org.orekit.forces.gravity
Class BalminoAttractionModel

java.lang.Object
  org.orekit.parameter.Parameterizable
      org.orekit.parameter.JacobiansParameterizable
          org.orekit.forces.gravity.BalminoAttractionModel

All Implemented Interfaces:

Serializable, ForceModel, GradientModel, AttractionModel, IJacobiansParameterizable, IParameterizable

public class BalminoAttractionModel
extends JacobiansParameterizable
implements ForceModel, GradientModel, AttractionModel

Computation of central body attraction with normalized coefficients and Helmholtz Polynomials.

The algorithm implemented in this class has been designed by Balmino Georges (Observatoire Midi-Pyrénées/ Groupe de Recherche de Géodésie Spatiale (GRGS) / Centre National d’Etudes Spatiales (CNES), France) in his 1990 paper: Non-singular formulation of the gravity vector and gravity gradient tensor in spherical harmonics. (Manuscr. Geod., Vol. 15, No. 1, p. 11 - 16, 02/1990). It uses normalized C and S coefficients for greater accuracy.

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.

Since:

2.1

Version:

$Id: BalminoAttractionModel.java 15711 2016-04-01 08:51:41Z bignon $

Author:

Rami Houdroge

See Also:

Serialized Form

Concurrency :

not thread-safe, uses internal mutable attributes

Field Summary

static String

RADIUS Parameter name for equatorial radius.

Fields inherited from interface org.orekit.forces.gravity.AttractionModel

MU

Constructor Summary

BalminoAttractionModel(Frame frame, double ae, double mu, double[][] Ccoefs, double[][] Scoefs)
Create an instance of a normalized gravity computation model using normalized coefficients.

BalminoAttractionModel(Frame frame, double ae, double mu, double[][] Ccoefs, double[][] Scoefs, int degreePD, int orderPD)
Create an instance of a normalized gravity computation model using normalized coefficients.

BalminoAttractionModel(Frame frame, Parameter ae, Parameter mu, double[][] Ccoefs, double[][] Scoefs)
Create an instance of a normalized gravity computation model using normalized coefficients.

BalminoAttractionModel(Frame frame, Parameter ae, Parameter mu, double[][] Ccoefs, double[][] Scoefs, int degreePD, int orderPD)
Create an instance of a normalized gravity computation model using normalized coefficients.

Method Summary

void	addContribution(SpacecraftState s, TimeDerivativesEquations adder) Compute the contribution of the force model to the perturbing acceleration.
void	addDAccDParam(SpacecraftState s, Parameter param, double[] dAccdParam) Compute acceleration derivatives with respect to additional parameters.
void	addDAccDState(SpacecraftState s, double[][] dAccdPos, double[][] dAccdVel) Compute acceleration derivatives with respect to state parameters.
Vector3D	computeAcceleration(PVCoordinates pv) Acceleration in body frame.
Vector3D	computeAcceleration(SpacecraftState s) Compute the acceleration due to the force.
boolean	computeGradientPosition() This method returns true if the acceleration partial derivatives with respect to position have to be computed.
boolean	computeGradientVelocity() This method returns true if the acceleration partial derivatives with respect to velocity have to be computed.
EventDetector[]	getEventsDetectors() Get the discrete events related to the model.
double	getMu() Get the central attraction coefficient &mu.

Methods inherited from class org.orekit.parameter.JacobiansParameterizable

addJacobiansParameter, addJacobiansParameter, addJacobiansParameter, supportsJacobianParameter

Methods inherited from class org.orekit.parameter.Parameterizable

addParameter, getParameters, supportsParameter

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.parameter.IParameterizable

getParameters, supportsParameter

Field Detail

RADIUS

public static final String RADIUS

Parameter name for equatorial radius.

See Also:

Constant Field Values

Constructor Detail

BalminoAttractionModel

public BalminoAttractionModel(Frame frame,
                              double ae,
                              double mu,
                              double[][] Ccoefs,
                              double[][] Scoefs)

Create an instance of a normalized gravity computation model using normalized coefficients.

Parameters:

frame - central body frame

ae - equatorial radius constant

mu - standard gravitational constant

Ccoefs - Normalized c coefficients

Scoefs - Normalized s coefficients

BalminoAttractionModel

public BalminoAttractionModel(Frame frame,
                              double ae,
                              double mu,
                              double[][] Ccoefs,
                              double[][] Scoefs,
                              int degreePD,
                              int orderPD)

Create an instance of a normalized gravity computation model using normalized coefficients.

