Package org.orekit.propagation.events

Class ElevationExtremumDetector

java.lang.Object

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

org.orekit.propagation.events.ElevationExtremumDetector

All Implemented Interfaces:

Serializable, EventDetector

public class ElevationExtremumDetector
extends AbstractDetector<ElevationExtremumDetector>

Detector for elevation extremum with respect to a ground point.

This detector identifies when a spacecraft reaches its extremum elevation with respect to a ground point.

As in most cases only the elevation maximum is needed and the minimum is often irrelevant, this detector is often wrapped into an event slope filter configured with FilterType.TRIGGER_ONLY_DECREASING_EVENTS (i.e. when the elevation derivative decreases from positive values to negative values, which correspond to a maximum). Setting up this filter saves some computation time as the elevation minimum occurrences are not even looked at. It is however still often necessary to do an additional filtering

Since:

7.1

Author:

Luc Maisonobe

See Also:

Serialized Form

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor	Description
ElevationExtremumDetector(double maxCheck, double threshold, TopocentricFrame topo)	Build a detector.
ElevationExtremumDetector(TopocentricFrame topo)	Build a new detector.

Method Summary

Modifier and Type	Method	Description
protected ElevationExtremumDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super ElevationExtremumDetector> newHandler)	Build a new instance.
double	g(SpacecraftState s)	Compute the value of the detection function.
double	getElevation(SpacecraftState s)	Get the elevation value.
TopocentricFrame	getTopocentricFrame()	Returns the topocentric frame centered on ground point.

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

eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, init, isForward, resetState, withHandler, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Constructor Detail

ElevationExtremumDetector

public ElevationExtremumDetector(TopocentricFrame topo)

Build a new detector.

The new instance uses default values for maximal checking interval (AbstractDetector.DEFAULT_MAXCHECK) and convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

Parameters:

topo - topocentric frame centered on ground point

ElevationExtremumDetector

public ElevationExtremumDetector(double maxCheck,
                                 double threshold,
                                 TopocentricFrame topo)

Build a detector.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

topo - topocentric frame centered on ground point

Method Detail

create

protected ElevationExtremumDetector create(double newMaxCheck,
                                           double newThreshold,
                                           int newMaxIter,
                                           EventHandler<? super ElevationExtremumDetector> newHandler)

Build a new instance.

Specified by:

create in class AbstractDetector<ElevationExtremumDetector>

Parameters:

newMaxCheck - maximum checking interval (s)

newThreshold - convergence threshold (s)

newMaxIter - maximum number of iterations in the event time search

newHandler - event handler to call at event occurrences

Returns:

a new instance of the appropriate sub-type

getTopocentricFrame

public TopocentricFrame getTopocentricFrame()

Returns the topocentric frame centered on ground point.

Returns:

topocentric frame centered on ground point

getElevation

public double getElevation(SpacecraftState s)
                    throws OrekitException

Get the elevation value.

Parameters:

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

Returns:

spacecraft elevation

Throws:

OrekitException - if some specific error occurs

g

public double g(SpacecraftState s)
         throws OrekitException

Compute the value of the detection function.

The value is the spacecraft elevation first time derivative.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<ElevationExtremumDetector>

Parameters:

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

Returns:

spacecraft elevation first time derivative

Throws:

OrekitException - if some specific error occurs