Autonomous Visual rover

AUTONOMOUS VISUAL ROVER

Sean DayDiante ReidLiem Huynh

Project Overview

To create a vehicle that autonomously follows a moving object using color detection

To design a low cost, mobile robot that can track objects based on image processing

Implement all of the parts using the Atmel microcontroller

Track any color specified by the user

Requirements

Operate solely on 7.2 V Ni-Cad battery for at least 1 hour

Keep a minimum of 10 inches away from target at all time.

Have a dimension of no more than 12x15 inches

Track object within color range “0 80 0 80 50 255 “

Top Level DiagramCMUCam

2+

Maxbotix LV-EZ2

SensorsManage

rController

Actuators

Environment Images

UltrasonicSignals

PWM

Centroid and Servo Location

Target Location

Target Range

PWM

Software

Hardware

Environment

Target

Microcontroller - Arduino

ATMEGA328 USB Interface Cross-platform Easy to program Open source Well documented

Microcontroller Specs

Operating Voltage : 5V Digital I/O : 8 Pins PWM: 6 Pins Analog Input : 6 Pins Flash Memory : 32kB Clock Speed : 16 MHz Communication : UART

Printed Circuit Board

PCB123 software

$100 student credit from sunstone

Prototyped on the Arduino board

2 layer design Using through

hole and surface mount techniques

Image Processing Goals

Color detection Ability to distinguish between

specified color and other colors in environment

Detect centroid of specified object

Blob Detection

Middle Mass Determines if a group

of connecting pixels are related to each other by surroundings

Efficient in identifying separate objects in a scene

Image Processing Techniques

Edge Detection Canny detection Edges are areas

where a jump in intensity from one pixel to the next occurs

Able to reduce the amount of data processed by filtering out useless information

CMOS vs. CCD Sensor

CMOS CCD (charge coupled device)

Transistor based Flexible design Average picture

quality Low power

consumption Low Price

Analog device Rigid design Excellent picture

quality Power hungry Very Expensive

Choosing a Vision System

CMUcam1 CMUcam2 CMUcam3 AVRcam Logitech QuickCam Orbit AF Webcam

+ RoboRealm

CMUcam Comparison

Price Frame Rate Resolution RAM ROM SPEED

CMUcam1 $109.99 17 fps 80x143 136 bytes 2048 words 75 MHz

CMUcam2 $179.99 50 fps 176 x 255 263 bytes 4096 words 75 MHz

CMUcam3 $239.99 26 fps 352x288 64 KB 128 KB 60MHz

AVRcam $99.00 30 fps 88x144 700 bytes 512bytes 16MHZ

CMUcam2+ Vision Sensor

•Performs image processing duties for AVR•Track user defined color blobs at up to 50 Frames Per Second•Track motion using frame differencing at 26 Frames Per Second•Gather a 28 bin histogram of each color channel•Process Horizontally Edge Filtered Images

Why CMUcam2+

Compact Size Frame Buffering Affordable price Multiple Servo

Control User Support Histograms

CMUcam2+ Software Open Source

Programmable CMUcamGUI Allows user to see

from camera’s perspective

Power NeedsPart Watts

Ultrasonic Sensor

50mW

H-Bridge 10WSteering Servo 75mW

CMU cam2+ 1.5W

Voltage Regulation

All parts on AVR can run off of 5volts DC

 Stepping Down 7.2 Volt battery

LM7805 regulator

Ultrasonic Sensor Objectives

Purpose is to keep AVR within 10 inches of target object

Be able to fit on front bumper Will not loose the target object Low power consumption

Ultrasonic Sensor ComparisonSensor Model

Price Size Output Power

SRF08 $64.00 1.7” x .79” x .67”

