fr.cnes.sirius.patrius.propagation.events

Class AbstractDetector

java.lang.Object

fr.cnes.sirius.patrius.propagation.events.AbstractDetector

All Implemented Interfaces:

EventDetector, Serializable

Direct Known Subclasses:

AbstractDetectorWithTropoCorrection, AlignmentDetector, AltitudeDetector, AnomalyDetector, AOLDetector, ApparentElevationDetector, ApsideDetector, BetaAngleDetector, CentralBodyMaskCircularFOVDetector, CircularFieldOfViewDetector, CombinedPhenomenaDetector, DateDetector, DihedralFieldOfViewDetector, DistanceDetector, EarthZoneDetector, EclipseDetector, ElevationDetector, EventShifter, ExtremaDistanceDetector, ExtremaElevationDetector, ExtremaGenericDetector, ExtremaLatitudeDetector, ExtremaLongitudeDetector, ExtremaSightAxisDetector, ExtremaThreeBodiesAngleDetector, GroundMaskElevationDetector, ImpulseManeuver, LatitudeDetector, LocalTimeAngleDetector, LongitudeDetector, MaskingDetector, NadirSolarIncidenceDetector, NodeDetector, NullMassDetector, NullMassPartDetector, PerigeeAltitudeDetector, RFVisibilityDetector, SatToSatMutualVisibilityDetector, SensorInhibitionDetector, SensorVisibilityDetector, SolarTimeAngleDetector, TargetInFieldOfViewDetector, ThreeBodiesAngleDetector, VisibilityFromStationDetector

public abstract class AbstractDetector
extends Object
implements EventDetector

Common parts shared by several events finders. A default implementation of most of the methods of EventDetector Interface. Make it easier to create a new detector.

Author:

Luc Maisonobe

See Also:

Propagator.addEventDetector(EventDetector), Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractDetector.PropagationDelayType Propagation delay type.

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

EventDetector.Action

Field Summary

Fields

Modifier and Type	Field and Description
protected EventDetector.Action	actionAtEntry Action performed at entry
protected EventDetector.Action	actionAtExit Action performed at exit
static double	DEFAULT_MAXCHECK Default maximum checking interval (s).
static double	DEFAULT_THRESHOLD Default convergence threshold (s).
protected boolean	removeAtEntry True if detector should be removed at entry
protected boolean	removeAtExit True if detector should be removed at exit
protected boolean	shouldBeRemovedFlag True if detector should be removed (updated by eventOccured)

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

DECREASING, INCREASING, INCREASING_DECREASING

Constructor Summary

Constructors

Constructor and Description
AbstractDetector(double maxCheckIn, double thresholdIn) Build a new instance.
AbstractDetector(double maxCheckIn, double thresholdIn, EventDetector.Action actionAtEntryIn, EventDetector.Action actionAtExitIn, boolean removeAtEntryIn, boolean removeAtExitIn) Build a new instance.
AbstractDetector(int slopeSelectionIn, double maxCheckIn, double thresholdIn) Build a new instance.
AbstractDetector(int slopeSelectionIn, double maxCheckIn, double thresholdIn, EventDetector.Action actionIn, boolean removeIn) Build a new instance.
AbstractDetector(int slopeSelectionIn, double maxCheckIn, double thresholdIn, EventDetector.Action actionAtEntryIn, EventDetector.Action actionAtExitIn, boolean removeAtEntryIn, boolean removeAtExitIn) Build a new instance.

