Package org.orekit.propagation.semianalytical.dsst.forces

Class DSSTZonal

java.lang.Object

org.orekit.propagation.semianalytical.dsst.forces.DSSTZonal

All Implemented Interfaces:

EventDetectorsProvider, DSSTForceModel, ParameterDriversProvider

public class DSSTZonal
extends Object
implements DSSTForceModel

Zonal contribution to the central body gravitational perturbation.

Author:

Romain Di Costanzo, Pascal Parraud, Bryan Cazabonne (field translation)

Field Summary

Fields

Modifier and Type	Field	Description
static final String	SHORT_PERIOD_PREFIX	Name of the prefix for short period coefficients keys.

Fields inherited from interface org.orekit.propagation.events.EventDetectorsProvider

DATATION_ACCURACY

Constructor Summary

Constructors

Constructor	Description
DSSTZonal(UnnormalizedSphericalHarmonicsProvider provider)	Constructor with bodyFixedFrame = orbit frame, and default reference values.
DSSTZonal(UnnormalizedSphericalHarmonicsProvider provider, int maxDegreeShortPeriodics, int maxEccPowShortPeriodics, int maxFrequencyShortPeriodics)	Constructor with bodyFixedFrame = orbit frame.
DSSTZonal(Frame bodyFixedFrame, UnnormalizedSphericalHarmonicsProvider provider)	Constructor with default reference values.
DSSTZonal(Frame bodyFixedFrame, UnnormalizedSphericalHarmonicsProvider provider, int maxDegreeShortPeriodics, int maxEccPowShortPeriodics, int maxFrequencyShortPeriodics)	Constructor.

Method Summary

Modifier and Type	Method	Description
<T extends CalculusFieldElement<T>> T[]	getMeanElementRate(FieldSpacecraftState<T> spacecraftState, FieldAuxiliaryElements<T> auxiliaryElements, T[] parameters)	Computes the mean equinoctial elements rates dai / dt.
double[]	getMeanElementRate(SpacecraftState spacecraftState, AuxiliaryElements auxiliaryElements, double[] parameters)	Computes the mean equinoctial elements rates dai / dt.
List<ParameterDriver>	getParametersDrivers()	Get the drivers for parameters.
UnnormalizedSphericalHarmonicsProvider	getProvider()	Get the spherical harmonics provider.
List<ShortPeriodTerms>	initializeShortPeriodTerms(AuxiliaryElements auxiliaryElements, PropagationType type, double[] parameters)	Performs initialization prior to propagation for the current force model.
<T extends CalculusFieldElement<T>> List<FieldShortPeriodTerms<T>>	initializeShortPeriodTerms(FieldAuxiliaryElements<T> auxiliaryElements, PropagationType type, T[] parameters)	Performs initialization prior to propagation for the current force model.
void	registerAttitudeProvider(AttitudeProvider attitudeProvider)	Register an attitude provider.
void	updateShortPeriodTerms(double[] parameters, SpacecraftState... meanStates)	Update the short period terms.
<T extends CalculusFieldElement<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

extractParameters, extractParameters, getEventDetectors, getFieldEventDetectors, init, init

Methods inherited from interface org.orekit.propagation.events.EventDetectorsProvider

getDateDetector, getEventDetectors, getFieldDateDetector, getFieldEventDetectors

Methods inherited from interface org.orekit.utils.ParameterDriversProvider

getNbParametersDriversValue, getParameterDriver, getParameters, getParameters, getParameters, getParameters, getParametersAllValues, getParametersAllValues, isSupported

Field Details

SHORT_PERIOD_PREFIX

public static final String SHORT_PERIOD_PREFIX

Name of the prefix for short period coefficients keys.

See Also:

• Constant Field Values

Constructor Details

DSSTZonal

public DSSTZonal(Frame bodyFixedFrame,
 UnnormalizedSphericalHarmonicsProvider provider)

Constructor with default reference values.

