org.orekit.propagation.events

Class PositionAngleDetector

java.lang.Object

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

org.orekit.propagation.events.PositionAngleDetector

All Implemented Interfaces:

EventDetector

public class PositionAngleDetector
extends AbstractDetector<PositionAngleDetector>

Detector for in-orbit position angle.

The detector is based on anomaly for Keplerian orbits, latitude argument for circular orbits, or longitude argument for equinoctial orbits. It does not support Cartesian orbits. The angles can be either true, {link mean or eccentric angles.

Since:

7.1

Author:

Luc Maisonobe

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
PositionAngleDetector(double maxCheck, double threshold, OrbitType orbitType, PositionAngle positionAngle, double angle) Build a detector.
PositionAngleDetector(OrbitType orbitType, PositionAngle positionAngle, double angle) Build a new detector.

Method Summary

Modifier and Type	Method and Description
protected PositionAngleDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super PositionAngleDetector> newHandler) Build a new instance.
double	g(SpacecraftState s) Compute the value of the detection function.
double	getAngle() Get the fixed angle to be crossed (radians).
OrbitType	getOrbitType() Get the orbit type defining the angle type.
PositionAngle	getPositionAngle() Get the type of position angle.
void	init(SpacecraftState s0, AbsoluteDate t) Initialize event handler at the start of a propagation.

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

eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, 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

PositionAngleDetector

public PositionAngleDetector(OrbitType orbitType,
                             PositionAngle positionAngle,
                             double angle)
                      throws OrekitIllegalArgumentException

Build a new detector.

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

Parameters:

orbitType - orbit type defining the angle type

positionAngle - type of position angle

angle - fixed angle to be crossed

Throws:

OrekitIllegalArgumentException - if orbit type is OrbitType.CARTESIAN

PositionAngleDetector

public PositionAngleDetector(double maxCheck,
                             double threshold,
                             OrbitType orbitType,
                             PositionAngle positionAngle,
                             double angle)
                      throws OrekitIllegalArgumentException

Build a detector.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

orbitType - orbit type defining the angle type

positionAngle - type of position angle

angle - fixed angle to be crossed

Throws:

OrekitIllegalArgumentException - if orbit type is OrbitType.CARTESIAN

Method Detail

create

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

Build a new instance.

Specified by:

create in class AbstractDetector<PositionAngleDetector>

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

getOrbitType

public OrbitType getOrbitType()

Get the orbit type defining the angle type.

Returns:

orbit type defining the angle type

getPositionAngle

public PositionAngle getPositionAngle()

Get the type of position angle.

Returns:

type of position angle

getAngle

public double getAngle()

Get the fixed angle to be crossed (radians).

Returns:

fixed angle to be crossed (radians)

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)

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.

The default implementation does nothing

This implementation sets the direction of propagation and initializes the event handler. If a subclass overrides this method it should call super.init(s0, t).

Specified by:

init in interface EventDetector

Overrides:

init in class AbstractDetector<PositionAngleDetector>

Parameters:

s0 - initial state

t - target time for the integration

g

public double g(SpacecraftState s)

Compute the value of the detection function.

The value is the angle difference between the spacecraft and the fixed angle to be crossed, with some sign tweaks to ensure continuity. These tweaks imply the increasing flag in events detection becomes irrelevant here! As an example, the angle always increase in a Keplerian orbit, but this g function will increase and decrease so it will cross the zero value once per orbit, in increasing and decreasing directions on alternate orbits..

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<PositionAngleDetector>

Parameters:

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

Returns:

angle difference between the spacecraft and the fixed angle, with some sign tweaks to ensure continuity