Module: thrustRWDesat

Executive Summary

This algorithm is used to control both the RCS and DV thrusters when executing a trajectory adjustment.

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
rwSpeedInMsg	RWSpeedMsgPayload	RW speed input message
rwConfigInMsg	RWConstellationMsgPayload	RW configuration input message
thrConfigInMsg	THRArrayConfigMsgPayload	Thruster configuration input message
vecConfigInMsg	VehicleConfigMsgPayload	spacecraft configuration input message
thrCmdOutMsg	THRArrayOnTimeCmdMsgPayload	thruster array commanded on time output message

---

Functions

void SelfInit_thrustRWDesat(thrustRWDesatConfig *configData, int64_t moduleID)

This method initializes the configData for the thruster-based RW desat module. It checks to ensure that the inputs are sane and then creates the output message

Parameters

• configData – The configuration data associated with the thruster desat

• moduleID – The module ID associated with configData

Returns

void

void Reset_thrustRWDesat(thrustRWDesatConfig *configData, uint64_t callTime, int64_t moduleID)

void Update_thrustRWDesat(thrustRWDesatConfig *configData, uint64_t callTime, int64_t moduleID)

This method takes in the current oberved reaction wheel angular velocities.

Parameters

• configData – The configuration data associated with the RW desat logic

• callTime – The clock time at which the function was called (nanoseconds)

• moduleID – The ID associated with the configData

Returns

void

struct thrustRWDesatConfig

#include <thrustRWDesat.h>

module configuration message

Public Members

RWSpeedMsg_C rwSpeedInMsg

(-) The name of the input RW speeds message

RWConstellationMsg_C rwConfigInMsg

[-] The name of the RWA configuration message

THRArrayConfigMsg_C thrConfigInMsg

[-] The name of the thruster configuration message

VehicleConfigMsg_C vecConfigInMsg

[-] The name of the input spacecraft mass properties message

THRArrayOnTimeCmdMsg_C thrCmdOutMsg

(-) The name of the output thrust command block

double rwAlignMap[3 * MAX_EFF_CNT]

(-) Alignment of the reaction wheel spin axes

double thrAlignMap[3 * MAX_EFF_CNT]

(-) Alignment of the vehicle thrusters

double thrTorqueMap[3 * MAX_EFF_CNT]

(-) Alignment of the vehicle thruster torques

double maxFiring

(s) Maximum time to fire a jet for

double thrFiringPeriod

(s) The amount of time to rest between thruster firings

int numRWAs

(-) Number of reaction wheels being desaturated

int numThrusters

(-) Number of thrusters available in the align map

double accumulatedImp[3]

(s) The accumulated firing in the body frame

double currDMDir[3]

(-) The current direction of momentum reduction

double totalAccumFiring

(s) The total thruster duration we’ve commanded

double DMThresh

(r/s) The point at which to stop decrementing momentum

uint64_t previousFiring

(ns) Time that the last firing command was given

BSKLogger *bskLogger

BSK Logging.