Package org.orekit.forces.maneuvers

Class ImpulseManeuver<T extends EventDetector>

java.lang.Object

org.orekit.propagation.events.AbstractDetector<ImpulseManeuver<T>>

org.orekit.forces.maneuvers.ImpulseManeuver<T>

Type Parameters:

T - class type for the generic version

All Implemented Interfaces:

Serializable, EventDetector

public class ImpulseManeuver<T extends EventDetector>
extends AbstractDetector<ImpulseManeuver<T>>

Impulse maneuver model.

This class implements an impulse maneuver as a discrete event that can be provided to any Propagator.

The maneuver is triggered when an underlying event generates a STOP event, in which case this class will generate a RESET_STATE event (the stop event from the underlying object is therefore filtered out). In the simple cases, the underlying event detector may be a basic date event, but it can also be a more elaborate apside event for apogee maneuvers for example.

The maneuver is defined by a single velocity increment in satellite frame. The current attitude of the spacecraft, defined by the current spacecraft state, will be used to compute the velocity direction in inertial frame. A typical case for tangential maneuvers is to use a LOF aligned attitude provider for state propagation and a velocity increment along the +X satellite axis.

Beware that the triggering event detector must behave properly both before and after maneuver. If for example a node detector is used to trigger an inclination maneuver and the maneuver change the orbit to an equatorial one, the node detector will fail just after the maneuver, being unable to find a node on an equatorial orbit! This is a real case that has been encountered during validation ...

Author:

Luc Maisonobe

See Also:

Propagator.addEventDetector(EventDetector), Serialized Form

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor	Description
ImpulseManeuver(T trigger, Vector3D deltaVSat, double isp)	Build a new instance.
ImpulseManeuver(T trigger, AttitudeProvider attitudeOverride, Vector3D deltaVSat, double isp)	Build a new instance.

Method Summary

Modifier and Type	Method	Description
protected ImpulseManeuver<T>	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super ImpulseManeuver<T>> newHandler)	Build a new instance.
double	g(SpacecraftState s)	Compute the value of the switching function.
AttitudeProvider	getAttitudeOverride()	Get the Attitude Provider to use during maneuver.
Vector3D	getDeltaVSat()	Get the velocity increment in satellite frame.
double	getIsp()	Get the specific impulse.
T	getTrigger()	Get the triggering event.
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

ImpulseManeuver

public ImpulseManeuver(T trigger,
                       Vector3D deltaVSat,
                       double isp)

Build a new instance.

Parameters:

trigger - triggering event

deltaVSat - velocity increment in satellite frame

isp - engine specific impulse (s)

ImpulseManeuver

public ImpulseManeuver(T trigger,
                       AttitudeProvider attitudeOverride,
                       Vector3D deltaVSat,
                       double isp)

Build a new instance.

Parameters:

trigger - triggering event

attitudeOverride - the attitude provider to use for the maneuver

deltaVSat - velocity increment in satellite frame

isp - engine specific impulse (s)

Method Detail

create

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

Build a new instance.

Specified by:

create in class AbstractDetector<ImpulseManeuver<T extends EventDetector>>

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

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<ImpulseManeuver<T extends EventDetector>>

Parameters:

s0 - initial state

t - target time for the integration

g

public double g(SpacecraftState s)
         throws OrekitException

Compute the value of the switching function. This function must be continuous (at least in its roots neighborhood), as the integrator will need to find its roots to locate the events.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<ImpulseManeuver<T extends EventDetector>>

Parameters:

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

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs

getAttitudeOverride

public AttitudeProvider getAttitudeOverride()

Get the Attitude Provider to use during maneuver.

Returns:

the attitude provider

getTrigger

public T getTrigger()

Get the triggering event.

Returns:

triggering event

getDeltaVSat

public Vector3D getDeltaVSat()

Get the velocity increment in satellite frame.

Returns:

velocity increment in satellite frame

getIsp

public double getIsp()

Get the specific impulse.

Returns:

specific impulse