Module: thrFiringRemainder

A thruster force message is read in and converted to a thruster on-time output message. The module ensures the requested on-time is at least as large as the thruster’s minimum on time. If not then the on-time is zeroed, but the unimplemented thrust time is kept as a remainder calculation. If these add up to reach the minimum on time, then a thruster pulse is requested. If the thruster on time is larger than the control period, then an on-time that is 1.1 times the control period is requested. More information can be found in the PDF Description. The paper Steady-State Attitude and Control Effort Sensitivity Analysis of Discretized Thruster Implementations includes a detailed discussion on the Remainder Trigger algorithm and compares it to other thruster firing methods.

Functions

void SelfInit_thrFiringRemainder(thrFiringRemainderConfig *configData, int64_t moduleID)

This method initializes the configData for this module. It creates a single output message of type THRArrayOnTimeCmdIntMsg.

Return

void

Parameters

  • configData: The configuration data associated with this module

void CrossInit_thrFiringRemainder(thrFiringRemainderConfig *configData, int64_t moduleID)

This method performs the second stage of initialization for this module. It links to 2 required input messages of type THRArrayCmdForceFswMsg and THRArrayConfigFswMsg.

Return

void

Parameters

  • configData: The configuration data associated with this module

void Update_thrFiringRemainder(thrFiringRemainderConfig *configData, uint64_t callTime, int64_t moduleID)

This method maps the input thruster command forces into thruster on times using a remainder tracking logic.

Return

void

Parameters

  • configData: The configuration data associated with the module

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

void Reset_thrFiringRemainder(thrFiringRemainderConfig *configData, uint64_t callTime, int64_t moduleID)

This method performs a complete reset of the module. Local module variables that retain time varying states between function calls are reset to their default values.

Return

void

Parameters

  • configData: The configuration data associated with the module

struct thrFiringRemainderConfig
#include <thrFiringRemainder.h>

Top level structure for the sub-module routines.

Public Members

double pulseRemainder[MAX_EFF_CNT]

[-] Unimplemented thrust pulses (number of minimum pulses)

double thrMinFireTime

[s] Minimum fire time

int numThrusters

[-] The number of thrusters available on vehicle

double maxThrust[MAX_EFF_CNT]

[N] Max thrust

int baseThrustState

[-] Indicates on-pulsing (0) or off-pusling (1)

uint64_t prevCallTime

callTime from previous function call

char thrForceInMsgName[MAX_STAT_MSG_LENGTH]

The name of the Input message.

int32_t thrForceInMsgId

ID for the incoming message.

char onTimeOutMsgName[MAX_STAT_MSG_LENGTH]

The name of the output message, onTimeOutMsgName.

int32_t onTimeOutMsgId

ID for the outgoing message.

char thrConfInMsgName[MAX_STAT_MSG_LENGTH]

The name of the thruster cluster Input message.

int32_t thrConfInMsgId

ID for the incoming Thruster configuration data.

BSKLogger *bskLogger

BSK Logging.