rateDamp

Executive Summary

This module implements a feedback control law to damp the angular rates of the spacecraft until they are brought to zero.

Message Connection Descriptions

The following table lists all the module input and output messages. 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
navAttInMsg	NavAttMsgPayload	Input navigation message
cmdTorqueOutMsg	CmdTorqueBodyMsgPayload	Output C++-wrapped message containing the rate-damping torque in Body-frame coordinates
cmdTorqueOutMsgC	CmdTorqueBodyMsgPayload	Output C-wrapped message containing the rate-damping torque in Body-frame coordinates

Detailed Module Description

The control law implemented is the following:

\[\boldsymbol{u} = - P \boldsymbol{\omega}_\mathcal{B/N}\]

where \(P\) is a positive, user-defined scalar quantity. The control law is globally asymptotically stabilizing.

User Guide

The required module configuration is:

attControl = rateDamp.RateDamp()
attControl.setRateGain(P)
attControl.modelTag = "rateDamp"

Class RateDamp

class RateDamp : public SysModel

A class to compute rate damping control.

Public Functions

void reset(uint64_t currentSimNanos)

This method is used to reset the module.

Returns:

void

void updateState(uint64_t currentSimNanos)

This method is the main carrier for the computation of the control torque.

Parameters:

currentSimNanos – The current simulation time for system

Returns:

void

void setRateGain(double const p)

Set the module rate feedback gain

Parameters:

double – P

Returns:

void

double getRateGain() const

Get the module rate feedback gain

Parameters:

double – measurementNoiseScale

Returns:

void

Public Members

ReadFunctor<NavAttMsgPayload> attNavInMsg

input msg measured attitude

Message<CmdTorqueBodyMsgPayload> cmdTorqueOutMsg

commanded torque output message