fr.cnes.sirius.patrius.propagation.events

Class AltitudeDetector

java.lang.Object

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

fr.cnes.sirius.patrius.propagation.events.AltitudeDetector

All Implemented Interfaces:

EventDetector, Serializable

public class AltitudeDetector
extends AbstractDetector

Finder for satellite altitude crossing events.

This class finds altitude events (i.e. satellite crossing a predefined altitude level above ground).

The default implementation behavior is to continue propagation when ascending and to stop propagation when descending. This can be changed by using provided constructors.

Author:

Luc Maisonobe

See Also:

Propagator.addEventDetector(EventDetector), Serialized Form

Nested Class Summary

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

EventDetector.Action

Field Summary

Fields

Modifier and Type	Field and Description
static int	ASCENDING Flag for ascending altitude detection (slopeSelection = 0).
static int	ASCENDING_DESCENDING Flag for both ascending and descending altitude detection (slopeSelection = 2).
static int	DESCENDING Flag for descending altitude detection (slopeSelection = 1).

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

DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

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

DECREASING, INCREASING, INCREASING_DECREASING

Constructor Summary

Constructors

Constructor and Description
AltitudeDetector(double altitudeIn, BodyShape bodyShapeIn) Build a new altitude detector.
AltitudeDetector(double altitudeIn, BodyShape bodyShapeIn, double maxCheck) Build a new altitude detector.
AltitudeDetector(double altitudeIn, BodyShape bodyShapeIn, double maxCheck, double threshold) Build a new altitude detector.
AltitudeDetector(double altitudeIn, BodyShape bodyShapeIn, double maxCheck, double threshold, EventDetector.Action ascending, EventDetector.Action descending) Build a new altitude detector.
AltitudeDetector(double altitudeIn, BodyShape bodyShapeIn, double maxCheck, double threshold, EventDetector.Action ascending, EventDetector.Action descending, boolean removeAscending, boolean removeDescending) Build a new altitude detector.
AltitudeDetector(double altitudeIn, BodyShape bodyShapeIn, int slopeSelection, double maxCheck, double threshold, EventDetector.Action action, boolean remove) Build a new altitude detector with slope selection.

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 altitude event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function.
EventDetector.Action	getActionAtAscending() Returns action at ascending detection.
EventDetector.Action	getActionAtDescending() Returns action at descending detection.
double	getAltitude() Get the threshold altitude value.
BodyShape	getBodyShape() Get the body shape.
boolean	removeAtAscending() Returns true if detection is removed after ascending detection.
boolean	removeAtDescending() Returns true if detection is removed after descending detection.
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.propagation.events.AbstractDetector

getMaxCheckInterval, getMaxIterationCount, getSlopeSelection, getThreshold, init, resetState

Methods inherited from class java.lang.Object

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

Field Detail

ASCENDING

public static final int ASCENDING

Flag for ascending altitude detection (slopeSelection = 0).

See Also:

Constant Field Values

DESCENDING

public static final int DESCENDING

Flag for descending altitude detection (slopeSelection = 1).

See Also:

Constant Field Values

ASCENDING_DESCENDING

public static final int ASCENDING_DESCENDING

Flag for both ascending and descending altitude detection (slopeSelection = 2).

See Also:

Constant Field Values

Constructor Detail

AltitudeDetector

public AltitudeDetector(double altitudeIn,
                        BodyShape bodyShapeIn)

Build a new altitude detector.

This simple constructor takes default values for maximal checking interval ( AbstractDetector.DEFAULT_MAXCHECK) and convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

The default implementation behavior is to continue propagation when ascending and to stop propagation when descending.

Parameters:

altitudeIn - threshold altitude value

bodyShapeIn - body shape with respect to which altitude should be evaluated

AltitudeDetector

public AltitudeDetector(double altitudeIn,
                        BodyShape bodyShapeIn,
                        double maxCheck)

Build a new altitude detector.

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

The maximal interval between altitude 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 continue propagation when ascending and to stop propagation when descending.

Parameters:

altitudeIn - threshold altitude value (m)

bodyShapeIn - body shape with respect to which altitude should be evaluated

maxCheck - maximal checking interval (s)

AltitudeDetector

public AltitudeDetector(double altitudeIn,
                        BodyShape bodyShapeIn,
                        double maxCheck,
                        double threshold)

Build a new altitude detector.

The maximal interval between altitude 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 continue propagation when ascending and to stop propagation when descending.

Parameters:

altitudeIn - threshold altitude value (m)

bodyShapeIn - body shape with respect to which altitude should be evaluated

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

AltitudeDetector

public AltitudeDetector(double altitudeIn,
                        BodyShape bodyShapeIn,
                        double maxCheck,
                        double threshold,
                        EventDetector.Action ascending,
                        EventDetector.Action descending)

Build a new altitude detector.

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

Parameters:

altitudeIn - threshold altitude value (m)

bodyShapeIn - body shape with respect to which altitude should be evaluated

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

ascending - action performed when ascending

descending - action performed when descending

AltitudeDetector

public AltitudeDetector(double altitudeIn,
                        BodyShape bodyShapeIn,
                        double maxCheck,
                        double threshold,
                        EventDetector.Action ascending,
                        EventDetector.Action descending,
                        boolean removeAscending,
                        boolean removeDescending)

Build a new altitude detector.

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

Parameters:

altitudeIn - threshold altitude value (m)

bodyShapeIn - body shape with respect to which altitude should be evaluated

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

ascending - action performed when ascending

descending - action performed when descending

removeAscending - true if detector should be removed at ascending altitude detection

removeDescending - true if detector should be removed at descending altitude detection

Since:

3.1

AltitudeDetector

public AltitudeDetector(double altitudeIn,
                        BodyShape bodyShapeIn,
                        int slopeSelection,
                        double maxCheck,
                        double threshold,
                        EventDetector.Action action,
                        boolean remove)

Build a new altitude detector with slope selection.

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

Parameters:

altitudeIn - threshold altitude value (m)

bodyShapeIn - body shape with respect to which altitude should be evaluated

slopeSelection - slope selection

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

action - action performed

remove - true if detector should be removed at altitude detection

Since:

3.1

Method Detail

getAltitude

public double getAltitude()

Get the threshold altitude value.

Returns:

the threshold altitude value (m)

getBodyShape

public BodyShape getBodyShape()

Get the body shape.

Returns:

the body shape

getActionAtAscending

public EventDetector.Action getActionAtAscending()

Returns action at ascending detection.

Returns:

action at ascending detection

getActionAtDescending

public EventDetector.Action getActionAtDescending()

Returns action at descending detection.

Returns:

action at descending detection

removeAtAscending

public boolean removeAtAscending()

Returns true if detection is removed after ascending detection.

Returns:

true if detection is removed after ascending detection

removeAtDescending

public boolean removeAtDescending()

Returns true if detection is removed after descending detection.

Returns:

true if detection is removed after descending detection

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

Specified by:

shouldBeRemoved in class AbstractDetector

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 altitude 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 altitude is reached.

Throws:

PatriusException - if some specific error occurs

g

public double g(SpacecraftState s)
         throws PatriusException

Compute the value of the switching function. This function measures the difference between the current altitude and the threshold altitude.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector

Parameters:

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

Returns:

value of the switching function

Throws:

PatriusException - if some specific error occurs

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.

The following attributes are not deeply copied:

• bodyShape: BodyShape

Returns:

a copy of the detector.