Page 22 - Robotics Designing the Mechanisms for Automated Machinery

1.2 Definition of Levels or Kinds of Robots 11

monious action. This case is shown schematically in Figure 1.5. As an example we can
take an automatic line for producing pistons for internal combustion engines.

We must emphasize here that there are no rigid borders between one case and
another. For example, a machine can as a whole belong to group (5), but for some spe-
cific task it may be provided with a feedback, say, signalling the lack of blanks followed
by stopping of the action to avoid idle work. Another example is a car which is man-
ually controlled but has an automatically acting engine. The solution to the argument
about the definition of a robot probably lies somewhere between case (5) and case (7)
in the above-given classification. Thus, it would be more useful to employ the termi-
nology "automatically acting manufacturing machines (AAMM) and systems" instead
of the foggy concept of robot. The means which provide the action of such a system
at almost every level of complexity can be of purely mechanical, electromechanical,
electronic, pneumatic, hydraulic or of mixed nature.
Irrespective of the level or kind of AAMM—numerically controlled or a computer-
ized flexible manufacturing system (FMS)—its working part is mechanical. In other
words, regardless of the control "intelligence" the device carries out a mechanical
action. For example, the crochet hooks of a knitting machine execute a specific move-
ment to produce socks; X-Ytables realize a mechanical motion corresponding to a
program to position a circuit base so that electronic items can be assembled on it; and
the cutter of a milling machine runs along a defined trajectory to manufacture a
machine part. Cutters, grippers, burners, punches, and electrodes are tools and as such
their operation is the realization of mechanical motion. (Even if the tool is a light beam,
its source must be moved relative to the processed part.)
Being adherents of mechanics, we deem it appropriate at this stage to make a short
digression into the glory of mechanics. In our times, it is customary to sing hymns of
praise to electronics, to computer techniques, and to programming. Sometimes, we
tend to forget that, regardless of the ingenuity of the invented electronics or created
programs, or of the elegance of the computation languages, or of the convenience of
the display on the terminal screen, all these elements are closely intertwined with
mechanics. This connection reveals itself at least in two aspects. The first is that the
production of electronic chips, plates, and contacts, i.e., the so-called hardware, is
carried out by highly automated mechanical means (of course, in combination with
other technologies) from mechanical materials. The second aspect is connected with
the purely mechanical problems occurring in the parts and elements making up the
computer. For instance, the thermal stresses caused by heat generation in the elec-
tronic elements cause purely mechanical problems in circuit design; the contacts which
connect the separate blocks and plates into a unit suffer from mechanical wear and
contact pressure, and information storage systems which are often purely mechani-
cal (diskette and tape drives, and diskette-changing manipulators) are subject to a
number of dynamic, kinematic, and accuracy problems. Another example is that of
pushbuttons which are a source of bouncing problems between the contacts, which,
in turn, lead to the appearance of false signals, thus lowering the quality of the appa-
ratus. Thus, this brief and far-from-complete list of mechanical problems that may
appear in the "brains" of advanced robots illustrates the importance of the mechani-
cal aspects of robot design.
The AAMM designer will always have to solve the following mechanical problems: