org.orekit.forces.maneuvers

Class ConstantThrustManeuver

java.lang.Object

org.orekit.forces.AbstractForceModel

org.orekit.forces.maneuvers.ConstantThrustManeuver

All Implemented Interfaces:

ForceModel

public class ConstantThrustManeuver
extends AbstractForceModel

This class implements a simple maneuver with constant thrust.

The maneuver is defined by a direction in satellite frame. The current attitude of the spacecraft, defined by the current spacecraft state, will be used to compute the thrust direction in inertial frame. A typical case for tangential maneuvers is to use a LOF aligned attitude provider for state propagation and a velocity increment along the +X satellite axis.

Author:

Fabien Maussion, Véronique Pommier-Maurussane, Luc Maisonobe

Field Summary

Fields

Modifier and Type	Field and Description
static String	FLOW_RATE Parameter name for flow rate.
static String	THRUST Parameter name for thrust.

Constructor Summary

Constructors

Constructor and Description
ConstantThrustManeuver(AbsoluteDate date, double duration, double thrust, double isp, Vector3D direction) Simple constructor for a constant direction and constant thrust.
ConstantThrustManeuver(AbsoluteDate date, double duration, double thrust, double isp, Vector3D direction, String driversNamePrefix) Simple constructor for a constant direction and constant thrust.

Method Summary

Modifier and Type	Method and Description
<T extends RealFieldElement<T>> FieldVector3D<T>	acceleration(FieldSpacecraftState<T> s, T[] parameters) Compute acceleration.
Vector3D	acceleration(SpacecraftState state, double[] parameters) Compute acceleration.
<T extends RealFieldElement<T>> void	addContribution(FieldSpacecraftState<T> s, FieldTimeDerivativesEquations<T> adder) Compute the contribution of the force model to the perturbing acceleration.
void	addContribution(SpacecraftState s, TimeDerivativesEquations adder) Compute the contribution of the force model to the perturbing acceleration.
boolean	dependsOnPositionOnly() Check if force models depends on position only.
Stream<EventDetector>	getEventsDetectors() Get the discrete events related to the model.
<T extends RealFieldElement<T>> Stream<FieldEventDetector<T>>	getFieldEventsDetectors(Field<T> field) Get the discrete events related to the model.
double	getFlowRate() Get the flow rate.
double	getISP() Get the specific impulse.
ParameterDriver[]	getParametersDrivers() Get the drivers for force model parameters.
double	getThrust() Get the thrust.
void	init(SpacecraftState s0, AbsoluteDate t) Initialize the force model at the start of propagation.

Methods inherited from class org.orekit.forces.AbstractForceModel

complainIfNotSupported, getParameterDriver, isSupported

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

getParameters, getParameters

Field Detail

THRUST

public static final String THRUST

Parameter name for thrust.

See Also:

Constant Field Values

FLOW_RATE

public static final String FLOW_RATE

Parameter name for flow rate.

See Also:

Constant Field Values

Constructor Detail

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              double thrust,
                              double isp,
                              Vector3D direction)

Simple constructor for a constant direction and constant thrust.

Calling this constructor is equivalent to call ConstantThrustManeuver(date, duration, thrust, isp, direction, ""), hence not using any prefix for the parameters drivers names.

Parameters:

date - maneuver date

duration - the duration of the thrust (s) (if negative, the date is considered to be the stop date)

thrust - the thrust force (N)

isp - engine specific impulse (s)

direction - the acceleration direction in satellite frame.

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              double thrust,
                              double isp,
                              Vector3D direction,
                              String driversNamePrefix)

Simple constructor for a constant direction and constant thrust.

If the driversNamePrefix is empty, the names will be "thrust" and "flow rate", otherwise the prefix is prepended to these fixed strings. A typical use case is to use something like "1A-" or "2B-" as a prefix corresponding to the name of the thruster to use, so separate parameters can be adjusted for the different thrusters involved during an orbit determination where maneuvers parameters are estimated.

Parameters:

date - maneuver date

duration - the duration of the thrust (s) (if negative, the date is considered to be the stop date)

thrust - the thrust force (N)

isp - engine specific impulse (s)

direction - the acceleration direction in satellite frame

driversNamePrefix - prefix for the parameters drivers

Since:

9.0

Method Detail

dependsOnPositionOnly

public boolean dependsOnPositionOnly()

Check if force models depends on position only.

Returns:

true if force model depends on position only, false if it depends on velocity, either directly or due to a dependency on attitude

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)

Initialize the force model at the start of propagation. This method will be called before any calls to ForceModel.addContribution(SpacecraftState, TimeDerivativesEquations), ForceModel.addContribution(FieldSpacecraftState, FieldTimeDerivativesEquations), ForceModel.acceleration(SpacecraftState, double[]) or ForceModel.acceleration(FieldSpacecraftState, RealFieldElement[])

The default implementation of this method does nothing.

Parameters:

s0 - spacecraft state at the start of propagation.

t - date of propagation. Not equal to initialState.getDate().

getThrust

public double getThrust()

Get the thrust.

Returns:

thrust force (N).

getISP

public double getISP()

Get the specific impulse.

Returns:

specific impulse (s).

getFlowRate

public double getFlowRate()

Get the flow rate.

Returns:

flow rate (negative, kg/s).

addContribution

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

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

The default implementation simply adds the acceleration as a non-Keplerian acceleration.

Parameters:

s - current state information: date, kinematics, attitude

adder - object where the contribution should be added

Throws:

OrekitException - if some specific error occurs

addContribution

public <T extends RealFieldElement<T>> void addContribution(FieldSpacecraftState<T> s,
                                                            FieldTimeDerivativesEquations<T> adder)
                                                     throws OrekitException

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

Type Parameters:

T - type of the elements

Parameters:

s - current state information: date, kinematics, attitude

adder - object where the contribution should be added

Throws:

OrekitException - if some specific error occurs

acceleration

public Vector3D acceleration(SpacecraftState state,
                             double[] parameters)

Compute acceleration.

Parameters:

state - current state information: date, kinematics, attitude

parameters - values of the force model parameters

Returns:

acceleration in same frame as state

acceleration

public <T extends RealFieldElement<T>> FieldVector3D<T> acceleration(FieldSpacecraftState<T> s,
                                                                     T[] parameters)

Compute acceleration.

Type Parameters:

T - type of the elements

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters

Returns:

acceleration in same frame as state

getEventsDetectors

public Stream<EventDetector> getEventsDetectors()

Get the discrete events related to the model.

Returns:

stream of events detectors

getParametersDrivers

public ParameterDriver[] getParametersDrivers()

Get the drivers for force model parameters.

Returns:

drivers for force model parameters

getFieldEventsDetectors

public <T extends RealFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventsDetectors(Field<T> field)

Get the discrete events related to the model.

Type Parameters:

T - extends RealFieldElement

Parameters:

field - field to which the state belongs

Returns:

stream of events detectors