Table of Contents

Class ReactionWheelArray

Namespace
NominalSystems.Classes
Assembly
NominalSystems.Classes.dll

[Nominal] This component models a reaction wheel array connected to a rigid body. Reaction wheel arrays may be constructed from three different model: balanced wheels, simple jitter, and fully-coupled imbalanced wheels.

public class ReactionWheelArray : StateEffector
Inheritance
ReactionWheelArray

Constructors

ReactionWheelArray()

Default constructor

protected ReactionWheelArray()

Fields

In_MotorTorqueArrayMsg

Message ID for incoming motor torque data

public MotorTorqueArrayMessage? In_MotorTorqueArrayMsg

Field Value

MotorTorqueArrayMessage

Out_RWArrayConfigMsg

Output Message for array of reaction wheel configs

public RWArrayConfigMessage? Out_RWArrayConfigMsg

Field Value

RWArrayConfigMessage

Out_RWArraySpeedMsg

Output message for the reaction wheels

public RWArraySpeedMessage? Out_RWArraySpeedMsg

Field Value

RWArraySpeedMessage

Properties

CenterOfMassL_L

[m] The center of mass of the component within its own local coordinates. This does not include any of the sub-components.
Overridden to always return Vector3(0,0,0)

public override Vector3 CenterOfMassL_L { get; set; }

Property Value

Vector3

Mass

The mass of the reaction wheel array, excluding child objects. Overridden to always return 0.

public override double Mass { get; set; }

Property Value

double

MaxTorques

The maximum RW motor torque. This is the 'UMax' parameter.

[Unit(UnitType.NEWTON_METRE)]
[ReadOnly]
[Metadata(ContainedIn = "Out_RWArrayConfigMsg")]
public double[] MaxTorques { get; set; }

Property Value

double[]

MomentOfInertia_LB

[kg m^2] The moment of inertia of the component within its own local coordinates. This does not include any of the sub-components.
Overridden to always return a Matrix of 0.

public override Matrix3 MomentOfInertia_LB { get; set; }

Property Value

Matrix3

NumRW

The number of reaction wheels linked to the RWArray config message.

[Unit(UnitType.NONE)]
[ReadOnly]
[Metadata(ContainedIn = "Out_RWArrayConfigMsg")]
public int NumRW { get; set; }

Property Value

int

SpinAxis_B

The RW spin axis matrix in body frame coordinates. This is the 'GsMatrix_B' parameter.

[Unit(UnitType.NONE)]
[ReadOnly]
[Metadata(ContainedIn = "Out_RWArrayConfigMsg")]
public Vector3[] SpinAxis_B { get; set; }

Property Value

Vector3[]

SpinInertias

The spin axis inertia for RWs as a list of wheel values. This is the 'JsList' parameter.

[Unit(UnitType.KILOGRAM_SQUARE_METRE)]
[ReadOnly]
[Metadata(ContainedIn = "Out_RWArrayConfigMsg")]
public double[] SpinInertias { get; set; }

Property Value

double[]

Methods

ComputeDerivatives(double, Vector3, Vector3, Vector3)

Computers the Derivatives of the Body along with the Kinematic Derivatives

public override void ComputeDerivatives(double time, Vector3 rDDot_BN_N, Vector3 omegaDot_BN_B, Vector3 sigma_BN)

Parameters

time double

The current computation time

rDDot_BN_N Vector3

The acceleration in the body frame

omegaDot_BN_B Vector3

The derivative of the attitude rate in the body frame

sigma_BN Vector3

The current attitude in the body frame

CreateReactionWheel(double, Vector3, Vector3, RWModelType, double, double, bool, bool, bool, double, double, double, double, double, double, double, double, double)

Creates a new reaction wheel and adds the wheel to the current array. This will also initialise the reaction wheel with some default properties.

public ReactionWheel CreateReactionWheel(double wheelMass, Vector3 wheelPosition_B, Vector3 wheelSpinAxis_B, RWModelType wheelModelType = RWModelType.Balanced, double omega = 0, double omegaMax = 6000, bool useFriction = false, bool useMinTorque = false, bool useMaxTorque = false, double maxTorque = 0, double minTorque = 1E-05, double maxMomentum = 100, double frictionCoulomb = 0, double frictionStatic = 0, double betaStatic = -1, double frictionViscous = 0, double staticImbalance = 0, double dynamicImbalance = 0)

