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Paper 6
ROBOTICS: THE INTERPLAY OF INDUSTRIAL AND ACADEMIC ACTIVITY
OPENS A MAJOR NEW FIELD OF RESEAE~H
EARLY HISTORY
ffl e history of robotics, a subject area that is only now coming to the
forefront of interest in computer science, is worth examining for the
interplay that it exhibits between direct marketplace concerns and
far-reaching research goals inspired by artificial intelligence.
The intelligent robot is an old dream of mankind, robots having
played a role in fiction since ancient days. The second-century
Chinese general Chu-ko-Liang was reputed to have constructed robot
donkeys and horses for use in his military transport operations, and in
the thirteenth century, the English monk Roger Bacon was rumored to
have built a talking bronze head that served him as a personal oracle.
Robots are also prominent actors in twentieth-century science fiction.
However, the development we shall trace first began to take on
substantial flesh in the middle to late l950s. By that time, the
availability of advanced servomechanism theory, the increasing
sophistication and falling costs of electronics, and the fundamentally
new capability provided by the stored program computer began to tempt
engineers concerned with industrial automation to look at generalized,
computer-controlled mechanical devices of broad potential applicability.
The numerically controlled machine tool was one outcome, and the first
robot manipulators another result of the climate of innovation to which
the confluence of these three technological streams led.
Viewed narrowly, industrial robots are simply computer-controlled
machine tools specialized for the manipulation of work pieces. Seen in
this light, they might be considered close relatives of numerically
controlled machine tools, the most sophisticated of which are also
regulated by stored programs, but which serve for cutting blank stock
rather than for the manipulation and assembly of preformed parts.
However, since the general environment of parts assembly is far more
varied and complex than that of parts cutting, robot manipulators
require programs that are more sophisticated than the simple geometric
routines that suffice for numerically controlled machine tools. Hence
robotics proper begins with the construction of the robot manipulators
rather than with the simpler numerical machine tool technology.
The loci of innovation were at first purely industrial, universities
not being active in the earliest years of robotics. Two main companies,
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Unimation and AMF (American Machine and Foundry) dominated developments
in these years. Joseph Engelberger, George Devol, and Maurice Dunn led
the early technical work at Unimation and are still active today. An
aspect of the early history worth noting is that Unimation was from the
start a specialized company whose future wan strongly conditioned by
the need to make a success of the robot manipulators they were
developing. This circumstance concentrated the attention of Unimation's
management and technical developers on robotic. and did in fact lead to
success. Tb survive in the relatively adverse technical environment of
these pioneering days was not easy, since among other things, computers
were still quite expensive and no clear market for robot devices had
been established. By contrast, AMF, another pioneering company, was a
large organization with much higher inertia and a much more limited
focus on and commitment to robotics. In consequence of this, AMF's
initial efforts soon fell by the wayside, and Rudy Malenkovic, the
technically successful pioneer of robotics at AMF, moved to the Ford
Motor Company, where his work concentrated more narrowly on the
application of robots to automobile assembly lines. mis bit of
history illustrates the critical importance of major innovations of
small, fast-moving, specifically committed companies.
Although Unimation survived, the years from 1956 to 1970 were lean
ones for robotics. The general technological context in which robotics
research was constrained to operate was insufficiently~favorable to
allow any dramatic commercial success. Compared to the price of labor,
the price at which robot assembly devices could be offered was simply
too high. The technology was viewed with suspicion by many members of
its potential customer base. Most robot-oriented companies other than
Unimation simply went under or moved on to other activities.
At this point, however, academic activity in robotics began to
become significant. Marvin Minsky, realizing the technical depth of
the robotic language/vision/manipulator control problem, persuaded AMF
to give him a robot for use at the MIT artificial intelligence
laboratory. m e MIT work with robots was undertaken as part of their
general exploration of the broad area of artificial intelligence, and
thus drew inspiration from the same very far-reaching goals as the MIT
work on scene analysis, game playing, semantic nets, etc. At about the
same time, John McCarthy, Jerome Feldman, and m omas Binford at
Stanford began work on robotic hand-eye systems. m e most successful
early outcomes of this university research lay in the areas of computer
vision, geometrical reasoning and modeling, and general AI-like schemes
for planning robot motions. Direct research on the manipulation
problems of more immediate interest to potential industrial users of
robots (e.g., the problems of grasp planning, force-guided motion
control, work to close tolerances, etc.) was by contrast limited.
