fr.cnes.sirius.patrius.forces.gravity

Class CunninghamGravityModel

java.lang.Object

fr.cnes.sirius.patrius.forces.gravity.AbstractGravityModel

fr.cnes.sirius.patrius.forces.gravity.AbstractHarmonicGravityModel

fr.cnes.sirius.patrius.forces.gravity.CunninghamGravityModel

All Implemented Interfaces:

GravityModel, Serializable

public class CunninghamGravityModel
extends AbstractHarmonicGravityModel

This class represents the gravitational field of a celestial body.

The algorithm implemented in this class has been designed by Leland E. Cunningham (Lockheed Missiles and Space Company, Sunnyvale and Astronomy Department University of California, Berkeley) in his 1969 paper: On the computation of the spherical harmonic terms needed during the numerical integration of the orbital motion of an artificial satellite (Celestial Mechanics 2, 1970).

The implementation of this class enables the computation of partial derivatives by finite differences with respect to the central attraction coefficient.

Warning: using a 0x0 Earth potential model is equivalent to a simple Newtonian attraction. However computation times will be much slower since this case is not particularized and hence conversion from body frame (often ITRF) to integration frame is necessary.

Author:

Fabien Maussion, Luc Maisonobe, Véronique Pommier-Maurussane

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	RADIUS Parameter name for equatorial radius.

Fields inherited from class fr.cnes.sirius.patrius.forces.gravity.AbstractGravityModel

bodyFrame, centralTermContribution, MU, paramMu

Constructor Summary

Constructors

Constructor and Description
CunninghamGravityModel(Frame centralBodyFrame, double equatorialRadius, double mu, double[][] cIn, double[][] sIn) Creates a new instance.
CunninghamGravityModel(Frame centralBodyFrame, double equatorialRadius, double mu, double[][] cIn, double[][] sIn, int degreePD, int orderPD) Creates a new instance.
CunninghamGravityModel(Frame centralBodyFrame, Parameter equatorialRadius, Parameter mu, double[][] cIn, double[][] sIn) Creates a new instance using Parameter.
CunninghamGravityModel(Frame centralBodyFrame, Parameter equatorialRadius, Parameter mu, double[][] cIn, double[][] sIn, int degreePD, int orderPD) Creates a new instance using Parameter.
CunninghamGravityModel(Frame centralBodyFrame, Parameter equatorialRadius, Parameter mu, double[][] cIn, double[][] sIn, int degreePD, int orderPD, boolean centralTermContributionIn) Creates a new instance using Parameter.

Method Summary

Modifier and Type	Method and Description
void	checkData(AbsoluteDate start, AbsoluteDate end) This methods throws an exception if the user did not provide all the required data to perform model call on provided range [start; end].
Vector3D	computeNonCentralTermsAcceleration(Vector3D pos, AbsoluteDate date, Transform bodyFrameToPositionFrame) Compute the acceleration due to the non-central terms of the gravitational attraction.
double[][]	computeNonCentralTermsDAccDPos(Vector3D pos, Frame frame, AbsoluteDate date) Compute acceleration derivatives with respect to the state parameters for the non-central terms.
double	getAe() Get the equatorial radius.
double[][]	getC()
double[][]	getS()
void	setAe(double aeIn) Set the equatorial radius.

Methods inherited from class fr.cnes.sirius.patrius.forces.gravity.AbstractHarmonicGravityModel

computeAcceleration, computeCentralTermAcceleration, computeCentralTermDAccDPos, computeDAccDPos, isCentralTermContributionApplied, setCentralTermContribution

Methods inherited from class fr.cnes.sirius.patrius.forces.gravity.AbstractGravityModel

getBodyFrame, getMu, setMu

Methods inherited from class java.lang.Object

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

Field Detail

RADIUS

public static final String RADIUS

Parameter name for equatorial radius.