Parameters

wheelMass double

[kg] RW mass

wheelPosition_B Vector3

[m] Position vector of the RW relative to the spacecraft body frame

wheelSpinAxis_B Vector3

[-] Spin axis unit vector gsHat in B-frame components

wheelModelType RWModelType

[-] RW model type such as BalancedWheels, JitterSimple and JitterFullyCoupled

omega double

[RPM] Initial RW speed

omegaMax double

[RPM] Maximum RW speed

useFriction bool

[-] Set to TRUE to turn on RW internal wheel friction

useMinTorque bool

[-] Set to TRUE to clip any torque below a minimum torque value

useMaxTorque bool

[-] Set to TRUE to clip any torque value above a maximum torque value

maxTorque double

[Nm] Maximum RW motor torque

minTorque double

[Nm] Minimum RW motor torque

maxMomentum double

[Nms] Maximum RW wheel momentum in Nms

frictionCoulomb double

[Nm] Coulomb friction torque model

frictionStatic double

[Nm] Static friction torque magnitude

betaStatic double

[-] Stribeck friction coefficient, positive turns Stribeck friction on, negative turns this friction off

frictionViscous double

[-] Viscous friction coefficient

staticImbalance double

[kg*m]*10^-6 static RW imbalance

dynamicImbalance double

[kg*m^2]*10^-6 dynamic RW imbalance

Returns

ReactionWheel

GetReactionWheel(int)

Returns a particular reaction wheel from the reaction wheel array, if it exists.

public ReactionWheel? GetReactionWheel(int index)

Parameters

index int

The reaction wheel index

Returns

ReactionWheel

The reaction wheel reference if it exists

GetReactionWheelMessage(int)

Return a reference to the message of the reaction wheel at the specified index.

public RWConfigMessage? GetReactionWheelMessage(int index)

Parameters

index int

The index of the reaction wheel within the array.

Returns

RWConfigMessage

The reaction wheel configuration message for this wheel

LinkStateProperties(StateModel?)

Links and registers any of the states from the state model that is associated with the root object.

public override void LinkStateProperties(StateModel? properties)

Parameters

properties StateModel

The model that contains the list of states to fetch

OnChildAttached(UniverseObject)

This event is called when a child has been attached to this object. This will pass in the reference to the child object that was added.

protected override void OnChildAttached(UniverseObject child)

Parameters

child UniverseObject

The child object that was added

OnChildDetached(UniverseObject)

This event is called when a child has been detached from this object. This will pass in the child object that was removed.

protected override void OnChildDetached(UniverseObject child)

Parameters

child UniverseObject

The child object that was detached

OnCreate()

Called when the 'Component' is created from the controller.

protected override void OnCreate()

OnFinish(double)

Called when the object is deleted from the simulation and can handle any cleanup of variables.

protected override void OnFinish(double time)

Parameters

time double

[s] The current clock time when deleted

OnLoad(double)

Called after all of the data has been loaded from a save state on this object. This enables any post-load operations to be performed and extra data to be loaded from the metadata.

protected override void OnLoad(double time)

Parameters

time double

[s] The current clock time of the simulation

OnUpdate(double, double)

Called when the object should update from the simulation tick. This will take in a time and a step, where the time is the time of the clock before updating the object.

protected override void OnUpdate(double time, double step)

Parameters

time double

[s] Current time of the simulation before the update

step double

[s] The time-step to update during this tick

UpdateBackContributions(double, ref BackSubstitutionMatrices, Vector3, Vector3, Vector3)

Substitutes in the Back Substitution Matrices and performs some calculations.

public override void UpdateBackContributions(double time, ref BackSubstitutionMatrices backSubContribution, Vector3 sigma_BN, Vector3 omega_BN_B, Vector3 g_N)

Parameters

time double

The current time [s]

backSubContribution BackSubstitutionMatrices
sigma_BN Vector3

The current Attitude

omega_BN_B Vector3

The current Attitude rate

g_N Vector3

The spacecraft local gravity vector

UpdateEnergyContributions(double, ref Vector3, ref double, Vector3)

Computes the Energy and Momentum Contributions from the Body

public override void UpdateEnergyContributions(double time, ref Vector3 angMomentum_B, ref double energy, Vector3 omega_BN_B)

Parameters

time double

The current time [s]

angMomentum_B Vector3

A reference to the Angular Momentum Vector

energy double

A reference to the Energy Contribution value

omega_BN_B Vector3

The current Attitude Rate of the body

UpdateMassProperties(double, double)

Updates the mass properties of the current physical object at a particular time.

public override void UpdateMassProperties(double time, double step)

Parameters

time double

[s] The current time of the simulation

step double

[s] The delta time between the updates

WriteOutputMessages(double)

Updates the payload messages with some new states

protected void WriteOutputMessages(double time)

Parameters

time double

The current time [s]

WriteOutputStateMessages(double)

Writes state messages after integration

public override void WriteOutputStateMessages(double time)

Parameters

time double

The current time [s]