An industrial robot is a
robot
A robot is a machine—especially one programmable by a computer—capable of carrying out a complex series of actions automatically. A robot can be guided by an external control device, or the control may be embedded within. Robots may be c ...
system used for
manufacturing
Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a r ...
. Industrial robots are automated, programmable and capable of movement on three or more axes.
Typical applications of robots include
welding
Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing Fusion welding, fusion. Welding is distinct from lower ...
, painting, assembly,
disassembly
A disassembler is a computer program that translates machine language into assembly language—the inverse operation to that of an assembler. A disassembler differs from a decompiler, which targets a high-level language rather than an assembly lan ...
,
pick and place for
printed circuit board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...
s,
packaging and labeling
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a ...
,
palletizing
A pallet (also called a skid) is a flat transport structure, which supports goods in a stable fashion while being lifted by a forklift, a pallet jack, a front loader, a jacking device, or an erect crane. A pallet is the structural foundat ...
, product inspection, and testing; all accomplished with high endurance, speed, and precision. They can assist in
material handling
Material handling involves short-distance movement within the confines of a building or between a building and a transportation vehicle. It uses a wide range of manual, semi-automated, and automated equipment and includes consideration of the pro ...
.
In the year 2020, an estimated 1.64 million industrial robots were in operation worldwide according to
International Federation of Robotics (IFR).
Types and features
There are six types of industrial robots.
Articulated robots
Articulated robots
are the most common industrial robots.
They look like a
human arm
In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...
, which is why they are also called
robotic arm
A robotic arm is a type of mechanical arm, usually programmable, with similar functions to a human arm; the arm may be the sum total of the mechanism or may be part of a more complex robot. The links of such a manipulator are connected by joints ...
or
manipulator arm. Their articulations with several
degrees of freedom allow the articulated arms a wide range of movements.
Cartesian coordinate robots
Cartesian robots,
also called rectilinear, gantry robots, and x-y-z robots
have three
prismatic joint
A prismatic joint is a one- degree-of-freedom kinematic pair which constrains the motion of two bodies to sliding along a common axis, without rotation; for this reason it is often called a slider (as in the slider-crank linkage) or a sliding ...
s for the movement of the tool and three rotary joints for its orientation in space.
To be able to move and orient the effector organ in all directions, such a robot needs 6 axes (or degrees of freedom). In a 2-dimensional environment, three axes are sufficient, two for displacement and one for orientation.
Cylindrical coordinate robots
The
cylindrical coordinate robots
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infin ...
are characterized by their rotary joint at the base and at least one prismatic joint connecting its links.
They can move vertically and horizontally by sliding. The compact effector design allows the robot to reach tight work-spaces without any loss of speed.
Spherical coordinate robots
Spherical coordinate robots only have rotary joints.
They are one of the first robots to have been used in industrial applications.
They are commonly used for
machine tending
{{unreferenced, date=August 2016
Machine tending refers to the automated operation of industrial machine tools in a manufacturing plant, primarily using robot automation systems. While loading and unloading is the primary function of machine ten ...
in die-casting, plastic injection and extrusion, and for welding.
SCARA robots
SCARA
is an acronym for Selective Compliance Assembly Robot Arm. SCARA robots are recognized by their two
parallel joints which provide movement in the X-Y plane.
Rotating shafts are positioned vertically at the effector..
SCARA robots are used for jobs that require precise lateral movements. They are ideal for assembly applications.
Delta robots
Delta robots
are also referred to as parallel link robots.
They consist of parallel links connected to a common base. Delta robots are particularly useful for direct control tasks and high maneuvering operations (such as quick pick-and-place tasks). Delta robots take advantage of four bar or parallelogram linkage systems.
Furthermore, industrial robots can have a serial or parallel architecture.
Serial manipulators
Serial architectures a.k.a Serial manipulators are the most common industrial robots and they are designed as a series of links connected by motor-actuated joints that extend from a base to an end-effector. SCARA, Stanford manipulators are typical examples of this category.