There was, however, some significant university work on design of
small, fast manipulators, especially that of Victor Scheinemann, who
was associated with both Stanford and MIT before moving on to Unimation;
commercial versions of the Scheinemann arm are now being offered by
Unimation. Real-time software for control of the kinematic chains
constituting manipulators of this type was also developed at Stanford
and MIT by Roth, Piper, and Paul at Stanford and Horn at MIT based on
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prior work of Hartenberg and Uicker. The MIT/Stanford kinematic
control software was of direct practical importance, since it allowed
the users of robots to plan robot motions in normal Cartesian
coordinates, rather than involving them constantly with the complicated
geometry of motions planned in joint-angle terms.
Other significant robotic research efforts were also undertaken at
the Stanford Research Institute, which concentrated on problems of
locomotion and computer vision, and at Edinburgh, where problems of
computer vision, but more significantly some of the basic problems of
robot assembly, were also studied. The work at SRI on a robot rover
that navigated in a complex room environment became well-known and
helped enlarge the general view of what robotic techniques might
accomplish. m e Edinburgh work on the assembly problem also
demonstrated some interesting technical points, but unfortunately the
Edinburgh manipulator hardware was only suitable for solving toy
assembly problems that industry could not regard as realistic. This
group's lack of suitable industrial and governmental contacts and
sponsors provided a critical obstacle to the transfer of their ideas
into serious industrial practice.
It is also worth noting that some of the early university work on
robots was motivated by enthusiastic expectations of immediate progress
and generally reflected the hope that short intense efforts would
suffice to reach goals that still have not been attained. m e Stanford
hand-eye work had the goal of assemblying a Heathkit radio, which it
was hoped would become possible within two years of program inception.
Fifteen years later, an assembly operation of this complexity is still
well beyond the state of robotic art. Since much of the early
university research was funded by the Advanced Research Projects Agency
of the Department of Defense, reports at that time had it that early
fielding of robot troops or robot-run military vehicles was hoped for.
m is, too, requires technological capabilities that we are still far
from having. Nevertheless, in spite of the failure of their most
ambitious expectations, these university efforts did lay a technical
base and they did train initial groups of researchers that supplied
manpower for the rapid growth in robotics that began during the early
1970s.
THE SECOND DECADE
By the early 1970s, inexpensive minicomputers were readily available,
and much cheaper microcomputers were obviously on the horizon. These
dramatic strides in electronic technology clearly promised to remove
one significant cost factor, the cost of computing power for manipulator
control, that had impeded the application of robot technology. This
fact, obvious to industrial groups both in the United States and abroad,
triggered an expansion in the level of industrial robotic research, with
major companies such as IBM, Cincinnati Milacron, Texas Instruments,
Westinghouse, GE, and GTE all becoming involved in robotic research and
development. Japan became a major focus of robotic activity at this
time, with Hitachi, Fujitsu, and the powerful research group at the
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National Electronic Laboratory all building up robotic research groups.
Olivetti in Italy, ASEA in Sweden, Volkswagen in Germany, and Renault
in France all entered robotic research as well. While a part of this
expanded activity was simply inspired by hopes that the use of robotic
techniques could alleviate some of the internal productivity problems
that the companies involved were facing, at least a few of the companies
building up robotics groups (including Olivetti, Fujitsu, IBM, and
Cincinnati Milacron) saw robotics as a potential opportunity for major
expansion of existing product lines.
m e level of robotic research at universities and university-related
research institutions also rose substantially. The Electronics
Directorate at the National Science Foundation began to fund university
work in this area, and increased funding soon became available under
the more specialized NSF Research Applied to National Needs (RANN) and
Productivity Technology programs. The NSF funding allowed the Stanford
robotics efforts to expand to three-dimensional modeling systems. A
significant robotics activity was also built up at MIT's Charles Stark
Draper Laboratory. The Draper work focused on the problems of
industrial assembly, specifically the mating of parts that must be
fitted together to very close tolerances. Here the inventiveness of a
very able group of mechanical engineers contributed an outstanding
mechanical device, the so-called remote center compliance device, which
made it possible for a robot manipulator to mate parts that had to be
fitted to closer assembly tolerances than the maximum geometric
precision of the manipulators themselves.
