Page 14 - Robotics Designing the Mechanisms for Automated Machinery

1.1 What Robots Are 3

stop at no more than 2Nlocations (where location includes position and orientation).
Some controllers do offer the capability of program selection of one of several mechan-
ical stops to be used. Often very good repeatability can be obtained with a fixed-stop
robot."
"Android—A robot which resembles a human in physical appearance."
"Sensory-controlled robot—A robot whose program sequence can be modified as a
function of information sensed from its environment. Robot can be servoed or nonser-
voed. (See Intelligent robot.)"
"Open-loop robot—A robot which incorporates no feedback, i.e., no means of com-
paring actual output to command input of position or rate."
"Mobile robot—A robot mounted on a movable platform."
"Limited-degree-of-freedom robot—A robot able to position and orient its end effec-
tor in fewer than six degrees of freedom."
We will not discuss here the problem of the possibility (or impossibility) of actu-
ally creating a robot with a "human soul." The subject of our discussion will be limited
mainly to industrial robots, including those which belong to the family of bangbang
robots. The application of these robots in the modern world must meet the require-
ments of industry, including functional and manufacturing demands and economic
interests. Obviously, esthetics and environmental considerations are also involved. The
mechanical component of the design of robotic systems constitutes the main focus of
our consideration.
Historically, the development of robot systems and devices may be considered as
the merging of two distinct lines of creativity: 1) early automation and watchmaking,
and 2) innovations and refinements in industrial machinery. A brief description of
some of these devices will be useful for illustrating these two lines. As long ago as
400-350 B.C. Archytas of Tarentum, a Greek, built a wooden model of a pigeon actu-
ated by a steam jet. In about the first century A.D., Hero of Alexandria designed a
number of devices actuated by water, falling weights, and steam. In about 500 A.D. in
Gaza the Byzantines erected a huge water-operated clock in which the figure of Her-
cules struck the hour in an automatic manner. Roaring lions and singing birds were
employed to impress foreigners by the Byzantine emperor Theophilus (829-842). Roger
Bacon (1220-1292) created a talking head, and at approximately the same time Alber-
tus Magnus (1200-1280) created an iron man. These two manmade creatures may be
classified as "androids." A "magic fountain" was designed in 1242 by a Parisian gold-
smith, Guillaume Boucher. The German astronomer and mathematician Johann Muller
(1436-1476) built a flying iron eagle. In the Fifteenth century, a truly portable source
of mechanical power was invented and applied—the coiled tempered-steel spring.
This energy source stimulated the creation of a number of sophisticated mechanical
automatons. In 1738, Jacques de Vancanson (1709-1782) built a "flute player" capable
of playing a dozen songs. During the eighteenth century, another group of gifted men,
Jacquet-Droz, his son Pierre, his grandson Henri-Louis, and Jean-Frederic Leshot,
created several androids which wrote, drew, or played musical instruments. The list of
automatically actuated animals, men, birds, and so forth is never-ending, and we do
not need to discuss it in detail, but two important conclusions do emerge:
1. This line of technical creativity was intended for entertainment purposes, and
nothing productive was supposed to be achieved by these devices.