A Portable Device for the A Portable Device for the Translation of Braille to Literary Translation of Braille to Literary

TextText

Andrew PasqualeAndrew Pasquale Curtin University of TechnologyCurtin University of Technology

IntroductionIntroduction Purpose of the DevicePurpose of the Device The Braille SystemThe Braille System Prototype operationPrototype operation The Prototype SystemThe Prototype System

– Image CaptureImage Capture– Quadrature Linear Motion DetectionQuadrature Linear Motion Detection– Optical Braille Character RecognitionOptical Braille Character Recognition

Future DevelopmentFuture Development

Purpose of the DevicePurpose of the Device

Written communications barrier between Written communications barrier between seeing and blind person’sseeing and blind person’s– Schooling systemSchooling system– Workplace Workplace

Diabetic Peripheral Polyneuropathy Diabetic Peripheral Polyneuropathy (diabetes being the major cause of (diabetes being the major cause of blindness is Australia)blindness is Australia)

All specifications and requirements were All specifications and requirements were sourced from the Association for the Blind sourced from the Association for the Blind WA WA

The Braille SystemThe Braille System 6 embossed dots gives 64 possible 6 embossed dots gives 64 possible

combinationscombinations Many different grades of braille (ie English, Many different grades of braille (ie English,

US, Greek, Arabic, math, music etc etc) US, Greek, Arabic, math, music etc etc) – each with respective context sensitive each with respective context sensitive

contraction rules, is similar to shorthand textcontraction rules, is similar to shorthand text e.g, English Grade 2e.g, English Grade 2

– p p == ‘people’ ‘people’ – :: = ‘wh’ OR ‘which’ OR ‘:’ (colon) = ‘wh’ OR ‘which’ OR ‘:’ (colon)

Prototype Block DiagramPrototype Block Diagram

Prototype ImplementationPrototype Implementation

Scanner OperationScanner Operation

Image CaptureImage Capture

CCD OperationCCD Operation 128 pixel linear CCD array128 pixel linear CCD array 100 Hz frame rate (SI pulse triggered)100 Hz frame rate (SI pulse triggered) Pixel voltages clocked out serially at Pixel voltages clocked out serially at

50 KHz50 KHz

Image Capture OperationImage Capture Operation

Quadrature Linear Motion Quadrature Linear Motion DetectionDetection

To provide the DSP with reference distance and To provide the DSP with reference distance and direction information for the correlation of camera direction information for the correlation of camera frames with physical braille dotsframes with physical braille dots

Provides interrupt pulse signals to the DSP to capture Provides interrupt pulse signals to the DSP to capture exactly 92 frames per inch from the CCD’s continuous exactly 92 frames per inch from the CCD’s continuous outputsoutputs

Information on scanner’s direction of movement allows Information on scanner’s direction of movement allows CCD frames resulting from hand jitter and back CCD frames resulting from hand jitter and back scanning to be corrected for.scanning to be corrected for.

DSP can then form an accurate 2D image of DSP can then form an accurate 2D image of braille page from a 1D camera systembraille page from a 1D camera system

Theory of OperationTheory of Operation Codewheel (slotted disk) and a pair of IR LED’s / Codewheel (slotted disk) and a pair of IR LED’s /

photodiodes from a computer mousephotodiodes from a computer mouse DSP performs logicDSP performs logic

DSP PlatformDSP Platform Texas Instruments TMS320VC5402 DSP Evaluation BoardTexas Instruments TMS320VC5402 DSP Evaluation Board

– 100 MHz Operation with low power usage100 MHz Operation with low power usage– Onboard programmable 22 KHz ADC, DACOnboard programmable 22 KHz ADC, DAC– Real time DSP output and debugging through parallel Real time DSP output and debugging through parallel

port to host PCport to host PC– C bases IDE with extensive code libraryC bases IDE with extensive code library

DSP OperationDSP Operation Interrupt Driven DSP Software Algorithm:Interrupt Driven DSP Software Algorithm:

