org.orekit.forces.maneuvers
Class ConstantThrustManeuver

java.lang.Object
  org.orekit.parameter.Parameterizable
      org.orekit.parameter.JacobiansParameterizable
          org.orekit.forces.maneuvers.ConstantThrustManeuver

All Implemented Interfaces:

Serializable, ForceModel, GradientModel, IJacobiansParameterizable, IParameterizable

public class ConstantThrustManeuver
extends JacobiansParameterizable
implements ForceModel, GradientModel

This class implements a simple maneuver with constant thrust.

The maneuver is defined by a direction in satellite frame or in a frame defined by user or in a LOF with type defined by user. In first case, the current attitude of the spacecraft, defined by the current spacecraft state, will be used to convert the thrust direction in satellite frame into inertial frame when direction is defined in satellite 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.

The implementation of this class enables the computation of partial derivatives by finite differences with respect to thrust and flow rate.

The maneuver is associated to two triggering EventDetector (one to start the thrust, the other one to stop the thrust): the maneuver is triggered only if the underlying event generates a STOP event, in which case this class will generate a RESET_STATE event (the stop event from the underlying object is therefore filtered out).

Note: including this force in a numerical propagator with adaptive step-size integrator may require to set up a small lower bound for step-size (such as 1E-8s) since force discontinuity may cause difficulties to the integrator when the maneuver stops.

Author:

Fabien Maussion, Véronique Pommier-Maurussane, Luc Maisonobe

See Also:

Serialized Form

Field Summary

static String	FLOW_RATE Parameter name for flow rate.
static String	THRUST Parameter name for thrust.

Constructor Summary

ConstantThrustManeuver(AbsoluteDate date, double duration, double thrust, double isp, Vector3D direction, MassProvider massProvider, String partName)
Constructor for a constant direction in satellite frame and constant thrust.

ConstantThrustManeuver(AbsoluteDate date, double duration, double thrust, double isp, Vector3D direction, MassProvider massProvider, String partName, Frame frame)
Constructor for a constant direction in provided frame and constant thrust.

ConstantThrustManeuver(AbsoluteDate date, double duration, double thrust, double isp, Vector3D direction, MassProvider massProvider, String partName, LOFType lofType)
Constructor for a constant direction in provided local orbital frame and constant thrust.

ConstantThrustManeuver(AbsoluteDate date, double duration, Parameter thrust, Parameter flowRate, Vector3D direction, MassProvider massProvider, String partName)
Constructor for a constant direction in satellite frame and constant thrust using Parameter.

ConstantThrustManeuver(AbsoluteDate date, double duration, Parameter thrust, Parameter flowRate, Vector3D direction, MassProvider massProvider, String partName, Frame frame)
Constructor for a constant direction in provided frame and constant thrust using Parameter.

ConstantThrustManeuver(AbsoluteDate date, double duration, Parameter thrust, Parameter flowRate, Vector3D direction, MassProvider massProvider, String partName, LOFType lofType)
Constructor for a constant direction in provided local orbital frame and constant thrust using Parameter with a local orbital frame defined by its type.

ConstantThrustManeuver(EventDetector startEventDetector, EventDetector stopEventDetector, double thrust, double isp, Vector3D direction, MassProvider massProvider, String partName)
Constructor for a constant direction in satellite frame and constant thrust.

ConstantThrustManeuver(EventDetector startEventDetector, EventDetector stopEventDetector, double thrust, double isp, Vector3D direction, MassProvider massProvider, String partName, Frame frame)
Constructor for a constant direction in provided frame and constant thrust.

ConstantThrustManeuver(EventDetector startEventDetector, EventDetector stopEventDetector, double thrust, double isp, Vector3D direction, MassProvider massProvider, String partName, LOFType lofType)
Constructor for a constant direction in provided local orbital frame and constant thrust.

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(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.
AbsoluteDate	getEndDate() Return the maneuver stop date (if a date or a DateDetector as been provided).
EventDetector[]	getEventsDetectors() Get the discrete events related to the model.
Frame	getFrame() Get the frame of the acceleration direction.
double	getISP() Get the specific impulse.
AbsoluteDate	getStartDate() Return the maneuver start date (if a date or a DateDetector as been provided).
boolean	isFiring() Returns maneuver status (firing or not).
void	setFiring(boolean isFiring) Set maneuver status.

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

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,
                              MassProvider massProvider,
                              String partName)

Constructor for a constant direction in satellite frame and constant thrust.

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.

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              double thrust,
                              double isp,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName,
                              Frame frame)

Constructor for a constant direction in provided frame and constant thrust.

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 the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

frame - the frame of the acceleration direction. SpacecraftFrame class is an unsupported frame.

