Developing a LowCost Robot Colony

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Developing a Low-Cost Robot Colony

• General Dynamics Robotic Systems
• April 19, 2007

Felix Duvallet Colony Project, Robotics Club
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Robotics Club at Carnegie Mellon

• Building robots for fun since 1984
• Mostly undergraduates (over 100 members)
• Several ongoing projects
• Colony
• Battlebots
• RobOrchestra
• Operates out of University Center basement
• Lab space
• Machine Shop

www.roboticsclub.org
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Colony Project

• Robotics Club Project, started in 2003
• About 16 undergraduates
• Various years
• Different majors (mostly Engineering/CS)
• Four weekly meetings
• Sources of Funding
• Small Undergraduate Research Grant
• Ford Undergraduate Research Grant
• Leverage existing research projects (Choset)

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Motivation (Why Colonies)

• Colonies are everywhere in nature
• Robustness to robot failure
• Many tasks require cooperation
• Coverage may necessitate multiple agents
• Inherently interesting research problems
• Robots are awesome
• More robots are more awesome

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Goals

• Low-cost robots (350)
• Homogeneous, distributed architecture (no
  super-node)
• Develop applications that are robust to
  non-idealities
• Noisy sensor data
• Limited computation
• Communication delays
• Use the Colony as a research platform
• Emergent behavior
• Path planning
• Cooperation
• Control
• SLAM

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Where Colony is now

• Past
• Substantial work has gone into developing the
  Colony hardware (robot, sensors)
• Infrastructure has been developed (wireless
  communication, localization)
• Present
• Currently developing behaviors
• Autonomous recharging and self-sustainability
• Future
• Extended duration, large-scale cooperation

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Outline

• Past Work
• Robots
• Sensors
• Infrastructure
• Behaviors
• Sustainability
• Future Work

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Robots
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Colony Robot
BOM
Dragonfly Board
Bearing and Orientation Module (BOM) robot
localization.
ORBs
Motors
Microcontroller
Range-Finders
Tri-color LED x 2
Diff-drive robot.
Obstacle avoidance
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Colony Robot
BOM
Dragonfly Board
Program robotUser I/O
ORBs
Motors
Range-Finders
Enables robot recharging
USB
Charging Contacts
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Microcontroller

• ATMega 128
• 8MHz max
• 128Kbytes program memory
• Programmed in C
• arv-libc, avr-gcc
• open-source, multi-platform tools

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Sensors
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Sensors

• Standard off-the-shelf sensors
• Sharp IR Rangefinder
• Bump Sensors
• Photoresistors
• Pyroelectric sensor (heat) Previously used
• Custom Sensor
• Bearing and Orientation Module (BOM)

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Bearing and Orientation Module

• IR emitter/detector ring
• Emitter mode
• All emitters are powered simultaneously (beacon)
• Detector mode
• Detectors can be polled individually for analog
  intensity readings

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Bearing and Orientation Module

• IR emissions from one robot are highly visible to
  all robots within line of sight
• All BOMs are coplanar across the colony
• Most excited detector is pointing in the
  direction of the emitting robot

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InfrastructureWireless Communication,
Localization
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Communication Network

• ZigBee wireless protocol
• XBee module (MaxStream)
• 30m indoor / 100m outdoor range
• Network features
• Ad-hoc
• Distributed
• Fault-tolerant
• Issues to consider
• Packet collisions
• No threading on robot
• Very low bandwidth

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Network Topology

• Problem Packet collisions

Token-Ring Network
Fully-Connected Network
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Network Topology

• Solution Robots take turns, yet communicate with
  all other robots

Leverage wireless network and BOM to perform
communication and localization simultaneously
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Wireless Network

• Integrate BOM and Wireless
• Robots beacon BOM when sending a wireless packet
• When receiving a packet, poll BOM for direction
  of sender robot
• Propagate connectivity matrix

Token path
Token path
Wireless Data
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Connectivity/Bearing Matrix
You share your data
1
2
0
you
And you receive these rows
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Topological Localization

• Advantages
• Simple
• Fast
• No processing (use sensor data directly)
• Metric maps can be extracted

Relative Localization in Colony Robots, in
Proceedings of the National Conference on
Undergraduate Research, 2005
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Robot Behaviors
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Behaviors

• Use sensor data to control actions
• Simple local interactions can yield complex
  global actions
• Emergent behavior
• Individual and multiple robot behaviors

• Individual Robot
• Light-seeking
• Feeding/Hunger
• Roaming
• Obstacle Avoidance
• Homing

• Multiple Robots
• Lemmings
• Robots follow a leader in a chain
• Hunter/Prey (Tag)
• One prey, many hunters
• Robots can switch roles

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Roaming/Obstacle Avoidance

• Robots uses Sharp IR rangefinder to avoid
  obstacles
• Behavior can be reproduced on many robots

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Marching band

• Each robot programmed with own music sequence and
  dance moves
• Wireless used for synchronization between robots

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Lemmings (multi-robot)

• Simple follow the leader
• Uses both the BOM and wireless network
  (localization)

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Simulation

• Player/Stage
• Simulate larger number of robots
• Eases behavior development
• Additions to simulate the BOM

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Lemmings (simulation)
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Hunter/Prey (simulation)
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Formation Control (simulator)
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Cooperative Maze Solving

• Given a maze and a goal, robots cooperate to seek
  the goal

Start
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Cooperative Maze Solving

• Given a maze and a goal, robots cooperate to seek
  the goal

Cooperation
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Cooperative Maze Solving

• Given a maze and a goal, robots cooperate to seek
  the goal

Goal
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Cooperative Maze Solving

• Warning Early Colony videos ahead

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Cooperative Maze Solving
Cooperative Maze Solving
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Cooperative Maze Solving (night vision)
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Autonomous Recharging
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Towards Self-Sustainability

• Goal is to develop a self-sustainable robot
  colony
• Operate unassisted for long periods of time
• Requirements
• Autonomous recharging
• Task allocation

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Charging Station
Controller
Power

• One controller oversees up to 8 bays
• Power supply powers bays and charges robots
• Wireless communication to talk to colony

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Charging Bay Pair
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Charging Bay Pair
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Charging Station

• Controller
• Salvaged robot controller with XBee module
• Acts as robot manager
• Bay allocation
• Scheduling
• Bays
• 12V supply
• Linear BOM
• Homing beacon

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Robot charging

• Charge board
• Charges batteries
• Communicates with robot over I2C
• Homing sensor
• Leverage wireless and BOM localization

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IR Beacon Homing
Beacon
Max pulse width n 3n 2n
Left Center Right
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Docking with Bay Procedure

• Request charge bay, wait for accept
• Locate bay, get to homing range
• Home to docking bay
• Dock

Wireless
BOM/Wireless
Homing Sensor
Robot
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Docking Video
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Incorporating a Task

• Roaming

Button press instead of battery threshold in the
interest of time
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Future Work

• More complex tasks
• Extended duration
• Larger scale cooperation problems
• Robustness

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Colony Members

• Felix Duvallet
• Christopher Mar
• Austin Buchan
• Brian Coltin
• Brad Neuman
• Justin Scheiner
• Siyuan Feng
• Duncan Alexander
• Cornell Wright

• Eugene Marinelli
• Suresh Nidhiry
• Andrew Yeager
• Greg Tress
• James Kong
• Kevin Woo
• Ben Berkowitz
• Jason Knichel
• Aaron Johnson
• Prof. George Kantor

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www.robotcolony.orgfelixd_at_cmu.edu