Assistive Technology Computer Mouse Movement for Quadriplegics

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Assistive TechnologyComputer Mouse Movement for
Quadriplegics
February 10th, 2004
Senior Engineers Joseph Lee (COEN) Jarrod
Tsukada (ELEN) Advisors Dr. Shoba
Krishnan Dr. Neil Quinn
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Abstract

• Designing and implementing a system that will
  track the movements of a users head to control a
  computer mouse cursor.

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Motivations

• Main focus directed at individuals without full
  functionality of their hands
• Create a reliable, accurate system that is easy
  to control
• Cost-effectiveness
• Many existing systems do not fulfill these
  requirements

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Existing Technology

• Gyroscope technology
• Infrared technology
• Camera Eye tracking technology
• Mechanical sensory
• Touch-pads, trackballs and alternate hand clickers

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Design Rationale

• Several Designs were considered
• Eye tracking
• Cheek, tongue or face movement for control
• Touch-screen style monitors (but with use of
  lasers)
• Sensors along the outside of the screen
• Physical devices for clicking

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Design Rationale

• Final design is a combination of ideas
• Laser and camera used together to control mouse
  cursor
• Initially camera was to track the user
• Revised camera tracks laser pointer controlled
  by users head.
• Mouse click controlled by eye blink.
• Decision based on comfort and userability factors.

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User Diagram
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User Example
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Design Rationale

• Movement Design
• Pointing Camera at Monitor
• Relative Positioning vs. Exact Positioning

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Design Rationale

• Mouse Click
• Photodiode vs. physical device
• Use of Ambient light / Photodiode

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Design OVERVIEW

• Two Models
• Initial Prototype
• Final Model

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Design ELEN

• Mouse Movement Data
• Mouse Signal Reproduction
• Photodiode Clicking Circuit

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Design ELEN

• Mouse Movement Data
• Bit streams produced by PS2 Microsoft Mouse

Will be reproduced by Xilinx Tools
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Design ELEN

• Xilinx FPGA Mouse Signal Reproduction

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Design ELEN

• Photodiode Clicking Circuit

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Design COEN

• Image processing
• PS2 input / Parallel bit stream output
• Compacting code into interface device

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Design COEN

• Image processing Pseudocode
• //Initialize Camera, and grab initial frame
• coordinate1 compute avg. coordinate of laser
  pointer
• while(1)
• grab frame
• coordinate2 compute avg. coordinate of laser
  pointer
• compare coordinates
• send appropriate signal
• coordinate1 coordinate 2

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Design COEN

• Image processing
• Noise
• Error correction
• PS2 input / Parallel bit stream output

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Challenges

• Photodiode operation
• Compacting code into interface device
• Interpreting inconsistent photodiode signals

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Questions Answers

• Thank you for your time and contribution