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

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, List<AdditionalEquations> additionalEquations, double arcDuration, double tolerance, String additionalName) Simple Constructor.

Method Summary

Modifier and Type	Method and Description
void	addConstraint(int patchNumber, 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(SpacecraftState initialState, AdditionalEquations additionalEquations2) Compute the additional state from the additionalEquations.
protected Map<Integer,Double>	getConstraintsMap() Get the map of patch points components which are constrained.
protected boolean[]	getFreeEpochMap() Get the flags representing the free epoch of patch points.
protected boolean[]	getFreePatchPointMap() Get the flags representing the free components of patch points.
protected int	getNumberOfConstraints() Get the number of constraints.
protected int	getNumberOfFreeEpoch() Get the number of free epoch.
protected int	getNumberOfFreeVariables() Get the number of free variables.
protected List<SpacecraftState>	getPatchedSpacecraftState() Get the list of patched spacecraft states.
protected List<NumericalPropagator>	getPropagatorList() Get the list of propagators.
protected boolean	isClosedOrbit() Get he flag representing if the orbit is closed.
void	setClosedOrbitConstraint(boolean isClosed) Set the constraint of a closed orbit or not.
void	setEpochFreedom(int patchNumber, boolean isFree) Set the epoch a patch point to free or not.
void	setPatchPointComponentFreedom(int patchNumber, int componentIndex, boolean isFree) Set a component of a patch point to free or not.
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,
                                   List<AdditionalEquations> additionalEquations,
                                   double arcDuration,
                                   double tolerance,
                                   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.

additionalEquations - list of additional equations linked to propagatorList.

arcDuration - initial guess of the duration of each arc.

tolerance - convergence tolerance on the constraint vector.

additionalName - name of the additional equations

Method Detail

setPatchPointComponentFreedom

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

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

Parameters:

patchNumber - Patch point with constraint

componentIndex - Component of the patch points which are constrained.

isFree - constraint value

addConstraint

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

Add a constraint on one component of one patch point.

Parameters:

patchNumber - Patch point with constraint

componentIndex - Component of the patch points which are constrained.

constraintValue - constraint value

setEpochFreedom

public void setEpochFreedom(int patchNumber,
                            boolean isFree)

Set the epoch a patch point to free or not.

Parameters:

patchNumber - Patch point

isFree - 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:

fxAdditionnal 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(SpacecraftState initialState,
                                                            AdditionalEquations additionalEquations2)

Compute the additional state from the additionalEquations.

Parameters:

initialState - SpacecraftState without the additional state

additionalEquations2 - Additional Equations.

Returns:

augmentedSP SpacecraftState with the additional state within.

setClosedOrbitConstraint

public void setClosedOrbitConstraint(boolean isClosed)

Set the constraint of a closed orbit or not.

Parameters:

isClosed - true if orbit should be closed

getNumberOfFreeVariables

protected int getNumberOfFreeVariables()

Get the number of free variables.

Returns:

the number of free variables

getNumberOfFreeEpoch

protected int getNumberOfFreeEpoch()

Get the number of free epoch.

Returns:

the number of free epoch

getNumberOfConstraints

protected int getNumberOfConstraints()

Get the number of constraints.

Returns:

the number of constraints

getFreePatchPointMap

protected boolean[] getFreePatchPointMap()

Get the flags representing the free components of patch points.

Returns:

an array of flags representing the free components of patch points

getFreeEpochMap

protected boolean[] getFreeEpochMap()

Get the flags representing the free epoch of patch points.

Returns:

an array of flags representing the free epoch of patch points

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

getPropagatorList

protected List<NumericalPropagator> getPropagatorList()

Get the list of propagators.

Returns:

a list of propagators

isClosedOrbit

protected boolean isClosedOrbit()

Get he flag representing if the orbit is closed.

Returns:

true if orbit is closed