PADSParaplegic Assisted Driving System

Aaron BroomeRobert GrahamLamar TurnbullTylor PalumboErick Moton

Georgia Institute of TechnologyECE 4007 Moore

Fall 2010

Project Overview Autonomous speed control system

Provide paraplegics with an alternative means of transportation through the use of the following:○ Linear Actuator controlled acceleration/braking○ Updated speed and related information display ○ LED display○ Accurate speed calculation○ 4-color recognition (Red, green, blue, black)○ Manual override switch for emergency shutdown and

reset

Equipment Cost: $654

Technical ObjectivesAutonomous Speed Control

Use object recognition to detect 3 speed zones and stop sign

○ Matlab RGB color detection

Calculate speed and compare with latest detected sign

○ Measure revolutions/sec from PIC timer and counter ○ Compare with RGB values obtained from Matlab

Control gas/brake pedal to adjust to desired speed

○ High/low output logic from PIC sent to H-bridge based on color and speed

Project GoalsGoals

Proposed Specifications

Actual

Specifications Units

Response Time for Matlab to recognize signs < 1 < 1 sec

Refresh rate of speed calculation < 1 0.5 sec

Time required to completely stop vehicle from maximum speed

< 7 < 7 sec

Time required to adjust speed for new speed zone ≤ 5 ≤ 5 sec

Achieve accurate speed for speed zone ± 2 ± 2 mph

Accurate reading of zone colors (Red (STOP), Blue (5 mph), Black (10 mph) Yellow (13mph))

± 20 N/A RGB

Prototype Design OverviewLaptop w/ USB camera

& Matlab

Hall Effect Speed Sensor

4” and 6” Linear Actuators

Golf Cart

Qwikflash (PIC18F452) Development Board

Prototype Design Overview

Linear Actuators

Qwikflash Development Board

H-Bridge

Hall Effect Speed Sensor

Hardware Block Diagram

Hall Effect Speed Sensor

Laptop with USB Camera Serial Connection

Dual H-Bridge

4/6” Linear Actuators

12V Sealed Lead Acid Battery

Qwikflash Board

Linear Actuator Installation

Dimensions: 20”x16”16.5”

Prototype Design & Description

Prototype currently works as desired in each speed zone. Desired specifications hit or miss

Tests:Color Recognition Time: Matlab Timing FunctionZone Reaction Times: Real-time road tests

Testing ResultsGoals

Desired Specifications Tested Values Units

Response Time for USB cam to recognize signs

<1 0.22 Sec

Time required to completely stop vehicle from different

speeds<7

5mph - 5.86Sec10mph - 6.70

13mph - 7.82

Time required to adjust speed for new speed zone

≤ 5

5mph-10mph – 14.4

Sec5mph-13mph – 17.8310mph-13mph – 8.9410mph-5mph – 17.6713mph-5mph – 15.09 13mph-10mph – 8.52

Achieve accurate speed for speed zone

± 25mph – 5.35mph

Mph10mph – 9.99mph13mph – 12.84mph

Procedure Flow Diagram

Counter/Timer0 Speed Sensor Pulse (Input Port Signal)

LCD DisplayRS232 Send/Receive

Subroutine

H-Bridge (Output Port Signal)

Webcam Color Detection

Speed Calculator

RS232 Send/Receive Subroutine

Speed/Color Combined Response

Subroutine

Matlab OperationsPIC18F452 Operations

Pushbutton (Reset)

Hall Effect Speed Sensor Speed Calculation

Matlab Object Recognition

Problems & SolutionsSpeed Calculation via Timer/Counter

Refresh rate for reading input pulses/sec

Color Sensing and Object RecognitionRGB threshold for various lighting conditions

Number of Magnets Mounted to WheelQuality of sample used to calculate speed

Linear Actuator Response Timing

.5 seconds used as refresh in order to keep speed updated at a regular rate

RGB value threshold was eliminated due to lack of time

8 strips of magnets were attached to wheel to increase accuracy of speed calculation

Linear actuator set to extend and/or retract for one second every response period

Budget AnalysisPart Name Cost

CMUcam2 $109

Actuators $180

Magnetic Sensor

$20

Microcontroller $205

Actuator Housing

$60

Power Supply $80

Total $654

Project Budget: $440

Amount spent to date: $439.79

Microcontroller provided by Georgia Tech Savannah

Future Work The PADS prototype

system can be continued by future ECE students with additional work that could consist of the following: Implementation of LIDAR

for object avoidance Autonomous control of

the steering wheel GPS-assisted route

navigation

Additional information located on project website: http://www.tinyurl.com/gtsavseniordesign

Questions