Page 361 - Concise Encyclopedia of Robotics

Wrist-Force Sensing
envelope, which represents the region of space that an end effector can
reach when a robot is in a particular location.
In the case of a ground-based, mobile robot, the work environment can
be defined in simplistic terms using a two-dimensional (2-D) coordinate
system, specifying points on the surface such as latitude and longitude.
With submarine or airborne mobile robots, the work environment is
three-dimensional (3-D). Compare CONFIGURATION SPACE and WORK ENVELOPE.
WORLD MODEL
The term world model refers to the concept that a robot develops about its
work environment. This concept is obtained from sensor outputs, previ-
ously obtained data (if any), and information the robot controller deduces
concerning its optimum behavior. The world model should approximate
physical and causative realities as closely as possible.
Every individual person has a concept of the environment—“the
world around us”—but this differs slightly depending on various factors.
In the same way, a robot’s view of the world depends on factors such as
• The location of the robot
• The phenomena the robot can sense
• The sensitivity of the sensors
• The resolution of the sensors (if applicable)
• The computer map (if any) the robot controller has
• Information obtained from other robots
• Information obtained from humans
• The presence or absence of misleading input
Two identical robots in the same general location, and subjected to
identical conditions, have identical world models unless one or both
machines malfunctions, or one of the robots has a knowledge base that
differs from that of the other. If the two robots have artificial intelligence
(AI), and their “life experiences” differ, the robots can be expected to
perceive the environment differently, even if they are in the same general
location. Compare WORK ENVIRONMENT.

WORLD SPACE
See WORK ENVIRONMENT.

WRIST-FORCE SENSING
Several different forces exist at the point where a robot arm joins the end
effector. This point is called the wrist. It has one or more joints that move
in various ways. A wrist-force sensor can detect and measure these forces.
It consists of specialized pressure sensors known as strain gauges. The

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