User Manual 4.3 Attitude law - Historique des versions

Admin le 4 juin 2019 à 07:58

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	Here is how an attitudes sequence is built:		Here is how an attitudes sequence is built:

	* An empty attitudes sequence is created: <code>new AttitudesSequence()</code>		* An empty attitudes sequence is created: <code>new AttitudesSequence()</code>;

	* The attitudes laws that will compose the sequence are instantiated		* The attitudes laws that will compose the sequence are instantiated;

	* The switching detectors are instantiated and set up using the addSwitchingCondition ~~method. In~~ addition to the event detector, the previous and the next attitude laws associated to the switching condition are specified; Warning: switching detectors should have <code>Action.RESET_STATE</code> as action.		* The switching detectors are instantiated and set up using the <code>addSwitchingCondition(AttitudeLaw, EventDetector, boolean, boolean, AttitudeLaw)</code> command; in addition to the event detector, the previous and the next attitude laws associated to the switching condition are specified; Warning: switching detectors should have <code>Action.RESET_STATE</code> as action.

	* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.		* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.

Admin le 3 juin 2019 à 14:59

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	* The attitudes laws that will compose the sequence are instantiated		* The attitudes laws that will compose the sequence are instantiated

	* The switching detectors are instantiated and set up using the addSwitchingCondition method		* The switching detectors are instantiated and set up using the addSwitchingCondition method. In addition to the event detector, the previous and the next attitude laws associated to the switching condition are specified; Warning: switching detectors should have <code>Action.RESET_STATE</code> as action.

	* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.		* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.

Admin le 3 juin 2019 à 14:59

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	* The attitudes laws that will compose the sequence are instantiated		* The attitudes laws that will compose the sequence are instantiated

	* The switching detectors are instantiated and set up		* The switching detectors are instantiated and set up using the addSwitchingCondition method

	* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.		* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.

Admin le 3 juin 2019 à 14:58

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	* The attitudes laws that will compose the sequence are instantiated		* The attitudes laws that will compose the sequence are instantiated

			* The switching detectors are instantiated and set up

	* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.		* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.

Admin le 3 juin 2019 à 14:56

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	* The attitudes laws that will compose the sequence are instantiated		* The attitudes laws that will compose the sequence are instantiated

			* The <code>registerSwitchEvents(Propagator)</code> method is called once before propagation, after the switching conditions have been set, in order to wrap switch events to the propagator.

	==== Code sample ====		==== Code sample ====

Admin le 3 juin 2019 à 14:55

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	Unlike the <code>AttitudeLeg</code> objects, the <code>AttitudeLaw</code> instances do not have an interval of validity, therefore the switching from one law to another can not be based on time intervals.		Unlike the <code>AttitudeLeg</code> objects, the <code>AttitudeLaw</code> instances do not have an interval of validity, therefore the switching from one law to another can not be based on time intervals.
	For a given date, only one attitude law in the sequence is in an "active" state, so that the attitude of the spacecraft is computed from that attitude law. The laws are activated in turn according to some switching events, which are added to the sequence before starting the propagation.		For a given date, only one attitude law in the sequence is in an "active" state, so that the attitude of the spacecraft is computed from that attitude law. The laws are activated in turn according to some switching events, which are added to the sequence before starting the propagation.

			==== Building an attitudes sequence ====

			Here is how an attitudes sequence is built:

			* An empty attitudes sequence is created: <code>new AttitudesSequence()</code>

			* The attitudes laws that will compose the sequence are instantiated

	==== Code sample ====		==== Code sample ====

Admin le 3 juin 2019 à 14:53

2019-06-03T14:53:57Z

@@ Ligne 168 : / Ligne 168 : @@
 Unlike the <code>AttitudeLeg</code> objects, the <code>AttitudeLaw</code> instances do not have an interval of validity, therefore the switching from one law to another can not be based on time intervals.
 For a given date, only one attitude law in the sequence is in an "active" state, so that the attitude of the spacecraft is computed from that attitude law. The laws are activated in turn according to some switching events, which are added to the sequence before starting the propagation.
 === Attitude composition ===

