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									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
• 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
• 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 Diagram
Microcontroller Choices
        Microcontroller – Arduino
• ATMEGA328          • Open source
• USB Interface      • 32 KB Flash Memory
• Cross-platform     • Well documented
   Compass Module – HMC6352
• Simple I2C interface        • 1 degree repeatability
• 2.7 to 5.2 V supply range   • Supply current: 1 mA @ 3
• 1 to 20 Hz selectable         V
  update rate                 • 0.5 degree heading
                      Power Needs
                          Volts         milliamps
       Rangefinder         5V             2 mA

        DC Motors          3V            150 mA
         Compass           5V            10 mA

        Xbee 1 mW         3.3 V          50 mA
       Chip Antenna

• 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.
• SN754410 Quad Half H-
• Capable of driving high
  voltage motors using TTL
  5V logic levels
• Can drive 4.5V up to 36V
  at 1A continuous output
    Pololu QTR- 1RC Reflectance
• Operating Voltage : 5 V
• Supply current: 25 mA
• Max recommended
  sensing distance: 0.25”
• 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-
          XBee Chip Antenna
• 3.3V at 50 mA            • 300 ft range
• 250 kbps Max data rate   • 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
  • It has many holes and slots to
    mount the hardware
  • Low cost at $25
  • Able to turn on a dime
  • Light weight
• DC Motors
• RC Motors
• Stepper Motors
                    DC Motors
• Compact Size             • Low inertia
• High efficiency          • Reliable
  – Low current              – Longer service life
    consumption              – Low inductance
  – Low starting voltage
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
      Turn back

•If you are traversing an old path and you encounter a old
      Take a new path if available, otherwise take an old path

•If you encounter a dead end:
      Turn back
Mazes as Graphs
Mazes as Graphs
                         Graph Traversal
Search (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
  SeedStudio Ultrasonic Range Finder

• Efficient communication between
  the micro-controller
• Best if used in 30°
•   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    Part Name        # of Parts   Price
Pololu QTR-         4        $52.06   Xbee 1mW Chip         2        $69.75
    1RC                                  Antenna
Reflectance                            Xbee Wirless         2        $73.56
   Sensor                                Shield
Pololu Round        2         $25     H-Bridge Motor       10        $23.50
Robot Chassis                             Driver
SeeedStudio         2        $38.25    Arduino Uno          2        $59.90
Range Finder                             Arduino            1        $54.94
Bluetooth USB       2        $33.58     Starter Kit
 Module Mini
                                                          Total      $510.39
Xbee Explorer       2        $49.90
  Project Budget and Financing
• The Budget of just the Robot Parts
            Part Name           # of Parts    Price
         Pololu QTR-1RC             4        $52.06
         Reflectance Sensor
        Pololu Round Robot          2         $25
       SeeedStudio Ultrasonic       2        $38.25
           Range Finder
           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

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