Method Summary

Modifier and Type	Method and Description
EventDetector.Action	eventOccurred(SpacecraftState s, boolean increasing, boolean forward) Handle an event and choose what to do next.
abstract double	g(SpacecraftState s) Compute the value of the switching function.
EventDetector.Action	getActionAtEntry()
EventDetector.Action	getActionAtExit()
Frame	getInertialFrame() Gets the inertial frame used for signal propagation computation.
double	getMaxCheckInterval() Get maximal time interval between switching function checks.
int	getMaxIterationCount() Get maximal number of iterations in the event time search.
AbstractDetector.PropagationDelayType	getPropagationDelayType() Returns the propagation delay type.
protected AbsoluteDate	getSignalEmissionDate(PVCoordinatesProvider emitter, PVCoordinatesProvider orbit, AbsoluteDate date, double epsilon) Compute signal emission date which is the date at which the signal received by the spacecraft (receiver) has been emitted by the emitter depending on AbstractDetector.PropagationDelayType.
protected AbsoluteDate	getSignalReceptionDate(PVCoordinatesProvider receiver, PVCoordinatesProvider orbit, AbsoluteDate date, double epsilon) Compute signal reception date which is the date at which the signal emitted by the spacecraft (emitter) has been received by the receiver depending on AbstractDetector.PropagationDelayType.
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	isRemoveAtEntry()
boolean	isRemoveAtExit()
static SpacecraftState	logEventsOverTimeInterval(CodedEventsLogger eventsLogger, Propagator satProp, CodingEventDetector detector, AbsoluteDateInterval interval) Log detected events on a given time interval into the entered events logger.
SpacecraftState	resetState(SpacecraftState oldState) Reset the state (including additional states) prior to continue propagation.
void	setMaxCheckInterval(double maxCheckIn) Setter for the max check interval.
protected void	setPropagationDelayType(AbstractDetector.PropagationDelayType propagationDelayTypeIn, Frame frameIn) Setter for propagation delay computation type.
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

Methods inherited from interface fr.cnes.sirius.patrius.propagation.events.EventDetector

copy

Field Detail

DEFAULT_MAXCHECK

public static final double DEFAULT_MAXCHECK

Default maximum checking interval (s).

See Also:

Constant Field Values

DEFAULT_THRESHOLD

public static final double DEFAULT_THRESHOLD

Default convergence threshold (s).

See Also:

Constant Field Values

actionAtEntry

protected EventDetector.Action actionAtEntry

Action performed at entry

actionAtExit

protected EventDetector.Action actionAtExit

Action performed at exit

removeAtEntry

protected boolean removeAtEntry

True if detector should be removed at entry

removeAtExit

protected boolean removeAtExit

True if detector should be removed at exit

shouldBeRemovedFlag

protected boolean shouldBeRemovedFlag

True if detector should be removed (updated by eventOccured)

Constructor Detail

AbstractDetector

public AbstractDetector(double maxCheckIn,
                        double thresholdIn)

Build a new instance. The detector will detect both ascending and descending g-function related events.

Parameters:

maxCheckIn - maximum checking interval (s)

thresholdIn - convergence threshold (s)

AbstractDetector

public AbstractDetector(int slopeSelectionIn,
                        double maxCheckIn,
                        double thresholdIn)

Build a new instance.

Parameters:

slopeSelectionIn - g-function slope selection (0, 1, or 2)

maxCheckIn - maximum checking interval (s)

thresholdIn - convergence threshold (s)

AbstractDetector

public AbstractDetector(int slopeSelectionIn,
                        double maxCheckIn,
                        double thresholdIn,
                        EventDetector.Action actionIn,
                        boolean removeIn)

Build a new instance.

Parameters:

slopeSelectionIn - g-function slope selection (0, 1, or 2)

maxCheckIn - maximum checking interval (s)

thresholdIn - convergence threshold (s)

actionIn - action performed when entering/exiting the eclipse depending on slope selection

removeIn - when the spacecraft point enters or exit the zone depending on slope selection

AbstractDetector

public AbstractDetector(double maxCheckIn,
                        double thresholdIn,
                        EventDetector.Action actionAtEntryIn,
                        EventDetector.Action actionAtExitIn,
                        boolean removeAtEntryIn,
                        boolean removeAtExitIn)

Build a new instance. The detector will detect both ascending and descending g-function related events.

Parameters:

maxCheckIn - maximum checking interval (s)

thresholdIn - convergence threshold (s)

actionAtEntryIn - action performed at increasing event detection

actionAtExitIn - action performed at decreasing event detection

removeAtEntryIn - states if the detector should be removed at increasing event detection

removeAtExitIn - states if the detector should be removed at decreasing event detection

AbstractDetector

public AbstractDetector(int slopeSelectionIn,
                        double maxCheckIn,
                        double thresholdIn,
                        EventDetector.Action actionAtEntryIn,
                        EventDetector.Action actionAtExitIn,
                        boolean removeAtEntryIn,
                        boolean removeAtExitIn)

Build a new instance.

