The Low Cost Autonomous Mobile Robot

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The Low Cost Autonomous Mobile Robot
By Byron Johns Mentor Dr Emmanuel Collins
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How Did I Make It? (built from scratch)

• 30 Gauge Thin Aluminum Sheet Metal
• Aluminum Stock (base)
• Aluminum Bar Stock
• Steel Tubing Rod used as a load support
• Rubber Tubing placed around side panels

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Removable Side Panels

• Convenient access into robot
• Attach easily with Velcro.
• Rubber tubing placed around edges to prevent
  injury.

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What drives it?

• OMNI-DIRECTIONAL WHEEL

• Drive train cut out of 2 thick aluminum stock
• High torque gear motors placed securely in drive
  train.
• Bevel gears mounted at 90 angle with the axles
• Sports Tire wheel set

• High Torque DC Motor

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What Does This Cool Thing Do?

• Detect stationary and moving objects (humans,
  pets, etc.)
• Perform wall-following (maneuver through a simple
  maze)
• Scan or sweep a room or area for objects
• Measure its own distance traveled
• Be set to travel a certain distance
• Equipped with a bumper in case it runs into an
  object

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The Brain

• The Handy Board
• HC11 micro controller system to build for robots
  various purposes
• 32K memory
• 16K of memory is used for your programs (my
  largest program was 5K)
• Uses Interactive C, which allows you to easily
  write and compile C programs and download them
  into the Handy board's memory.
• Output drivers for 4 DC motors
• Analog and Digital inputs. Digital Outputs.
  Works with sensors.
• LCD Screen to display whatever you want
• Internal, rechargeable battery pack.

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The Expansion Board

• 10 additional analog sensor inputs
• 4 inputs for reflectance sensors and shaft
  encoders
• 9 digital outputs
• 6 servo motor control signals
• optional external power for servo motors
• connector mount for Polaroid 6500 Ultrasonic
  Ranger

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Digital Infrared Sensor Micro Switch

• Digital infrared sensor
• Emits infrared beam off of an object and reports
  a logic value (0 or 1) if an object is detected
  in the path.
• maximum range at 12
• can be interfered by light and reflectivity of
  the target

• Digital Micro Switch
• Basic touch switch used on robot as a bumper.

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SRF04 Sonar Ranger

• ultrasonic ranger with wide range (1 inch 10
  feet!)
• Minimal power requirements (5V)
• sends out an ultrasonic ping, and measures the
  time it takes to receive echo.
• connects to the digital I/O lines of the Handy
  Board
• only one can be used on handy board at a time

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Infrared Sensor
Digital Switch
Sonar SRF04 Ranger
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Motion Detector

• uses a sensitive FET (field-effect transistor)
• detects infrared energy
• human body is about 93ºF and radiates infrared
  energy (a form of light ??10?m)
• sensor is made sensitive to wavelengths between
  8 ?m and 12 ?m (to detect human heat)
• Detects motion by detecting rapid change in
  infrared energy
• wide range of view due to lens, which allows you
  to bend and focus light

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Servo Motor

• efficient, easy way to precisely position or
  move things
• useful for lightweight robots
• Rotates at about 180. Can be modified to
  rotate at a full 360.
• High torque
• Only need 4.8V-6V DC.

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Servo Motor with rod attached to Motion Detector
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Shaft Encoder

• U-shaped so that it constantly transmits and
  receives an infrared beam when turned on.
• Two of these can be interfaced with Handy Board
  at a time
• Used to measure distance robot moved and its
  speed
• Works best with LEGO 6-hole wheel.

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Future Add-Ons

• Place bumper switches around entire robot or just
  the front.
• Replace the front Infrared Sensor with Sonar
  Ranger
• Attach more Infrared Sensors around top of robot
  to detect objects around it.

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More Future Additions

• Digital Compass
• High-performance magnetic field sensing
• Remote terrestrial antenna direction indicators
• operates at only 3V

• CMU Cam
• low-power sensor for mobile robots which does
  different kinds vision processing
• track position and size of a colorful object
• dump complete image over the serial port
• acquire and track objects

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Reference Books

• Robotic Explorations
• Fred G. Martin
• Prentice Hall 2001
• Introduction to Autonomous Mobile Robots
• Roland Siegwart, Illah R. Nourbakhsh
• Massachusetts Institute of Technology 2004

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Acknowledgements

• Dr. Emmanuel Collins
• FAMU/FSU Mechanical Engineering Professor
• Dr. Carl Moore
• FAMU/FSU Mechanical Engineering Professor

THE END!