Package org.orekit.forces

Interface ForceModel

All Known Implementing Classes:

AbstractForceModel, AbstractParametricAcceleration, ConstantThrustManeuver, DragForce, HarmonicParametricAcceleration, HolmesFeatherstoneAttractionModel, NewtonianAttraction, OceanTides, PolynomialParametricAcceleration, Relativity, SolarRadiationPressure, SolidTides, ThirdBodyAttraction

public interface ForceModel

This interface represents a force modifying spacecraft motion.

Objects implementing this interface are intended to be added to a numerical propagator before the propagation is started.

The propagator will call at each step the addContribution(SpacecraftState, TimeDerivativesEquations) method. The force model instance will extract all the state data it needs (date, position, velocity, frame, attitude, mass) from the first parameter. From these state data, it will compute the perturbing acceleration. It will then add this acceleration to the second parameter which will take thins contribution into account and will use the Gauss equations to evaluate its impact on the global state derivative.

Force models which create discontinuous acceleration patterns (typically for maneuvers start/stop or solar eclipses entry/exit) must provide one or more events detectors to the propagator thanks to their getEventsDetectors() method. This method is called once just before propagation starts. The events states will be checked by the propagator to ensure accurate propagation and proper events handling.

Author:

Mathieu Roméro, Luc Maisonobe, Véronique Pommier-Maurussane

Method Summary

Modifier and Type	Method	Description
<T extends RealFieldElement<T>> FieldVector3D<T>	acceleration(FieldSpacecraftState<T> s, T[] parameters)	Compute acceleration.
Vector3D	acceleration(SpacecraftState s, double[] parameters)	Compute acceleration.
default <T extends RealFieldElement<T>> void	addContribution(FieldSpacecraftState<T> s, FieldTimeDerivativesEquations<T> adder)	Compute the contribution of the force model to the perturbing acceleration.
default void	addContribution(SpacecraftState s, TimeDerivativesEquations adder)	Compute the contribution of the force model to the perturbing acceleration.
boolean	dependsOnPositionOnly()	Check if force models depends on position only.
Stream<EventDetector>	getEventsDetectors()	Get the discrete events related to the model.
<T extends RealFieldElement<T>> Stream<FieldEventDetector<T>>	getFieldEventsDetectors(Field<T> field)	Get the discrete events related to the model.
ParameterDriver	getParameterDriver(String name)	Get parameter value from its name.
default double[]	getParameters()	Get force model parameters.
default <T extends RealFieldElement<T>> T[]	getParameters(Field<T> field)	Get force model parameters.
ParameterDriver[]	getParametersDrivers()	Get the drivers for force model parameters.
default void	init(SpacecraftState initialState, AbsoluteDate target)	Initialize the force model at the start of propagation.
boolean	isSupported(String name)	Check if a parameter is supported.

Method Detail

init

default void init(SpacecraftState initialState,
                  AbsoluteDate target)
           throws OrekitException

Initialize the force model at the start of propagation. This method will be called before any calls to addContribution(SpacecraftState, TimeDerivativesEquations), addContribution(FieldSpacecraftState, FieldTimeDerivativesEquations), acceleration(SpacecraftState, double[]) or acceleration(FieldSpacecraftState, RealFieldElement[])

The default implementation of this method does nothing.

Parameters:

initialState - spacecraft state at the start of propagation.

target - date of propagation. Not equal to initialState.getDate().

Throws:

OrekitException - if an implementing class overrides the default behavior and takes some action that throws an OrekitException.

addContribution

default void addContribution(SpacecraftState s,
                             TimeDerivativesEquations adder)
                      throws OrekitException

Compute the contribution of the force model to the perturbing acceleration.

The default implementation simply adds the acceleration as a non-Keplerian acceleration.

Parameters:

s - current state information: date, kinematics, attitude

adder - object where the contribution should be added

Throws:

OrekitException - if some specific error occurs

addContribution

default <T extends RealFieldElement<T>> void addContribution(FieldSpacecraftState<T> s,
                                                             FieldTimeDerivativesEquations<T> adder)
                                                      throws OrekitException

Compute the contribution of the force model to the perturbing acceleration.

Type Parameters:

T - type of the elements

Parameters:

s - current state information: date, kinematics, attitude

adder - object where the contribution should be added

Throws:

OrekitException - if some specific error occurs

getParameters

default double[] getParameters()

Get force model parameters.

Returns:

force model parameters

Since:

9.0

getParameters

default <T extends RealFieldElement<T>> T[] getParameters(Field<T> field)

Get force model parameters.

Type Parameters:

T - type of the elements

Parameters:

field - field to which the elements belong

Returns:

force model parameters

Since:

9.0

dependsOnPositionOnly

boolean dependsOnPositionOnly()

Check if force models depends on position only.

Returns:

true if force model depends on position only, false if it depends on velocity, either directly or due to a dependency on attitude

Since:

9.0

acceleration

Vector3D acceleration(SpacecraftState s,
                      double[] parameters)
               throws OrekitException

Compute acceleration.

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters

Returns:

acceleration in same frame as state

Throws:

OrekitException - if some specific error occurs

Since:

9.0

acceleration

<T extends RealFieldElement<T>> FieldVector3D<T> acceleration(FieldSpacecraftState<T> s,
                                                              T[] parameters)
                                                       throws OrekitException

Compute acceleration.

Type Parameters:

T - type of the elements

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters

Returns:

acceleration in same frame as state

Throws:

OrekitException - if some specific error occurs

Since:

9.0

getEventsDetectors

Stream<EventDetector> getEventsDetectors()

Get the discrete events related to the model.

Returns:

stream of events detectors

getFieldEventsDetectors

<T extends RealFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventsDetectors(Field<T> field)

Get the discrete events related to the model.

Type Parameters:

T - extends RealFieldElement

Parameters:

field - field to which the state belongs

Returns:

stream of events detectors

getParametersDrivers

ParameterDriver[] getParametersDrivers()

Get the drivers for force model parameters.

Returns:

drivers for force model parameters

Since:

8.0

getParameterDriver

ParameterDriver getParameterDriver(String name)
                            throws OrekitException

Get parameter value from its name.

Parameters:

name - parameter name

Returns:

parameter value

Throws:

OrekitException - if parameter is not supported

Since:

8.0

isSupported

boolean isSupported(String name)

Check if a parameter is supported.

Supported parameters are those listed by getParametersDrivers().

Parameters:

name - parameter name to check

Returns:

true if the parameter is supported

See Also:

getParametersDrivers()