Parallel Architecture
A parallel manipulator is designed so that each chain is usually short, simple and can thus be rigid against unwanted movement, compared to a
serial manipulator Serial manipulators are the most common industrial robots and they are designed as a series of links connected by motor-actuated joints that extend from a base to an end-effector. Often they have an anthropomorphic arm structure described as havin ...
. Errors in one chain's positioning are averaged in conjunction with the others, rather than being cumulative. Each actuator must still move within its own
degree of freedom
Degrees of freedom (often abbreviated df or DOF) refers to the number of independent variables or parameters of a thermodynamic system. In various scientific fields, the word "freedom" is used to describe the limits to which physical movement or ...
, as for a serial robot; however in the parallel robot the off-axis flexibility of a joint is also constrained by the effect of the other chains. It is this
closed-loop stiffness that makes the overall parallel manipulator stiff relative to its components, unlike the serial chain that becomes progressively less rigid with more components.
Lower mobility parallel manipulators and concomitant motion
A full parallel manipulator can move an object with up to 6
degrees of freedom (DoF), determined by 3 translation ''3T'' and 3 rotation ''3R'' coordinates for full ''3T3R m''obility. However, when a manipulation task requires less than 6 DoF, the use of lower mobility manipulators, with fewer than 6 DoF, may bring advantages in terms of simpler architecture, easier control, faster motion and lower cost. For example, the 3 DoF Delta robot has lower ''3T'' mobility and has proven to be very successful for rapid pick-and-place translational positioning applications. The workspace of lower mobility manipulators may be decomposed into `motion’ and `constraint’ subspaces. For example, 3 position coordinates constitute the motion subspace of the 3 DoF Delta robot and the 3 orientation coordinates are in the constraint subspace. The motion subspace of lower mobility manipulators may be further decomposed into independent (desired) and dependent (concomitant) subspaces: consisting of `concomitant’ or `parasitic’ motion which is undesired motion of the manipulator. The debilitating effects of concomitant motion should be mitigated or eliminated in the successful design of lower mobility manipulators. For example, the Delta robot does not have parasitic motion since its end effector does not rotate.
Autonomy
Robots exhibit varying degrees of
autonomy
In developmental psychology and moral, political, and bioethical philosophy, autonomy, from , ''autonomos'', from αὐτο- ''auto-'' "self" and νόμος ''nomos'', "law", hence when combined understood to mean "one who gives oneself one's ...
.
Some robots are programmed to faithfully carry out specific actions over and over again (repetitive actions) without variation and with a high degree of accuracy. These actions are determined by programmed routines that specify the direction, acceleration, velocity, deceleration, and distance of a series of coordinated motions
Other robots are much more flexible as to the orientation of the object on which they are operating or even the task that has to be performed on the object itself, which the robot may even need to identify. For example, for more precise guidance, robots often contain
machine vision
Machine vision (MV) is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision refers to ...
sub-systems acting as their visual sensors, linked to powerful computers or controllers.
Artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech re ...
is becoming an increasingly important factor in the modern industrial robot.
History
The earliest known industrial robot, conforming to the ISO definition was completed by
"Bill" Griffith P. Taylor in 1937 and published in
Meccano Magazine
''Meccano Magazine'' was an English monthly hobby magazine published by Meccano Ltd between 1916 and 1963, and by other publishers between 1963 and 1981. The magazine was initially created for Meccano builders, but it soon became a general hobb ...
, March 1938.
The crane-like device was built almost entirely using
Meccano
Meccano is a brand of model construction system created in 1898 by Frank Hornby in Liverpool, England. The system consists of reusable metal strips, plates, angle girders, wheels, axles and gears, and plastic parts that are connected using nut ...
parts, and powered by a single electric motor. Five axes of movement were possible, including ''grab'' and ''grab rotation''. Automation was achieved using punched paper tape to energise solenoids, which would facilitate the movement of the crane's control levers. The
robot
A robot is a machine—especially one programmable by a computer—capable of carrying out a complex series of actions automatically. A robot can be guided by an external control device, or the control may be embedded within. Robots may be c ...
could stack wooden blocks in pre-programmed patterns. The number of motor revolutions required for each desired movement was first plotted on graph paper. This information was then transferred to the paper tape, which was also driven by the robot's single motor. Chris Shute built a complete replica of the robot in 1997.
