agi.foundation.celestial

(agi.foundation.orbitpropagation-2024r1.jar)

Class ContinuousThrustForceModel

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.celestial.ForceModel

agi.foundation.celestial.ContinuousThrustForceModel

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable, IPartialDifferentiable

public final class ContinuousThrustForceModel
extends ForceModel
implements IPartialDifferentiable

Represents a force generated by continuous thrust.

Constructor Summary

Constructors

Constructor and Description
ContinuousThrustForceModel() Initialize a new instance.
ContinuousThrustForceModel(Vector thrustVector, Axes integrationAxes) Initialize a new instance.
ContinuousThrustForceModel(Vector thrustVector, Axes integrationAxes, boolean ignorePartials) Initialize a new instance.

Method Summary

Modifier and Type	Method and Description
void	buildForceEvaluator(ResultantForceBuilder builder, EvaluatorGroup group) Build lists of principal and perturbation forces based on this model in order to create an overall resultant force.
protected boolean	checkForSameDefinition(ForceModel other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
static Vector	createIspThrustVector(Scalar isp, Scalar massFlowRate, Axes burnAxes, Cartesian thrustDirection) Creates a thrust Vector where the thrust is computed from the isp, and massFlowRate pointing in the thrustDirection in the specified burnAxes.
static Vector	createVeThrustVector(Scalar exhaustSpeed, Scalar massFlowRate, Axes burnAxes, Vector thrustDirection) Creates a thrust Vector where the thrust is computed from the exhaustSpeed, and massFlowRate pointing in the thrustDirection in the specified burnAxes.
void	enumerateDependencies(DependencyEnumerator enumerator) Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon.
int	getDimension() Gets the dimension of the values produced by the object.
ForceEvaluator	getForceEvaluator(EvaluatorGroup group) Gets an instance of an evaluator that can compute the force.
Axes	getIntegrationAxes() Gets the axes that this force model will be integrated in.
PartialDerivativesEvaluator	getPartialDerivativesEvaluator(List<IPartialDifferentiable> independentVariables, EvaluatorGroup group) Gets an evaluator that calculates the partial derivatives of the two body gravity acceleration with respect to any of the independentVariables parameters that apply.
Vector	getThrustVector() Gets the thrust vector.
void	setIntegrationAxes(Axes value) Sets the axes that this force model will be integrated in.
void	setThrustVector(Vector value) Sets the thrust vector.

Methods inherited from class agi.foundation.celestial.ForceModel

checkForSameDefinition, freezeAggregatedObjects, getForceEvaluator, getForceVector, getKind, getRole

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, freeze, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

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

Methods inherited from interface agi.foundation.infrastructure.IEquatableDefinition

getDefinitionHashCode, isSameDefinition

Constructor Detail

ContinuousThrustForceModel

public ContinuousThrustForceModel()

Initialize a new instance.

ContinuousThrustForceModel

public ContinuousThrustForceModel(Vector thrustVector,
                                  Axes integrationAxes)

Initialize a new instance.

Parameters:

thrustVector - The thrust vector being applied.

integrationAxes - The axes to integrate this force model in.

ContinuousThrustForceModel

public ContinuousThrustForceModel(Vector thrustVector,
                                  Axes integrationAxes,
                                  boolean ignorePartials)

Initialize a new instance.

Parameters:

thrustVector - The thrust vector being applied.

integrationAxes - The axes to integrate this force model in.

ignorePartials - Whether or not to ignore partials. This defaults to false.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Specified by:

clone in class DefinitionalObject

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected boolean checkForSameDefinition(ForceModel other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Specified by:

checkForSameDefinition in class ForceModel

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the ContinuousThrustForceModel.checkForSameDefinition(agi.foundation.celestial.ForceModel) method.

Overrides:

computeCurrentDefinitionHashCode in class ForceModel

Returns:

The computed hash code.

enumerateDependencies

public void enumerateDependencies(DependencyEnumerator enumerator)

Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon. Derived classes which contain additional dependencies MUST override this method, call the base implementation, and enumerate dependencies introduced by the derived class.