Parameters:

frame - central body frame

ae - equatorial radius constant

mu - standard gravitational constant

Ccoefs - Normalized c coefficients for acceleration computation

Scoefs - Normalized s coefficients for acceleration computation

degreePD - degree for partial derivatives

orderPD - order for partial derivatives

BalminoAttractionModel

public BalminoAttractionModel(Frame frame,
                              Parameter ae,
                              Parameter mu,
                              double[][] Ccoefs,
                              double[][] Scoefs)

Create an instance of a normalized gravity computation model using normalized coefficients.

Parameters:

frame - central body frame

ae - parameter storing equatorial radius

mu - parameter storing standard gravitational

Ccoefs - Normalized c coefficients

Scoefs - Normalized s coefficients

BalminoAttractionModel

public BalminoAttractionModel(Frame frame,
                              Parameter ae,
                              Parameter mu,
                              double[][] Ccoefs,
                              double[][] Scoefs,
                              int degreePD,
                              int orderPD)

Create an instance of a normalized gravity computation model using normalized coefficients.

Parameters:

frame - central body frame

ae - parameter storing equatorial radius

mu - parameter storing standard gravitational

Ccoefs - Normalized c coefficients for acceleration computation

Scoefs - Normalized s coefficients for acceleration computation

degreePD - degree for partial derivatives

orderPD - order for partial derivatives

Method Detail

addContribution

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

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

Specified by:

addContribution in interface ForceModel

Parameters:

s - current state information: date, kinematics, attitude

adder - object where the contribution should be added

Throws:

OrekitException - if some specific error occurs

computeAcceleration

public Vector3D computeAcceleration(SpacecraftState s)
                             throws OrekitException

Compute the acceleration due to the force..

Specified by:

computeAcceleration in interface ForceModel

Parameters:

s - current state information: date, kinematics, attitude

Returns:

acceleration in the SpacecraftState frame

Throws:

OrekitException - if some specific error occurs

computeAcceleration

public final Vector3D computeAcceleration(PVCoordinates pv)

Acceleration in body frame.

Parameters:

pv - the PVCoordinates of the spacecraft in the body frame

Returns:

the computed acceleration

getEventsDetectors

public EventDetector[] getEventsDetectors()

Get the discrete events related to the model..

Specified by:

getEventsDetectors in interface ForceModel

Returns:

array of events detectors or null if the model is not related to any discrete events

computeGradientPosition

public boolean computeGradientPosition()

This method returns true if the acceleration partial derivatives with respect to position have to be computed..

Specified by:

computeGradientPosition in interface GradientModel

Returns:

true if the derivatives have to be computed, false otherwise

computeGradientVelocity

public boolean computeGradientVelocity()

This method returns true if the acceleration partial derivatives with respect to velocity have to be computed..

Specified by:

computeGradientVelocity in interface GradientModel

Returns:

true if the derivatives have to be computed, false otherwise

addDAccDState

public final void addDAccDState(SpacecraftState s,
                                double[][] dAccdPos,
                                double[][] dAccdVel)
                         throws OrekitException

Compute acceleration derivatives with respect to state parameters..

Specified by:

addDAccDState in interface IJacobiansParameterizable

Parameters:

s - spacecraft state

dAccdPos - acceleration derivatives with respect to position

dAccdVel - acceleration derivatives with respect to velocity

Throws:

OrekitException - if derivatives cannot be computed

addDAccDParam

public void addDAccDParam(SpacecraftState s,
                          Parameter param,
                          double[] dAccdParam)
                   throws OrekitException

Compute acceleration derivatives with respect to additional parameters.. No parameter is supported by this force model.

Specified by:

addDAccDParam in interface IJacobiansParameterizable

Parameters:

s - spacecraft state

param - the parameter with respect to which derivatives are required

dAccdParam - acceleration derivatives with respect to specified parameters

Throws:

OrekitException - if derivatives cannot be computed

getMu

public double getMu()

Get the central attraction coefficient &mu..

Specified by:

getMu in interface AttractionModel

Returns:

mu central attraction coefficient (m³/s²)