NSF-funded work at the University of Rhode Island demonstrated that
computer vision could be practically and successfully combined with
robot manipulation. m e Rhode Island work concentrated on a single
problem of great industrial importance, namely that of picking up parts
made available to a robot in disorganized tote bins. This well-chosen
concentration made it possible for the Rhode Island work to succeed
much more markedly than other groups whose research aims were perhaps
broader but whose focus was also more diffuse.
During this same period, industrial robotics pitched at a number of
specialized applications began to achieve real commercial success.
Concentrated attention to one specific application area--automobile
spot welding--made it possible for this operation to be performed
reliably and well. In this application a heavy tool (a welding gun)
must be positioned to within a few hundredths of an inch, with specified
orientation, at prespecified points on an automobile frame. When the
tool reaches a significant point, it is activated and a weld made. m e
first successful welding applications required the auto frame being
welded to remain stationary, but, as computing power increased, the
more complex task of making welds on a body moving along an assembly
line was mastered. Other similar applications--for example, paint
spraying and die casting--were also studied in depth and opened
important new markets for the sale of robots.
During the 1970s, various industrial and university research groups
began experimenting with sensor-equipped robots. As already noted, the
Stanford, SRI, and Rhode Island work involved the combination of
computer vision and robot manipulation systems. Other work at
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Stanford, IBM, and elsewhere involved the use of more or less
sophisticated tactile sensors. m e use of such sensors demands control
software of much greater sophistication than that needed for robots
whose control is fixed and purely geometric. For fixed geometric
control, simple lists defining the path that a manipulator is to
traverse suffices but in the presence of sensors, one needs software
that can deal with many sensed conditions, choosing among alternative
actions and reacting immediately via interrupt-handling software to
detected external events. Accordingly, the development of more
sophisticated sensors pushed roboticists, perhaps for the first time,
into active concern with the sophisticated software and programming
language issues that had been central to other branches of computer
science. Out of this involvement with software design questions came
the control languages that are being sold with the more sophisticated
of the commercial arms available today. For example, the Unimate model
250 and 500 manipulators (which are largely based upon Scheinemann's
Stanford and MTT work) are programmed in a language called VAL, which
is a direct derivative of the experimental AI robotic language
developed during the early 1970s at Stanford. The relatively advanced
AML language supporting the IBM line of robot manipulators also
reflects the Stanford influence, several key members of the IBM group
having been trained at Stanford. The importance of this Stanford work
can be seen by contrasting the Stanford-descended manipulators with
some of the other robot manipulators being sold today that still make
use of more primitive software concepts that derive from pre-1970s
research. For example, the Cincinnati-Milacron manipulators and some
of the other robot manipulators being sold today still make use of more
primitive software concepts that derive from pre-1970s research, and
are programmed in a language reminiscent of the APT machine-tool
programming language.
The expansion of robotic research and development activity that
characterized the 1970s has continued and intensified during the first
years of the present decade. Westinghouse Corporation has recently
established a separate division within their research and development
organization to develop robots for internal use. This initiative was
undertaken after a visit of the Westinghouse board chairman to Japan
made him aware of the relatively advanced assembly techniques being
used at Hitachi. Robots for electric motor assembly are of particular
interest to Westinghouse. General Electric has announced its intention
to undertake a major reorganization of its manufacturing operations,
with greatly increased use of robotics. General Motors has stated that
it aims to increase its population of working robots substantially.
The level of university robotics-related research is also growing
rapidly. A major new activity, organized as a Robotics Institute, has
begun at Carnegie-Mellon University. The Carnegie-Mellon group combines
the interests and talents of the university's computer science, mech-
anical engineering, electrical engineering, and industrial engineering
departments, and can be expected to bring a broad spectrum of pragmatic
and theoretical talents, covering algorithm, software, and hardware
design, to the ambitious work that they have undertaken. The University
of Florida has also established a Robotics Institute, and the powerful
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MIT group is undergoing major expansion. Many other universities are
starting to involve themselves in robotics, and are actively seeking
industrial connections that can ease their entry into this field.
