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From the Unimate to the Delta robot: the early
decades of Industrial Robotics
A. Gasparetto and L. Scalera
Polytechnic Department of Engineering and Architecture – University of Udine,
Udine, Italy, e-mail: firstname.lastname@example.org /
Abstract. In this paper, the early decades of the history of industrial robots (from the 1950’s to the be-
ginning of the 1990’s, approximately) will be described. The history of industrial robotics can be con-
sidered starting with Unimate, the first industrial robot designed and built by Devol and Engelberger.
The subsequent evolutions of industrial robotics are described in the manuscript, taking into account
both the technical and the economic point of view, until the beginning of the 1990’s, when new kine-
matic structures (parallel robots) appeared, allowing high-speed operations.
Key words: Industrial robots, history, Unimate, Stanford Arm, Delta robot
Since ancient times, the humanity conceived the idea to design and to build some
kind of beings, or devices, which could substitute men in heavy or repetitive work.
Such beings, called automata, date back to the Greek-Hellenistic age and have
been conceived by several civilizations throughout the centuries. A historical per-
spective of Robotics may be found in  and , while a brief history of automata
and robots, from ancient times up to the Industrial Revolution, can be found in .
From the Industrial Revolution on, some forms of automatization took place in the
industrial environment; however, it is only in the 1950’s that what is known as
“industrial robotics” started.
A chronological categorization of industrial robots has been proposed in terms of
“generations” . Four generations have been proposed, namely: first generation
(1950-1967), second generation (1968-1977), third generation (1978-1999), fourth
generation (from 2000 on).
The industrial robots of first generation are defined as programmable machines
without the possibility of controlling the real modes of execution and without
communication with the external environment. The robots of the first generation
2 A. Gasparetto and L. Scalera
use low-tech equipment and did not employ servo-controllers. They are character-
ized by the strong noise made by their arms when colliding with the mechanical
stops used to limit their movements. Almost all the robots of the first generation
are pneumatic and their automatic regulators generally consist of air-actuated logic
gates, implemented by means of drums that divide segments from cams that are
used to activate pneumatic valves, or relays that control solenoid pneumatic
valves. The first generation of robots of the sixties is essentially used for load-
ing/unloading purposes or for carrying out simple material handling operations.
The second generation of industrial robots consists of programmable machines
with self-adaptive behavior with elementary possibilities of recognition of the ex-
ternal environment. Such robots are equipped with servo-controllers, which can be
programmed to move from point to point or along a continuous path. Their con-
troller is based on programmable logic controllers (PLC) or minicomputers. A
teach-box allows the users to online program the robot motion. The second gener-
ation of industrial robots is able to perform more complex tasks, with respect to
the first one, such as the control of the work centers. Each robot is provided with
dedicated software for a specific application: hence, it is rather difficult to use the
same robot for a different task, because to do so, it would be necessary to substan-
tially modify the control system and the operating software. Furthermore, the sec-
ond generation robots has low diagnostic capabilities, which are generally limited
to report failures to the operator by means of indicator lights. It is up to the opera-
tor to trace the actual causes of the failure.
The third generation robots are self-programmable machines interacting with the
external environment and the operator in a more complex way (vision, voice, etc.),
with some (limited) capability to reprogram themselves for the execution of an as-
signed task. The third-generation robots are machines that operated under servo
control and can be programmed to move from point to point or along continuous
paths. Scheduling could take place online by means of a prehensile keyboard or
off line through a video display. This type of robot uses high-level programming
languages and can be interfaced with a CAD database or with a host computer for
the loading/unloading of programs. The available control systems can process sen-
sory data to adjust the movements and compensate for changes in position and
orientation of parts. Furthermore, thanks to the feedback of sensory data and the
interfacing with a CAD database or a host computer, the third generation robots
can send messages to the operator, to describe the nature and location of any fail-
ure. The third generation robots evolved to the point of being able to perform
some sort of "intelligent" tasks, such as adaptive arc welding (during which the
robot uses vision or perception "through the arc" to locate the welding joint and
get information to guide the movement), or other complex tasks such as tactile in-
spections, freehand machining and assembly operations.