Admin le 3 juin 2019 à 14:53

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	- <code>leg.getAttitude(pvProv, date, frame)</code> is the date is contained in the interval of validity of leg<br>		- <code>leg.getAttitude(pvProv, date, frame)</code> is the date is contained in the interval of validity of leg<br>
	- <code>lawAfter.getAttitude(pvProv, date, frame)</code> is the date is superior to the the interval of validity of leg		- <code>lawAfter.getAttitude(pvProv, date, frame)</code> is the date is superior to the the interval of validity of leg

			=== Attitudes sequence ===
			The attitudes sequence represents a sequence of several attitude laws (<code>AttitudeLaw</code> instances).

			Unlike the <code>AttitudeLeg</code> objects, the <code>AttitudeLaw</code> instances do not have an interval of validity, therefore the switching from one law to another can not be based on time intervals.
			For a given date, only one attitude law in the sequence is in an "active" state, so that the attitude of the spacecraft is computed from that attitude law. The laws are activated in turn according to some switching events, which are added to the sequence before starting the propagation.

	=== Attitude composition ===		=== Attitude composition ===

Admin le 3 juin 2019 à 14:51

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	This attitude law can be used to represent the '''GAP''' (geocentric), and the '''SUP''' (heliocentric) pointing laws.		This attitude law can be used to represent the '''GAP''' (geocentric), and the '''SUP''' (heliocentric) pointing laws.

			==== RelativeTabulatedAttitudeLaw ====
			<code>RelativeTabulatedAttitudeLaw</code> is an implementation of <code>AttitudeLaw</code>. It is composed of a <code>AttitudeLegLaw:attitudeLegLaw</code> attribute defined by :<br>
			- An instance of <code>RelativeTabulatedAttitudeLeg:leg</code> built with an <code>List<Pair<Double, Rotation>></code> (or an <code>List<Pair<Double, AngularCoordinates>>)</code> input.<br>
			- Two instances of <code>AttitudeLaw</code> to apply if the input date is inferior or superior to the interval of validity of <code>leg</code>. These laws can be of two types : <code>ConstantAttitudeLaw</code> or <code>ExtrapolatedAttitudeLaw</code> (local private class of <code>RelativeTabulatedAttitudeLaw</code>).

			The <code>ConstantAttitudeLaw</code> is created with the input frame of <code>RelativeTabulatedAttitudeLaw</code>, and the value of the rotation to the bound of the interval (minimum or maximum).

			The <code>ExtrapolatedAttitudeLaw</code> is a local private class. It is an implementation of <code>AttitudeLaw</code>. It is created with an <code>AngularCoordinates</code> and the expression frame of this attitude. Its method <code>getAttitude()</code> returns <code>AngularCoordinates.shiftedBy(double)</code>.

			The <code>ExtrapolatedAttitudeLaw</code> is created with :<br>
			- the input frame of <code>RelativeTabulatedAttitudeLaw</code><br>
			- the <code>AngularCoordinates</code> to the bound of the interval (minimum or maximum).<br>
			Here is an example of a creation of an instance of <code>RelativeTabulatedAttitudeLaw</code> :

			<syntaxhighlight lang="java">

			// build law before as a ConstantAttitudeLaw
			final RelativeTabulatedAttitudeLaw.AroundAttitudetype lawBefore =
			RelativeTabulatedAttitudeLaw.AroundAttitudetype.CONSTANT_ATT;

			// build law after as a ExtrapolatedAttitudeLaw
			final RelativeTabulatedAttitudeLaw.AroundAttitudetype lawAfter =
			RelativeTabulatedAttitudeLaw.AroundAttitudetype.EXTRAPOLATED_ATT;

			// build RelativeTabulatedAttitudeLaw
			final RelativeTabulatedAttitudeLaw relativeTabulatedAttitudeLaw =
			new RelativeTabulatedAttitudeLaw(refDate, listAr, frame, lawBefore, lawAfter);

