fr.cnes.sirius.patrius.stela.propagation
Class StelaAbstractPropagator

java.lang.Object
  fr.cnes.sirius.patrius.stela.propagation.StelaAbstractPropagator

All Implemented Interfaces:

Serializable, Propagator, PVCoordinatesProvider

Direct Known Subclasses:

StelaGTOPropagator

public abstract class StelaAbstractPropagator
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 two methods must be implemented by derived classes: propagateSpacecraftState(AbsoluteDate) and getMass(AbsoluteDate). The first method should perform straightforward propagation starting from some internally stored initial state up to the specified target date.

See Also:

Serialized Form

Field Summary

protected AttitudeProvider	attitudeProviderByDefault Attitude provider given by default for one attitude.
protected AttitudeProvider	attitudeProviderEvents Attitude provider for events computation.
protected AttitudeProvider	attitudeProviderForces Attitude provider for forces computation.
protected Collection<EventState>	eventsStates Event steps.
protected FirstOrderIntegrator	integrator Integrator for the orbital extrapolation process.
protected OrekitFixedStepHandler	oldStepHandler Entry Step handler.

Fields inherited from interface org.orekit.propagation.Propagator

EPHEMERIS_GENERATION_MODE, MASTER_MODE, SLAVE_MODE

Constructor Summary

protected	StelaAbstractPropagator(AttitudeProvider attitudeProviderInForces, AttitudeProvider attitudeProviderInEvents, StelaBasicInterpolator inInterpolator) Build a new instance.
protected	StelaAbstractPropagator(AttitudeProvider attitudeProviderIn, StelaBasicInterpolator inInterpolator) 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	addEventDetector(EventDetector detector) Add an event detector.
protected SpacecraftState	basicPropagate(AbsoluteDate date) Propagate a SpacecraftState 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.
protected abstract double	getMass(AbsoluteDate date) Get the mass.
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 abstract List<OrekitStepHandler>	getStepHandlers() Provides a list of step handlers to be performed during propagation.
List<TimeDerivativeData>	getTimeDerivativesList() Returns time derivatives list.
SpacecraftState	goAhead(double stepSize, double dt, AbsoluteDate target) go one step ahead
boolean	isStoreTimeDerivatives() Returns flag indicating if time derivatives dE'/dt must be stored.
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 SpacecraftState	propagateSpacecraftState(AbsoluteDate date) Extrapolate a spacecraftState up to a specific target date.
SpacecraftState	propagationManagement(SpacecraftState state, double stepSize, double dt, AbsoluteDate target) Manages the current step, method to override when user wants to deal with exceptions during the propagation.
void	resetInitialState(SpacecraftState state) Reset the propagator initial state.
void	setAttitudeProvider(AttitudeProvider attitudeProviderIn) Set attitude provider for forces and events computation.
void	setAttitudeProviderEvents(AttitudeProvider attitudeProviderIn) Set attitude provider for events computation.
void	setAttitudeProviderForces(AttitudeProvider attitudeProviderIn) Set attitude provider for forces computation.
void	setEphemerisMode() Set the propagator to ephemeris generation mode.
void	setIntegrator(FirstOrderIntegrator inIntegrator) Set the integrator.
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 startDateIn) Set a start date.
void	setStoreTimeDerivatives(boolean isStoreTimeDerivatives) Setter for flag indicating if time derivatives dE'/dt must be stored.

Methods inherited from class java.lang.Object

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

Field Detail

oldStepHandler

protected OrekitFixedStepHandler oldStepHandler

Entry Step handler.

eventsStates

protected final Collection<EventState> eventsStates

Event steps.

integrator

protected FirstOrderIntegrator integrator

Integrator for the orbital extrapolation process.

attitudeProviderForces

protected AttitudeProvider attitudeProviderForces

Attitude provider for forces computation.

attitudeProviderEvents

protected AttitudeProvider attitudeProviderEvents

Attitude provider for events computation.

attitudeProviderByDefault

protected AttitudeProvider attitudeProviderByDefault

Attitude provider given by default for one attitude.