George Devol
George Charles Devol Jr. (February 20, 1912 – August 11, 2011) was an American inventor, best known for creating Unimate, the first industrial robot. Devol's invention earned him the title "Grandfather of Robotics". The National Inventor ...
applied for the first robotics
patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
s in 1954 (granted in 1961). The first company to produce a robot was
Unimation
Unimation was the world's first robotics company. It was founded in 1962 by Joseph F. Engelberger and George Devol and was located in Danbury, Connecticut. Devol had already applied for a patent an industrial robotic arm in 1954; was issued in ...
, founded by Devol and
Joseph F. Engelberger
Joseph Frederick Engelberger (July 26, 1925 – December 1, 2015) was an American physicist, engineer and entrepreneur. Licensing the original patent awarded to inventor George Devol, Engelberger developed the first industrial robot in the Uni ...
in 1956. Unimation robots were also called ''programmable transfer machines'' since their main use at first was to transfer objects from one point to another, less than a dozen feet or so apart. They used
hydraulic
Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counte ...
actuators and were programmed in ''joint
coordinates
In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space. The order of the coordinates is sig ...
'', i.e. the angles of the various joints were stored during a teaching phase and replayed in operation. They were accurate to within 1/10,000 of an inch (note: although accuracy is not an appropriate measure for robots, usually evaluated in terms of repeatability - see later). Unimation later licensed their technology to
Kawasaki Heavy Industries
(or simply Kawasaki) is a Japanese Public company, public multinational corporation manufacturer of motorcycles, engines, Heavy equipment (construction), heavy equipment, aerospace and Military, defense equipment, rolling stock and ships, headq ...
and
GKN
GKN Ltd is a British multinational automotive and aerospace components business headquartered in Redditch, England. It is a long-running business known for many decades as Guest, Keen and Nettlefolds. It can trace its origins back to 1759 an ...
, manufacturing
Unimate
Unimate was the first industrial robot,
which worked on a General Motors assembly line at the Inland Fisher Guide Plant in Ewing Township, New Jersey, in 1961.Mickle, Paul"1961: A peep into the automated future" ''The Trentonian''. Accessed Aug ...
s in Japan and England respectively. For some time Unimation's only competitor was
Cincinnati Milacron
Milacron is an American limited liability company that manufactures and distributes plastic processing equipment for fields such as injection molding and extrusion molding. Milacron is one of many operating companies that make up Hillenbrand, ...
Inc. of
Ohio
Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
. This changed radically in the late 1970s when several big Japanese conglomerates began producing similar industrial robots.
In 1969
Victor Scheinman
Victor David Scheinman (December 28, 1942 – September 20, 2016) was an American pioneer in the field of robotics.
He was born in Augusta, Georgia, where his father Leonard was stationed with the US Army. At the end of the war the family mov ...
at
Stanford University
Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...
invented the
Stanford arm
Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is considere ...
, an all-electric, 6-axis articulated robot designed to permit an
arm solution
In the engineering field of robotics, an arm solution is a set of calculations that allow the real-time computation of the control commands needed to place the end of a robotic arm at a desired position and orientation in space.
A typical indust ...
. This allowed it accurately to follow arbitrary paths in space and widened the potential use of the robot to more sophisticated applications such as assembly and welding. Scheinman then designed a second arm for the
MIT
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the m ...
AI Lab, called the "MIT arm." Scheinman, after receiving a fellowship from Unimation to develop his designs, sold those designs to Unimation who further developed them with support from
General Motors
The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...
and later marketed it as the
Programmable Universal Machine for Assembly
The PUMA (''Programmable Universal Machine for Assembly'', or ''Programmable Universal Manipulation Arm'') is an industrial robotic arm developed by Victor Scheinman at pioneering robot company Unimation. Initially developed for General Motors, ...
