Page 432 - Sensors and Control Systems in Manufacturing

386
Ei g h t
Cha p te r

8.3.4 Robot Visual Sensing Tasks
Robots will work in unpleasant locations. Health hazards are of no
concern to them. Special safety equipment is not required for a robot
spraying paint, welding, or handling radioactive materials or chemi-
cals. All this adds up to reduced production costs. As the day pro-
gresses, the tired worker has a tendency to pay less attention to details,
and the quality of the finished product may suffer. This is especially
noticeable in automobiles where spray paint can run or sag and weld
joints may not be made perfectly. The panels of the car may not be
aligned, and the finished product may not operate properly, with pre-
dictable customer dissatisfaction. In pharmaceutical production, too,
an operator inspecting and verifying lot number and expiration date
may become fatigued and fail to inspect for sensitive information.
Robots, on the other hand, do not tire or change their work habits
unless they are programmed to do so. They maintain the same level of
operation throughout the day. With vision-sensing systems and robots,
it is possible for American manufacturers to compete against lower
labor costs in foreign countries. The initial investment is the only prob-
lem. After such an investment, the overall operation costs of the pro-
duction line are reduced or held constant. Small educational robots
can be used to retrain humans to operate and maintain robots.
The roles of robots with machine vision can be summarized as
follows:
• Handling and assembly. Recognizing position/orientation of
objects to be handled or assembled, determining presence or
absence of parts, and detecting parts not meeting required
specifications
• Part classification. Identifying objects and recognizing char-
acters
• Inspection. Checking for assembly and processing, surface
defects, and dimensions
• Fabrications. Making investment castings, grinding, deburr-
ing, water-jet cutting, assembling wire harnesses, gluing,
sealing, puttying, drilling, fitting, and routing
• Welding. automobiles, furniture, and steel structures
• Spray painting. automobiles, furniture, and other objects
8.3.5 Robots Utilizing Vision Systems to Recognize Objects
A basic use of vision is recognizing familiar objects. It is easy to see
that this ability should be an important one for robot vision. It can be
a task in itself, as in counting the number of each kind of bolt in a
mixed lot on a conveyer belt. It can also be an adjunct to other tasks—
for example, recognizing a particular object before trying to locate it
precisely, or before inspecting it for defects.