SDP Presentation 1

STEVI: Sensory Technology Enhancement

for the Visually Impaired

10/20/2009

Preliminary Design Review

Alex Starosielski Signal Processing Web-Developer

Brendan Gavin Sensors / Integration Treasurer

Charbel Kobrianos Sensors / Integration Team Administrator

Yi Lin Feedback / Integration Slide Developments

Team Vouvakis

Electrical and Computer Engineering

SDP Presentation 2Electrical and Computer Engineering

The Problem

The visually impaired can not navigate without assistance.

•Cane

•People

•The Guide Dog

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Long Cane

• Common Solution

•Simple, cheap, robust and reliable

• Limited range

• Problems with obstacles above waist.

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Electronic SolutionsElectronic Travel Aids (ETAs) • Detect obstacles with sensors

•Typically ultrasonic

• Indicate obstructions to user

•Feedback often auditory or tactile

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Limitations of Existing Electronic Aids

•Expensive! $400 to $1000

•Trouble with stairs and slopes

•Insufficient directivity

•Problems with reflections indoors

•Problems with absorbing objects

Requirement Specifications

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Society Needs Engineering Constraints Project Specs

Form Factor Handheld Size 5in x 5in x 2in (handheld)

Detection Range

0 – infinity Power and price 0.5-4m

Detection Angle

0 – 180° User interface and signal processing 20°

Obstacle sizes

All sizes Limitations of sensors > 3in x 3in

Cost Free Part, manufacturing and labor costs < $400

Battery Life Infinite Size, power consumption > 7 hours

Weight Negligible Hardware mass < 3 lbs

Big Picture

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Proposed Solution - STEVI

Sensor Fusion!

Auditory & Tactile Feedback

Ultrasound Laser Infrared

Small Objects X

Slanted Surfaces X X

Directionality X

Reflections Signal Processing

Absorbent Objects Signal Processing

Block Diagram - Basic

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Block Diagram - Intermediate

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Block Diagram – Full Function

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Ultrasonic Sensors2 x Maxbotix UT

• Average time of flight to calculate distance

• Angle calculated from difference in signal return times

c = speed of sound in air = 343 m/s

www.sparkfun.com

SDP Presentation 13Electrical and Computer Engineering

Laser

• Detect distances with triangulation

• Used for handling stairs, curbs, angled walls and smaller objects

•(1/3-inch Sony Supper HAD Color CCD Wired Mini Pinhole Camera

Camera view:

Setup:Sony Supper HAD

www.lightinthebox.com

Infra Red

• Detect closer objects

• Prevents user from hitting objects while sweeping left and right

www.sparkfun.com

• Has a viewing angle of 40 deg.

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Microcontroller

• 3 x 28 pin ATMega88PA• Features: • 8kB Program Space • 20 MIPs at 20 MHz

• 23 I/O Lines, 6-channel 10 bit ADC• In-circuit programming - JTAG

www.digikey.com

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User Feedback

3 x ROB-08449 Vibrating Motor

• Closer obstacle - stronger vibrations• Vibrating pad location - obstacle direction• Alternative Feedback - Audio Jack

www.sparkfun.com

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Prices

Component Cost

Microcontrollers (3)www.digikey.com

$8

Vibrating Motors (3)www.sparkfun.com

$15

IR Emitter/Detector (2)www.sparkfun.com

$4

Ultrasonic Transducers (2)www.sparkfun.com

$10

Laser/Camera Assemblywww.allelectronics.com

$140

PCB Fabrication $100

Total Cost $277

Initial Balance $500

Net Savings $223

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Proposed MDR Deliverables

Demonstration of Ultrasonic Detection• Block Diagram 2 • Ultrasonic Transducers• Transducer Microcontroller• Vibrating Motor Array

Principles of Laser Detection• Laser and Camera• Computer Processing

Gantt Chart of STEVI

Thank You

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