Page 246 - Concise Encyclopedia of Robotics

Polymorphic Robot
the saving of life against increased costs. Perhaps the cost of robotic
technology will decline, and the quality will increase, until someday,
part or most of our metropolitan police forces can be roboticized at a
reasonable cost.
See also MILITARY ROBOT, SENTRY ROBOT, and SECURITY ROBOT.
POLYMORPHIC ROBOT
A polymorphic robot, also called a shape-shifting robot, is designed to con-
form to its environment by altering its geometry. There are numerous
designs that can accomplish this. A simple example of a polymorphic
robot gripper is the active chord mechanism, which conforms to objects
by wrapping around them.
Specialized track-driven robots can change their shapes in order to
travel over rough terrain,or climb and descend stairs.Such robots can also
alter their body orientation (horizontal or vertical).Some robots are shaped
like snakes, with numerous joints that allow them to maneuver in, and
reach into, complex work spaces.
See also ACTIVE CHORD MECHANISM, TRACK-DRIVE LOCOMOTION, and TRI-STAR WHEEL
LOCOMOTION.
POSITION SENSING
Robot position sensing falls into either of two categories. In the larger
sense, the robot can locate itself. This is important in guidance and nav-
igation. In the smaller sense, a part of a robot can move to a spot within
its work envelope, using devices that tell it exactly where it is. Specific
definitions in this book that deal with position sensing include CARTESIAN
COORDINATE GEOMETRY, COMPUTER MAP, CYLINDRICAL COORDINATE GEOMETRY, DIRECTION FIND-
ING, DIRECTION RESOLUTION, DISPLACEMENT TRANSDUCER, DISTANCE MEASUREMENT, DISTANCE
RESOLUTION, EDGE DETECTION, EPIPOLAR NAVIGATION, EYE-IN-HAND SYSTEM, GUIDANCE SYSTEM,
LANDMARK, LOCAL FEATURE FOCUS, ODOMETRY, PARALLAX, PHOTOELECTRIC PROXIMITY SENSOR,
POLAR COORDINATE GEOMETRY, PROXIMITY SENSING, SONAR, SPHERICAL COORDINATE GEOMETRY,
and VISION SYSTEM.
POTENTIAL FIELD
A potential field is a rendition of robot behavior or characteristics within
a specific work area. Such fields are commonly rendered as vector arrays
in a two-dimensional (2-D) coordinate system. The vectors can represent
any quantity that affects the robot, or that the robot exhibits, such as
magnetic field strength, velocity, or acceleration. More complex potential
fields exist in three-dimensional (3-D) space. The following exam-
ples, and the accompanying illustrations, involve 2-D space (a flat sur-
face) for simplicity.

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