Class LongitudeCrossingDetector
- java.lang.Object
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- org.orekit.propagation.events.AbstractDetector<LongitudeCrossingDetector>
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- org.orekit.propagation.events.LongitudeCrossingDetector
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- All Implemented Interfaces:
EventDetector
public class LongitudeCrossingDetector extends AbstractDetector<LongitudeCrossingDetector>
Detector for geographic longitude crossing.This detector identifies when a spacecraft crosses a fixed longitude with respect to a central body.
- Since:
- 7.1
- Author:
- Luc Maisonobe
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Field Summary
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Fields inherited from class org.orekit.propagation.events.AbstractDetector
DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD
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Constructor Summary
Constructors Modifier Constructor Description LongitudeCrossingDetector(double maxCheck, double threshold, OneAxisEllipsoid body, double longitude)
Build a detector.LongitudeCrossingDetector(OneAxisEllipsoid body, double longitude)
Build a new detector.protected
LongitudeCrossingDetector(AdaptableInterval maxCheck, double threshold, int maxIter, EventHandler handler, OneAxisEllipsoid body, double longitude)
Protected constructor with full parameters.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected LongitudeCrossingDetector
create(AdaptableInterval newMaxCheck, double newThreshold, int newMaxIter, EventHandler newHandler)
Build a new instance.double
g(SpacecraftState s)
Compute the value of the detection function.OneAxisEllipsoid
getBody()
Get the body on which the geographic zone is defined.double
getLongitude()
Get the fixed longitude to be crossed (radians).void
init(SpacecraftState s0, AbsoluteDate t)
Initialize event handler at the start of a propagation.-
Methods inherited from class org.orekit.propagation.events.AbstractDetector
getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, isForward, withHandler, withMaxCheck, withMaxCheck, withMaxIter, withThreshold
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Constructor Detail
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LongitudeCrossingDetector
public LongitudeCrossingDetector(OneAxisEllipsoid body, double longitude)
Build a new detector.The new instance uses default values for maximal checking interval (
AbstractDetector.DEFAULT_MAXCHECK
) and convergence threshold (AbstractDetector.DEFAULT_THRESHOLD
).- Parameters:
body
- body on which the longitude is definedlongitude
- longitude to be crossed
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LongitudeCrossingDetector
public LongitudeCrossingDetector(double maxCheck, double threshold, OneAxisEllipsoid body, double longitude)
Build a detector.- Parameters:
maxCheck
- maximal checking interval (s)threshold
- convergence threshold (s)body
- body on which the longitude is definedlongitude
- longitude to be crossed
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LongitudeCrossingDetector
protected LongitudeCrossingDetector(AdaptableInterval maxCheck, double threshold, int maxIter, EventHandler handler, OneAxisEllipsoid body, double longitude)
Protected constructor with full parameters.This constructor is not public as users are expected to use the builder API with the various
withXxx()
methods to set up the instance in a readable manner without using a huge amount of parameters.- Parameters:
maxCheck
- maximum checking intervalthreshold
- convergence threshold (s)maxIter
- maximum number of iterations in the event time searchhandler
- event handler to call at event occurrencesbody
- body on which the longitude is definedlongitude
- longitude to be crossed
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Method Detail
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create
protected LongitudeCrossingDetector create(AdaptableInterval newMaxCheck, double newThreshold, int newMaxIter, EventHandler newHandler)
Build a new instance.- Specified by:
create
in classAbstractDetector<LongitudeCrossingDetector>
- Parameters:
newMaxCheck
- maximum checking interval (s)newThreshold
- convergence threshold (s)newMaxIter
- maximum number of iterations in the event time searchnewHandler
- event handler to call at event occurrences- Returns:
- a new instance of the appropriate sub-type
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getBody
public OneAxisEllipsoid getBody()
Get the body on which the geographic zone is defined.- Returns:
- body on which the geographic zone is defined
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getLongitude
public double getLongitude()
Get the fixed longitude to be crossed (radians).- Returns:
- fixed longitude to be crossed (radians)
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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 interfaceEventDetector
- Overrides:
init
in classAbstractDetector<LongitudeCrossingDetector>
- Parameters:
s0
- initial statet
- target time for the integration
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g
public double g(SpacecraftState s)
Compute the value of the detection function.The value is the longitude difference between the spacecraft and the fixed longitude 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 longitude of a prograde spacecraft will always increase, 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. If eastwards and westwards crossing have to be distinguished, the velocity direction has to be checked instead of looking at theincreasing
flag.- Specified by:
g
in interfaceEventDetector
- Specified by:
g
in classAbstractDetector<LongitudeCrossingDetector>
- Parameters:
s
- the current state information: date, kinematics, attitude- Returns:
- longitude difference between the spacecraft and the fixed longitude, with some sign tweaks to ensure continuity
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