Introduction to Robotics

1
Introduction to Robotics Multi-robot systems

• Speaker Wen-Chieh Fang
• Time 2005/08

2
Agenda

• The Study of Agency
• Related Courses
• Mobile robots
• Architecture
• Hierarchical Paradigm
• Reactive Paradigm
• Hybrid Paradigm
• Communication
• 5 Categories of Communication
• Communication Structure
• What Do Robots Say to Each Other?
• Languages for multi-agents
• Applications
• Multi-robot Sensing
• Sensory coverage
• Control
• Reference

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The Study of Agency(after Stone and Veloso 2002)
Murphy 2000 slides
Distributed Artificial Intelligence
How to solve problems Or meet goals by divide
and conquer
Distributed Problem Solving
Multi- Agent Systems

• Single computer
• How to decompose task?
• How to synthesize solutions?

• Divide among agents
• Who to subcontract to?
• How do they cooperate?

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Related Courses

• Robotics
• Artificial Intelligence
• Distributed Artificial Intelligence (DAI)
• Multi-agent systems
• Animal behavior (optional)

5
Mobile robots

• Navigation
• Maximum Navigation Test (MNT)
• The robot is placed in an environment that is
  unknown, large, complex and dynamic. After a time
  needed by the robot to explore the environment,
  the robot must be able to go to any selected
  place, trying to minimize a cost function (e.g.
  time, energy, etc).

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Mobile robots (Cont.)

• Motion Control problem
• World Modeling problem
• Localization problem
• Planning problem
• Architecture problem

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Architecture

• Hierarchical Paradigm
• Reactive Paradigm
• Hybrid Paradigm

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Hierarchical Paradigm

• Organization

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Reactive Paradigm

• Vertical decomposition of tasks

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Hybrid Paradigm

• Organization

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5 Categories of Communication Murphy 2000
slides

• Infinite
• comms are free
• Motion
• costs as much to communicate as it would to move
• ex. Box pushing (if other robot can feel the box,
  its comms)
• Low
• comms costs more than moving from one location to
  another
• Zero
• no communication between agents
• Topology
• Broadcast, address, tree, graph

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Communication Structure

• Interaction via Environment
• Environment is the communication medium (a shared
  memory)
• Interaction via Sensing
• Without explicit communication
• Interaction via Communications
• Explicit communication by either directed or
  broadcast intentional messages

Adopted from Parker et.al.2003
Adopted from Yoshida et.al. 1994
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What Do Robots Say to Each Other? Murphy 2000
slides

• How do they talk?
• Implicit signaling, postures, smell
• Explicit language
• Who does the talking?
• the boss -Centralized control
• Everybody - Distributed control

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What do Robots Say? (after Jung and Zelinsky 02)
Murphy 2000 slides

• Communication without meaning preservation
• Emitter cant interpret its own signal
• Receiver reacts in a specific way
  (stimulus-response)
• Ex. Mating displays, bacteria emit chemicals
• Communication with meaning preservation
• Shared common representation
• Ex. Ant leaves pheromone trail to food, itself
  peers can follow
• Ex. Wolves leave scent markings

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Languages for multi-agents

• To abstract the important information and
  minimize explicit communication
• Does an increase on the amount of transmitted
  data imply better performance? Castelpietra et.
  al. 2000
• How to make agents to speak the same language?
  (how to translate syntactically and semantically
  the data or information structures of the sender
  to the receiver?) Ye et. al. 2002
• How to make agents mean the same meaning when
  they communicate? (how to make sure that agents
  use the same ontology?) Ye et. al. 2002

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Multi-robot Sensing Murphy 2000

• Proprioceptive sensors (which robots measures a
  signal originating within itself)
• Shaft encoder
• GPS
• Proximity sensors
• Sonar or ultrasonics
• Infrared (IR)
• Bump and feeler sensors
• Computer Vision
• Range from vision
• Stereo camera pairs
• Light stripers
• Laser ranging

Adopted from Werger Mataric 2000
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Sensory coverage

• Topics
• Target tracking/search
• Variations
• Numbers speeds of sensor targets
• Communication, sensing movement capabilities
• Terrain
• Predictability of targets
• Multi-sensor fusion

Adopted from Jung Sukhatme 2002
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Control

• Centralized control
• Distributed control

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Reference

• English reference
• R. R. Murphy, Introduction to AI Robotics. The
  MIT Press, 2000.
• Chinese reference
• ?????, ???????, ???????????????????, ????,
  2002
• ?????????, "???????????????", ??, 2003
• ????????, "????????????????", ????, 2004

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Reference

• Castelpietra et. al. 2000
• C. Castelpietra, L. Iocchi, D. Nardi, and R.
  Rosati, Coordination in
• multi-agent autonomous cognitive robotic
  systems, in
• Proceedings of 2nd International Cognitive
  Robotics Workshop,
• 2000.
• Ye et. al. 2002
• Y. Ye, S. Boies, J. Liu, and X. Yi,
  Collective perception in massive,
• open, and heterogeneous multi-agent
  environment, in
• Proceedings of 1st International Joint
  Conference on Autonomous
• Agents and Multi-agent Systems (AAMAS02),
  2002.