org.orekit.forces.gravity
Class DrozinerAttractionModel

java.lang.Object
  org.orekit.parameter.Parameterizable
      org.orekit.forces.gravity.DrozinerAttractionModel

All Implemented Interfaces:

Serializable, ForceModel, GradientModel, AttractionModel, IParameterizable

public class DrozinerAttractionModel
extends Parameterizable
implements ForceModel, GradientModel, AttractionModel

This class represents the gravitational field of a celestial body.

The algorithm implemented in this class has been designed by Andrzej Droziner (Institute of Mathematical Machines, Warsaw) in his 1976 paper: An algorithm for recurrent calculation of gravitational acceleration (artificial satellites, Vol. 12, No 2, June 1977).

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

static String

RADIUS Parameter name for equatorial radius.

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

MU

Constructor Summary

DrozinerAttractionModel(Frame centralBodyFrame, double equatorialRadius, double mu, double[][] C, double[][] S)
Creates a new instance.

DrozinerAttractionModel(Frame centralBodyFrame, double equatorialRadius, double mu, double[][] C, double[][] S, boolean computePDPos, boolean computePDVel)
Creates a new instance.

DrozinerAttractionModel(Frame centralBodyFrame, Parameter equatorialRadius, Parameter mu, double[][] C, double[][] S)
Creates a new instance using Parameter.

DrozinerAttractionModel(Frame centralBodyFrame, Parameter equatorialRadius, Parameter mu, double[][] C, double[][] S, boolean computePDPos, boolean computePDVel)
Creates a new instance using Parameter.

Method Summary

void	addContribution(SpacecraftState s, TimeDerivativesEquations adder) Compute the contribution of the force model to the perturbing acceleration.
Vector3D	computeAcceleration(PVCoordinates pv, AbsoluteDate date) Method to compute the acceleration.
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.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

DrozinerAttractionModel

public DrozinerAttractionModel(Frame centralBodyFrame,
                               double equatorialRadius,
                               double mu,
                               double[][] C,
                               double[][] S)
                        throws IllegalArgumentException

Creates a new instance.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - central body attraction coefficient (m³/s²)

C - un-normalized coefficients array (cosine part)

S - un-normalized coefficients array (sine part)

Throws:

IllegalArgumentException - if coefficients array do not match

DrozinerAttractionModel

public DrozinerAttractionModel(Frame centralBodyFrame,
                               double equatorialRadius,
                               double mu,
                               double[][] C,
                               double[][] S,
                               boolean computePDPos,
                               boolean computePDVel)
                        throws IllegalArgumentException

Creates a new instance.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - reference equatorial radius of the potential

mu - central body attraction coefficient (m³/s²)

C - un-normalized coefficients array (cosine part)

S - un-normalized coefficients array (sine part)

computePDPos - true if partial derivatives wrt position have to be computed

computePDVel - true if partial derivatives wrt velocity have to be computed

Throws:

IllegalArgumentException - if coefficients array do not match

DrozinerAttractionModel

public DrozinerAttractionModel(Frame centralBodyFrame,
                               Parameter equatorialRadius,
                               Parameter mu,
                               double[][] C,
                               double[][] S)
                        throws IllegalArgumentException

Creates a new instance using Parameter.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - parameter representing reference equatorial radius of the potential

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

C - un-normalized coefficients array (cosine part)

S - un-normalized coefficients array (sine part)

Throws:

IllegalArgumentException - if coefficients array do not match

DrozinerAttractionModel

public DrozinerAttractionModel(Frame centralBodyFrame,
                               Parameter equatorialRadius,
                               Parameter mu,
                               double[][] C,
                               double[][] S,
                               boolean computePDPos,
                               boolean computePDVel)
                        throws IllegalArgumentException

Creates a new instance using Parameter.

Parameters:

centralBodyFrame - rotating body frame

equatorialRadius - parameter representing reference equatorial radius of the potential

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

C - un-normalized coefficients array (cosine part)

S - un-normalized coefficients array (sine part)

computePDPos - true if partial derivatives wrt position have to be computed

computePDVel - true if partial derivatives wrt velocity have to be computed

Throws:

IllegalArgumentException - if coefficients array do not match

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

getEventsDetectors

public final 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

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,
                                          AbsoluteDate date)
                                   throws OrekitException

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.

(see Story #V82 and Feature #34 on https://www.orekit.org/forge/issues/34)

Out of the validation context, one must use the method Vector3D computeAcceleration(final SpacecraftState s)

Parameters:

pv - PV coordinates of the spacecraft

date - date

Returns:

acceleration vector

Throws:

OrekitException - if an Orekit error occurs

getMu

public double getMu()

Get the central attraction coefficient &mu..

Specified by:

getMu in interface AttractionModel

Returns:

mu central attraction coefficient (m³/s²)