org.orekit.forces.gravity
Class GravityToolbox

java.lang.Object
  org.orekit.forces.gravity.GravityToolbox

public final class GravityToolbox
extends Object

Toolbox for tides.

Since:

1.2

Version:

$Id: GravityToolbox.java 13619 2015-06-24 11:16:12Z trapier $

Author:

Julie Anton, Gerald Mercadier, Rami Houdroge

Concurrency :

immutable

Method Summary

static Vector3D	computeBalminoAcceleration(PVCoordinates pv, double[][] coefficientsC, double[][] coefficientsS, double muc, double eqRadius, int degree, int order, HelmholtzPolynomial helm) Method to compute the acceleration, from Balmino algorithm (see BalminoAttractionModel).
static Vector3D	computeCunninghamAcceleration(PVCoordinates pv, double equatorialRadius, double[][] coefC, double[][] coefS, int degree, int order, double mu) Method to compute the acceleration.
static double[][]	computeDAccDPos(PVCoordinates pv, AbsoluteDate date, double equatorialRadius, double mu, double[][] C, double[][] S) Compute the partial derivatives of the acceleration (Cunningham algorithm) with respect to the position.
static Vector3D	computeDrozinerAcceleration(PVCoordinates pv, Frame frame, double[][] coefficientsC, double[][] coefficientsS, double muc, double eqRadius, double threshold, int degree, int order) Method to compute the acceleration, from Droziner algorithm (see DrozinerAttractionModel).
static double[][]	deNormalize(double[][] tab) Denormalize an array of coefficients.
static double[][]	normalize(double[][] tab) Normalize an array of coefficients.
static double[][]	unNormalize(double[][] normalized) Unnormalize a coefficients array.

Methods inherited from class java.lang.Object

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

Method Detail

computeBalminoAcceleration

public static Vector3D computeBalminoAcceleration(PVCoordinates pv,
                                                  double[][] coefficientsC,
                                                  double[][] coefficientsS,
                                                  double muc,
                                                  double eqRadius,
                                                  int degree,
                                                  int order,
                                                  HelmholtzPolynomial helm)

Method to compute the acceleration, from Balmino algorithm (see BalminoAttractionModel).

Parameters:

pv - PV coordinates of the spacecraft in body frame

coefficientsC - array of "C" coeffs

coefficientsS - array of "S" coeffs

muc - Central body attraction coefficient

eqRadius - Reference equatorial radius of the potential

degree - Number of zonal coefficients

order - Number of tesseral coefficients

helm - Helmholtz polynomial

Returns:

acceleration vector

computeDrozinerAcceleration

public static Vector3D computeDrozinerAcceleration(PVCoordinates pv,
                                                   Frame frame,
                                                   double[][] coefficientsC,
                                                   double[][] coefficientsS,
                                                   double muc,
                                                   double eqRadius,
                                                   double threshold,
                                                   int degree,
                                                   int order)
                                            throws OrekitException

Method to compute the acceleration, from Droziner algorithm (see DrozinerAttractionModel).

Parameters:

pv - PV coordinates of the spacecraft

frame - frame in which the acceleration is computed

coefficientsC - array of "C" coeffs

coefficientsS - array of "S" coeffs

muc - Central body attraction coefficient

eqRadius - Reference equatorial radius of the potential

threshold - threshold

degree - Number of zonal coefficients

order - Number of tesseral coefficients

Returns:

acceleration vector

Throws:

OrekitException - if an Orekit error occurs

computeCunninghamAcceleration

public static Vector3D computeCunninghamAcceleration(PVCoordinates pv,
                                                     double equatorialRadius,
                                                     double[][] coefC,
                                                     double[][] coefS,
                                                     int degree,
                                                     int order,
                                                     double mu)

Method to compute the acceleration. This method has been implemented in order to validate the force model only. The reason is that for the validation context, we do not want to set up an instance of the SpacecraftState object to avoid the inertial frame of the spacecraft orbit.

Method taken from CunninghamAttractionModel

Parameters:

pv - PV coordinates of the spacecraft in the rotating frame of the central body

equatorialRadius - equatorial radius of earth

coefC - C coefficients array

coefS - S coefficients array

degree - degree

order - order

mu - gravitation constant

Returns:

acceleration vector

See Also:

CunninghamAttractionModel

deNormalize

public static double[][] deNormalize(double[][] tab)

Denormalize an array of coefficients.

Parameters:

tab - normalized coefficients array

Returns:

unnormalized coefficients array

Additional comments :

works up to degree + order = 179

normalize

public static double[][] normalize(double[][] tab)

Normalize an array of coefficients.

Parameters:

tab - normalized coefficients array

Returns:

unnormalized coefficients array

Additional comments :

works up to degree + order = 179

unNormalize

public static double[][] unNormalize(double[][] normalized)

Unnormalize a coefficients array.

Parameters:

normalized - normalized coefficients array

Returns:

unnormalized array

computeDAccDPos

public static double[][] computeDAccDPos(PVCoordinates pv,
                                         AbsoluteDate date,
                                         double equatorialRadius,
                                         double mu,
                                         double[][] C,
                                         double[][] S)

Compute the partial derivatives of the acceleration (Cunningham algorithm) with respect to the position.

Parameters:

pv - : position and velocity of the spacecraft

date - : date

equatorialRadius - equatorial radius

mu - gravitational parameter

C - C coefficients

S - S coefficients

Returns:

array of the partial derivatives See the following article : "On the computation of spherical harmonic terms needed during the numerical integration of the orbital motion of an artifical satellite" , Leland E. Cunningham