Page 65 - Concise Encyclopedia of Robotics

Color Sensing
that all processes continue to run smoothly without undesired side effects.
In uncomplicated systems, a high-level part of the system can tem-
porarily take over the tasks of a lower-level part, without regard for details
of the event. In scenarios where the possibilities are diverse and variable,
certain additional procedural steps, not normally necessary, are sometimes
required to ensure smooth operation while the lower-level device or sub-
system is repaired.
Consider the case of a smart home equipped with smoke detectors,
heat sensors, a telephone link to the fire department, and a set of sprin-
klers. What should the system do if a heat sensor is set off by a mischie-
vous child with a hair dryer, causing a false alarm? An unsophisticated
system calls the fire department and actuates the sprinklers, causing
embarrassment and unnecessary damage to furniture. A sophisticated
system can prevent these undesirable things from taking place, pro-
vided the owner of the house, or some backup sensing system, is pres-
ent to determine that there is actually no fire. The owner or backup
system must be cognizant of the fact that the alarm is false. Then the
sprinkler system can be disabled, a call can be made to the fire depart-
ment to cancel the alarm, and the offending sensor, if it has been dam-
aged, can be shut down until it is replaced. (The child can be disciplined
as well, although this is the responsibility of the human home owner.)
Compare GRACEFUL DEGRADATION.
COLOR SENSING
Many robotic vision systems function only in grayscale. Color sensing
can be added, in a manner similar to the way it is added to television
(TV) systems.
Color sensing can help a robot determine the identity or nature of an
object. Is an observed horizontal surface a floor or a grassy yard? (If it is
green, it is probably a grassy yard.) Sometimes, objects have regions of
different colors that have identical brightness as seen by a grayscale system.
Such objects can be analyzed better with a color-sensing system than with
a vision system that sees only shades of gray.
The drawing shows a block diagram of a color-sensing system. Three
grayscale cameras are used. Each camera has a color filter in its lens. One
filter is red, another is green, and another is blue. These are the three
primary colors of radiant light. All possible hues, brightnesses, and satu-
rations are comprised of these three colors in various ratios. The signals
from the three cameras are processed by a microcomputer, and the result
is fed to the robot controller.
See also GRAYSCALE, OBJECT RECOGNITION, TEXTURE SENSING, and VISION SYSTEM.

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