org.orekit.propagation.events
Class DistanceDetector

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

All Implemented Interfaces:

Serializable, EventDetector

public class DistanceDetector
extends AbstractDetector

Detects when the distance from the spacecraft to a given body reaches a predetermined value.

The default implementation behaviour is to stop propagation when the distance is reached. This can be changed by using provided constructors.

Since:

1.1

Version:

$Id: DistanceDetector.java 14857 2015-12-03 14:17:42Z bignon $

Author:

cardosop

See Also:

EventDetector, Serialized Form

Concurrency :

not thread-safe

Concurrency comment :

attributes are mutable and related to propagation.

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

DistanceDetector(PVCoordinatesProvider dBody, double dist)
Constructor for a DistanceDetector instance.

DistanceDetector(PVCoordinatesProvider dBody, double dist, double maxCheck, double threshold)
Constructor for a DistanceDetector instance with complimentary parameters.

DistanceDetector(PVCoordinatesProvider dBody, double dist, double maxCheck, double threshold, EventDetector.Action action)
Constructor for a DistanceDetector instance with complimentary parameters.

DistanceDetector(PVCoordinatesProvider dBody, double dist, double maxCheck, double threshold, EventDetector.Action action, boolean remove)
Constructor for a DistanceDetector instance with complimentary parameters.

Method Summary

EventDetector.Action	eventOccurred(SpacecraftState s, boolean increasing, boolean forward) Handle a distance event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function.
PVCoordinatesProvider	getBody() Returns the body.
double	getDistance() Returns the distance triggering the event.
void	init(SpacecraftState s0, AbsoluteDate t) Initialize event handler at the start of a propagation.
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, resetState

Methods inherited from class java.lang.Object

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

Constructor Detail

DistanceDetector

public DistanceDetector(PVCoordinatesProvider dBody,
                        double dist)

Constructor for a DistanceDetector instance.

Parameters:

dBody - the body whose distance is watched.

dist - distance in m triggering the event.

Throws:

IllegalArgumentException - when the distance is negative

DistanceDetector

public DistanceDetector(PVCoordinatesProvider dBody,
                        double dist,
                        double maxCheck,
                        double threshold)

Constructor for a DistanceDetector instance with complimentary parameters.

The default implementation behavior is to stop propagation when the distance is reached.

Parameters:

dBody - the body whose distance is watched.

dist - distance in m triggering the event.

maxCheck - maximum check (see AbstractDetector)

threshold - threshold (see AbstractDetector)

Throws:

IllegalArgumentException - when the distance is negative

DistanceDetector

public DistanceDetector(PVCoordinatesProvider dBody,
                        double dist,
                        double maxCheck,
                        double threshold,
                        EventDetector.Action action)

Constructor for a DistanceDetector instance with complimentary parameters.

Parameters:

dBody - the body whose distance is watched.

dist - distance in m triggering the event.

maxCheck - maximum check (see AbstractDetector)

threshold - threshold (see AbstractDetector)

action - action performed at distance detection

Throws:

IllegalArgumentException - when the distance is negative

DistanceDetector

public DistanceDetector(PVCoordinatesProvider dBody,
                        double dist,
                        double maxCheck,
                        double threshold,
                        EventDetector.Action action,
                        boolean remove)

Constructor for a DistanceDetector instance with complimentary parameters.

Parameters:

dBody - the body whose distance is watched.

dist - distance in m triggering the event.

maxCheck - maximum check (see AbstractDetector)

threshold - threshold (see AbstractDetector)

action - action performed at distance detection

remove - true if detector should be removed

Throws:

IllegalArgumentException - when the distance is negative

Since:

3.1

Method Detail

eventOccurred

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

Handle a distance 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 time increases around event

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

Returns:

the action performed when the expected distance is reached

Throws:

OrekitException - if some specific error occurs

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

g

public double g(SpacecraftState s)
         throws OrekitException

Description copied from class: AbstractDetector

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

Specified by:

g in class AbstractDetector

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:

OrekitException - if some specific error occurs

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)

Description copied from class: AbstractDetector

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

getDistance

public double getDistance()

Returns the distance triggering the event.

Returns:

the distance triggering the event.

getBody

public PVCoordinatesProvider getBody()

Returns the body.

Returns:

the body.