In the fourth generation, the “intelligent” capabilities of the robots reach a high
level (advanced computing capabilities, logical reasoning and learning, complex
control strategies, collaborative behavior). This generation extends up to the cur-
From the Unimate to the Delta robot: the early decades of Industrial Robotics 3
In this paper, the focus will be set on the history of industrial robots in the XX
century, in particular from Unimate (1959), the world's first industrial robot, to the
Delta robot (1992), the first parallel robot installed in the industry.
It should be mentioned that very few papers about the history of industrial robots
are present in the literature. Sketches of history of industrial robotics appear in
some internal reports (such as  and ), as well as in some robotics books (as
for instance in , ,  and ).
2 The dawn of industrial robotics: Devon, Engelberger
and the Unimate robot
Before dealing with the history of industrial robots, some important developments
in automatization, which happened before the appearance of the first industrial ro-
bot, should be mentioned.
In 1938, Willard Pollard and Harold Roselund built the first “programmable”
mechanism, namely a paint-sprayer for the DeVilbiss company.
In 1952 the first NC machine was developed at MIT in Boston by John Parsons
and Frank Stulen, who filed a patent on "Motor Controlled Apparatus for Position-
ing Machine Tool". Such a machine was a milling machine numerically program-
mable for short series: it was a technical breakthrough in the automation scenario.
The patent for this machine was granted in 1958 .
In 1949 Raymond Goertz filed a patent for a tele-operated articulated arm on be-
half of the Atomic Energy Commission. This arm is considered an early version of
master-slave manipulators. The patent for this device, named “Remote-control
manipulator”, was granted in 1953 .
The real start of the history of industrial robots is set in 1954, when John Devol,
an American scientist, filed a patent for a “programmable article transfer” (patent
granted in 1963) . The method described in this patent was the key to the de-
velopment of Unimate, the world's first industrial robot.
In 1956, during a cocktail party in Connecticut, Devol met Joseph Engelberger,
a space-industry engineer. They discussed about the possible use of the machine
patented by Devol, and conceived the idea to set up a company to design and build
manipulators to be employed in the industry. In the following years, Devol and
Engelberger visited many factories (mainly in the automotive sector), to better un-
derstand the needs of the production plants. In 1961, they founded the company
Unimaton, which manufactured what is considered the first industrial robot, name-
ly a hydraulically actuated manipulator called Unimate (Fig. 1), In the same year,
the first Unimate was installed in the General Motors factory located in Trenton
(USA): it could perform a single task, namely extracting parts from a die-casting
machine. Further versions of Unimate were employed, in the following years, for
workpiece handling and for spot-welding of car bodies.
4 A. Gasparetto and L. Scalera
Fig. 1 George Devol and the Unimate 
In the meanwhile, several other entrepreneurs understood the potential of these
new devices, and many companies that manufactured manipulators were created.
The automotive companies (especially General Motors and Ford) launched plans
to “automatize” their production plants, and placed big orders of manipulators,
thus giving a boost to the robotic industry.
AMF Corporation developed in 1962 an industrial robot with a cylindrical co-
ordinate frame, named Versatran (from the words “versatile transfer”), which was
installed at the Ford factory located in Canton (USA). This robot (Fig. 2) was the
first one imported in Japan in 1967; two years later, the company Kawasaki Heavy
Industries Ltd. obtained from Unimation the license to build robots: this fact defi-
nitely gave a boost to the diffusion of robots in Japan.
From the Unimate to the Delta robot: the early decades of Industrial Robotics 5
Fig. 2 Versatran (from )
The first robots in Europe were installed in 1967 at Svenska Metallverken in
Upplands Väsby (Sweden): their tasks were simple and repetitive pick-and-place
movements. In 1969, the Norwegian company Tralffa developed the first painting
robot, which was employed in the painting of wheelbarrows.
