User Manual 3.3 Events detection: Presentation - Historique des versions

Admin : /* Combination of boolean phenomena */

2018-03-01T14:43:35Z

Combination of boolean phenomena

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	=== Combination of boolean phenomena ===		=== Combination of boolean phenomena ===
	Sometimes an event (a zero of a g function) can be seen as a begin (passing zero from positive to negative or invert) or a end ( other way ) of a phenomena. For example the eclipse event can be the begin (detected when g function goes from positive to negative) or the end (when g function goes from negative to positive) of an eclipse. (cf. [~~MIS_ORB_Home~~#~~HEclipseDetectorandGenericEclipseDetector~~ Eclipse detector].)		Sometimes an event (a zero of a g function) can be seen as a begin (passing zero from positive to negative or invert) or a end ( other way ) of a phenomena. For example the eclipse event can be the begin (detected when g function goes from positive to negative) or the end (when g function goes from negative to positive) of an eclipse. (cf. [[User Manual 3.3 Events: orbital#EclipseDetector\|Eclipse detector]].)

	One can choose to create an event as a combination of these phenomena, for example a station visibility outside an interference period. In this case a user can create a detector as a combination of existing detectors.		One can choose to create an event as a combination of these phenomena, for example a station visibility outside an interference period. In this case a user can create a detector as a combination of existing detectors.
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	Once a new detector have been created in this way, it is possible to combine it with another one and so on.		Once a new detector have been created in this way, it is possible to combine it with another one and so on.

	For example the [~~MIS_SENSORS_Home~~#~~HCentralBodyMaskCircularFOVDetector~~ CentralBodyMaskCircularFOVDetector] detects when a target is in a circular field of view and outside of an eclipse, that is translated by :		For example the [[User Manual 3.3 Events: sensors#CentralBodyMaskCircularFOVDetector\|CentralBodyMaskCircularFOVDetector]] detects when a target is in a circular field of view and outside of an eclipse, that is translated by :

	* Outside of eclipse : when EllipsoidEclipseDetecor g function is positive		* Outside of eclipse : when EllipsoidEclipseDetecor g function is positive

Admin : /* Available event detectors */

2018-03-01T14:36:06Z

Available event detectors

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	* [[User Manual 3.3 Events: ground stations and satellites\|Ground stations and satellites events]]		* [[User Manual 3.3 Events: ground stations and satellites\|Ground stations and satellites events]]

	All these event detectors can be used [[User Manual 3.3 Events detection: Presentation#Event Detection\|directly]] or as [[User Manual 3.3 Events detection: Presentation#Generating coded events and phenomena\|coded events]].		All these event detectors can be used [[User Manual 3.3 Events detection: Presentation#Event Detection and multi event Detection\|directly]] or as [[User Manual 3.3 Events detection: Presentation#Generating coded events and phenomena\|coded events]].

	It also exists multi events detectors applied on several states. These detectors can only be used in multi propagation case.		It also exists multi events detectors applied on several states. These detectors can only be used in multi propagation case.

Admin : /* Available event detectors */

2018-03-01T14:34:47Z

Available event detectors

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	The available mono events detectors are presented in specific pages:		The available mono events detectors are presented in specific pages:

	* [~~MIS_ORB_Home~~ Orbit determination events]		* [[User Manual 3.3 Events: orbital\|Orbit determination events]]
	* [~~MIS_SENSORS_Home~~ Sensors events]		* [[User Manual 3.3 Events: sensors\|Sensors events]]
	* [~~MIS_STASAT_Home~~ Ground stations and satellites events]		* [[User Manual 3.3 Events: ground stations and satellites\|Ground stations and satellites events]]

	All these event detectors can be used [~~MIS_EVT_Home~~#~~HEventDetection~~ directly] or as [~~MIS_EVT_Home~~#~~HGeneratingcodedeventsandphenomena~~ coded events].		All these event detectors can be used [[User Manual 3.3 Events detection: Presentation#Event Detection\|directly]] or as [[User Manual 3.3 Events detection: Presentation#Generating coded events and phenomena\|coded events]].