(PUMA).
Industrial robotics took off quite quickly in Europe, with both
ABB Robotics and
KUKA Robotics
KUKA is a German manufacturer of industrial robots and systems for factory automation. It has been predominantly owned by the Chinese company Midea Group since 2016.
The KUKA Robotics Corporation has 25 subsidiaries, mostly sales and servic ...
bringing robots to the market in 1973. ABB Robotics (formerly ASEA) introduced IRB 6, among the world's first ''commercially available'' all electric micro-processor controlled robot. The first two IRB 6 robots were sold to Magnusson in Sweden for grinding and polishing pipe bends and were installed in production in January 1974. Also in 1973 KUKA Robotics built its first robot, known as
FAMULUS, also one of the first articulated robots to have six electromechanically driven axes.
Interest in robotics increased in the late 1970s and many US companies entered the field, including large firms like
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
, and
General Motors
The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...
(which formed
joint venture
A joint venture (JV) is a business entity created by two or more parties, generally characterized by shared ownership, shared returns and economic risk, risks, and shared governance. Companies typically pursue joint ventures for one of four rea ...
FANUC Robotics
FANUC ( or ; often styled Fanuc) is a Japanese group of companies that provide automation products and services such as robotics and computer numerical control wireless systems. These companies are principally of Japan, Fanuc America Corporat ...
with
FANUC
FANUC ( or ; often styled Fanuc) is a Japanese group of companies that provide automation products and services such as robotics and computer numerical control wireless systems. These companies are principally of Japan, Fanuc America Corpor ...
LTD of Japan). U.S.
startup companies
A startup or start-up is a company or project undertaken by an entrepreneur to seek, develop, and validate a scalable business model. While entrepreneurship refers to all new businesses, including self-employment and businesses that never intend t ...
included
Automatix
Automatix Inc., founded in January 1980, was the first company to market industrial robots with built-in machine vision. Its founders were Victor Scheinman, inventor of the Stanford arm; Phillippe Villers, Michael Cronin, and Arnold Reinhold o ...
and
Adept Technology
Omron Adept Technology, Inc. is a multinational corporation with headquarters in Pleasanton, California (San Francisco Bay Area). The company focus on industrial automation and robotics, including software and vision guidance. Adept has offices t ...
, Inc. At the height of the robot boom in 1984, Unimation was acquired by
Westinghouse Electric Corporation
The Westinghouse Electric Corporation was an American manufacturing company founded in 1886 by George Westinghouse. It was originally named "Westinghouse Electric & Manufacturing Company" and was renamed "Westinghouse Electric Corporation" in ...
for 107 million U.S. dollars. Westinghouse sold Unimation to
Stäubli Faverges SCA of
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
in 1988, which is still making articulated robots for general industrial and
cleanroom
A cleanroom or clean room is an engineered space, which maintains a very low concentration of airborne particulates. It is well isolated, well-controlled from contamination, and actively cleansed. Such rooms are commonly needed for scientif ...
applications and even bought the robotic division of
Bosch in late 2004.
Only a few non-Japanese companies ultimately managed to survive in this market, the major ones being:
Adept Technology
Omron Adept Technology, Inc. is a multinational corporation with headquarters in Pleasanton, California (San Francisco Bay Area). The company focus on industrial automation and robotics, including software and vision guidance. Adept has offices t ...
,
Stäubli
Stäubli (in English usually written as Staubli) is a Swiss mechatronics company, primarily known for its textile machinery, connectors and robotics products.
History
Stäubli was founded in Horgen, Switzerland in 1892 as "Schelling & Stäubli" ...