When this constructor is used, maximum allowed values are used for the short periodic coefficients:

• maxDegreeShortPeriodics is set to provider.getMaxDegree()
• maxEccPowShortPeriodics is set to min(provider.getMaxDegree() - 1, 4). This parameter should not exceed 4 as higher values will exceed computer capacity
• maxFrequencyShortPeriodics is set to 2 * provider.getMaxDegree() + 1

Parameters:

bodyFixedFrame - rotating body frame

If set, this frame will be used to compute the Earth pole direction and the zonal contribution. If not, the inertial frame from the propagator will be used.
Ideally this frame should be always set to ITRF. However, using TOD is advised since it's generally a good trade-off between performance and precision.

provider - provider for spherical harmonics

Since:

12.1

DSSTZonal

public DSSTZonal(UnnormalizedSphericalHarmonicsProvider provider)

Constructor with bodyFixedFrame = orbit frame, and default reference values.

Kept for compatibility with anterior versions.

Setting bodyFixedFrame to null will lead to large errors if the orbit frame is far from Earth rotating frame (GCRF, EME2000...). The error gets smaller as the orbit frame gets closer to Earth rotating frame (MOD, then TOD).

Parameters:

provider - provider for spherical harmonics

Since:

10.1

See Also:

• issue-1104 on the forge

  When this constructor is used, maximum allowed values are used for the short periodic coefficients:

  • maxDegreeShortPeriodics is set to provider.getMaxDegree()
  • maxEccPowShortPeriodics is set to min(provider.getMaxDegree() - 1, 4). This parameter should not exceed 4 as higher values will exceed computer capacity
  • maxFrequencyShortPeriodics is set to 2 * provider.getMaxDegree() + 1
• issue-1104 on the forge

DSSTZonal

public DSSTZonal(Frame bodyFixedFrame,
 UnnormalizedSphericalHarmonicsProvider provider,
 int maxDegreeShortPeriodics,
 int maxEccPowShortPeriodics,
 int maxFrequencyShortPeriodics)

Constructor.

Parameters:

bodyFixedFrame - rotating body frame

If set, this frame will be used to compute the Earth pole direction and the zonal contribution. If not, the inertial frame from the propagator will be used.
Ideally this frame should be always set to ITRF. However, using TOD is advised since it's a good trade-off between performance and precision.

provider - provider for spherical harmonics

maxDegreeShortPeriodics - maximum degree to consider for short periodics zonal harmonics potential (must be between 2 and provider.getMaxDegree())

maxEccPowShortPeriodics - maximum power of the eccentricity to be used in short periodic computations (must be between 0 and maxDegreeShortPeriodics - 1, but should typically not exceed 4 as higher values will exceed computer capacity)

maxFrequencyShortPeriodics - maximum frequency in true longitude for short periodic computations (must be between 1 and 2 * maxDegreeShortPeriodics + 1)

Since:

12.1

DSSTZonal

public DSSTZonal(UnnormalizedSphericalHarmonicsProvider provider,
 int maxDegreeShortPeriodics,
 int maxEccPowShortPeriodics,
 int maxFrequencyShortPeriodics)

Constructor with bodyFixedFrame = orbit frame.

Added for retro-compatibility with anterior versions for initialization.

Setting bodyFixedFrame to null will lead to large errors if the orbit frame is far from Earth rotating frame (GCRF, EME2000...). The error gets smaller as the orbit frame gets closer to Earth rotating frame (MOD, then TOD).

Parameters:

provider - provider for spherical harmonics

maxDegreeShortPeriodics - maximum degree to consider for short periodics zonal harmonics potential (must be between 2 and provider.getMaxDegree())

maxEccPowShortPeriodics - maximum power of the eccentricity to be used in short periodic computations (must be between 0 and maxDegreeShortPeriodics - 1, but should typically not exceed 4 as higher values will exceed computer capacity)

maxFrequencyShortPeriodics - maximum frequency in true longitude for short periodic computations (must be between 1 and 2 * maxDegreeShortPeriodics + 1)

Since:

7.2

See Also:

• issue-1104 on the forge
• issue-1104 on the forge

Method Details

getProvider

public UnnormalizedSphericalHarmonicsProvider getProvider()

Get the spherical harmonics provider.