– Wait for codewheel interrupt, is scanner moving forward?Wait for codewheel interrupt, is scanner moving forward? Wait for next SI (camera frame) interrupt (is within 10 ms)Wait for next SI (camera frame) interrupt (is within 10 ms)

– Sample incoming CCD frame dataSample incoming CCD frame data– determine braille celldetermine braille cell

Dot Recognition in FrameDot Recognition in Frame

Vertical Misalignment Vertical Misalignment Assuming the linear CCD array will always be correctly Assuming the linear CCD array will always be correctly

aligned to braille dots is an impractical assumptionaligned to braille dots is an impractical assumption

Vertical Misalignment Correction Vertical Misalignment Correction TechniqueTechnique

Simply perform logical OR operation of Simply perform logical OR operation of successive successive capturedcaptured camera frames camera frames

Cell CompilationCell Compilation

Create ‘slice’ variable representing the presence of dots Create ‘slice’ variable representing the presence of dots within a specific camera frame within a specific camera frame

correlate right ‘slice’ of braille cell with left ‘slice’ of braille cell correlate right ‘slice’ of braille cell with left ‘slice’ of braille cell to create complete braille cellto create complete braille cell

the physical ambiguity inherent in single sided braille cells can the physical ambiguity inherent in single sided braille cells can be compensated for by using simple rules (depending on the be compensated for by using simple rules (depending on the type of braille medium)type of braille medium)– e.ge.g

is = decimal point, if inbetween two numbersis = decimal point, if inbetween two numbers is = k, if not between two numbersis = k, if not between two numbers

Cell CompilationCell Compilation

Represent each braille Represent each braille cell by binary braille cell by binary braille codecode

Conversion into various Conversion into various braille types can then braille types can then use binary code as use binary code as basis to apply basis to apply contraction rulescontraction rules

Braille DecompressionBraille Decompression

Decompression algorithms for converting braille mediums into Decompression algorithms for converting braille mediums into text are availabletext are available

eg, algorithm developed by Paul Blenkhorn/Iain Murray eg, algorithm developed by Paul Blenkhorn/Iain Murray basically a state machine with exception handling functionality (for basically a state machine with exception handling functionality (for

non-printable contraction characters such as capital/ number non-printable contraction characters such as capital/ number indicator etc)indicator etc)

uses switchable look up table that includes the context sensitive uses switchable look up table that includes the context sensitive contraction rules of the respective braille code (English, Arabic, math contraction rules of the respective braille code (English, Arabic, math etc) being readetc) being read

Conversion into various braille types can then use binary code as basis to Conversion into various braille types can then use binary code as basis to apply contraction rules toapply contraction rules to

Future ImprovementsFuture Improvements

LCD display or text to speech converter LCD display or text to speech converter outputoutput

Ergonomics: eg four wheel tracking Ergonomics: eg four wheel tracking systemsystem

Area CCD arrayArea CCD array Double as “Text Reader” Double as “Text Reader”

ConclusionConclusion

Project AchievementsProject Achievements– implementation and utilisation of implementation and utilisation of

quadrature linear motion detectionquadrature linear motion detection– image capture of physical braille mediumimage capture of physical braille medium– Computer system able of optical Computer system able of optical

character recognition from a dynamic character recognition from a dynamic medium medium

– proven basis for a portable, real time proven basis for a portable, real time braille to literary text translation devicebraille to literary text translation device

ConclusionConclusion

Once developed, the device has Once developed, the device has potential to act as a written potential to act as a written communication’s gateway between communication’s gateway between seeing and vision impaired seeing and vision impaired person’s.person’s.

AcknowledgementsAcknowledgements

Academic Supervisor: Iain MurrayAcademic Supervisor: Iain Murray Tech Support at ECE Curtin Tech Support at ECE Curtin

UniversityUniversity John Heppel, Mark Fowler, Ivus SiewartJohn Heppel, Mark Fowler, Ivus Siewart

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