Robotics has become a matter of interest to the press and general
public and is seen as a vital key to gains that will ensure the ability
of the United States to compete internationally. Access to the flow of
funds critical for continued robotic research and development is
assured by the limited but very real practical successes outlined
above. Although science fiction, perhaps abetted by the speculations
of some artificial intelligence enthusiasts, has conditioned the public
to expect spectacular events, incremental progress based upon complex
and strenuous research efforts is more likely to characterize the
coming decade. Commercially successful new applications of robotics
will become possible at those points where the most advanced concepts
projected by research laboratories can be cut back to yield more
limited, but well-engineered, reliable devices that answer the
immediate needs of industry. Industrial acceptance is, of course,
critically conditioned by cost, so that robot systems limited in their
kinematic and sensory complexity and in their demand for computing
power will come into wide use before more flexible but expensive
systems. Another factor bound to condition the rate at which industry
demands robot equipment will be the need to rework the existing
industrial environment of fixtures, -~ _
to better adapt them to robot-based - ~ -
nart feeding, and transport devices
production styles. But, as the
cost of robots falls, and as these inherently universal devices grow in
adaptability and reliability, broad industrial acceptance seems
inevitable.
CURRENT RESEARCH EMPHASES
To manage the technical problems of robotics, very challenging research
will have to be undertaken, and complex, expensive developmental
activities mounted as well. m is will require both extensive university
research efforts and major industrial developments. Here we perceive
an area in which well-structured university-industry cooperation could
accelerate the growth of a very challenging technology. To make a
robot manipulator useful commercially involves a significant software
effort, which must at the very least provide for real-time manipulator
control, rapid handling of sensor-generated interrupts, and complex
geometric computations. These requirements will increase significantly
as multiarmed robot systems come to be employed.
In robotics, computer science confronts the kinematic and dynamical
reality of three-dimensional space, a circumstance that has already
begun to involve robotics researchers in many fields whose relationship
to the pragmatic requirements of computer science was previously
marginal. Among these newly critical subject areas, computational
algebra and geometry, Lagrangian dynamics, and the theory of friction
and of elasticity may all be listed. All this implies that the complex
of issues that researchers in robotics need to face is extraordinarily
broad, so that practical progress in this field is likely to be more
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dependent on advanced research than is the case for other computer
application fields. Since little of this scientific material has until
now been part of the computer science curriculum, we can also expect
the requirements of robotics to encourage a substantial revision and
mathematical deepening of the curriculum that university computer
science departments will have to offer.
Although robotics research seems certain to touch upon a par-
ticularly broad range of technologies and scientific disciplines, we
can gain some understanding of the areas likely to be of greatest
significance over the next decades by surveying the near-term
requirements of industrial robotics. These include the following:
1. In-depth studies of important current applications. Robot
spotwelding has become routine, and attention is now turning to the
more complex physical problems associated with continuous arc welding,
where proper control of welder robots requires some understanding of
the thermodynamics of the liquid-solid arc pool. Ways of specializing
robots to work in environments that are hazardous or inaccessible to
humans, e.g., high-purity clean rooms, deep-sea environments, nuclear
reactors, and space, also require detailed study and will sometimes
raise complex dynamical and other problems.
2. Improvement of visual, tactile, and other robot sensors.
Current computer vision software is of limited reliability and quite
expensive computationally. Much faster and more stable picture-
processing algorithms and devices are required. To produce these will
require penetrating theoretical research, as well as the development of
specialized high-performance VLSI chips whose logic will have to embody
the best algorithms that research can make available. Vision systems
that are easily reprogrammable for a wide range of applications are
particularly desirable, but at present it is not at all clear how these
can be created.
Tactile sensing plays a particularly important role in dextrous
manual assembly. The subtlety of the human tactile sense is far from
being matched by the relatively crude tactile sensors currently avail-
able with robot manipulators. It seems clear that greatly improved
sensors will be required if complex assemblies, especially of fragile
and deformable parts, are to be attempted, and if more sophisticated
methods of grasping are to be developed. m is has been recognized as
an important research issue, and work on improved tactile sensors under
way now should yield considerably improved sensors within a few years.
Better sensors will in turn call for more sophisticated software to
manage them, a consideration that emphasizes the importance of improved
programming techniques to the general progress of robotics.
It is also important to develop improved proximity sensors able to
give advance warning of impending collisions. One will probably never
be willing to set robot arms into rapid motion in an environment that
is at all unpredictable. His makes it plain that development of better
proximity sensors can contribute substantially to the productivity of
robot systems, and also to their flexibility. Such systems will in
turn demand software able to react appropriately to warnings that they
supply.
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3. Force-controlled motion primitives. The motion-control
primitives supplied with today's robot systems are purely geometric in
character, but cannot, as they stand, be used to cause a robot arm to
move smoothly while maintaining contact with a curved surface of unknown
shape. The ability to do this is essential for the logically flexible
adaptation of a manipulator to an environment whose whole geometry is
not known in precise detail. Force-controlled motions play an essential
role in manual assembly, and the demonstrated advantages of devices like
the Draper Laboratories' remote center compliance device point clearly
to their importance for robot manipulators as well. Near-term research
and development efforts to make motion primitives of this kind available
in the commonly used robot-programming languages are therefore likely.