			</syntaxhighlight>

			==== AeroAttitudeLaw ====
			<code>AeroAttitudeLaw </code> is a law that aligns platform frame (Ox, Oy, Oz) with a frame defined by 3 angles: angle of attack, sideslip and velocity roll.
			With the following conventions:<br>
			- Platform frame is (Ox, Oy, Oz) with Ox along main frame, Oz in the symmetry plane of the aircraft toward up direction.<br>
			- Velocity frame is (Oxv, Oyv, Ozv) with Oxv being along velocity and Ozv in the symmetry plane of the aircraft toward up direction.<br>
			The three angles are defined in the following way:<br>
			- Angle of attack is angle between (Oxv, Oyv) plane and Ox vector.<br>
			- Sideslip is angle between Oxv vector and (Ox, Oz) symmetry plane<br>
			- Velocity roll is angle around velocity vector.

			==== AttitudeLegLaw ====
			<code>AttitudeLegLaw</code> is an implementation of <code>AttitudeLaw</code>. It is composed of : an instance of <code>AttitudeLeg:leg</code>, an instance of <code>AttitudeLaw:lawbefore</code> and an other instance of <code>AttitudeLaw:lawAfter</code>. Its method <code>getAttitude(pvProv, date, frame)</code> returns : <br>
			- <code>lawbefore.getAttitude(pvProv, date, frame)</code> is the date is inferior to the interval of validity of leg<br>
			- <code>leg.getAttitude(pvProv, date, frame)</code> is the date is contained in the interval of validity of leg<br>
			- <code>lawAfter.getAttitude(pvProv, date, frame)</code> is the date is superior to the the interval of validity of leg

	=== Attitude composition ===		=== Attitude composition ===

Admin le 3 juin 2019 à 14:50

2019-06-03T14:50:45Z

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	This attitude law can be used to represent the '''GAP''' (geocentric), and the '''SUP''' (heliocentric) pointing laws.		This attitude law can be used to represent the '''GAP''' (geocentric), and the '''SUP''' (heliocentric) pointing laws.

			=== Attitude composition ===
			The <code>ComposedAttitudeLaw</code> class allows to compose a main attitude law (implementing the <code>AttitudeLaw</code> interface) and one or several orientation laws (<code>IOrientationLaw</code> interface) whose purpose is to modify this law in order to obtain the "composed" attitude law.

			It shall be created this way :

			<syntaxhighlight lang="java">
			// attitude law creation
			AttitudeLaw attitudeLaw = new MyAttitudeLaw(...);

			// orientation laws creation (modifiers)
			IOrientationLaw orientationLaw1 = new AnyOrientationLaw(...);
			IOrientationLaw orientationLaw2 = new AnyOtherOrientationLaw(...);

			// modifiers list creation
			final LinkedList<IOrientationLaw> modifiers = new LinkedList<IOrientationLaw>();

			modifiers.add(orientationLaw1);
			modifiers.add(orientationLaw2);

			// composed attitude creation
			final ComposedAttitudeLaw composedAtt = new ComposedAttitudeLaw(attitudeLaw, modifiers);
			</syntaxhighlight>

			The <code>ComposedAttitudeLaw</code> class implements the <code>AttitudeLawModifier</code> interface : it shall be used as any <code>AttitudeLaw</code>, and can also provide its "underlying attitude law" (the main attitude law used to build it).

			Dedicated frames exist to describe those laws and are used to compute the composition :

			* The <code>AttitudeFrame</code> is a frame defined by any attitude law (<code>AttitudeProvider</code>) and position velocity coordinates (<code>PVCoordinatesProvider</code>). At any date, its center is the position of the <code>PVCoordinatesProvider</code>, and its rotation from a reference frame is given by the attitude law.

			* The <code>OrientationFrame</code> is defined from another <code>OrientationFrame</code> or from an <code>AttitudeFrame</code> by the corrections (<code>IOrientationLaw</code> objects) applied to them.

			The <code>ComposedAttitudeLaw</code> class can be used to represent a biased geocentric pointing law ('''biased GAP'''): a geocentric attitude law is associated to a "modifier" that represents a constant rotation. This specific pointing law is used for the thrust: the bias added to the main pointing direction is the direction of the thrust.

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