Administrative Introduction

• Our goals for this project is for the two robots to work together intelligently using wireless communication

• Not only did we want a cost effective robot we wanted to make the whole process of an autonomous robot solving a maze more efficient and faster.

Project Goals• To build 2 robots that work together to navigate a

maze

• The robots must communicate wirelessly and analyze information intelligently

• The robots must use each other’s information to gain information on how to solve the maze

• The robots should be able to figure out where and how far the walls are from them and record which routes have been taken to learn the maze

Specifications and Requirements

• 2 robots that communicate through a wireless connection

• The base of the vehicle should be able to rotate 360°• The code should execute immediately and the robots

should not pause longer than 10s • Robots should be able to measure their distance from

the wall to a degree of error not greater than 4 cm• Robots should be able to store maze information and

send it• The robot should be able to identify dead ends in no

more than 5s• Each robot should cost less than $150 to construct

System Design DiagramSystem Design Diagram

Microcontroller Choices

Microcontroller – Arduino Duemilnaove

• ATMEGA328

• USB Interface

• Cross-platform

• Open source

• 32 KB Flash Memory

• Well documented

Compass Module – HMC6352

• Simple I2C interface

• 2.7 to 5.2 V supply range

• 1 to 20 Hz selectable update rate

• 1 degree repeatability

• Supply current: 1 mA @ 3 V

• 0.5 degree heading resolution

Batteries

Power Needs

Volts milliamps

Rangefinder 5 V 2 mA

DC Motors 3 V 150 mA

Compass 5 V 10 mA

Xbee 1 mW Chip Antenna

3.3 V 50 mA

• From testing we discovered that it was beneficial to power the motors and the microcontroller separately with a 9 V battery and a 4.5 V DC battery.

H-Bridge

• SN754410 Quad Half H-Bridge

• Capable of driving high voltage motors using TTL 5V logic levels

• Can drive 4.5V up to 36V at 1A continuous output current

Pololu QTR- 1RC Reflectance Sensor

• Operating Voltage : 5 V• Supply current: 25 mA• Max recommended

sensing distance: 0.25” (6mm)

• Optimal sensing distance: 0.125” (3mm)

• Digital I/O compatible

Xbee Shield

• Mounts directly onto your Arduino

• 3.3V power regulation and level shifting on-board

XBee Chip Antenna

• 3.3V at 50 mA

• 250 kbps Max data rate

• 300 ft range

• 6 10-bit ADC input pins

• 8 digital IO pins

Base Vehicle• In deciding the body of the autonomous

robot a number of concerns came into play.

• The robot needs to be sturdy yet lightweight in order to mount all the additional parts

• The robot must be able to turn on a dime and navigate corners in order to travel the maze effectively

• The platform of the robot should be a disc like shape

Navigational system• The navigational system we had to choose from

– Two wheel

• Light Weight

• More effective in maneuvering the maze

• Cost effective

– Three wheel

• Center of gravity is in a triangular shape which makes it very easy to fall

• Does not perform well on any form of rough terrain

• Not as efficient or cost effective

– Four wheel

• Its much harder to build and much more costly

Frame of Vehicle– Pololu Round Robot

Chassis• It has many holes and slots to

mount the hardware

• Low cost at $25

• Able to turn on a dime

• Light weight

Servos

• DC Motors

• RC Motors

• Stepper Motors

DC Motors

• Compact Size

• High efficiency– Low current

consumption

– Low starting voltage

• Low inertia

• Reliable– Longer service life

– Low inductance

Labyrinth

Simply Connected Maze

Disjoint Maze

Tremaux's Algorithm•If you encounter a new junction:

Pick a direction at random

•If you are traversing a new path and you encounter an old junction:

Turn back

•If you are traversing an old path and you encounter a old junction:

Take a new path if available, otherwise take an old path

•If you encounter a dead end:

Turn back

Graphs

Mazes as Graphs

Mazes as Graphs

Graph TraversalSearch (Vertex startV)

List vertices = empty List

Set visited = empty Set

Add startV to vertices

while (vertices is not empty)

{

Vertex V = remove element from vertices

if (visited does not contain V)

{

// Handle V here

// (e.g. check if destination Vertex)

Add V to visited

for every Vertex X connected to V

if (visited does not contain X)

Add X to vertices

}

}

}

Constructing the Maze

SeedStudio Ultrasonic Range Finder

• Breadboard friendly• Arduino library ready• Light weight• Wide range from 3cm – 400

cm

SeedStudio Ultrasonic Range Finder

• Efficient communication between the micro-controller

• Best if used in 30°

Testing

• DC Motor/H-Bridge wheels test

• Chassis test with wheels turning on axis

• Rangefinder test

• Compass test

• Pololu QTR- 1RC Reflectance Sensor Test

Project Budget and Financing• The Budget to the End of the Project

Part Name # of Parts Price

Pololu QTR-1RC

Reflectance Sensor

4 $52.06

Pololu Round Robot Chassis

2 $25

SeeedStudio Ultrasonic

Range Finder

2 $38.25

Bluetooth USB Module Mini

2 $33.58

Xbee Explorer Dongle

2 $49.90

Part Name # of Parts Price

Xbee 1mW Chip Antenna

2 $69.75

Xbee Wirless Shield

2 $73.56

H-Bridge Motor Driver

10 $23.50

Arduino Uno 2 $59.90

Arduino Duemilanove

Starter Kit

1 $54.94

Total $510.39

Project Budget and Financing

• The Budget of just the Robot PartsPart Name # of Parts Price

Pololu QTR-1RC Reflectance Sensor

4 $52.06

Pololu Round Robot Chassis

2 $25

SeeedStudio Ultrasonic Range Finder

2 $38.25

Arduino Uno 2 $59.90

H-Bridge Motor Driver 2 $4.70

Xbee Wireless Shield 2 $49.90

Xbee 1mW Chip Antenna 2 $45.90

Total $270.71

Questions?