org.orekit.propagation.semianalytical.dsst.forces

Class AbstractGaussianContribution

java.lang.Object

org.orekit.propagation.semianalytical.dsst.forces.AbstractGaussianContribution

All Implemented Interfaces:

DSSTForceModel

Direct Known Subclasses:

DSSTAtmosphericDrag, DSSTSolarRadiationPressure

public abstract class AbstractGaussianContribution
extends Object
implements DSSTForceModel

Common handling of DSSTForceModel methods for Gaussian contributions to DSST propagation.

This abstract class allows to provide easily a subset of DSSTForceModel methods for specific Gaussian contributions.

This class implements the notion of numerical averaging of the DSST theory. Numerical averaging is mainly used for non-conservative disturbing forces such as atmospheric drag and solar radiation pressure.

Gaussian contributions can be expressed as: da_i/dt = δa_i/δv . q
where:

• a_i are the six equinoctial elements
• v is the velocity vector
• q is the perturbing acceleration due to the considered force

The averaging process and other considerations lead to integrate this contribution over the true longitude L possibly taking into account some limits.

To create a numerically averaged contribution, one needs only to provide a ForceModel and to implement in the derived class the methods: getLLimits(SpacecraftState, AuxiliaryElements) and getParametersDriversWithoutMu().

Author:

Pascal Parraud, Bryan Cazabonne (field translation)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractGaussianContribution(String coefficientsKeyPrefix, double threshold, ForceModel contribution, double mu) Build a new instance.

Method Summary

Modifier and Type	Method and Description
protected abstract <T extends RealFieldElement<T>> T[]	getLLimits(FieldSpacecraftState<T> state, FieldAuxiliaryElements<T> auxiliaryElements) Compute the limits in L, the true longitude, for integration.
protected abstract double[]	getLLimits(SpacecraftState state, AuxiliaryElements auxiliaryElements) Compute the limits in L, the true longitude, for integration.
<T extends RealFieldElement<T>> T[]	getMeanElementRate(FieldSpacecraftState<T> state, FieldAuxiliaryElements<T> auxiliaryElements, T[] parameters) Computes the mean equinoctial elements rates dai / dt.
double[]	getMeanElementRate(SpacecraftState state, AuxiliaryElements auxiliaryElements, double[] parameters) Computes the mean equinoctial elements rates dai / dt.
ParameterDriver[]	getParametersDrivers() Get the drivers for force model parameters.
protected abstract ParameterDriver[]	getParametersDriversWithoutMu() Get the drivers for force model parameters except the one for the central attraction coefficient.
List<ShortPeriodTerms>	initialize(AuxiliaryElements auxiliaryElements, PropagationType type, double[] parameters) Performs initialization prior to propagation for the current force model.
<T extends RealFieldElement<T>> List<FieldShortPeriodTerms<T>>	initialize(FieldAuxiliaryElements<T> auxiliaryElements, PropagationType type, T[] parameters) Performs initialization prior to propagation for the current force model.
void	registerAttitudeProvider(AttitudeProvider provider) Register an attitude provider.
void	updateShortPeriodTerms(double[] parameters, SpacecraftState... meanStates) Update the short period terms.
<T extends RealFieldElement<T>> void	updateShortPeriodTerms(T[] parameters, FieldSpacecraftState<T>... meanStates) Update the short period terms.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.propagation.semianalytical.dsst.forces.DSSTForceModel

getEventsDetectors, getFieldEventsDetectors, getParameters, getParameters

Constructor Detail

AbstractGaussianContribution

protected AbstractGaussianContribution(String coefficientsKeyPrefix,
                                       double threshold,
                                       ForceModel contribution,
                                       double mu)

Build a new instance.

Parameters:

coefficientsKeyPrefix - prefix for coefficients keys

threshold - tolerance for the choice of the Gauss quadrature order

contribution - the ForceModel to be numerically averaged

mu - central attraction coefficient

Method Detail

getParametersDrivers

public ParameterDriver[] getParametersDrivers()

Get the drivers for force model parameters.

Specified by:

getParametersDrivers in interface DSSTForceModel

Returns:

drivers for force model parameters

getParametersDriversWithoutMu

protected abstract ParameterDriver[] getParametersDriversWithoutMu()

Get the drivers for force model parameters except the one for the central attraction coefficient.

The driver for central attraction coefficient is automatically added at the last element of the ParameterDriver array into getParametersDrivers() method.

