Wireless Networks for Multi-Robot Communications

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Wireless Networks for Multi-Robot Communications

• Creating a Sensor Network of Robots.

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Project Purpose

• Create a sensor network of robots that, together,
  achieve a shared goal.

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What is a Sensor Network?

• A sensor network contains multiple devices.
• Each device has devices on it that can sense
  conditions of the outside world, or sensors.
• Each device communicates to other devices in
  order to achieve a shared goal.

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Advantages of Sensor Networks

• Jobs can be complete with large numbers of units
  in parallel
• Redundancy Each unit of the network can be
  destroyed with little to no damage to the network
  as a whole

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Jobs of Sensor Network

• Surveillance Sensor network can cover a large
  are, and collate the data before it reaches the
  user
• Search Sensor networks can cover multiple parts
  simultaneously for quicker results.
• Remote Monitoring and Control

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Design Problem

• Develop a wireless communication network for
  multi-robot teams. This network, preferably made
  with radio frequency transceivers, plus the on
  board sensors of the robots themselves, will form
  a sensor network, in order to locate a light
  source.

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Existing Implementations

• DARPA has sponsored a project for smart dust a
  sensor network of thousands all small enough to
  float in the wind, to be used for surveillance.

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TinyOS and TinyDB

• Part of the DARPA project is the creation of an
  embedded operating system to run units on the
  sensor network, called TinyOS, and a data
  gathering utility, TinyDB

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RFID Tags

• These tags are small devices that transmit an ID
  number when hit with a radio frequency.

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Design Constraints

• The project must
• Maneuver around objects.
• Search for target.
• Realize it has found target.
• Signal other robots.
• Search for robot that signals.
• Wait for turn to communicate.
• Not interfere or be interfered with in terms of
  RF communications.

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Design Constraints

• The project should
• Be easy to modify system behavior.
• Be easy to interface.
• Use parts and tools readily available.
• Sense obstacles to avoid contact.
• Use small enough area to ensure the RF
  transmitters can reach all distances.

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Feasibility Study

• Show the project is physically, technically, and
  economically feasible in the time available.
• Similar projects have been successfully
  completed.
• Can use past projects for guidelines and ideas.
• Budget is within reason.
• Using mature technologies such as RF and
  photocells.
• Easy to interface with robots.

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Survey of Products

• AmigoBot (ActiveMedia)
• Khepera (K-Team)
• Trilobot (Arrick Electronics)
• Hexapod (LynxMotion)
• Boebot (Parallax)

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AmigoBot

• Comes with battery and battery charger
• Comes with AmigoOS and AmigoBot User Guide
• Great Indoor/Outdoor range
• Comes with various packages (e.g. Wirefree)
• Too Expensive

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Khepera

• Not Enough Payload to add on RF products
• Shorter whiskers than Boebot
• Light, compact design
• Limited kits available

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Trilobot

• Heaviest of all robots
• 8 whiskers around base
• 4 light level sensors
• Digital tempature sensor
• Engineered for easy expansion
• Once again

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Hexapod

• Never specified payload
• Lacking Documentation and manuals
• Affordable Price

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Boebot

• Comes with BasicStamp2
• Get Full Kit with each robot purchase
• Extensive Documentation and very adaptable
• Price is right!

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Budget

• Product Quantity
  Price
• Boebot Full Kit 5
  1145.00
• (w/shipping) 1157.28
• Transmitter (TWS-434) 5
  38.25
• Receiver (RWS-434) 5
  38.25
• 433 MHz Antenna 5
  45.00
• (w/shipping)
  130.84
• Alkaline Batteries (AA)
  100.00
• Total Cost 1388.12

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Design Validation

• Test servos, whiskers, photoresistors, and IR
  subsystem individually as outlined in Boe-Bot
  manual
• Integrate and test servos, whiskers,
  photoresistors, and IR subsystem

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Search and Communicate

• Implement and test random search for light using
  single Boe-Bot
• Implement and test patterned search for light
  using single Boe-Bot

• Implement and test RF communication between two
  Boe-Bots
• Develop, implement, and test a communication
  protocol for multiple Boe-Bots

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Putting it all Together

• Combine communication protocol with individual
  Boe-Bot random and pattern searches
• Begin stepwise refinement
• Determine which search is best
• Determine how close Boe-Bots should get to each
  other before moving away from each other
• Enhance communication protocol

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Complications

• Test with various objects blocking the search
• Test with Boe-Bots being dynamically added and
  removed from the search