Behavior Based Robots

oregontrimmingAI and Robotics

Nov 2, 2013 (3 years and 9 months ago)

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Introduction to Behavior
-
Based Robotics

Based on the book

Behavior
-
Based Robotics
by Ronald C. Arkin

What is a Robot?


A robot is a re
-
programmable, multi
-
functional, manipulator designed to move
material, parts, tools, or specialized
devices through variable programmed
motions for the performance of a variety
of tasks.


Robotics is the intelligent connection of
perception to action.

What is a Robot? (cont.)


An intelligent robot is a machine able to
extract information from its environment
and use knowledge about its world to
move safely in a meaningful and
purposive manner.

Related Areas


Cybernetics


Artificial intelligence


Robotics

Spectrum of Robot Control


Deliberative/Hierarchical control


Requires relatively complete knowledge about the
world.


Requires strong assumptions about this world model.


Hierarchical in structure with a clear identifiable
subdivision of functionality.


Communication and control occurs in a predictable
and predetermined manner.


Higher levels in the hierarchy provide subgoals for
lower subordinate levels.


Planning scope changes during descent in the
hierarchy.

Spectrum of Robot Control (cont)


Reactive control


Reactive control is a technique for tightly coupling
perception and action, typically in the context of
motor behaviors, to produce timely robotic response
in dynamic and unstructured worlds.


Behaviors serve as the basic building blocks for
robotic actions.


Use of explicit abstract representational knowledge is
avoided in the generation of a response.


Animal models of behavior often serve as a basis.


Reactive systems are inherently modular from a
software design perspective.



Design Paradigms for Building
Behavior
-
Based Systems


Ethologically guided/constrained design


Situated activity
-
based design


Experimentally driven design

Expressions of Behaviors


Stimulus
-
response (SR) diagrams




Functional notation



b(s) = r


Finite state acceptor (FSA) diagrams

Behavior

Response

Stimulus

Expressions of Behaviors (cont)


A Navigational Example


Consider a student going from one classroom to
another. The following kinds of things are
involved.


Getting to the destination from current location


Not bumping into anything along the way


Skillfully negotiating the way around other students


Observing cultural customs


Coping with change and doing whatever else is
necessary

Behavior Encoding


Mapping from the stimulus plane to the
motor plane.


A behavior can be expressed as a triple (
S,
R,
β
)
where
S

denotes the domain of all
interpretable stimuli, R denotes the range
of possible responses, and
β
denotes the
mapping
β
:S
-
>R.


Discrete encoding


Continuous functional encoding

Assembling Behaviors


Behavioral coordination


Competitive methods


Cooperative methods

Behavior
-
Based Architectures


Definition


Robot architecture is the discipline
devoted to the design of highly specific
and individual robots from a collection of
common software building blocks.

Behavior
-
Based Architectures (cont)


Evaluation Criteria


Supporting for parallelism


Hardware targetability


Niche targetability


Support for modularity


Robustness


Timeliness in development


Run time flexibility


Performance effectiveness


Behavior
-
Based Architectures (cont)


A foraging example


The tasks consists of a robot

s moving
away from a home base area looking for
attractor objects.


Wander


Acquire


Retrieve

Behavior
-
Based Architectures (cont)


Subsumption architecture (Brooks)


AFSM model


It is a layered architecture that uses arbitration
strategies and AFSM as its basis.


Coordination: Inhibition and suppression


Pros


Hardware retargetability


Support for parallelism


Niche targetability


Cons


Run time flexibility


Support for modularity

Behavior
-
Based Architectures (cont)


Motor schemas (Arkin)


A schema is the basic unit of behavior from
which complex actions can be constructed; it
consists of the knowledge of how to act or
perceive as well as the computational process
by which it is enacted.


Motor schemas are a software
-
oriented
dynamic reactive architecture that is non
-
layered and cooperative.

Behavior
-
Based Architectures (cont)


Motor schemas (cont)


Coordination: vector summation


Pros


Support for parallelism


Run time flexibility


Timeliness for development and support for
modularity


Cons


Niche targetability


Hardware retargetability

Behavior
-
Based Architectures (cont)


Other architectures


Circuit architecture


Colony architecture


Animate agent architecture


Distributed architecture for mobile navigation


Skill network architecture