4. Improved robot-programming techniques. A large existing
industrial assembly manual literature gives detailed directions for
producing a great many common manufactured items. Finding some way of
translating these manuals automatically into robot assembly programs
would be ideal, but unfortunately, this far exceeds the capability of
today's robotics programming languages. For anything close to the
language of standard industrial assembly manuals to be accepted as
robot control input, much more sophisticated languages than those now
coming into use will be required. m e compilers for such languages
will have to incorporate knowledge of the part and subpart structure of
partly assembled manufactured objects. They will also have to
incorporate a routine capable of planning the way in which such objects
can be grasped, moved without collision through a cluttered environment,
and inserted into a constrained position within a large assembly. This
level of programming sophistication only becomes feasible if a robot
system can either maintain a detailed model of the environment with
which it is dealing through a whole complex sequence of manipulations,
or acquire and refresh such a model through visual analysis of the
scene before it. Although no robotic language with nearly this degree
of sophistication has actually been produced, such languages have at
least been projected, e.g., in the work on AUTOPASS at IBM, and its
Stanford, MIT, and Edinburgh relatives AL, LAMA, and RAPT, respectively.
It should be noted that the implementation of languages of this
sophistication will require solution of many levels of fairly complex
mathematical and geometric problems. One basic problem of this kind is
that of planning collision-free motions of three-dimensional bodies
through obstacle-filled environments. This problem, studied by
researchers at Caltech, MIT, New York University, and elsewhere, has by
now been brought to a preliminary stage of solution, but from the
practical point of view this work merely reveals the complexity of
computations that motion planning can involve and the importance of
seeking much more efficient motion-planning schemes.
The work carried out by Fahlman at MIT is also suggestive of
possibilities for more advanced robot activity-planning software.
Working within a simulated world of blocks, Fahlman constructed a
program that could combine geometric knowledge of the collection of
blocks given it with an understanding of the final assembly desired, to
produce a fully sequenced assembly plan. This demonstration program
was even capable of using some of the blocks available to it to
construct fixtures useful in the assembly of the remaining blocks.
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5. Improved manipulator hardware. m e essential elements of a
complete robot manipulator subsystem are-a manipulator arm, the grippers
and sensors with which it is furnished, and the computer circuitry that
controls it. University groups can be expected to contribute substan-
tially to the design of new hardware and software control schemes and
improved grippers and sensors, but the high costs associated with the
development of a new mechanical hardware are likely to make this a
matter for industry rather than universities. It may be necessary to
include features supporting advanced control concepts such as that of
force-guarded motion directly in the basic mechanical structure of a
manipulator, a possibility that argues for the importance of close
industry-university collaboration in the continued development of robot
manipulators.
SOME CONCLUSIONS
Advances in robotics can certainly contribute to increased U.S.
productivity. However, the research issues that will need to be faced
in developing robot technology are extremely broad; geometry, dynamics,
elasticity theory, materials design, and electronic and software
science are all involved. University researchers will find many deep
issues to ponder, and industrial development groups will have many
large systems to build. In order to realize the great potential of
robotics, it will be particularly important to combine the abilities of
these two communities and to encourage them to work closely together;
this will give industry the mathematical skills that the field demands,
and assist universities to find the capital resources and engineering
capacity that they will need.
As the potential of robot technology is realized over the next few
decades through the mastery of successive practical tasks, and as the
cost of robot manipulators and their controls continues to fall,
economic pressures will increasingly favor wide robot deployment. The
immediate technical steps that will lead in this direction are the
improvement of manipulators and grippers, the close study of numerous
significant applications, and the development of improved sensors and
their integration into standard systems. Universities will contribute
deeper investigation of the complex mathematical and programming
problems of robotics.
A word of caution is in order. AS the robot development works
itself out, our ability to deal with its social consequences is likely
to be challenged. If we fail to respond adequately to this challenge,
social unrest and latter-day Luddite tendencies may become a bigger
inhibition to the wide deployment of robots than technological
difficulties, which in time will surely be overcome. Society will have
to decide what it wants to do with the new industrial capabilities that
robotics research is creating.
Representative terms from entire chapter:
robotic research
