org.orekit.propagation
Class AbstractPropagator

java.lang.Object
  org.orekit.propagation.AbstractPropagator

All Implemented Interfaces:

Serializable, Propagator, PVCoordinatesProvider

Direct Known Subclasses:

AbstractEphemeris, AbstractLyddanePropagator, AdapterPropagator, Analytical2DPropagator, AnalyticalIntegratedEphemeris, EcksteinHechlerPropagator, Ephemeris, IntegratedEphemeris, J2SecularPropagator, KeplerianPropagator, MultiIntegratedEphemeris, PVCoordinatePropagator, TLEPropagator

public abstract class AbstractPropagator
extends Object
implements Propagator

Common handling of Propagator methods for analytical propagators.

This abstract class allows to provide easily the full set of Propagator methods, including all propagation modes support and discrete events support for any simple propagation method. Only one method must be implemented by derived classes: propagateOrbit(AbsoluteDate). The first method should perform straightforward propagation starting from some internally stored initial state up to the specified target date.

Author:

Luc Maisonobe

See Also:

Serialized Form

Field Summary

static String

MASS Default prefix for additional state provider from MassProvider.

Fields inherited from interface org.orekit.propagation.Propagator

EPHEMERIS_GENERATION_MODE, MASTER_MODE, SLAVE_MODE

Constructor Summary

protected	AbstractPropagator(AttitudeProvider attitudeProvider) Build a new instance.
protected	AbstractPropagator(AttitudeProvider attitudeProviderForces, AttitudeProvider attitudeProviderEvents) Build a new instance.

Method Summary

protected SpacecraftState	acceptStep(AbsoluteDate target, double epsilon) Accept a step, triggering events and step handlers.
void	addAdditionalStateProvider(AdditionalStateProvider additionalStateProvider) Add a set of user-specified state parameters to be computed along with the orbit propagation.
void	addAdditionalStateProvider(MassProvider massProvider) Add a set of state parameters from MassProvider to be computed along with the orbit propagation.
void	addEventDetector(EventDetector detector) Add an event detector.
protected SpacecraftState	basicPropagate(AbsoluteDate date) Propagate an orbit without any fancy features.
void	clearEventsDetectors() Remove all events detectors.
AttitudeProvider	getAttitudeProvider() Get attitude provider.
AttitudeProvider	getAttitudeProviderEvents() Get attitude provider for events computation.
AttitudeProvider	getAttitudeProviderForces() Get attitude provider for forces computation.
Collection<EventDetector>	getEventsDetectors() Get all the events detectors that have been added.
Frame	getFrame() Get the frame in which the orbit is propagated.
BoundedPropagator	getGeneratedEphemeris() Get the ephemeris generated during propagation.
SpacecraftState	getInitialState() Get the propagator initial state.
int	getMode() Get the current operating mode of the propagator.
PVCoordinates	getPVCoordinates(AbsoluteDate date, Frame frame) Get the PVCoordinates of the body in the selected frame.
PVCoordinatesProvider	getPvProvider() Get PV coordinates provider.
protected void	manageStateFrame() Manage the state frame : the orbit to propagate is converted in the propagation frame.
SpacecraftState	propagate(AbsoluteDate target) Propagate towards a target date.
SpacecraftState	propagate(AbsoluteDate start, AbsoluteDate target) Propagate from a start date towards a target date.
protected abstract Orbit	propagateOrbit(AbsoluteDate date) Extrapolate an orbit up to a specific target date.
void	resetInitialState(SpacecraftState state) Reset the propagator initial state.
void	setAttitudeProvider(AttitudeProvider attitudeProvider) Set attitude provider for forces and events computation.
void	setAttitudeProviderEvents(AttitudeProvider attProviderEvents) Set attitude provider for events computation.
void	setAttitudeProviderForces(AttitudeProvider attProviderForces) Set attitude provider for forces computation.
void	setEphemerisMode() Set the propagator to ephemeris generation mode.
void	setMasterMode(double h, OrekitFixedStepHandler handler) Set the propagator to master mode with fixed steps.
void	setMasterMode(OrekitStepHandler handler) Set the propagator to master mode with variable steps.
void	setOrbitFrame(Frame frame) Set propagation frame.
void	setSlaveMode() Set the propagator to slave mode.
protected void	setStartDate(AbsoluteDate startDate) Set a start date.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MASS

public static final String MASS

Default prefix for additional state provider from MassProvider.