	It also exists multi events detectors applied on several states. These detectors can only be used in multi propagation case.		It also exists multi events detectors applied on several states. These detectors can only be used in multi propagation case.
	Notice that some detectors that implies several satellite coul be used in multi or mono satellite context ; ([{{JavaDoc3.3}}/fr/cnes/sirius/patrius/events/sensor/SatToSatMutualVisibilityDetector.html SatToSatMutualVisibilityDetector], [{{JavaDoc3.3}}/org/orekit/propagation/events/ThreeBodiesAngleDetector.html ThreeBodiesAngleDetector] or [{{JavaDoc3.3}}/org/orekit/propagation/events/ExtremaThreeBodiesAngleDetector.html ExtremaThreeBodiesAngleDetector])		Notice that some detectors that implies several satellite coul be used in multi or mono satellite context ; ([{{JavaDoc3.3}}/fr/cnes/sirius/patrius/events/sensor/SatToSatMutualVisibilityDetector.html SatToSatMutualVisibilityDetector], [{{JavaDoc3.3}}/org/orekit/propagation/events/ThreeBodiesAngleDetector.html ThreeBodiesAngleDetector] or [{{JavaDoc3.3}}/org/orekit/propagation/events/ExtremaThreeBodiesAngleDetector.html ExtremaThreeBodiesAngleDetector])

	All these event detectors can be used [~~MIS_EVT_Home~~#~~HMultiEventDetection~~ directly] or as [~~MIS_EVT_Home~~#~~HGeneratingcodedeventsandphenomena~~ coded events].		All these event detectors can be used [[User Manual 3.3 Events detection: Presentation#Event Detection and multi event Detection\|directly]] or as [[User Manual 3.3 Events detection: Presentation#Generating coded events and phenomena\|coded events]].

	==== Nth occurrence detector ====		==== Nth occurrence detector ====

Admin : /* When to use Coded events and phenomena */

2018-03-01T14:27:47Z

When to use Coded events and phenomena

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	* To build easier time lines of events		* To build easier time lines of events
	* To manipulate easier phenomena (for example between "starting" and "ending" events) and associate to them specific computations (for example the evolution of the illumination during an eclipse)		* To manipulate easier phenomena (for example between "starting" and "ending" events) and associate to them specific computations (for example the evolution of the illumination during an eclipse)
	* To apply some [~~MIS_POSTP_Home~~ post-processing filters]		* To apply some [[User Manual 3.3 Postprocessing\|post-processing filters]]

	== Getting Started ==		== Getting Started ==

Admin : /* Combination of boolean phenomena */

2018-02-27T15:56:05Z

Combination of boolean phenomena

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	The user simply has to provide the following parameters :		The user simply has to provide the following parameters :
	1. First detector and the way to use it (g is positive or negative during the phenomena to combine)		#First detector and the way to use it (g is positive or negative during the phenomena to combine)<br>
	2. Second detector and the way to use it		#Second detector and the way to use it
	3. How to combine the phenomenom : both are during phenomena (will be detected as the minimum of the two g function) or at least one (will be detected as the maximum of the two g function) is during phenomena		#How to combine the phenomenom : both are during phenomena (will be detected as the minimum of the two g function) or at least one (will be detected as the maximum of the two g function) is during phenomena

	Once a new detector have been created in this way, it is possible to combine it with another one and so on.		Once a new detector have been created in this way, it is possible to combine it with another one and so on.
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	new CentralBodyMaskCircularFOVDetector(targetPVP, targetRadius, spheroEarth, false, fovDir, halfAp, MAXCHK, THRS);		new CentralBodyMaskCircularFOVDetector(targetPVP, targetRadius, spheroEarth, false, fovDir, halfAp, MAXCHK, THRS);
	</syntaxhighlight>		</syntaxhighlight>


	== Tutorials ==		== Tutorials ==

Admin : /* Examples */

2018-02-27T15:55:35Z

Examples

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	==== Examples ====		==== Examples ====

	The CodedEvent instances and Phenomenon instances are meant to be produced using :		The CodedEvent instances and Phenomenon instances are meant to be produced using :<br>
	- CodingEventDetector implementations that provide information about events and phenomena,		- CodingEventDetector implementations that provide information about events and phenomena,<br>
	- a CodingEventsLogger, that uses the CodingEventDetector instances to build the events and phenomena.		- a CodingEventsLogger, that uses the CodingEventDetector instances to build the events and phenomena.

Admin : Admin a déplacé la page Events detection: Presentation vers User Manual 3.3 Events detection: Presentation sans laisser de redirection

2018-02-27T14:55:23Z

Admin a déplacé la page Events detection: Presentation vers User Manual 3.3 Events detection: Presentation sans laisser de redirection

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Admin le 27 février 2018 à 14:54

2018-02-27T14:54:47Z

Admin le 27 février 2018 à 14:50

2018-02-27T14:50:31Z

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	=== Tutorial 2 ===		=== Tutorial 2 ===
	{{specialInclusion prefix=$theme_sub section="Tuto2"/}}		{{specialInclusion prefix=$theme_sub section="Tuto2"/}}

			[[Category:User_Manual_3.3_Mission]]

Admin : /* Nth occurrence detector */

2018-02-27T14:49:52Z

Nth occurrence detector

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	==== Nth occurrence detector ====		==== Nth occurrence detector ====

