Evolving Robots

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Evolving Robots

• Presented by Kedar A. Shiroor
• Authors Stefano Nolfi, Dario Floreano

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Overview

• What is ER?
• Behavior Based Robotics and ER
• Khepera Concept
• Co-evolution of Body and Brain
• Evolution in Plastic Individuals
• Conclusion

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What is Evolutionary Robotics?

• Evolutionary Robotics attempt to develop robots
  and their control system through an automatic
  design process involving artificial evolution.
• Initial population of different artificial
  chromosomes, encoding the control system of a
  robot is randomly created and put in the
  environment.
• Robots then allowed to move freely and
  performance is evaluated.
• Fittest robots reproduce by generating copies of
  their genotypes.
• Process repeated for several generations till
  Individual meeting satisfactory performance
  criterion is born.
• Phylogenetic and Ontogenetic changes during
  lifetime.

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Evolutionary Robotics and its Exploits

• Self-Organization Represents a way to overcome
  a series of problems depending on their
  complexity.
• Embodiedness Receive Input and produce actions
  as outputs.
• Situatedness Study of systems
  (natural/artificial) situated within the
  environment.

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Distinction between Innate and Learned

• Innate Behavior Case where the control system
  is relatively fixed and has genetically specified
  mechanisms.
• Learned Behavior Case when the robot generates
  behavior with a plastic control system.

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Behavior-Based Robotics ER
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Exploiting Environmental Interactions

• Embodied and situated organisms behavior is a
  emergent result of the dynamical interaction
  between the nervous system, the body and the
  environment.
• Important aspect Motor actions partially
  determine the sensory patterns that organisms
  receive from the environment.
• E.g. Drosophila the fly and its adjustment to
  recognize patterns.

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The Khepera Concept

• - Experiment to determine whether Evolving robots
  are capable of locating and staying close to a
  pre-decided target.
• After a few generations the robot was able to
  quite easily identify and stay close to the
  target.
• This implied the robots were able to distinguish
  between walls and cylinders.
• Complex task Involved a number of
  sensory-motor interactions with the environment.
  The objects in the world had very similar sensory
  patterns.

The Khepera is a mobile robot with a diameter of
6 cm, equipped with two wheels and 8 infrared
sensors.
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Ways to exploit sensory-motor coordination.

• Increase frequency of sensor-states to which they
  can respond effectively and decrease the others.
• Select sensory states in which groups of sensory
  patterns requiring different motor-answers do not
  overlap.
• Increase perceived differences between different
  objects.
• Select useful learning experiences.

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Co-Evolution of Body and Brain

• Apart from the control system, morphology can
  also affect the resulting behavior. i.e. The
  control system and the morphology are related.
• Natural organisms have prospered due to the
  marked interaction and co-evolution of the
  control system and morphology.

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Co-Evolution in Natural Organisms

• E.g. Crickets and their ability to filter out
  irrelevant sound to detect a mating call.
• Termites build their homes on the basis of a
  certain smell that they associate with
  pre-manufactured mud balls with chemical traces.

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Co-Evolution in Robots

• Cliff et al. and Harvey et al. co-evolved the
  control system and the sensory morphology of a
  mobile robot.
• Genotype consisted of the control system and the
  sensory morphology.
• The evolved robots were able to rely on simple
  strategies such as comparing the correlated
  activities of only two visual receptors located
  at strategic positions.

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Co-Evolution in Robots contd

• Lund et al. co-evolved in simulation the control
  system and some characteristics of the body of
  Khepera-like robots (chosen for their navigation
  skills while avoiding obstacles).
• Pollack and workers explored the possibility of
  evolving the morphology of physical robots.
  Preliminary work involved simulations and later
  they worked with Lego bricks (evolved
  structures).

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Evolution of Plastic Individuals

• Phylogenetic evolution had been explored but the
  need arose for exploring Ontogenetic evolution.
• Studies conducted for two purposes. (1)
  Advantages of combining adaptive techniques.(2)
  Understand role of interaction between two
  adaptive processes that resort to different
  mechanisms and occur at different timescales.
• Advantages (1) Allowance to adapt during a
  lifetime.(2) Significantly speed up synthesis of
  viable individuals.(3) Ability to scale up to
  problems with larger search space.

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E.g. of Plastic Individuals

• A mobile Khepera robot equipped with a vision
  module performed sequential tasks that involved
  switching a light on and then moving toward the
  light bulb.
• In one particular lifetime plastic individuals
  were found to perform better than non-plastic
  ones.

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Conclusion

• Evolving robots are a bold step toward making
  machine life more adaptive toward the environment
  and thus more self reliant.
• This study has also given us an insight into the
  importance of the environment and behavior in
  cognition (Connectionists would argue
  vehemently!!).

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Questions???