See Also:

Constant Field Values

Constructor Detail

CunninghamGravityModel

public CunninghamGravityModel(Frame centralBodyFrame,
                              double equatorialRadius,
                              double mu,
                              double[][] cIn,
                              double[][] sIn)

Creates a new instance.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - central body attraction coefficient (m³/s²)

cIn - un-normalized coefficients array (cosine part)

sIn - un-normalized coefficients array (sine part)

Throws:

IllegalArgumentException - if coefficients array do not match

CunninghamGravityModel

public CunninghamGravityModel(Frame centralBodyFrame,
                              double equatorialRadius,
                              double mu,
                              double[][] cIn,
                              double[][] sIn,
                              int degreePD,
                              int orderPD)

Creates a new instance.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - central body attraction coefficient (m³/s²)

cIn - un-normalized coefficients array (cosine part)

sIn - un-normalized coefficients array (sine part)

degreePD - degree for partial derivatives

orderPD - order for partial derivatives

Throws:

IllegalArgumentException - if coefficients array do not match or degree and/or order for partial derivatives is higher than degree and/or order for acceleration

CunninghamGravityModel

public CunninghamGravityModel(Frame centralBodyFrame,
                              Parameter equatorialRadius,
                              Parameter mu,
                              double[][] cIn,
                              double[][] sIn)

Creates a new instance using Parameter.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - parameter representing central body attraction coefficient (m³/s²)

cIn - parameter representing un-normalized coefficients array (cosine part)

sIn - un-normalized coefficients array (sine part)

Throws:

IllegalArgumentException - if coefficients array do not match

CunninghamGravityModel

public CunninghamGravityModel(Frame centralBodyFrame,
                              Parameter equatorialRadius,
                              Parameter mu,
                              double[][] cIn,
                              double[][] sIn,
                              int degreePD,
                              int orderPD)

Creates a new instance using Parameter.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - parameter representing central body attraction coefficient (m³/s²)

cIn - parameter representing un-normalized coefficients array (cosine part)

sIn - un-normalized coefficients array (sine part)

degreePD - degree for partial derivatives

orderPD - order for partial derivatives

Throws:

IllegalArgumentException - if coefficients array do not match or degree and/or order for partial derivatives is higher than degree and/or order for acceleration

CunninghamGravityModel

public CunninghamGravityModel(Frame centralBodyFrame,
                              Parameter equatorialRadius,
                              Parameter mu,
                              double[][] cIn,
                              double[][] sIn,
                              int degreePD,
                              int orderPD,
                              boolean centralTermContributionIn)

Creates a new instance using Parameter.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - parameter representing central body attraction coefficient (m³/s²)

cIn - parameter representing un-normalized coefficients array (cosine part)

sIn - un-normalized coefficients array (sine part)

degreePD - degree for partial derivatives

orderPD - order for partial derivatives

centralTermContributionIn - true if central term contribution should be considered (by default), false if not

Throws:

IllegalArgumentException - if coefficients array do not match or degree and/or order for partial derivatives is higher than degree and/or order for acceleration

Method Detail

computeNonCentralTermsAcceleration

public Vector3D computeNonCentralTermsAcceleration(Vector3D pos,
                                                   AbsoluteDate date,
                                                   Transform bodyFrameToPositionFrame)

Compute the acceleration due to the non-central terms of the gravitational attraction..

Specified by:

computeNonCentralTermsAcceleration in class AbstractHarmonicGravityModel

Parameters:

pos - position of the spacecraft

date - date

bodyFrameToPositionFrame - body frame to frame in which position is provided transformation (used for computation times speed-up)

Returns:

the non-central terms acceleration in the given frame

computeNonCentralTermsDAccDPos

public final double[][] computeNonCentralTermsDAccDPos(Vector3D pos,
                                                       Frame frame,
                                                       AbsoluteDate date)
                                                throws PatriusException

Compute acceleration derivatives with respect to the state parameters for the non-central terms..

Specified by:

computeNonCentralTermsDAccDPos in class AbstractHarmonicGravityModel

Parameters:

pos - position of the spacecraft

frame - frame in which the acceleration derivatives are computed

date - date

Returns:

acceleration derivatives with respect to position

Throws:

PatriusException - if derivatives cannot be computed

checkData

public void checkData(AbsoluteDate start,
                      AbsoluteDate end)
               throws PatriusException

This methods throws an exception if the user did not provide all the required data to perform model call on provided range [start; end]. It is the responsibility of the model implementation to properly throw exceptions.

Parameters:

start - range start date

end - range end date

Throws:

PatriusException - thrown if some data is missing

getAe

public double getAe()

Get the equatorial radius.

Returns:

equatorial radius (m)

setAe

public void setAe(double aeIn)

Set the equatorial radius.

Parameters:

aeIn - the equatorial radius.

getC

public double[][] getC()

Returns:

the normalized C coefficients.

getS

public double[][] getS()

Returns:

the normalized S coefficients.