backward in time)

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

Returns:

one of EventDetector.Action.STOP, EventDetector.Action.RESET_STATE, EventDetector.Action.RESET_DERIVATIVES, EventDetector.Action.CONTINUE

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

Returns:

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

resetState

public final SpacecraftState resetState(SpacecraftState oldState)
                                 throws PatriusException

Reset the state (including additional states) prior to continue propagation.

This method is called after the step handler has returned and before the next step is started, but only when EventDetector.eventOccurred(fr.cnes.sirius.patrius.propagation.SpacecraftState, boolean, boolean) has itself returned the EventDetector.Action.RESET_STATE indicator. It allows the user to reset the state for the next step, without perturbing the step handler of the finishing step. If the EventDetector.eventOccurred(fr.cnes.sirius.patrius.propagation.SpacecraftState, boolean, boolean) never returns the EventDetector.Action.RESET_STATE indicator, this function will never be called, and it is safe to simply return null.

Specified by:

resetState in interface EventDetector

Parameters:

oldState - old state

Returns:

new state

Throws:

PatriusException - if the state cannot be reseted

getThreshold

public final double getThreshold()

Get the convergence threshold in the event time search.

Specified by:

getThreshold in interface EventDetector

Returns:

convergence threshold (s)

getMaxCheckInterval

public final double getMaxCheckInterval()

Get maximal time interval between switching function checks.

Specified by:

getMaxCheckInterval in interface EventDetector

Returns:

maximal time interval (s) between switching function checks

getMaxIterationCount

public final int getMaxIterationCount()

Get maximal number of iterations in the event time search.

Specified by:

getMaxIterationCount in interface EventDetector

Returns:

maximal number of iterations in the event time search

buildCodedEvent

public final CodedEvent buildCodedEvent(SpacecraftState s,
                                        boolean increasing)

Build a CodedEvent instance appropriate for the provided SpacecraftState.

Specified by:

buildCodedEvent in interface CodingEventDetector

Parameters:

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

increasing - if true, g function increases around event date.

Returns:

the CodedEvent

buildDelayedCodedEvent

public final CodedEvent buildDelayedCodedEvent(SpacecraftState s,
                                               boolean increasing)

Build a delayed CodedEvent instance appropriate for the provided SpacecraftState. This instance will have a delay with respect to the associated detected event.

Specified by:

buildDelayedCodedEvent in interface CodingEventDetector

Parameters:

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

increasing - if true, g function increases around event date.

Returns:

the CodedEvent

buildOccurrenceCodedEvent

public final CodedEvent buildOccurrenceCodedEvent(SpacecraftState s,
                                                  boolean increasing)

Build a CodedEvent instance appropriate for the provided SpacecraftState. This method will return an instance only if it is be the nth occurrence of the corresponding event, otherwise it will return null. A delay can be applied to the event.

Specified by:

buildOccurrenceCodedEvent in interface CodingEventDetector

Parameters:

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

increasing - if true, g function increases around event date.

Returns:

the CodedEvent

positiveSignMeansActive

public final boolean positiveSignMeansActive()

Get the sign of the g method that means "the phenomenon associated to the event is active".
This method has been implemented because of the inconsistency of the sign of the g functions in the EventDetector classes in Orekit: for some events, g is positive when its associated phenomenon is active, and for others, g is positive when its phenomenon is not active.
WARNING : If Phenomena are not supported, the behavior of this method is undefined.

Specified by:

positiveSignMeansActive in interface CodingEventDetector

Returns:

true for positive, false for negative.

getPhenomenonCode

public final String getPhenomenonCode()

If the implementation supports a Phenomenon, provides a code for the phenomenon associated to the event. If not, returns null.

Specified by:

getPhenomenonCode in interface CodingEventDetector

Returns:

either a code, or null if Phenomena are not supported.

isStateActive

public final boolean isStateActive(SpacecraftState state)
                            throws PatriusException

Tells if the event state is "active" for the given input. If phenomena are unsupported by this instance, it will always return false.

Parameters:

state - the input SpacecraftState

Returns:

true if the state is "active" according to the convention chosen in the constructor.

Throws:

PatriusException - from the wrapped event detector.

getEventType

public final String getEventType()

Gets a code indicating the type of event we want to log: DELAY when a delay is associated to the logged events with respect to the detected events, N_OCCURRENCE when we want to log the nth occurrence of the detected events, STANDARD when no delays and no occurrence numbers are taken into consideration.

Specified by:

getEventType in interface CodingEventDetector

Returns:

the type of event to log

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

Parameters:

s0 - initial state

t - target time for the integration

Throws:

PatriusException - thrown if initialization failed

getSlopeSelection

public int getSlopeSelection()

Get the parameter in charge of the selection of detected events by the slope of the g-function.

Specified by:

getSlopeSelection in interface EventDetector

Returns:

EventDetector.INCREASING (0): events related to the increasing g-function;
EventDetector.DECREASING (1): events related to the decreasing g-function;
EventDetector.INCREASING_DECREASING (2): events related to both increasing and decreasing g-function.

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.

Specified by:

copy in interface EventDetector

Returns:

a copy of the detector.

logEventsOverTimeInterval

public static SpacecraftState logEventsOverTimeInterval(CodedEventsLogger eventsLogger,
                                                        Propagator satProp,
                                                        CodingEventDetector detector,
                                                        AbsoluteDateInterval interval)
                                                 throws PatriusException

Log detected events on a given time interval into the entered events logger.

Parameters:

eventsLogger - input events logger in which the events must be recorded

satProp - spacecraft orbit propagator

detector - detector to be monitored

interval - time interval on which the events are looked for

Returns:

the spacecraft state after propagation

Throws:

PatriusException - if spacecraft state cannot be propagated

filterEvent

public boolean filterEvent(SpacecraftState state,
                           boolean increasing,
                           boolean forward)
                    throws PatriusException

Filter last event: returns true if the last event is a false detection, false otherwise.

This method is called right before EventDetector.eventOccurred(SpacecraftState, boolean, boolean) method.

This may be useful in order to filter some events in particular when angles are at stake (see for example LocalTimeAngleDetector).

Specified by:

filterEvent in interface EventDetector

Parameters:

state - state at last event occurrence

increasing - if true, the value of the switching function increases when times increases around event (note that increase is measured with respect to physical time, not with respect to propagation which may go backward in time)

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

Returns:

true if the last event is a false detection, false otherwise

Throws:

PatriusException - thrown if computation failed for some reasons