Package org.orekit.propagation.events

Class RelativeDistanceDetector

java.lang.Object

org.orekit.propagation.events.AbstractDetector<RelativeDistanceDetector>

org.orekit.propagation.events.RelativeDistanceDetector

All Implemented Interfaces:

EventDetector

public class RelativeDistanceDetector
extends AbstractDetector<RelativeDistanceDetector>

Detector of specific value for the distance relative to another trajectory (using the Euclidean norm).

The default implementation behavior is to stop propagation. This can be changed by calling AbstractDetector.withHandler(EventHandler) after construction.

As this detector needs two objects (moving relative to each other), it embeds one coordinates provider for the secondary object and is registered as an event detector in the propagator of the primary object. The secondary object coordinates provider will therefore be driven by this detector (and hence by the propagator in which this detector is registered).

In order to avoid infinite recursion, care must be taken to have the secondary object provider being completely independent from anything else. In particular, if the provider is a propagator, it should not be run together in a propagators parallelizer with the propagator this detector is registered in. It is fine however to configure two separate propagators PsA and PsB with similar settings for the secondary object and one propagator Pm for the primary object and then use Psa in this detector registered within Pm while Pm and Psb are run in the context of a propagators parallelizer.

For efficiency reason during the event search loop, it is recommended to have the secondary provider be an analytical propagator or an ephemeris. A numerical propagator as a secondary propagator works but is expected to be computationally costly.

Since:

12.1

Author:

Romain Serra

See Also:

• Propagator.addEventDetector(EventDetector)

Field Summary

Fields inherited from class org.orekit.propagation.events.AbstractDetector

DEFAULT_MAX_CHECK, DEFAULT_MAX_ITER, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	RelativeDistanceDetector(EventDetectionSettings detectionSettings, EventHandler handler, PVCoordinatesProvider secondaryPVProvider, double distanceThreshold)	Constructor.
	RelativeDistanceDetector(PVCoordinatesProvider secondaryPVProvider, double distanceThreshold)	Constructor with default values.

Method Summary

Modifier and Type	Method	Description
protected RelativeDistanceDetector	create(EventDetectionSettings detectionSettings, EventHandler newHandler)	Build a new instance.
double	g(SpacecraftState s)	The g is positive when the relative distance is larger or equal than the threshold, non-positive otherwise.
double	getDistanceThreshold()	Get the relative distance threshold.
PVCoordinatesProvider	getSecondaryPVProvider()	Get the secondary position-velocity provider stored in this instance.

Methods inherited from class org.orekit.propagation.events.AbstractDetector

checkIfForward, getDetectionSettings, getEventFunction, getHandler, init, isForward, withDetectionSettings, withHandler, withMaxCheck, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.propagation.events.EventDetector

finish, getMaxCheckInterval, getMaxIterationCount, getThreshold, reset

Constructor Details

RelativeDistanceDetector

public RelativeDistanceDetector(PVCoordinatesProvider secondaryPVProvider,
 double distanceThreshold)

Constructor with default values.

By default, the implemented behavior is to stop propagation at detection.

Parameters:

secondaryPVProvider - PVCoordinates provider of the other object defining relative distance.

distanceThreshold - Relative distance threshold for event detection

RelativeDistanceDetector

protected RelativeDistanceDetector(EventDetectionSettings detectionSettings,
 EventHandler handler,
 PVCoordinatesProvider secondaryPVProvider,
 double distanceThreshold)

Constructor.

This constructor is to be used if the user wants to change the default behavior of the detector.

Parameters:

detectionSettings - Detection settings

handler - Event handler to call at event occurrences.

secondaryPVProvider - PVCoordinates provider of the other object defining relative distance.

distanceThreshold - Relative distance threshold for event detection

Since:

12.2

See Also:

• EventHandler

Method Details

g

public double g(SpacecraftState s)

The g is positive when the relative distance is larger or equal than the threshold, non-positive otherwise.

Parameters:

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

Returns:

value of the switching function

create

protected RelativeDistanceDetector create(EventDetectionSettings detectionSettings,
 EventHandler newHandler)

Build a new instance.

Specified by:

create in class AbstractDetector<RelativeDistanceDetector>

Parameters:

detectionSettings - detection settings

newHandler - event handler to call at event occurrences

Returns:

a new instance of the appropriate sub-type

getSecondaryPVProvider

public PVCoordinatesProvider getSecondaryPVProvider()

Get the secondary position-velocity provider stored in this instance.

Returns:

the secondary position-velocity provider stored in this instance

getDistanceThreshold

public double getDistanceThreshold()

Get the relative distance threshold.

Returns:

threshold triggering detection