See Also:

Constant Field Values

Constructor Detail

AbstractPropagator

protected AbstractPropagator(AttitudeProvider attitudeProvider)

Build a new instance.

Parameters:

attitudeProvider - provider for attitude computation in case of both forces and events computation

AbstractPropagator

protected AbstractPropagator(AttitudeProvider attitudeProviderForces,
                             AttitudeProvider attitudeProviderEvents)

Build a new instance.

Parameters:

attitudeProviderForces - provider for attitude computation in case of forces computation

attitudeProviderEvents - provider for attitude computation in case of events computation

Method Detail

setStartDate

protected void setStartDate(AbsoluteDate startDate)

Set a start date.

Parameters:

startDate - start date

getAttitudeProvider

public AttitudeProvider getAttitudeProvider()

Get attitude provider.

Specified by:

getAttitudeProvider in interface Propagator

Returns:

attitude provider for forces computation (by default)

getAttitudeProviderForces

public AttitudeProvider getAttitudeProviderForces()

Get attitude provider for forces computation.

Specified by:

getAttitudeProviderForces in interface Propagator

Returns:

attitude provider for forces computation

getAttitudeProviderEvents

public AttitudeProvider getAttitudeProviderEvents()

Get attitude provider for events computation.

Specified by:

getAttitudeProviderEvents in interface Propagator

Returns:

attitude provider for events computation

setAttitudeProvider

public void setAttitudeProvider(AttitudeProvider attitudeProvider)

Set attitude provider for forces and events computation. A default attitude provider is available in ConstantAttitudeLaw.

Specified by:

setAttitudeProvider in interface Propagator

Parameters:

attitudeProvider - attitude provider

setAttitudeProviderForces

public void setAttitudeProviderForces(AttitudeProvider attProviderForces)

Set attitude provider for forces computation. A default attitude provider is available in ConstantAttitudeLaw.

Specified by:

setAttitudeProviderForces in interface Propagator

Parameters:

attProviderForces - attitude provider for forces computation

setAttitudeProviderEvents

public void setAttitudeProviderEvents(AttitudeProvider attProviderEvents)

Set attitude provider for events computation. A default attitude provider is available in ConstantAttitudeLaw.

Specified by:

setAttitudeProviderEvents in interface Propagator

Parameters:

attProviderEvents - attitude provider for events computation

setOrbitFrame

public void setOrbitFrame(Frame frame)
                   throws OrekitException

Set propagation frame.

Specified by:

setOrbitFrame in interface Propagator

Parameters:

frame - the frame to use. This frame must be inertial or pseudo-inertial, otherwise an exception is raised.

Throws:

OrekitException - if frame is not inertial or pseudo-inertial

getPvProvider

public PVCoordinatesProvider getPvProvider()

Get PV coordinates provider.

Returns:

PV coordinates provider

getInitialState

public SpacecraftState getInitialState()
                                throws OrekitException

Get the propagator initial state.

Specified by:

getInitialState in interface Propagator

Returns:

initial state

Throws:

OrekitException - if state cannot be retrieved

getMode

public int getMode()

Get the current operating mode of the propagator.

Specified by:

getMode in interface Propagator

Returns:

one of Propagator.SLAVE_MODE, Propagator.MASTER_MODE, Propagator.EPHEMERIS_GENERATION_MODE

See Also:

Propagator.setSlaveMode(), Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setMasterMode(OrekitStepHandler), Propagator.setEphemerisMode()

getFrame

public Frame getFrame()

Get the frame in which the orbit is propagated.

