org.orekit.forces.gravity
Class ThirdBodyAttraction

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

All Implemented Interfaces:

Serializable, ForceModel, GradientModel, IJacobiansParameterizable, IParameterizable

public class ThirdBodyAttraction
extends JacobiansParameterizable
implements ForceModel, GradientModel

Third body attraction force model.

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

Author:

Fabien Maussion, Véronique Pommier-Maurussane

See Also:

Serialized Form

Constructor Summary

ThirdBodyAttraction(CelestialBody body)
Simple constructor.

ThirdBodyAttraction(CelestialBody body, boolean computePD)
Simple constructor.

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, Frame frame, 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.

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

Constructor Detail

ThirdBodyAttraction

public ThirdBodyAttraction(CelestialBody body)

Simple constructor.

Parameters:

body - the third body to consider (ex: CelestialBodyFactory.getSun() or CelestialBodyFactory.getMoon())

ThirdBodyAttraction

public ThirdBodyAttraction(CelestialBody body,
                           boolean computePD)

Simple constructor.

Parameters:

body - the third body to consider (ex: CelestialBodyFactory.getSun() or CelestialBodyFactory.getMoon())

computePD - true if partial derivatives have to be computed

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 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 Vector3D computeAcceleration(PVCoordinates pv,
                                    Frame frame,
                                    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 #V85 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

frame - frame in which the acceleration is computed

date - date

Returns:

acceleration vector

Throws:

OrekitException - if an Orekit error occurs

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 final 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