	The [{{JavaDoc3.3}}/~~NthOccurrenceDetector~~ org/orekit/propagation/events/NthOccurrenceDetector.html] is a detector that detects the nth occurrence of an underlying event detector.		The [{{JavaDoc3.3}}/org/orekit/propagation/events/NthOccurrenceDetector.html NthOccurrenceDetector] is a detector that detects the nth occurrence of an underlying event detector.
	However the <code>eventOccurred()</code> method is triggered at every event of the underlying detector. As a result, the behaviour of this detector is the following:		However the <code>eventOccurred()</code> method is triggered at every event of the underlying detector. As a result, the behaviour of this detector is the following:
	* Before and after the nth occurrence, the eventOccurred() method returns <code>Action.CONTINUE</code>.		* Before and after the nth occurrence, the eventOccurred() method returns <code>Action.CONTINUE</code>.

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	===== The phenomenon =====		===== The phenomenon =====

	The EventDetector provides a g() method whose sign change triggers an event. Sometimes the g() method can also be seen as conveying a "state" i.e. when g() is positive (resp. negative), a "phenomenon" is going on.		The EventDetector provides a g() method whose sign change triggers an event. Sometimes the g() method can also be seen as conveying a "state" i.e. when g() is positive (resp. negative), a "phenomenon" is going on.<br>
	The clearest example would be the EclipseDetector :		The clearest example would be the EclipseDetector :

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	* [{{JavaDoc3.3}}/org/orekit/propagation/events/multi/MultiEventDetector.html MultiEventDetector interface] in case of [{{JavaDoc3.3}}/fr/cnes/sirius/patrius/propagation/MultiPropagator.html multi satellite propagation].		* [{{JavaDoc3.3}}/org/orekit/propagation/events/multi/MultiEventDetector.html MultiEventDetector interface] in case of [{{JavaDoc3.3}}/fr/cnes/sirius/patrius/propagation/MultiPropagator.html multi satellite propagation].

	'''''Construction of a detector'''''		'''''Construction of a detector'''''<br>
	The action performed at event detection can be set by user at detector's construction. Several actions can be defined if several behavior are available (depending on state and/or on increasing/forward parameter). It is possible to specify at construction if the detector should be removed after event detection and thus not be detected any more. If a single action is available, a single boolean has to be provided by the user at construction. In the case where several actions are available, the same number of boolean has to be provided to determine if the detector has to be removed after event detection.		The action performed at event detection can be set by user at detector's construction. Several actions can be defined if several behavior are available (depending on state and/or on increasing/forward parameter). It is possible to specify at construction if the detector should be removed after event detection and thus not be detected any more. If a single action is available, a single boolean has to be provided by the user at construction. In the case where several actions are available, the same number of boolean has to be provided to determine if the detector has to be removed after event detection.
	Focusing on the <code> NodeDetector </code> for instance, two actions are possible at event detection :		Focusing on the <code> NodeDetector </code> for instance, two actions are possible at event detection :

	- action_at_ascending_node if an ascending node detection is done		- action_at_ascending_node if an ascending node detection is done<br>
	- action_at_descending_node if a descending node detection is performed		- action_at_descending_node if a descending node detection is performed

	If no actions are set, the user should be aware of the default implementation.		If no actions are set, the user should be aware of the default implementation.<br>
	By default, event detectors are never removed.		By default, event detectors are never removed.

	'''''Initialisation of eventOccurred()'''''		'''''Initialisation of eventOccurred()'''''<br>
	The returned action of the function eventOccurred could be set by user or defined by default.		The returned action of the function eventOccurred could be set by user or defined by default.

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	Note that the implementation of eventOccured must not contain any action. Even if the action does not impact the state vector, the action should be implemented in the resetState method.		Note that the implementation of eventOccured must not contain any action. Even if the action does not impact the state vector, the action should be implemented in the resetState method.

	'''''Initialisation of resetState() or resetStates()'''''		'''''Initialisation of resetState() or resetStates()'''''<br>
	If the event have an action, this action should be implemented in the resetState() method. In this case, the eventOccured() of the detector concerned should return a RESET_STATE action.		If the event have an action, this action should be implemented in the resetState() method. In this case, the eventOccured() of the detector concerned should return a RESET_STATE action.

	'''''Convergence threshold parametrisation'''''		'''''Convergence threshold parametrisation'''''<br>
	The convergence threshold represents the events detection precision; the following observations can help the user when choosing a value for this parameter:		The convergence threshold represents the events detection precision; the following observations can help the user when choosing a value for this parameter:

	1. if the convergence threshold increases, the execution time decreases (the precision becomes worst);		#if the convergence threshold increases, the execution time decreases (the precision becomes worst);
	2. if the convergence threshold is bigger than the max integration step, the events detection will fail.		#if the convergence threshold is bigger than the max integration step, the events detection will fail.

