Module: scanningInstrumentController

Executive Summary

Module to perform continuous instrument control if attitude error and attitude rate are within specified tolerances. If within the specified tolerances, the module will send an imaging command to the instrument. Applicable use case could be a continuous nadir imaging (scanning), where it must constantly check for attitude requirements.

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

accessInMsg

AccessMsgPayload

Ground location access input message

attGuidInMsg

AttGuidMsgPayload

Attitude guidance input message

deviceStatusInMsg

DeviceStatusMsgPayload

(optional) Device status input message

deviceCmdOutMsg

DeviceCmdMsgPayload

Device status command output message

Detailed Module Description

This module writes out a DeviceCmdMsgPayload to turn on an instrument, i.e. Module: simpleInstrument, continuously while the requirement conditions are met.

The module first checks if the instrument controller is active using the controllerStatus variable. This variable defaults to 0 (inactive) due to swig initialization of the module, but the user may set the variable to 1 (active) with the deviceStatusInMsg or controllerStatus variable. If the instrument controller is active, the module then checks if the norm of the attitude error is less than the user specified tolerance and if the Module: groundLocation is accessible. If both are true, the module sets the deviceCmd to 1. Otherwise, the deviceCmd is set to 0.

User Guide

Two variables must be set, attErrTolerance and useRateTolerance. The variable attErrTolerance is the norm of the acceptable attitude error in MRPs; It must be set at the beginning of the sim. Also, useRateTolerance must be set to specify if the module should check for attitude rate requirements (set useRateTolerance to 1 to check, otherwise set to 0).

If useRateTolerance is set to 1, rateErrTolerance must be set to the norm of the acceptable attitude rate in rad/s. Otherwise, if useRateTolerance is set to 0, rateErrTolerance is not used.

If the user desires to make the instrument controller inactive, the controllerStatus variable should be set to 0. This may be done if the controller is to match the status of corresponding instrument data and power modules. This may also be accomplished by writing out a DeviceStatusMsgPayload to the deviceStatusInMsg.

Functions

void SelfInit_scanningInstrumentController(scanningInstrumentControllerConfig *configData, int64_t moduleID)

This method initializes the output messages for this module.

Parameters

  • configData – The configuration data associated with this module

  • moduleID – The module identifier

Returns

void

void Update_scanningInstrumentController(scanningInstrumentControllerConfig *configData, uint64_t callTime, int64_t moduleID)

This method checks the status of the device and if there is access to target, as well if the magnitude of the attitude error and attitude rate are within the tolerance. If so, the instrument is turned on, otherwise it is turned off.

Parameters

  • configData – The configuration data associated with the module

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

  • moduleID – The module identifier

Returns

void

void Reset_scanningInstrumentController(scanningInstrumentControllerConfig *configData, uint64_t callTime, int64_t moduleID)

This method checks if required input messages (accessInMsg and attGuidInMsg) are connected.

Parameters

  • configData – The configuration data associated with the module

  • callTime – [ns] time the method is called

  • moduleID – The module identifier

Returns

void

struct scanningInstrumentControllerConfig
#include <scanningInstrumentController.h>

Module to perform continuous instrument control.

Public Members

double attErrTolerance

Normalized MRP attitude error tolerance.

unsigned int useRateTolerance

Flag to enable rate error tolerance.

double rateErrTolerance

Rate error tolerance in rad/s.

unsigned int controllerStatus

dictates whether or not the controller should be running

AccessMsg_C accessInMsg

Ground location access.

AttGuidMsg_C attGuidInMsg

Attitude guidance input message.

DeviceStatusMsg_C deviceStatusInMsg

Device status input message.

DeviceCmdMsg_C deviceCmdOutMsg

Device status output message.

BSKLogger *bskLogger

BSK Logging.