The first welding robots were produced by Unimation, and installed at the Gen-
eral Motors assembly plants in Lordstown (USA) in 1969, to perform spot-
welding to car bodies. In Europe, the first welding robots appeared at FIAT plants
in Turin (Italy) in 1972.
3 From hydraulic to electric robots: Scheinman, the
Stanford Arm and the PUMA robot
A breakthrough milestone in the history of industrial robots is the Stanford Arm
(Fig. 3) built in 1969 by Victor Scheinman , a mechanical engineering student
working in the Stanford Artificial Intelligence Laboratory (SAIL). It was the first
all-electric manipulator, controlled by a microprocessor (PDP-6). It had six de-
grees-of-freedom (5 revolute joints and a prismatic joint): such a configuration al-
lowed to quickly solve the inverse kinematics in a closed form, thus speeding up
the computations required to the microprocessor. The robot actuators were six DC
electric motors, and the kinematic chain was composed of harmonic drives and
spur gear reducers. The manipulator was also provided with sensors, namely po-
6 A. Gasparetto and L. Scalera
tentiometers and tachometers for measuring position and velocity, for controlling
Fig. 3 Stanford Arm (from )
In 1973 Scheinman founded a company (Vicarm Inc.) to produce Vicarm, an
electric robot intended for assembly operation. The idea was to build a manipula-
tor smaller and lighter than Unimate, which could be employed for operations
where it was not required to lift heavy loads. Vicarm was the first conception of
electric robot: years later, the company founded by Scheinman was bought by Un-
imation and Vicarm was the basis for the development of the PUMA robot.
Scheinman’s concepts greatly influenced the subsequent development of indus-
trial robotics. Besides that, the results of the research and the development of the
1960’s were ready to appear in commercial products in the middle of the 1970’s.
In particular, the new microelectronic components, and especially the micropro-
cessors, reached the technical maturity and could be used as a basis for cost-
effective and powerful control systems, which could be applied to computationally
expensive tasks such as robot control. Furthermore, even economic and geopoliti-
cal events gave a boost to the automatization of industrial production: the oil crisis
of October 1973 forced many companies to look for more efficient ways of pro-
duction, and introducing robots in the production plants could serve this aim very
well. For all these reasons, in the second half of the 1970’s, the sales of industrial
robots grew very rapidly, with a yearly increase of more than 30% in the average.
From the Unimate to the Delta robot: the early decades of Industrial Robotics 7
In 1973 KUKA developed Famulus, the first robot to have six electromechani-
cally driven axes. A year later (1974), the first microcomputer-controlled robot
was introduced by Cincinnati Milacron, the biggest machine-tool manufacturer in
the world. It was named T3 (“The Tomorrow Tool”, Fig. 4), and was sold to sev-
eral companies, especially of the automotive sector (Volvo in particular). In 1990
ABB bought the robotic division of Cincinnati Milacron .
Fig. 4 The Cincinnati Milacron T3 robot (from )
In the same year (1974), ASEA (now ABB) developed the first all-electric in-
dustrial robot, controlled by a microprocessor. It was named IRB-6 (Fig. 5) and
was able to perform continuous paths: for this reason, it was widely employed in
the factories for tasks such as arc-welding or machining. The robots of the IRB se-
ries (characterized by their typical orange color) had a great success, and the pro-
duction continued for more than 20 years.
8 A. Gasparetto and L. Scalera
Fig. 5 The “legendary” IRB-6 (from )
In 1978, Unimation released, together with General Motors, a novel anthropo-
morphic robot named PUMA (an acronym for Programmable Universal Machine
for Assembly). PUMA (Fig. 6) was considered archetypal for the anthropo-
morphic robots, and its kinematics was taken as an example in several robotics
books in the academy worldwide.