	If the resetState(s) could modify others event detectors, the convergence threshold should be low in order to avoid any unpredictable behavior.		If the resetState(s) could modify others event detectors, the convergence threshold should be low in order to avoid any unpredictable behavior.

	'''''Max check interval parametrisation'''''		'''''Max check interval parametrisation'''''<br>
	The max check interval parameter represents the maximum interval in which the propagator checks for an event (i.e. for a sign change of the g switching function). When choosing this parameter, the user should keep in mind the following remarks:		The max check interval parameter represents the maximum interval in which the propagator checks for an event (i.e. for a sign change of the g switching function). When choosing this parameter, the user should keep in mind the following remarks:

	1. if max check interval is smaller than the integration step, the execution time increases if the max check interval decreases (the events detection is more accurate);		#if max check interval is smaller than the integration step, the execution time increases if the max check interval decreases (the events detection is more accurate);
	2. if max check interval is bigger than the max integration step, it will be replaced by the max integration step during the events detection process; in this case the max check interval is a useless parameter that will never be used by the propagator.		#if max check interval is bigger than the max integration step, it will be replaced by the max integration step during the events detection process; in this case the max check interval is a useless parameter that will never be used by the propagator.

	In general, the user should always choose the max check interval value as a function of the integration step used during propagation.		In general, the user should always choose the max check interval value as a function of the integration step used during propagation.

	'''''Initialisation of the event detection'''''		'''''Initialisation of the event detection'''''<br>
	If an event occurs exactly at the propagation start date, i.e if g() equal to zero, the event is processed. This case is extremely rare. Note that in some case however, due to numerical quality rounds-off, an event may not be detected at the propagation start date although it's theoritically supposed to occur. For example, starting propagation at periapsis with a periapsis detector may not detect periapsis since the g() function of PeriapsisDetector is based on position- velocity scalar product and due to rounds-off errors, its values may be around 1E-7 which is not exactly zero.		If an event occurs exactly at the propagation start date, i.e if g() equal to zero, the event is processed. This case is extremely rare. Note that in some case however, due to numerical quality rounds-off, an event may not be detected at the propagation start date although it's theoritically supposed to occur. For example, starting propagation at periapsis with a periapsis detector may not detect periapsis since the g() function of PeriapsisDetector is based on position- velocity scalar product and due to rounds-off errors, its values may be around 1E-7 which is not exactly zero.
	Also, if at the propagation start date the g() function is not continuous but changes its sign (for example value-1 before event date, value 1 after), the event will also not be detected since the g() function value is not zero.		Also, if at the propagation start date the g() function is not continuous but changes its sign (for example value-1 before event date, value 1 after), the event will also not be detected since the g() function value is not zero.

	'''''Ephemeris propagator event detection'''''		'''''Ephemeris propagator event detection'''''<br>
	Sometimes the event detection is performed on a substep a little larger than the real one. Consequently, when propagating with a bounded propagator, if the last substep is larger than the real one then the real end date is exceeded, raising an exception. Therefore, in this case, it is recommended to '''propagate over an interval shorter than the interval of validity of the bounded propagator'''.		Sometimes the event detection is performed on a substep a little larger than the real one. Consequently, when propagating with a bounded propagator, if the last substep is larger than the real one then the real end date is exceeded, raising an exception. Therefore, in this case, it is recommended to '''propagate over an interval shorter than the interval of validity of the bounded propagator'''.

	'''''Events occurring at the same date'''''		'''''Events occurring at the same date'''''<br>
	When two events occur at the same date, Orekit detects both of them, but the order in which they are processed is the order in which they are added to the propagator. If the detected event stops the propagation, the other events occuring at the same date are not processed.		When two events occur at the same date, Orekit detects both of them, but the order in which they are processed is the order in which they are added to the propagator. If the detected event stops the propagation, the other events occuring at the same date are not processed.

	'''''Events occurring at the end date'''''		'''''Events occurring at the end date'''''<br>
	If an event occurs exactly at the propagation end date, the event is not processed.		If an event occurs exactly at the propagation end date, the event is not processed.

User Manual 3.3 Events detection: Presentation - Historique des versions

Admin : /* Combination of boolean phenomena */

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Admin : /* Nth occurrence detector */

Admin : /* Combination of boolean phenomena */

Admin : /* Available event detectors */

Admin : /* Available event detectors */

Admin : /* When to use Coded events and phenomena */

Admin : /* Combination of boolean phenomena */

Admin : /* Examples */

Admin : Admin a déplacé la page Events detection: Presentation vers User Manual 3.3 Events detection: Presentation sans laisser de redirection

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