org.orekit.utils

Class AbstractMultipleShooting

java.lang.Object

org.orekit.utils.AbstractMultipleShooting

All Implemented Interfaces:

MultipleShooting

Direct Known Subclasses:

CR3BPMultipleShooter, MultipleShooter

public abstract class AbstractMultipleShooting
extends Object
implements MultipleShooting

Multiple shooting method using only constraints on state vectors of patch points (and possibly on epoch and integration time).

Since:

10.2

Author:

William Desprats, Alberto Fossà

See Also:

"TRAJECTORY DESIGN AND ORBIT MAINTENANCE STRATEGIES IN MULTI-BODY DYNAMICAL REGIMES by Thomas A. Pavlak, Purdue University"

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMultipleShooting(List<SpacecraftState> initialGuessList, List<NumericalPropagator> propagatorList, double tolerance, int maxIter, boolean isAutonomous, String additionalName) Simple Constructor.

Method Summary

Modifier and Type	Method and Description
void	addConstraint(int patchIndex, int componentIndex, double constraintValue) Add a constraint on one component of one patch point.
List<SpacecraftState>	compute() Return the list of corrected patch points.
protected abstract double[]	computeAdditionalConstraints(List<SpacecraftState> propagatedSP) Compute the additional constraints.
protected abstract double[][]	computeAdditionalJacobianMatrix(List<SpacecraftState> propagatedSP) Compute a part of the Jacobian matrix from additional constraints.
protected double[][]	computeEpochJacobianMatrix(List<SpacecraftState> propagatedSP) Compute a part of the Jacobian matrix with derivatives from epoch.
protected abstract SpacecraftState	getAugmentedInitialState(int i) Compute the additional state from the additionalEquations.
protected Map<Integer,Double>	getConstraintsMap() Get the map of patch points components which are constrained.
protected boolean[]	getFreeCompsMap() Get the map of free state components.
protected int	getNumberOfConstraints() Get the total number of constraints.
protected int	getNumberOfFreeComponents() Get the number of free state components.
protected List<SpacecraftState>	getPatchedSpacecraftState() Get the list of patched spacecraft states.
protected SpacecraftState	getPatchPoint(int i) Get a patch point.
void	setEpochFreedom(int patchIndex, boolean isFree) Set the epoch of a patch point to free or not.
void	setPatchPointComponentFreedom(int patchIndex, int componentIndex, boolean isFree) Set a component of a patch point to free or not.
void	setScaleLength(double scaleLength) Set the scale length.
void	setScaleTime(double scaleTime) Set the scale time.
protected void	updateAdditionalConstraints(int startIndex, double[] fxAdditional) Update the array of additional constraints.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractMultipleShooting

protected AbstractMultipleShooting(List<SpacecraftState> initialGuessList,
                                   List<NumericalPropagator> propagatorList,
                                   double tolerance,
                                   int maxIter,
                                   boolean isAutonomous,
                                   String additionalName)

Simple Constructor.

Standard constructor for multiple shooting

Parameters:

initialGuessList - initial patch points to be corrected

propagatorList - list of propagators associated to each patch point

tolerance - convergence tolerance on the constraint vector

maxIter - maximum number of iterations

isAutonomous - true if the dynamical system is autonomous (i.e. not dependent on the epoch)

additionalName - name of the additional equations

Since:

11.1

Method Detail

getPatchPoint

protected SpacecraftState getPatchPoint(int i)

Get a patch point.

Parameters:

i - index of the patch point

Returns:

state of the patch point

Since:

11.1

setPatchPointComponentFreedom

public void setPatchPointComponentFreedom(int patchIndex,
                                          int componentIndex,
                                          boolean isFree)

Set a component of a patch point to free or not.

Parameters:

patchIndex - Patch point index (zero-based)

componentIndex - Index of the component to be constrained (zero-based)

isFree - constraint value

setEpochFreedom

public void setEpochFreedom(int patchIndex,
                            boolean isFree)

Set the epoch of a patch point to free or not.

Parameters:

patchIndex - Patch point index (zero-based)

isFree - constraint value

setScaleTime

public void setScaleTime(double scaleTime)

Set the scale time.

Parameters:

scaleTime - scale time in seconds

setScaleLength

public void setScaleLength(double scaleLength)

Set the scale length.

Parameters:

scaleLength - scale length in meters

addConstraint

public void addConstraint(int patchIndex,
                          int componentIndex,
                          double constraintValue)

Add a constraint on one component of one patch point.

Parameters:

patchIndex - Patch point index (zero-based)

componentIndex - Index of the component which is constrained (zero-based)

constraintValue - constraint value

compute

public List<SpacecraftState> compute()

Return the list of corrected patch points. An optimizer is better suited for this problem

Specified by:

compute in interface MultipleShooting

Returns:

patchedSpacecraftStates patchedSpacecraftStates

computeEpochJacobianMatrix

protected double[][] computeEpochJacobianMatrix(List<SpacecraftState> propagatedSP)

Compute a part of the Jacobian matrix with derivatives from epoch. The CR3BP is a time invariant problem. The derivatives w.r.t. epoch are zero.

Parameters:

propagatedSP - propagatedSP

Returns:

jacobianMatrix Jacobian sub-matrix

updateAdditionalConstraints

protected void updateAdditionalConstraints(int startIndex,
                                           double[] fxAdditional)

Update the array of additional constraints.

Parameters:

startIndex - start index

fxAdditional - array of additional constraints

computeAdditionalConstraints

protected abstract double[] computeAdditionalConstraints(List<SpacecraftState> propagatedSP)

Compute the additional constraints.

Parameters:

propagatedSP - propagated SpacecraftState

Returns:

fxAdditional additional constraints

computeAdditionalJacobianMatrix

protected abstract double[][] computeAdditionalJacobianMatrix(List<SpacecraftState> propagatedSP)

Compute a part of the Jacobian matrix from additional constraints.

Parameters:

propagatedSP - propagatedSP

Returns:

jacobianMatrix Jacobian sub-matrix

getAugmentedInitialState

protected abstract SpacecraftState getAugmentedInitialState(int i)

Compute the additional state from the additionalEquations.

Parameters:

i - index of the state

Returns:

augmentedSP SpacecraftState with the additional state within.

Since:

11.1

getNumberOfFreeComponents

protected int getNumberOfFreeComponents()

Get the number of free state components.

Returns:

number of free components

getNumberOfConstraints

protected int getNumberOfConstraints()

Get the total number of constraints.

Returns:

the total number of constraints

getFreeCompsMap

protected boolean[] getFreeCompsMap()

Get the map of free state components.

Returns:

map of free state components

getConstraintsMap

protected Map<Integer,Double> getConstraintsMap()

Get the map of patch points components which are constrained.

Returns:

a map of patch points components which are constrained

getPatchedSpacecraftState

protected List<SpacecraftState> getPatchedSpacecraftState()

Get the list of patched spacecraft states.

Returns:

a list of patched spacecraft states