Constructor Detail

StelaAbstractPropagator

protected StelaAbstractPropagator(AttitudeProvider attitudeProviderIn,
                                  StelaBasicInterpolator inInterpolator)

Build a new instance.

Parameters:

attitudeProviderIn - provider for attitude computation

inInterpolator - the interpolator used during the propagation

StelaAbstractPropagator

protected StelaAbstractPropagator(AttitudeProvider attitudeProviderInForces,
                                  AttitudeProvider attitudeProviderInEvents,
                                  StelaBasicInterpolator inInterpolator)

Build a new instance.

Parameters:

attitudeProviderInForces - attitude for forces computation

attitudeProviderInEvents - attitude for events computation

inInterpolator - the interpolator used during the propagation

Method Detail

setStartDate

protected void setStartDate(AbsoluteDate startDateIn)

Set a start date.

Parameters:

startDateIn - 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 attitudeProviderIn)

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

Specified by:

setAttitudeProvider in interface Propagator

Parameters:

attitudeProviderIn - attitude provider

setAttitudeProviderForces

public void setAttitudeProviderForces(AttitudeProvider attitudeProviderIn)

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

Specified by:

setAttitudeProviderForces in interface Propagator

Parameters:

attitudeProviderIn - attitude provider for forces computation

setAttitudeProviderEvents

public void setAttitudeProviderEvents(AttitudeProvider attitudeProviderIn)

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

Specified by:

setAttitudeProviderEvents in interface Propagator

Parameters:

attitudeProviderIn - attitude provider for events computation

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

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

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)
                                throws OrekitException

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

Parameters:

additionalStateProvider - provider for additional state

Throws:

OrekitException - if an additional state with the same name is already present

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

getStepHandlers

protected abstract List<OrekitStepHandler> getStepHandlers()

Provides a list of step handlers to be performed during propagation.

Returns:

propagation list of step handlers.

goAhead

public SpacecraftState goAhead(double stepSize,
                               double dt,
                               AbsoluteDate target)
                        throws PropagationException

go one step ahead

Parameters:

stepSize - the current stepsize

dt - the dt time

target - target date to propagate

Returns:

finalState the final spacecraft state

Throws:

PropagationException - propagation exception

Since:

1.3

propagationManagement

public SpacecraftState propagationManagement(SpacecraftState state,
                                             double stepSize,
                                             double dt,
                                             AbsoluteDate target)
                                      throws OrekitException

Manages the current step, method to override when user wants to deal with exceptions during the propagation.

Parameters:

state - the current SpacecraftState

stepSize - the current stepsize

dt - the dt time

target - target date to propagate

Returns:

finalState the final spacecraft state

Throws:

OrekitException - Orekit exception

Since:

1.3

acceptStep

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

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

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 a SpacecraftState 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

propagateSpacecraftState

protected abstract SpacecraftState propagateSpacecraftState(AbsoluteDate date)
                                                     throws OrekitException

Extrapolate a spacecraftState up to a specific target date.

Parameters:

date - target date for the orbit

Returns:

extrapolated parameters

Throws:

OrekitException - * if some parameters are out of bounds

getMass

protected abstract double getMass(AbsoluteDate date)
                           throws PropagationException

Get the mass.

Parameters:

date - target date for the orbit

Returns:

mass mass

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

setIntegrator

public void setIntegrator(FirstOrderIntegrator inIntegrator)

Set the integrator.

Parameters:

inIntegrator - integrator to use for propagation.

isStoreTimeDerivatives

public boolean isStoreTimeDerivatives()

Returns flag indicating if time derivatives dE'/dt must be stored.

Returns:

flag indicating if time derivatives dE'/dt must be stored

setStoreTimeDerivatives

public void setStoreTimeDerivatives(boolean isStoreTimeDerivatives)

Setter for flag indicating if time derivatives dE'/dt must be stored.

Parameters:

isStoreTimeDerivatives - flag indicating if time derivatives dE'/dt must be stored

getTimeDerivativesList

public List<TimeDerivativeData> getTimeDerivativesList()

Returns time derivatives list.

Returns:

time derivatives list