Transcript Object Detection for the Visually Impaired

Object Detection for the
Visually Impaired
Justin Rice
Christopher Zeh
Zac Bond
Casey Morford
Motivation
• Enhance the lives of the visually
impaired through the creation of a
wearable tool
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Locate near and distant obstacles
Detect nearby people
Create inconspicuous system
Eliminate the need for a cane
Design Decisions
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Ultrasonic transducers to locate objects
Pyroelectric sensors to detect people
Tactile output using vibrational motors
Microcontrollers for processing the
inputs and regulating the output
Design Decisions
• Criteria for choosing sensors
– Range of detection
– Angle of coverage
– Cost
• Criteria for choosing microcontroller
– Input and output capability
– Cost and availability
Ultrasonic Sensors
• Previous work (Bomber Belt)
– 15 ultrasonic transducers on belt
– Sampled sequentially clockwise
– Communicates serially with PIC that
determines time of flight
Ultrasonic Sensors
• Modification to Bomber Belt system
– PIC polls only the five front sensors ten
timers per second
– PIC computes a distance estimate for
objects to the left, right, and middle
– Uses predefined thresholds to indicate the
relative closeness of objects detected
Pyroelectric Sensors
• RE200B Infrared detector
– Differential pair of sensors to cancel out
background heat sources
– Tuned to 8-14 µm for human detection
– Needs amplifier to boost 20mVpp output
– Unreliable, but manageable, output
Tactile Display
• Yokyo Parts FM31E
– 3 small vibrating motors (1/2 inch diameter)
– 4500 rpm @ 3V input
– Requires driver circuit to supply enough
current
Tactile Display
• 3 output motors: left, right, and center
• 5 vibration intensities
– Fully off for no objects or people
– 3 distance based levels
– Extra pulses for human detection
• Attached to Bomber Belt in final system
Microprocessors
• PIC18F242
– Time of flight computation for ultrasound
– Communicates sensor readings serially
• HC11 with Fox11 Development Board
– Reads in serial output from PIC
– Reads in pyroelectric data on input channel
– Sends control signals to motor driver circuit
Ugly Prototype
• Demonstration
– Ultrasonic transducers from the Bomber
Belt perform range finding
– Pyroelectric sensors detect moving people
– Motors vibrate according to distance
– All subsystems reside on different boards
– Wear the belt at your own risk (~400 V
pulses)
Future Work
• PIC and HC11 programs merged onto
one device
• Replace our 3 power supplies and 2
batteries with a single battery pack
• Sleeker, more stylish design
– Everything on one board
– Make it pretty
Questions?