Specified by:

enumerateDependencies in interface IEnumerateDependencies

Overrides:

enumerateDependencies in class ForceModel

Parameters:

enumerator - The enumerator that is informed of the dependencies of this object.

createVeThrustVector

@Nonnull
public static Vector createVeThrustVector(Scalar exhaustSpeed,
                                                    Scalar massFlowRate,
                                                    Axes burnAxes,
                                                    Vector thrustDirection)

Creates a thrust Vector where the thrust is computed from the exhaustSpeed, and massFlowRate pointing in the thrustDirection in the specified burnAxes.

Parameters:

exhaustSpeed - The speed of the exhaust.

burnAxes - The axes to compute the thrustDirection in.

thrustDirection - The direction of the thrust in the burnAxes.

massFlowRate - The fuel flow rate.

Returns:

A vector representing the thrust.

createIspThrustVector

@Nonnull
public static Vector createIspThrustVector(Scalar isp,
                                                     Scalar massFlowRate,
                                                     Axes burnAxes,
                                                     @Nonnull
                                                     Cartesian thrustDirection)

Creates a thrust Vector where the thrust is computed from the isp, and massFlowRate pointing in the thrustDirection in the specified burnAxes. This formulation uses Constants.EarthSurfaceGravity.

Parameters:

isp - The specific impulse.

burnAxes - The axes to compute the thrustDirection in.

thrustDirection - The direction of the thrust in the burnAxes.

massFlowRate - The fuel flow rate.

Returns:

A vector representing the thrust.

getThrustVector

public final Vector getThrustVector()

Gets the thrust vector. This should be pointing in the direction of the force applied to the object (the inverse of the exhaust direction).

setThrustVector

public final void setThrustVector(Vector value)

Sets the thrust vector. This should be pointing in the direction of the force applied to the object (the inverse of the exhaust direction).

getIntegrationAxes

public final Axes getIntegrationAxes()

Gets the axes that this force model will be integrated in.

setIntegrationAxes

public final void setIntegrationAxes(Axes value)

Sets the axes that this force model will be integrated in.

getDimension

public final int getDimension()

Gets the dimension of the values produced by the object. For example, Vectors would have a dimension of three, and Scalars of one. A PartialDerivativesEvaluator created by this type will have a RowDimension (get) equal to this property, and a ColumnDimension (get) equal to the summation of the dimensions of the independent variables that this object is dependent on.

Specified by:

getDimension in interface IPartialDifferentiable

getForceEvaluator

public ForceEvaluator getForceEvaluator(EvaluatorGroup group)

Gets an instance of an evaluator that can compute the force.

Overrides:

getForceEvaluator in class ForceModel

Parameters:

group - The group in which to create the evaluator and its dependents.

Returns:

The evaluator that computes the force.

Throws:

ArgumentNullException - Thrown when group is null.

buildForceEvaluator

public void buildForceEvaluator(ResultantForceBuilder builder,
                                EvaluatorGroup group)

Build lists of principal and perturbation forces based on this model in order to create an overall resultant force.

Specified by:

buildForceEvaluator in class ForceModel

Parameters:

builder - The builder object containing the lists and additional information on the Axes in which the overall resultant is defined.

group - The evaluator group in which to create evaluators.

getPartialDerivativesEvaluator

public final PartialDerivativesEvaluator getPartialDerivativesEvaluator(List<IPartialDifferentiable> independentVariables,
                                                                        EvaluatorGroup group)

Gets an evaluator that calculates the partial derivatives of the two body gravity acceleration with respect to any of the independentVariables parameters that apply.

Specified by:

getPartialDerivativesEvaluator in interface IPartialDifferentiable

Parameters:

independentVariables - The list of IPartialDifferentiable representing the independent variables that the created partial derivative evaluator calculates partials with respect to.

group - The evaluator group to contain the evaluator.

Returns:

The PartialDerivativesEvaluator.