Parameters:

slopeSelectionIn - g-function slope selection (0, 1, or 2)

maxCheckIn - maximum checking interval (s)

thresholdIn - convergence threshold (s)

actionAtEntryIn - action performed at increasing event detection

actionAtExitIn - action performed at decreasing event detection

removeAtEntryIn - states if the detector should be removed at increasing event detection

removeAtExitIn - states if the detector should be removed at decreasing event detection

Method Detail

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

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

eventOccurred

public 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

g

public abstract 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

getMaxCheckInterval

public 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 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

getThreshold

public double getThreshold()

Get the convergence threshold in the event time search.

Specified by:

getThreshold in interface EventDetector

Returns:

convergence threshold (s)

getActionAtEntry

public EventDetector.Action getActionAtEntry()

Returns:

the action at entry

getActionAtExit

public EventDetector.Action getActionAtExit()

Returns:

the action at exit

isRemoveAtEntry

public boolean isRemoveAtEntry()

Returns:

the flag removeAtEntry

isRemoveAtExit

public boolean isRemoveAtExit()

Returns:

the flag removeAtExit

resetState

public 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

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.

getSignalEmissionDate

protected AbsoluteDate getSignalEmissionDate(PVCoordinatesProvider emitter,
                                             PVCoordinatesProvider orbit,
                                             AbsoluteDate date,
                                             double epsilon)
                                      throws PatriusException

Compute signal emission date which is the date at which the signal received by the spacecraft (receiver) has been emitted by the emitter depending on AbstractDetector.PropagationDelayType.

Parameters:

emitter - emitter

orbit - orbit of the spacecraft (receiver)

date - date at which the spacecraft orbit is defined

epsilon - absolute duration threshold used for convergence of signal propagation computation. The epsilon is a time absolute error (ex: 1E-14s, in this case, the signal distance accuracy is 1E-14s x 3E8m/s = 3E-6m).

Returns:

signal emission date

Throws:

PatriusException - thrown if computation failed

getSignalReceptionDate

protected AbsoluteDate getSignalReceptionDate(PVCoordinatesProvider receiver,
                                              PVCoordinatesProvider orbit,
                                              AbsoluteDate date,
                                              double epsilon)
                                       throws PatriusException

Compute signal reception date which is the date at which the signal emitted by the spacecraft (emitter) has been received by the receiver depending on AbstractDetector.PropagationDelayType.

Parameters:

receiver - receiver

orbit - orbit of the spacecraft (emitter)

date - date at which the spacecraft orbit is defined

epsilon - absolute duration threshold used for convergence of signal propagation computation. The epsilon is a time absolute error (ex: 1E-14s, in this case, the signal distance accuracy is 1E-14s x 3E8m/s = 3E-6m).

Returns:

signal reception date

Throws:

PatriusException - thrown if computation failed

getPropagationDelayType

public AbstractDetector.PropagationDelayType getPropagationDelayType()

Returns the propagation delay type.

Returns:

the propagation delay type

getInertialFrame

public Frame getInertialFrame()

Gets the inertial frame used for signal propagation computation.

Returns:

the inertial frame

setPropagationDelayType

protected void setPropagationDelayType(AbstractDetector.PropagationDelayType propagationDelayTypeIn,
                                       Frame frameIn)

Setter for propagation delay computation type. Warning: check Javadoc of detector to see if detector takes into account propagation time delay. if not, signals are always considered instantaneous. The provided frame is used to compute the signal propagation when delay is taken into account.

Parameters:

propagationDelayTypeIn - propagation delay type used in events computation

frameIn - frame to use for signal propagation with delay (may be null if propagation delay type is considered instantaneous). Warning: the usage of a pseudo inertial frame is tolerated, however it will lead to some inaccuracies due to the non-invariance of the frame with respect to time. For this reason, it is suggested to use the ICRF frame or a frame which is frozen with respect to the ICRF.

Throws:

IllegalArgumentException - if the provided frame is not pseudo inertial.

setMaxCheckInterval

public void setMaxCheckInterval(double maxCheckIn)

Setter for the max check interval.

Parameters:

maxCheckIn - the max check interval to set

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