Page 94 - Concise Encyclopedia of Robotics

Distinctive Place
by, beacons located at strategic points in the work environment. A high-
end system of this kind can resolve distances down to a small fraction
of a millimeter.
See also BEACON, DISTANCE MEASUREMENT, RADAR, and SONAR.
DISTINCTIVE PLACE
A distinctive place is a point in a mobile robot’s work environment that
has special significance, or that can be used as a point of reference for
navigational purposes.Such points are determined on the basis of features
in specific regions, called neighborhoods, in the work environment.
Suppose a mobile robot is designed to function on a single level of an
office building. The work environment is the entire floor (the set of all
points) over which the machine can move. Each room can be considered
a neighborhood. Distinctive places might be defined as the centers of the
doorways between adjacent rooms, or between each room and the hallway.
Distinctive places might also include the physical (geographic) center of
the floor in each room, or the point on the floor that lies at the greatest
distance, in any given room, from fixed obstructions. Beacons can also
serve as distinctive places.
See also BEACON, COMPUTER MAP, and RELATIONAL GRAPH.
DISTRIBUTED CONTROL
In a system containing more than one robot, distributed control refers to
unit independence. In a robotic system that employs distributed control,
also known as decentralized control, each robot in the fleet is capable, to
some extent, of making its own decisions and operating without instruc-
tions from other robots or from a central controller. If there is a central
controller, its function is limited. This type of robotic system is analogous
to a peer-to-peer computer network.
In a robotic system that employs uniformly distributed control, there is
no main controller; each robot is fully autonomous, containing its own
controller. Each unit is equal to all the others in significance. In some
systems, there is a main controller that oversees some of the operations of
each unit in the fleet. This is known as partially distributed control. Another
example of partially distributed control is a system in which each robot
receives a set of instructions from a central controller, stores those instruc-
tions, and then carries them out independently of the central controller.
In some robotic systems, the individual units are completely and con-
tinuously dependent on the central controller, and cannot function if
the communication link is severed. Such a system is said to employ fully
centralized control. Compare CENTRALIZED CONTROL.
See also AUTONOMOUS ROBOT and INSECT ROBOT.

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