From the Unimate to the Delta robot: the early decades of Industrial Robotics 9
Fig. 6 The PUMA robot (from )
4 The robotic boom of the 1980’s
In the same year (1978), another important milestone in the history of industrial
robots came, when Hiroshi Makino of Yamanashi University (Japan) invented the
SCARA robot (Fig. 7). Such a manipulator, named after the acronym “Selective
Compliance Assembly Robot Arm”, had an innovative kinematics and was per-
fectly suited for assembly of small parts. The simplicity of the kinematic chain
made the control easy and very fast; moreover, the cost was considerably low,
compared to other types of manipulators. The diffusion of SCARA robots gave a
boost to the production of electronic consumer goods, which were assembled by
this type of robots. This made the Japanese robotics industry lead the robotics in-
dustry worldwide: indeed, in 1980 Japan became the world’s largest robot manu-
10 A. Gasparetto and L. Scalera
facturer. By the end of the decade, Japan had about 40 robot manufacturers that
dominated the global robot market.
Fig. 7 The first prototype of SCARA robot (from )
In 1981 Asada and Kanade build the first direct-drive arm at Carnegie Mellon
University (Fig. 8). It was named the CMU Direct Drive Arm .
Fig. 8 The CMU Direct Drive Arm (from )
From the Unimate to the Delta robot: the early decades of Industrial Robotics 11
In the 1980’s, industrial robotics enjoyed both an enormous interest and a con-
siderable increase in the number of installations. Robotics was identified, by in-
dustrialists, politicians, researchers and journalists, as a crucial area for industrial
development and a terrific tool to achieve increased competitiveness. Moreover, in
the second half of the 1980’s decade, advanced sensors (such as laser scanners,
cameras and force sensors) began to be employed in robotics, allowing robots to
perform increasingly complex tasks.
5 From serial to parallel kinematics: the Delta robot
Another important stream in the history of industrial robots is connected with the
search for high-speed operation. To this respect, a change in the kinematic config-
uration led to promising results: namely, parallel kinematic machines (called “par-
allel robots”) could be conceived. With respect to the “traditional” serial robots,
this kind of manipulators feature more lightweight structures, thus can reach high-
er operational speeds, at the cost of a reduction of the workspace volumes. Parallel
robots are therefore particularly suited for high-speed tasks, where precision is al-
so required (for example, picking or machining operations). The most important
example of parallel robot is definitely the Delta robot, developed by the Swiss
company Demaureux, which in 1992 used this kind of robot in an installation
named “Presto” (“soon” in Italian), aimed at performing pick-and-place tasks.
The Delta robot was based on the idea by Reymond Clavel, Professor at the EPFL
(Ecole Polytechnique Fédérale de Lausanne), who in his PhD thesis (1981) de-
signed a parallel robot, built with parallelograms, having three translational and
one rotational degrees of freedom  (Fig. 9).
The Delta robot had a huge success, due to its capability to perform high-speed
operations. Many versions of Delta robot were designed and built in the following
years, as for instance the IRB 340 Flexpicker manufactured by ABB (1999).
12 A. Gasparetto and L. Scalera
Fig. 9 Reymond Clavel (left) with a Delta robot
In this paper, the first decades of history of the industrial robotics are presented,
starting from the ideas of Devol and Engelberger, that led to the birth of Unimate,
the first industrial robot, up to the appearance of the Delta robot, which was the
first of a series of high-speed robots with parallel kinematics. In this historical
sketch, both technical and economic factors have been taken into account.
The evolution of industrial Robotics is still going on in the current day: it can be
said that new ideas and the technological progress gave a new life to industrial ro-
botics, which only few years ago seemed to have reached its complete maturity.
New human-robot interfaces, novel programming techniques based on artificial in-
telligence and “deep learning”, as well as an extraordinary development in the
sensors technology as well as in the wireless technology gave industrial robotics a
new youth, revolutionizing the traditional concepts of factory automation.
From the Unimate to the Delta robot: the early decades of Industrial Robotics 13
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