4 cases are possible:

• The propagation frame has been defined (using Propagator.setOrbitFrame(Frame)): it is returned.
• The propagation frame has not been defined and the initial state has been provided and is expressed in a pseudo-inertial frame: the initial state frame is returned.
• The propagation frame has not been defined and the initial state has been provided and is not expressed in a pseudo-inertial frame: null is returned.
• The propagation frame has not been defined and the initial state has not been provided: null is returned.

Specified by:

getFrame in interface Propagator

Returns:

frame in which the orbit is propagated

setSlaveMode

public void setSlaveMode()

Set the propagator to slave mode.

This mode is used when the user needs only the final orbit at the target time. The (slave) propagator computes this result and return it to the calling (master) application, without any intermediate feedback.

This is the default mode.

Specified by:

setSlaveMode in interface Propagator

See Also:

Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setMasterMode(OrekitStepHandler), Propagator.setEphemerisMode(), Propagator.getMode(), Propagator.SLAVE_MODE

setMasterMode

public void setMasterMode(double h,
                          OrekitFixedStepHandler handler)

Set the propagator to master mode with fixed steps.

This mode is used when the user needs to have some custom function called at the end of each finalized step during integration. The (master) propagator integration loop calls the (slave) application callback methods at each finalized step.

Specified by:

setMasterMode in interface Propagator

Parameters:

h - fixed stepsize (s)

handler - handler called at the end of each finalized step

See Also:

Propagator.setSlaveMode(), Propagator.setMasterMode(OrekitStepHandler), Propagator.setEphemerisMode(), Propagator.getMode(), Propagator.MASTER_MODE

setMasterMode

public void setMasterMode(OrekitStepHandler handler)

Set the propagator to master mode with variable steps.

This mode is used when the user needs to have some custom function called at the end of each finalized step during integration. The (master) propagator integration loop calls the (slave) application callback methods at each finalized step.

Specified by:

setMasterMode in interface Propagator

Parameters:

handler - handler called at the end of each finalized step

See Also:

Propagator.setSlaveMode(), Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setEphemerisMode(), Propagator.getMode(), Propagator.MASTER_MODE

setEphemerisMode

public void setEphemerisMode()

Set the propagator to ephemeris generation mode.

This mode is used when the user needs random access to the orbit state at any time between the initial and target times, and in no sequential order. A typical example is the implementation of search and iterative algorithms that may navigate forward and backward inside the propagation range before finding their result.

Beware that since this mode stores all intermediate results, it may be memory intensive for long integration ranges and high precision/short time steps.

Specified by:

setEphemerisMode in interface Propagator

See Also:

Propagator.getGeneratedEphemeris(), Propagator.setSlaveMode(), Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setMasterMode(OrekitStepHandler), Propagator.getMode(), Propagator.EPHEMERIS_GENERATION_MODE

getGeneratedEphemeris

public BoundedPropagator getGeneratedEphemeris()

Get the ephemeris generated during propagation.

Specified by:

getGeneratedEphemeris in interface Propagator

Returns:

generated ephemeris

See Also:

Propagator.setEphemerisMode()

addEventDetector

public void addEventDetector(EventDetector detector)

Add an event detector.

Specified by:

addEventDetector in interface Propagator

Parameters:

detector - event detector to add

See Also:

Propagator.clearEventsDetectors(), Propagator.getEventsDetectors()

getEventsDetectors

public Collection<EventDetector> getEventsDetectors()

Get all the events detectors that have been added.

Specified by:

getEventsDetectors in interface Propagator

Returns:

an unmodifiable collection of the added detectors

See Also:

Propagator.addEventDetector(EventDetector), Propagator.clearEventsDetectors()

clearEventsDetectors

public void clearEventsDetectors()

Remove all events detectors.