Analog/Digital

75mW

Ping Range Finder

$29.95 0.85 “ x 1.8 “ x 0.6 “

PWM 100mW

Maxbotics $27.95 .79 “ x .87 “ PWM/Analog

10mW

Maxbotics Ultrasonic Sensor Maxbotics EZ2 Will easily fit on

bumper Only draws 2mA of

current Easy to interface

Interfacing the Sensor

Pulse Width Modulation 147 microseconds/inch

Analog Input (Vcc/512)/inch

Communication RS-232 Serial Predetermined distance controlled by C

progam

H-Bridge

Pololu High-Power Motor Driver 18v15

70A stall current 1.3” x 0.8” 15A continuous

output Max PWM

frequency 40Hz

Batteries

Chassis

4 wheel drive 2 front turning

wheels 2 rear wheels for

going backward and forward

1 DC motor 1 Hobby servo Rooms for

expansion

DC Motor

Speed 19,200 Rpm

Stall Current 32A

No Load current 1.3A

Operating Voltage 3.6 to 6V

HiTec HS-311 Servo

Pan, Tilt, Steering

Max speed .15sec/60 °

Stall Torque 42 -49 oz/in

Operating Voltage 4.8-6.0V

Sensors Manager

getRange() Returns range from Ultrasonic Sensor in

inches getCentroid()

Returns centroid location of target in x and y format

getPan() Returns location of panning servo

getTilt() Returns location of tilting servo

Centroid tracking Tracking the object’s centroid

1 44 88

Coordinate Transformation CMUcam to Body alignment Body Frame, CMUcam Frame

β

Servo Positions

128, 0°

210, 90°46, -90°

β Servo Pos

Offset

-90° 46 -440° 128 090° 210 44

Offset = 44 sin( β )

Centroid_B = Centroid_C + Offset

Negative Stop Positive Stop

Navigation Flowchart

Initialization

ForwardStraight

Forward Right

yes

no

Object's range <=10

inches?

Centroid > 54Forward

Left

Centroid < 34

else

Stop

Object's range = 10

inches? yes

Reverse

no

yes

yes

yes

Object Found?

noyes

Good Detection?

no Enter Search Mode

Search Mode If no detection is found, AVR will go

into search mode Pan from negative stop to positive

stop (180°)

Pan leftObject Found? Servo Pos

> -90° & < 0?

no

yes

no

Pan rightObject Found?

Servo Pos < 90°?

no

yes

noExit

yes

yes

No detection

Fault-tolerance

AVR stores the last 10 detections into an array: 1 for hit 0 for miss

Confident level is defined by taking the average of the stored values

If confident level > 70% then it’s a good detection

1 1 1 0 0 1 1 0 1 1

Confident level= 70% Good Detection!!

Proportional Controller

P (Range) Plant+

-

Input Output

Error

• Variable speed depends on range from target• P gains need to be tuned• All control process is done through software

Testing

DC Motor/ H-bridge test Range Finding Test CMUcam2+ Pan and Tilt Test

Testing

Locomotion test with ultrasonic sensor stationary target

Locomotion test with ultrasonic sensor moving target

Locomotion test with CMUcam2+ with stationary target

Locomotion test with CMUcam2+ with moving target

Locomotion test with all sensors

FinancesPart

NumberPart Name Qt

y

Expected Cost

Real Cost

Development Cost

Order Date

Manufacturer

N/A Basic Breadboard

1 $11.95 $11.95 $11.95 6/30/09 SparkFun

LV-EZ2 Ultrasonic Range Finder Maxbotix LV-

EZ2

1 $27.95 $27.95 $27.95 6/30/09 Maxbotix

N/A Arduino Starter Kit

1 $49.95 $49.95 $49.95 6/30/09 Arduino

SN754410

H-Bridge 3 $12.00 --- $12.00 7/21/09 Texas Instruments

R245-CMUCAM2+-Plus

CMUcam2+ 1 $169.00 $169.00 $169.00 7/21/09 Acroname

FT232R USB to Serial kit

2 $29.00 $29.00 $58.00 7/21/09 FTDI Chip

n/a Battery/charger 2 $55.45 $55.45 $55.45 8/28/09 Tenergy

HS-311 RC servo 2 $25 $25 $25 9/3/09 HiTec

ROB-09107 H-Bridge 1 $39.95 $39.95 $39.95 11/01/09 Pololun/a Chassis 1 $109.00 $109.00 $109.00 10/01/09 Exceed-RC

LM 7805 Voltage Regulator 6 $10.00 $10.00 $10.00 9/01/09 Fairchild Semiconductors

n/a PCB 2 $100.00 $0.00 $100.00 11/12/09 Sunstone

n/a Miscellaneous 17 $25.00 $25.00 $25.00 --- ---

Total Cost --- 40 $664.25 $552.25 $693.25 --- ---

Thank you, feel free to ask any questions…please come next door for demo