Page 219 - Concise Encyclopedia of Robotics

proven itself to be the best way to build a computer. Neural-network
research has gone through boom-and-bust cycles, partly as a result of
differences of opinion.
Psychologists are interested in this technology because it might help
them answer questions about the human brain. However, no neural net-
work has come close to such complexity. Even the biggest neural networks
conceived, with billions of neurons and trillions of synapses, would be
less intelligent than a cat or dog. See OBJECT RECOGNITION, PATTERN RECOGNITION,
SPEECH RECOGNITION, and SPEECH SYNTHESIS. Noise
NODE
A node is a specific, important point in the path of a mobile robot or end
effector as it navigates its environment.The starting point is called the initial
node; the destination point is called the goal node. Decision points, if any,
between the initial and goal nodes are intermediate nodes. In metric path
planning, for example, a mobile robot in a complex environment with
many obstructions navigates between the initial and goal nodes by first
determining a set of intermediate nodes or waypoints, and then following
the paths between those nodes.
In a communications network,the term node refers to a specific location
at which data are processed or transferred. Examples include workstations,
servers, printers, and cameras. In a robotic system, the individual robots
constitute communications nodes if they can communicate with other ro-
bots or with a central controller.A central controller in a fleet of insect robots
is a communications node.
See also COMPUTER MAP, GRAPHICAL PATH PLANNING, METRIC PATH PLANNING, and
TOPOLOGICAL PATH PLANNING.
NOISE
Noise is a broadbanded alternating current (AC) or electromagnetic
(EM) field. In contrast to signals, noise does not convey information.
Noise can be natural or human-made.
Noise always degrades communications quality. It is a major concern in
any device or system in which data are sent from one place to another, such
as a fleet of mobile robots that must exchange data, or a swarm of insect
robots under the supervision of a central controller. The higher the noise
level, the stronger a signal must be if it is to be received error-free. At a
given signal power level, higher noise levels translate into more errors
and reduced communications range.
The illustration is a spectral display of signals and noise,with amplitude
as a function of frequency. The background noise level is called the noise
floor. The vertical lines, or pips, indicate signals that are stronger than the