Throws:

IllegalArgumentException - thrown if input frame is SpacecraftFrame.

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              double thrust,
                              double isp,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName,
                              LOFType lofType)

Constructor for a constant direction in provided local orbital frame and constant thrust.

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 the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

lofType - the LOF type of the acceleration direction

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              Parameter thrust,
                              Parameter flowRate,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName)

Constructor for a constant direction in satellite frame and constant thrust using Parameter.

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) parameter

flowRate - the flow rate parameter

direction - the acceleration direction in the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

Throws:

IllegalArgumentException - thrown if input frame is SpacecraftFrame.

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              Parameter thrust,
                              Parameter flowRate,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName,
                              Frame frame)

Constructor for a constant direction in provided frame and constant thrust using Parameter.

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) parameter

flowRate - the flow rate parameter

direction - the acceleration direction in the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

frame - the frame of the acceleration direction. SpacecraftFrame class is an unsupported frame.

Throws:

IllegalArgumentException - thrown if input frame is SpacecraftFrame.

ConstantThrustManeuver

public ConstantThrustManeuver(AbsoluteDate date,
                              double duration,
                              Parameter thrust,
                              Parameter flowRate,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName,
                              LOFType lofType)

Constructor for a constant direction in provided local orbital frame and constant thrust using Parameter with a local orbital frame defined by its type.

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) parameter

flowRate - the flow rate parameter

direction - the acceleration direction in the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

lofType - the LOF type of the acceleration direction

ConstantThrustManeuver

public ConstantThrustManeuver(EventDetector startEventDetector,
                              EventDetector stopEventDetector,
                              double thrust,
                              double isp,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName)

Constructor for a constant direction in satellite frame and constant thrust.

Parameters:

startEventDetector - event detector upon which maneuver should starts

stopEventDetector - event detector upon which maneuver should stops

thrust - the thrust force (N)

isp - engine specific impulse (s)

direction - the acceleration direction in satellite frame.

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

ConstantThrustManeuver

public ConstantThrustManeuver(EventDetector startEventDetector,
                              EventDetector stopEventDetector,
                              double thrust,
                              double isp,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName,
                              Frame frame)

Constructor for a constant direction in provided frame and constant thrust.

Parameters:

startEventDetector - event detector upon which maneuver should starts

stopEventDetector - event detector upon which maneuver should stops

thrust - the thrust force (N)

isp - engine specific impulse (s)

direction - the acceleration direction in the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

frame - the frame of the acceleration direction. SpacecraftFrame class is an unsupported frame.

Throws:

IllegalArgumentException - thrown if input frame is SpacecraftFrame.

ConstantThrustManeuver

public ConstantThrustManeuver(EventDetector startEventDetector,
                              EventDetector stopEventDetector,
                              double thrust,
                              double isp,
                              Vector3D direction,
                              MassProvider massProvider,
                              String partName,
                              LOFType lofType)

Constructor for a constant direction in provided local orbital frame and constant thrust.

Parameters:

startEventDetector - event detector upon which maneuver should starts

stopEventDetector - event detector upon which maneuver should stops

thrust - the thrust force (N)

isp - engine specific impulse (s)

direction - the acceleration direction in the frame defined by the user

massProvider - the mass provider

partName - the part of the mass provider whose mass diminishes

lofType - the LOF type of the acceleration direction

Method Detail

getISP

public double getISP()

Get the specific impulse.

Returns:

specific impulse (s).

getStartDate

public AbsoluteDate getStartDate()

Return the maneuver start date (if a date or a DateDetector as been provided).

Returns:

the maneuver start date if a date or a DateDetector as been provided, null otherwise.

getEndDate

public AbsoluteDate getEndDate()

Return the maneuver stop date (if a date or a DateDetector as been provided).

Returns:

the maneuver stop date if a date or a DateDetector as been provided, null otherwise.

getFrame

public Frame getFrame()

Get the frame of the acceleration direction. Null if the acceleration is expressed by default in the satellite frame.

Returns:

the frame

setFiring

public void setFiring(boolean isFiring)

Set maneuver status. This method is meant to be used if the propagation starts during a maneuver. As a result thrust will be firing at the beginning of the propagation and stops when crossing stop event.

Used in conjunction with isFiring(), the user can stop/restart a propagation during a maneuver.

Parameters:

isFiring - true if propagation should start during the maneuver

isFiring

public boolean isFiring()

Returns maneuver status (firing or not).

Used in conjunction with setFiring(boolean), the user can stop/restart a propagation during a maneuver.

Returns:

true if maneuver is thrust firing.

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

addDAccDState

public 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 jacobian 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

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