Module: reactionWheelStateEffector

Executive Summary

Class that is used to implement an effector impacting a dynamic body that does not itself maintain a state or represent a changing component of the body (for example: gravity, thrusters, solar radiation pressure, etc.)

The module PDF Description contains further information on this module’s function, how to run it, as well as testing.

Message Connection Descriptions

The following table lists all the module input and output messages. The module msg connection is set by the user from python. The msg type contains a link to the message structure definition, while the description provides information on what this message is used for.

Module I/O Messages
Msg Variable Name	Msg Type	Description
rwMotorCmdInMsg	ArrayMotorTorqueMsgPayload	(optional) RW motor torque array cmd input message. If not connected the motor torques are set to zero.
rwSpeedOutMsg	RWSpeedMsgPayload	RW speed array output message
rwOutMsgs	RWConfigLogMsgPayload	vector of RW log output messages

User Guide

The reaction wheel state effector module provides functionality for simulating reaction wheels in a spacecraft. It includes safety mechanisms to prevent numerical instability that can occur with excessive wheel acceleration or when using unlimited torque with small spacecraft inertia.

Threshold Parameters

The module includes two configurable threshold parameters:

maxWheelAcceleration: Maximum allowed wheel acceleration to prevent numerical instability. Default value is 1.0e6 rad/s^2.
largeTorqueThreshold: Threshold for warning about large torque with unlimited torque setting. Default value is 10.0 Nm.

These parameters can be accessed and modified using the following getter and setter methods:

# Get the current maximum wheel acceleration threshold
current_max_accel = reactionWheelStateEffector.getMaxWheelAcceleration()

# Set a new maximum wheel acceleration threshold
reactionWheelStateEffector.setMaxWheelAcceleration(2.0e6)  # rad/s^2

# Get the current large torque threshold
current_torque_threshold = reactionWheelStateEffector.getLargeTorqueThreshold()

# Set a new large torque threshold
reactionWheelStateEffector.setLargeTorqueThreshold(15.0)  # Nm

class ReactionWheelStateEffector : public SysModel, public StateEffector 

#include <reactionWheelStateEffector.h>

reaction wheel state effector class

Public Functions

ReactionWheelStateEffector()

~ReactionWheelStateEffector()

void registerStates(DynParamManager &states)

void linkInStates(DynParamManager &states)

void writeOutputStateMessages(uint64_t integTimeNanos)

This method is here to write the output message structure into the specified message.

Parameters:: integTimeNanos – The current time used for time-stamping the message

void computeDerivatives(double integTime, Eigen::Vector3d rDDot_BN_N, Eigen::Vector3d omegaDot_BN_B, Eigen::Vector3d sigma_BN)

void updateEffectorMassProps(double integTime): — Method for stateEffector to give mass contributions

void updateContributions(double integTime, BackSubMatrices &backSubContr, Eigen::Vector3d sigma_BN, Eigen::Vector3d omega_BN_B, Eigen::Vector3d g_N): — Back-sub contributions

void updateEnergyMomContributions(double integTime, Eigen::Vector3d &rotAngMomPntCContr_B, double &rotEnergyContr, Eigen::Vector3d omega_BN_B): — Energy and momentum calculations

void Reset(uint64_t CurrentSimNanos): Reset the module to origina configuration values.

void addReactionWheel(RWConfigMsgPayload *NewRW): add a RW data object to the reactionWheelStateEffector

void UpdateState(uint64_t CurrentSimNanos)

This method is the main cyclical call for the scheduled part of the RW dynamics model. It reads the current commands array and sets the RW configuration data based on that incoming command set. Note that the main dynamical method (ComputeDynamics()) is not called here and is intended to be called from the dynamics plant in the system

Parameters:: CurrentSimNanos – The current simulation time in nanoseconds

void WriteOutputMessages(uint64_t CurrentClock)

This method is here to write the output message structure into the specified message.

Parameters:: CurrentClock – The current time used for time-stamping the message

void ReadInputs(): This method is used to read the incoming command message and set the associated command structure for operating the RWs.

void ConfigureRWRequests(double CurrentTime)

This method is used to read the new commands vector and set the RW firings appropriately. It assumes that the ReadInputs method has already been run successfully.

Parameters:: CurrentTime – The current simulation time converted to a double

inline double getMaxWheelAcceleration() const

Get the maximum wheel acceleration threshold.

Returns:: Maximum wheel acceleration in rad/s^2

inline void setMaxWheelAcceleration(double val)

Set the maximum wheel acceleration threshold.

Parameters:: val – New maximum wheel acceleration value in rad/s^2

inline double getLargeTorqueThreshold() const

Get the large torque threshold for unlimited torque warning.

Returns:: Large torque threshold in Nm

inline void setLargeTorqueThreshold(double val)

Set the large torque threshold for unlimited torque warning.

Parameters:: val – New large torque threshold value in Nm

Public Members

std::vector<RWConfigMsgPayload*> ReactionWheelData: — RW information

ReadFunctor<ArrayMotorTorqueMsgPayload> rwMotorCmdInMsg: — RW motor torque array cmd input message

Message<RWSpeedMsgPayload> rwSpeedOutMsg: — RW speed array output message

std::vector<Message<RWConfigLogMsgPayload>*> rwOutMsgs: — vector of RW log output messages

std::vector<RWCmdMsgPayload> NewRWCmds: — Incoming attitude commands

RWSpeedMsgPayload rwSpeedMsgBuffer = {}: (-) Output data from the reaction wheels

std::string nameOfReactionWheelOmegasState: class variable

std::string nameOfReactionWheelThetasState: class variable

size_t numRW: number of reaction wheels

size_t numRWJitter: number of RW with jitter

BSKLogger bskLogger: — BSK Logging

Private Members

ArrayMotorTorqueMsgPayload incomingCmdBuffer = {}: — One-time allocation for savings

uint64_t prevCommandTime: — Time for previous valid thruster firing

StateData *OmegasState: class variable

StateData *thetasState: class variable

Eigen::MatrixXd *g_N: [m/s^2] Gravitational acceleration in N frame components

double maxWheelAcceleration = 1.0e6: [rad/s^2] Maximum allowed wheel acceleration to prevent numerical instability

double largeTorqueThreshold = 10.0: [Nm] Threshold for warning about large torque with unlimited torque setting