org.orekit.forces.drag

Class DragForce

java.lang.Object

org.orekit.forces.AbstractForceModel

org.orekit.forces.drag.DragForce

All Implemented Interfaces:

ForceModel

public class DragForce
extends AbstractForceModel

Atmospheric drag force model. The drag acceleration is computed as follows : γ = (1/2 * ρ * V² * S / Mass) * DragCoefVector With DragCoefVector = {C_x, C_y, C_z} and S given by the user through the interface DragSensitive

Author:

Édouard Delente, Fabien Maussion, Véronique Pommier-Maurussane, Pascal Parraud

Constructor Summary

Constructors

Constructor and Description
DragForce(Atmosphere atmosphere, DragSensitive spacecraft) Simple constructor.

Method Summary

Modifier and Type	Method and Description
FieldVector3D<DerivativeStructure>	accelerationDerivatives(AbsoluteDate date, Frame frame, FieldVector3D<DerivativeStructure> position, FieldVector3D<DerivativeStructure> velocity, FieldRotation<DerivativeStructure> rotation, DerivativeStructure mass) Compute acceleration derivatives with respect to state parameters.
FieldVector3D<DerivativeStructure>	accelerationDerivatives(SpacecraftState s, String paramName) Compute acceleration derivatives with respect to additional parameters.
void	addContribution(SpacecraftState s, TimeDerivativesEquations adder) Compute the contribution of the drag to the perturbing acceleration.
EventDetector[]	getEventsDetectors() There are no discrete events for this model.
ParameterDriver[]	getParametersDrivers() Get the drivers for force model parameters.

Methods inherited from class org.orekit.forces.AbstractForceModel

complainIfNotSupported, getParameter, getParameterDriver, getParametersNames, isSupported, setParameter

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.forces.ForceModel

init

Constructor Detail

DragForce

public DragForce(Atmosphere atmosphere,
                 DragSensitive spacecraft)

Simple constructor.

Parameters:

atmosphere - atmospheric model

spacecraft - the object physical and geometrical information

Method Detail

addContribution

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

Compute the contribution of the drag to the perturbing acceleration.

Parameters:

s - the 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()

There are no discrete events for this model.

Returns:

an empty array

getParametersDrivers

public ParameterDriver[] getParametersDrivers()

Get the drivers for force model parameters.

Returns:

drivers for force model parameters

accelerationDerivatives

public FieldVector3D<DerivativeStructure> accelerationDerivatives(AbsoluteDate date,
                                                                  Frame frame,
                                                                  FieldVector3D<DerivativeStructure> position,
                                                                  FieldVector3D<DerivativeStructure> velocity,
                                                                  FieldRotation<DerivativeStructure> rotation,
                                                                  DerivativeStructure mass)
                                                           throws OrekitException

Compute acceleration derivatives with respect to state parameters.

The derivatives should be computed with respect to position, velocity and optionnaly mass. The input parameters already take into account the free parameters (6 or 7 depending on derivation with respect to mass being considered or not) and order (always 1). Free parameters at indices 0, 1 and 2 correspond to derivatives with respect to position. Free parameters at indices 3, 4 and 5 correspond to derivatives with respect to velocity. Free parameter at index 6 (if present) corresponds to to derivatives with respect to mass.

Parameters:

date - current date

frame - inertial reference frame for state (both orbit and attitude)

position - position of spacecraft in reference frame

velocity - velocity of spacecraft in reference frame

rotation - orientation (attitude) of the spacecraft with respect to reference frame

mass - spacecraft mass

Returns:

acceleration with all derivatives specified by the input parameters own derivatives

Throws:

OrekitException - if derivatives cannot be computed

accelerationDerivatives

public FieldVector3D<DerivativeStructure> accelerationDerivatives(SpacecraftState s,
                                                                  String paramName)
                                                           throws OrekitException

Compute acceleration derivatives with respect to additional parameters.

Parameters:

s - spacecraft state

paramName - name of the parameter with respect to which derivatives are required

Returns:

acceleration with all derivatives specified by the input parameters own derivatives

Throws:

OrekitException - if derivatives cannot be computed