Object Detection for the Visually Impaired

Justin RiceJustin RiceChristopher ZehChristopher Zeh

Zac BondZac BondCasey MorfordCasey Morford

MotivationMotivation

• Enhance the lives of the visually Enhance the lives of the visually impaired through the creation of a impaired through the creation of a wearable toolwearable tool– Locate near and distant obstaclesLocate near and distant obstacles– Detect nearby peopleDetect nearby people– Create inconspicuous systemCreate inconspicuous system– Eliminate the need for a caneEliminate the need for a cane

Design DecisionsDesign Decisions

• Ultrasonic transducers to locate objectsUltrasonic transducers to locate objects• Pyroelectric sensors to detect peoplePyroelectric sensors to detect people• Tactile output using vibrational motorsTactile output using vibrational motors• Microcontrollers for processing the Microcontrollers for processing the

inputs and regulating the outputinputs and regulating the output

Design DecisionsDesign Decisions

• Criteria for choosing sensorsCriteria for choosing sensors– Range of detectionRange of detection– Angle of coverageAngle of coverage– CostCost

• Criteria for choosing microcontrollerCriteria for choosing microcontroller– Input and output capabilityInput and output capability– Cost and availabilityCost and availability

Ultrasonic SensorsUltrasonic Sensors

• Previous work (Bomber Belt)Previous work (Bomber Belt)– 15 ultrasonic transducers on belt15 ultrasonic transducers on belt– Sampled sequentially clockwiseSampled sequentially clockwise– Communicates serially with PIC that Communicates serially with PIC that

determines time of flightdetermines time of flight

Ultrasonic SensorsUltrasonic Sensors

• Modification to Bomber Belt systemModification to Bomber Belt system– PIC polls only the five front sensors ten PIC polls only the five front sensors ten

timers per secondtimers per second– PIC computes a distance estimate for PIC computes a distance estimate for

objects to the left, right, and middleobjects to the left, right, and middle– Uses predefined thresholds to indicate the Uses predefined thresholds to indicate the

relative closeness of objects detectedrelative closeness of objects detected

Pyroelectric SensorsPyroelectric Sensors

• RE200B Infrared detectorRE200B Infrared detector– Differential pair of sensors to cancel out Differential pair of sensors to cancel out

background heat sourcesbackground heat sources– Tuned to 8-14 Tuned to 8-14 µm for human detectionµm for human detection– Needs amplifier to boost 20mVpp outputNeeds amplifier to boost 20mVpp output– Unreliable, but manageable, outputUnreliable, but manageable, output

Tactile DisplayTactile Display

• Yokyo Parts FM31EYokyo Parts FM31E– 3 small vibrating motors (1/2 inch diameter)3 small vibrating motors (1/2 inch diameter)– 4500 rpm @ 3V input4500 rpm @ 3V input– Requires driver circuit to supply enough Requires driver circuit to supply enough

currentcurrent

Tactile DisplayTactile Display

• 3 output motors: left, right, and center3 output motors: left, right, and center• 5 vibration intensities5 vibration intensities

– Fully off for no objects or peopleFully off for no objects or people– 3 distance based levels3 distance based levels– Extra pulses for human detectionExtra pulses for human detection

• Attached to Bomber Belt in final systemAttached to Bomber Belt in final system

MicroprocessorsMicroprocessors

• PIC18F242PIC18F242– Time of flight computation for ultrasoundTime of flight computation for ultrasound– Communicates sensor readings seriallyCommunicates sensor readings serially

• HC11 with Fox11 Development BoardHC11 with Fox11 Development Board– Reads in serial output from PICReads in serial output from PIC– Reads in pyroelectric data on input channelReads in pyroelectric data on input channel– Sends control signals to motor driver circuitSends control signals to motor driver circuit

Ugly PrototypeUgly Prototype

• DemonstrationDemonstration– Ultrasonic transducers from the Bomber Belt Ultrasonic transducers from the Bomber Belt

perform range findingperform range finding– Pyroelectric sensors detect moving peoplePyroelectric sensors detect moving people– Motors vibrate according to distanceMotors vibrate according to distance– All subsystems reside on different boards All subsystems reside on different boards – Wear the belt at your own risk (~400 V pulses)Wear the belt at your own risk (~400 V pulses)

Future WorkFuture Work

• PIC and HC11 programs merged onto one PIC and HC11 programs merged onto one devicedevice

• Replace our 3 power supplies and 2 Replace our 3 power supplies and 2 batteries with a single battery packbatteries with a single battery pack

• Sleeker, more stylish designSleeker, more stylish design– Everything on one boardEverything on one board– Make it prettyMake it pretty

Questions?Questions?