Returns:

drivers for force model parameters

initialize

public List<ShortPeriodTerms> initialize(AuxiliaryElements auxiliaryElements,
                                         PropagationType type,
                                         double[] parameters)

Performs initialization prior to propagation for the current force model.

This method aims at being called at the very beginning of a propagation.

Specified by:

initialize in interface DSSTForceModel

Parameters:

auxiliaryElements - auxiliary elements related to the current orbit

type - type of the elements used during the propagation

parameters - values of the force model parameters

Returns:

a list of objects that will hold short period terms (the objects are also retained by the force model, which will update them during propagation)

initialize

public <T extends RealFieldElement<T>> List<FieldShortPeriodTerms<T>> initialize(FieldAuxiliaryElements<T> auxiliaryElements,
                                                                                 PropagationType type,
                                                                                 T[] parameters)

Performs initialization prior to propagation for the current force model.

This method aims at being called at the very beginning of a propagation.

Specified by:

initialize in interface DSSTForceModel

Type Parameters:

T - type of the elements

Parameters:

auxiliaryElements - auxiliary elements related to the current orbit

type - type of the elements used during the propagation

parameters - values of the force model parameters

Returns:

a list of objects that will hold short period terms (the objects are also retained by the force model, which will update them during propagation)

getMeanElementRate

public double[] getMeanElementRate(SpacecraftState state,
                                   AuxiliaryElements auxiliaryElements,
                                   double[] parameters)

Computes the mean equinoctial elements rates da_i / dt.

Specified by:

getMeanElementRate in interface DSSTForceModel

Parameters:

state - current state information: date, kinematics, attitude

auxiliaryElements - auxiliary elements related to the current orbit

parameters - values of the force model parameters

Returns:

the mean element rates dai/dt

getMeanElementRate

public <T extends RealFieldElement<T>> T[] getMeanElementRate(FieldSpacecraftState<T> state,
                                                              FieldAuxiliaryElements<T> auxiliaryElements,
                                                              T[] parameters)

Computes the mean equinoctial elements rates da_i / dt.

Specified by:

getMeanElementRate in interface DSSTForceModel

Type Parameters:

T - type of the elements

Parameters:

state - current state information: date, kinematics, attitude

auxiliaryElements - auxiliary elements related to the current orbit

parameters - values of the force model parameters

Returns:

the mean element rates dai/dt

getLLimits

protected abstract double[] getLLimits(SpacecraftState state,
                                       AuxiliaryElements auxiliaryElements)

Compute the limits in L, the true longitude, for integration.

Parameters:

state - current state information: date, kinematics, attitude

auxiliaryElements - auxiliary elements related to the current orbit

Returns:

the integration limits in L

getLLimits

protected abstract <T extends RealFieldElement<T>> T[] getLLimits(FieldSpacecraftState<T> state,
                                                                  FieldAuxiliaryElements<T> auxiliaryElements)

Compute the limits in L, the true longitude, for integration.

Type Parameters:

T - type of the elements

Parameters:

state - current state information: date, kinematics, attitude

auxiliaryElements - auxiliary elements related to the current orbit

Returns:

the integration limits in L

registerAttitudeProvider

public void registerAttitudeProvider(AttitudeProvider provider)

Register an attitude provider.

Register an attitude provider that can be used by the force model.

Specified by:

registerAttitudeProvider in interface DSSTForceModel

Parameters:

provider - the AttitudeProvider

updateShortPeriodTerms

public void updateShortPeriodTerms(double[] parameters,
                                   SpacecraftState... meanStates)

Update the short period terms.

The short period terms that will be updated are the ones that were returned during the call to DSSTForceModel.initialize(AuxiliaryElements, PropagationType, double[]).

Specified by:

updateShortPeriodTerms in interface DSSTForceModel

Parameters:

parameters - values of the force model parameters

meanStates - mean states information: date, kinematics, attitude

updateShortPeriodTerms

public <T extends RealFieldElement<T>> void updateShortPeriodTerms(T[] parameters,
                                                                   FieldSpacecraftState<T>... meanStates)

Update the short period terms.

The short period terms that will be updated are the ones that were returned during the call to DSSTForceModel.initialize(AuxiliaryElements, PropagationType, double[]).

Specified by:

updateShortPeriodTerms in interface DSSTForceModel

Type Parameters:

T - type of the elements

Parameters:

parameters - values of the force model parameters

meanStates - mean states information: date, kinematics, attitude