Class ExtremumApproachDetector
- java.lang.Object
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- org.orekit.propagation.events.AbstractDetector<ExtremumApproachDetector>
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- org.orekit.propagation.events.ExtremumApproachDetector
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- All Implemented Interfaces:
EventDetector
public class ExtremumApproachDetector extends AbstractDetector<ExtremumApproachDetector>
Finder for extremum approach events.This class finds extremum approach events (i.e. closest or farthest approach).
The default implementation behavior is to
continue
propagation at farthest approach and tostop
propagation at closest approach. This can be changed by callingAbstractDetector.withHandler(EventHandler)
after construction (go to the end of the documentation to see an example).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 objectcoordinates 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 apropagators 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.
Also, it is possible to detect solely one type of event using an
event slope filter
. For example in order to only detect closest approach, one should type the following :ExtremumApproachDetector extremumApproachDetector = new ExtremumApproachDetector(secondaryPVProvider); EventDetector closeApproachDetector = new EventSlopeFilter<ExtremumApproachDetector>(extremumApproachDetector,FilterType.TRIGGER_ONLY_INCREASING_EVENTS);
- Since:
- 11.3
- Author:
- Vincent Cucchietti
- See Also:
Propagator.addEventDetector(EventDetector)
,EventSlopeFilter
,FilterType
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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 Constructor Description ExtremumApproachDetector(double maxCheck, double threshold, int maxIter, EventHandler<? super ExtremumApproachDetector> handler, PVCoordinatesProvider secondaryPVProvider)
Constructor.ExtremumApproachDetector(PVCoordinatesProvider secondaryPVProvider)
Constructor with default values.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected PVCoordinates
computeDeltaPV(SpacecraftState s)
Compute the relative PV between primary and secondary objects.protected ExtremumApproachDetector
create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super ExtremumApproachDetector> newHandler)
Build a new instance.double
g(SpacecraftState s)
Theg
is positive when the primary object is getting further away from the secondary object and is negative when it is getting closer to it.-
Methods inherited from class org.orekit.propagation.events.AbstractDetector
eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, init, isForward, resetState, withHandler, withMaxCheck, withMaxIter, withThreshold
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Constructor Detail
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ExtremumApproachDetector
public ExtremumApproachDetector(PVCoordinatesProvider secondaryPVProvider)
Constructor with default values.By default, the implemented behavior is to
continue
propagation at farthest approach and tostop
propagation at closest approach.- Parameters:
secondaryPVProvider
- PVCoordinates provider of the other object with which we want to find out the extremum approach.
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ExtremumApproachDetector
public ExtremumApproachDetector(double maxCheck, double threshold, int maxIter, EventHandler<? super ExtremumApproachDetector> handler, PVCoordinatesProvider secondaryPVProvider)
Constructor.This constructor is to be used if the user wants to change the default behavior of the detector.
- Parameters:
maxCheck
- Maximum checking interval (s).threshold
- Convergence threshold (s).maxIter
- Maximum number of iterations in the event time search.handler
- Event handler to call at event occurrences.secondaryPVProvider
- PVCoordinates provider of the other object with which we want to find out the extremum * approach.- See Also:
EventHandler
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Method Detail
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g
public double g(SpacecraftState s)
Theg
is positive when the primary object is getting further away from the secondary object and is negative when it is getting closer to it.- Specified by:
g
in interfaceEventDetector
- Specified by:
g
in classAbstractDetector<ExtremumApproachDetector>
- Parameters:
s
- the current state information: date, kinematics, attitude- Returns:
- value of the switching function
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computeDeltaPV
protected PVCoordinates computeDeltaPV(SpacecraftState s)
Compute the relative PV between primary and secondary objects.- Parameters:
s
- Spacecraft state.- Returns:
- Relative position between primary (=s) and secondaryPVProvider.
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create
protected ExtremumApproachDetector create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super ExtremumApproachDetector> newHandler)
Build a new instance.- Specified by:
create
in classAbstractDetector<ExtremumApproachDetector>
- 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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