Specified by:

clearEventsDetectors in interface Propagator

See Also:

Propagator.addEventDetector(EventDetector), Propagator.getEventsDetectors()

addAdditionalStateProvider

public void addAdditionalStateProvider(AdditionalStateProvider additionalStateProvider)

Add a set of user-specified state parameters to be computed along with the orbit propagation.

Parameters:

additionalStateProvider - provider for additional state

addAdditionalStateProvider

public void addAdditionalStateProvider(MassProvider massProvider)

Add a set of state parameters from MassProvider to be computed along with the orbit propagation.

Parameters:

massProvider - mass provider for additional state

propagate

public SpacecraftState propagate(AbsoluteDate target)
                          throws PropagationException

Propagate towards a target date.

Simple propagators use only the target date as the specification for computing the propagated state. More feature rich propagators can consider other information and provide different operating modes or G-stop facilities to stop at pinpointed events occurrences. In these cases, the target date is only a hint, not a mandatory objective.

Specified by:

propagate in interface Propagator

Parameters:

target - target date towards which orbit state should be propagated

Returns:

propagated state

Throws:

PropagationException - if state cannot be propagated

propagate

public SpacecraftState propagate(AbsoluteDate start,
                                 AbsoluteDate target)
                          throws PropagationException

Propagate from a start date towards a target date.

Those propagators use a start date and a target date to compute the propagated state. For propagators using event detection mechanism, if the provided start date is different from the initial state date, a first, simple propagation is performed, without processing any event computation. Then complete propagation is performed from start date to target date.

Specified by:

propagate in interface Propagator

Parameters:

start - start date from which orbit state should be propagated

target - target date to which orbit state should be propagated

Returns:

propagated state

Throws:

PropagationException - if state cannot be propagated

acceptStep

protected SpacecraftState acceptStep(AbsoluteDate target,
                                     double epsilon)
                              throws OrekitException,
                                     TooManyEvaluationsException,
                                     NoBracketingException

Accept a step, triggering events and step handlers.

Parameters:

target - final propagation time

epsilon - threshold for end date detection

Returns:

state at the end of the step

Throws:

OrekitException - if the switching function cannot be evaluated

TooManyEvaluationsException - if an event cannot be located

NoBracketingException - if bracketing cannot be performed

manageStateFrame

protected void manageStateFrame()
                         throws OrekitException

Manage the state frame : the orbit to propagate is converted in the propagation frame.

Throws:

OrekitException - if the frame of the initial state is not inertial or pseudo-inertial

getPVCoordinates

public PVCoordinates getPVCoordinates(AbsoluteDate date,
                                      Frame frame)
                               throws OrekitException

Get the PVCoordinates of the body in the selected frame.

Specified by:

getPVCoordinates in interface PVCoordinatesProvider

Parameters:

date - current date

frame - the frame where to define the position

Returns:

position/velocity of the body (m and m/s)

Throws:

OrekitException - if position cannot be computed in given frame

basicPropagate

protected SpacecraftState basicPropagate(AbsoluteDate date)
                                  throws PropagationException

Propagate an orbit without any fancy features.

This method is similar in spirit to the propagate(org.orekit.time.AbsoluteDate) method, except that it does not call any handler during propagation, nor any discrete events. It always stop exactly at the specified date.

Parameters:

date - target date for propagation

Returns:

state at specified date

Throws:

PropagationException - if propagation cannot reach specified date

propagateOrbit

protected abstract Orbit propagateOrbit(AbsoluteDate date)
                                 throws PropagationException

Extrapolate an orbit up to a specific target date.

Parameters:

date - target date for the orbit

Returns:

extrapolated parameters

Throws:

PropagationException - if some parameters are out of bounds

resetInitialState

public void resetInitialState(SpacecraftState state)
                       throws PropagationException

Reset the propagator initial state.

Specified by:

resetInitialState in interface Propagator

Parameters:

state - new initial state to consider

Throws:

PropagationException - if initial state cannot be reset