Returns:

the spherical harmonics provider

initializeShortPeriodTerms

public List<ShortPeriodTerms> initializeShortPeriodTerms(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.

Computes the highest power of the eccentricity to appear in the truncated analytical power series expansion.

This method computes the upper value for the central body potential and determines the maximal power for the eccentricity producing potential terms bigger than a defined tolerance.

Specified by:

initializeShortPeriodTerms 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 for specific date (1 value only per parameter driver) obtained for example by calling ParameterDriversProvider.getParameters(AbsoluteDate) on force model.

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)

initializeShortPeriodTerms

public <T extends CalculusFieldElement<T>>
List<FieldShortPeriodTerms<T>> initializeShortPeriodTerms(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.

Computes the highest power of the eccentricity to appear in the truncated analytical power series expansion.

This method computes the upper value for the central body potential and determines the maximal power for the eccentricity producing potential terms bigger than a defined tolerance.

Specified by:

initializeShortPeriodTerms 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 for specific date (1 value only per parameter driver) obtained for example by calling ParameterDriversProvider.getParameters(AbsoluteDate) on force model or AbstractGradientConverter.getParametersAtStateDate(FieldSpacecraftState, ParameterDriversProvider) on gradient converter.

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 spacecraftState,
 AuxiliaryElements auxiliaryElements,
 double[] parameters)

Computes the mean equinoctial elements rates da_i / dt.

Specified by:

getMeanElementRate in interface DSSTForceModel

Parameters:

spacecraftState - current state information: date, kinematics, attitude

auxiliaryElements - auxiliary elements related to the current orbit

parameters - values of the force model parameters at state date (only 1 span for each parameter driver) obtained for example by calling ParameterDriversProvider.getParameters(AbsoluteDate) on force model.

Returns:

the mean element rates dai/dt

getMeanElementRate

public <T extends CalculusFieldElement<T>> T[] getMeanElementRate(FieldSpacecraftState<T> spacecraftState,
 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:

spacecraftState - current state information: date, kinematics, attitude

auxiliaryElements - auxiliary elements related to the current orbit

parameters - values of the force model parameters at state date (only 1 span for each parameter driver) obtained for example by calling ParameterDriversProvider.getParameters(Field, FieldAbsoluteDate) on force model or AbstractGradientConverter.getParametersAtStateDate(FieldSpacecraftState, ParameterDriversProvider) on gradient converter.

Returns:

the mean element rates dai/dt

registerAttitudeProvider

public void registerAttitudeProvider(AttitudeProvider attitudeProvider)

Register an attitude provider.

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

Specified by:

registerAttitudeProvider in interface DSSTForceModel

Parameters:

attitudeProvider - 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.initializeShortPeriodTerms(AuxiliaryElements, PropagationType, double[]).

Specified by:

updateShortPeriodTerms in interface DSSTForceModel

Parameters:

parameters - values of the force model parameters (all span values for each parameters) obtained for example by calling ParameterDriversProvider.getParametersAllValues() on force model. The extract parameter method DSSTForceModel.extractParameters(double[], AbsoluteDate) is called in the method to select the right parameter corresponding to the mean state date.

meanStates - mean states information: date, kinematics, attitude

updateShortPeriodTerms

public <T extends CalculusFieldElement<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.initializeShortPeriodTerms(AuxiliaryElements, PropagationType, double[]).

Specified by:

updateShortPeriodTerms in interface DSSTForceModel

Type Parameters:

T - type of the elements

Parameters:

parameters - values of the force model parameters (all span values for each parameters) obtained for example by calling ParameterDriversProvider.getParametersAllValues(Field) on force model or AbstractGradientConverter.getParameters(FieldSpacecraftState, ParameterDriversProvider) on gradient converter. The extract parameter method DSSTForceModel.extractParameters(CalculusFieldElement[], FieldAbsoluteDate) is called in the method to select the right parameter.

meanStates - mean states information: date, kinematics, attitude

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Get the drivers for parameters.

Specified by:

getParametersDrivers in interface ParameterDriversProvider

Returns:

drivers for parameters