BREAKING THE ACCESSIBILITY BARRIER: DEVELOPMENT OF SPECIAL COMPUTER ACCESS MECHANISMS FOR THE NEURO-MOTOR DISABLED IN INDIA

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BREAKING THE ACCESSIBILITY BARRIER DEVELOPMENT
OF SPECIAL COMPUTER ACCESS MECHANISMS FOR THE
NEURO-MOTOR DISABLED IN INDIA

• Presented By
• Animesh Mukherjee
• IIT Kharagpur

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A BRIEF INTRODUCTION

• In India, about 22 million people suffer from
  various kinds of disabilities.
• A large segment of the above population suffer
  from neuro-motor disorders.
• These disorders are caused by,
• Faulty development of motor areas in the brain,
  or,
• Damage of these motor areas.

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THE AFFECTED MOTOR AREAS OF THE BRAIN
The posterior (back) of the frontal lobe consists
of the premotor and motor areas. Nerve cells that
produce movement are located in the motor areas.
The premotor areas serve to modify movements.
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CONSEQUENCES

• Severe difficulty with fine motor tasks (like
  writing, stitching, using computer peripherals,
  and various other such tasks.)
• Severe difficulty with any kind of communication.

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AAC TECHNIQUES

• This population depends on various AAC techniques
  for their communication needs.
• These techniques may be based
• - On non-electronic communication boards
• Or,
• - On Computers

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PROBLEMS WITH COMPUTER BASED AAC TECHNIQUES

• Any computer based AAC system needs to be
  equipped with special mechanisms in order to make
  them accessible by this group of users.
• This is since they lack the fine motor control
  required to operate the peripherals like mouse,
  keyboard etc.

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PROBLEMS WITH COMPUTER BASED AAC TECHNIQUES(CONTD
)

• Access mechanisms commercially
• available are too costly for an average
• Indian user.
• Usually such systems come in special
• packages, the cost of which ranges
• from 600 to 6000

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OUR ENDEAVOR

• In response to this need we have tried to
• develop some AAC systems which are
• completely indigenous and available at an
• affordable price.
• In our paper we have mainly tried to
• discuss some of the access mechanisms
• tuned to these systems which are
• specifically meant for serving the purpose
• of the cerebral palsy (CP) affected users.

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COMPONENTS OF THE ACCESS MECHANISM

• Software Component
• - deals with making AAC system
• accessible to the user with
• special access devices
• Hardware Component
• - deals with the development of
• special hardware devices
• suitable for these users.

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THE SCANNING MECHANISMS

• Scanning refers to periodic focusing and
  defocusing of elements on a computer screen.
• The method of scanning can be broadly classified
  into two categories, namely
• - Co-ordinate Scanning, and,
• - Matrix Scanning

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CO-ORDINATE SCANNING

• Computer screen is thought of as a
  two-dimensional co-ordinate system.
• Each element is treated as a point.
• To get to specific point one or both the axes of
  the co-ordinate is made to sweep over the entire
  screen area.
• This movement can be either rotational or
  translational.

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POLAR SCHEME OF COORDINATE SCAN
Direction of movement of the mouse pointer
Direction of rotation of the axes
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CARTESIAN SCHEME OF COORDINATE SCAN
Direction of movement of the x-coordinate selector
Direction of movement of the mouse pointer
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MATRIX SCANNING

• The computer screen is thought of as a matrix.
• Screen elements correspond to the individual
  cells of this matrix.
• More suitable for applications with a known set
  regions that need to be frequently activated.

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VARIANTS OF MATRIX SCAN

• Three dimensional matrix scanning (block, row and
  cell levels).
• Two dimensional matrix scanning (row and cell
  levels).
• One dimensional matrix scanning (cell level).

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MATRIX SCAN ILLUSTRATED
Block Level Scan

Cell Level Scan
Row Level Scan
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STRATEGY FOR PLACEMENT OF ELEMENTS ON THE CELLS
OF THE MATRIX

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HARDWARE DEVICES

• Once an element of interest is reached by any of
  the scanning mechanisms the task left is to
  physically select that element.
• Special hardware devices called access switches
  are used for this purpose.
• Among such switches we have developed
• - Press switches
• - Touch Switches

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PRESS SWITCH

• With press switches, the modes
• of operation supported are,
• - Single switch mode,
• - Two switch mode,
• - Five switch mode.

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TOUCH SWITCH

• The modes of operation supported are,
• - Single switch mode,
• - Two switch mode.

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AN EXAMPLE AAC SYSTEM- THE VIRTUAL BENGALI
KEYBOARSD
Coordinate Scan
Matrix Scan