org.orekit.propagation.events
Class AltitudeDetector

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

All Implemented Interfaces:

Serializable, EventDetector

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 org.orekit.propagation.events.EventDetector

EventDetector.Action

Field Summary

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

AltitudeDetector(double altitude, BodyShape bodyShape)
Build a new altitude detector.

AltitudeDetector(double altitude, BodyShape bodyShape, double maxCheck)
Build a new altitude detector.

AltitudeDetector(double altitude, BodyShape bodyShape, double maxCheck, double threshold)
Build a new altitude detector.

AltitudeDetector(double altitude, BodyShape bodyShape, double maxCheck, double threshold, EventDetector.Action ascending, EventDetector.Action descending)
Build a new altitude detector.

AltitudeDetector(double altitude, BodyShape bodyShape, double maxCheck, double threshold, EventDetector.Action ascending, EventDetector.Action descending, boolean removeAscending, boolean removeDescending)
Build a new altitude detector.

Method Summary

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.
double	getAltitude() Get the threshold altitude value.
BodyShape	getBodyShape() Get the body shape.
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, init, resetState

Methods inherited from class java.lang.Object

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

Constructor Detail

AltitudeDetector

public AltitudeDetector(double altitude,
                        BodyShape bodyShape)

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:

altitude - threshold altitude value

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

AltitudeDetector

public AltitudeDetector(double altitude,
                        BodyShape bodyShape,
                        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:

altitude - threshold altitude value (m)

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

maxCheck - maximal checking interval (s)

AltitudeDetector

public AltitudeDetector(double altitude,
                        BodyShape bodyShape,
                        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:

altitude - threshold altitude value (m)

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

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

AltitudeDetector

public AltitudeDetector(double altitude,
                        BodyShape bodyShape,
                        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:

altitude - threshold altitude value (m)

bodyShape - 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 altitude,
                        BodyShape bodyShape,
                        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:

altitude - threshold altitude value (m)

bodyShape - 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

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

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

eventOccurred

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

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:

OrekitException - if some specific error occurs

g

public double g(SpacecraftState s)
         throws OrekitException

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:

OrekitException - if some specific error occurs