, the
Swedish
Swedish or ' may refer to:
Anything from or related to Sweden, a country in Northern Europe. Or, specifically:
* Swedish language, a North Germanic language spoken primarily in Sweden and Finland
** Swedish alphabet, the official alphabet used by ...
-
Swiss
Swiss may refer to:
* the adjectival form of Switzerland
* Swiss people
Places
* Swiss, Missouri
* Swiss, North Carolina
*Swiss, West Virginia
* Swiss, Wisconsin
Other uses
*Swiss-system tournament, in various games and sports
*Swiss Internation ...
company
ABB Asea Brown Boveri
ABB Ltd. is a Swedish-Swiss multinational corporation headquartered in Zürich, Switzerland. The company was formed in 1988 when Sweden's Allmänna Svenska Elektriska Aktiebolaget (ASEA) and Switzerland's Brown, Boveri & Cie merged to create ...
, the
German
German(s) may refer to:
* Germany (of or related to)
** Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ge ...
company
KUKA Robotics
KUKA is a German manufacturer of industrial robots and systems for factory automation. It has been predominantly owned by the Chinese company Midea Group since 2016.
The KUKA Robotics Corporation has 25 subsidiaries, mostly sales and servic ...
and the
Italian
Italian(s) may refer to:
* Anything of, from, or related to the people of Italy over the centuries
** Italians, an ethnic group or simply a citizen of the Italian Republic or Italian Kingdom
** Italian language, a Romance language
*** Regional Ita ...
company
Comau
Comau (''COnsorzio MAcchine Utensili'') is an Italian multinational company in the automation field based in Turin, Italy, and part of the automaker Stellantis. The company is present in 13 countries and employs 4,000 people and provides service ...
.
Technical description
Defining parameters
*''Number of axes'' – two axes are required to reach any point in a plane; three axes are required to reach any point in space. To fully control the orientation of the end of the arm(i.e. the ''wrist'') three more axes (
yaw, pitch, and roll
An aircraft in flight is free to rotate in three dimensions: '' yaw'', nose left or right about an axis running up and down; ''pitch'', nose up or down about an axis running from wing to wing; and ''roll'', rotation about an axis running from ...
) are required. Some designs (e.g. the SCARA robot) trade limitations in motion possibilities for cost, speed, and accuracy.
*''
Degrees of freedom'' – this is usually the same as the number of axes.
*''
Working envelope {{other uses, Envelope (disambiguation)
In mechanical engineering, an envelope is a solid representing all positions which may be occupied by an object during its normal range of motion.
Another (jargon) word for this is a "flop".
Wheel envelope
I ...
'' – the region of space a robot can reach.
*''
Kinematics
Kinematics is a subfield of physics, developed in classical mechanics, that describes the Motion (physics), motion of points, Physical object, bodies (objects), and systems of bodies (groups of objects) without considering the forces that cause ...
'' – the actual arrangement of rigid members and
joint
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw ...
s in the robot, which determines the robot's possible motions. Classes of robot kinematics include articulated, cartesian,
parallel
Parallel is a geometric term of location which may refer to:
Computing
* Parallel algorithm
* Parallel computing
* Parallel metaheuristic
* Parallel (software), a UNIX utility for running programs in parallel
* Parallel Sysplex, a cluster of ...
and SCARA.
*''Carrying capacity or
payload
Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...
'' – how much weight a robot can lift.
*''Speed'' – how fast the robot can position the end of its arm. This may be defined in terms of the angular or linear speed of each axis or as a compound speed i.e. the speed of the end of the arm when all axes are moving.
*''Acceleration'' – how quickly an axis can accelerate. Since this is a limiting factor a robot may not be able to reach its specified maximum speed for movements over a short distance or a complex path requiring frequent changes of direction.
*''Accuracy'' – how closely a robot can reach a commanded position. When the absolute position of the robot is measured and compared to the commanded position the error is a measure of accuracy. Accuracy can be improved with external sensing for example a vision system or Infra-Red. See
robot calibration
Robot calibration is a process used to improve the accuracy of robots, particularly industrial robots which are highly repeatable but not accurate. Robot calibration is the process of identifying certain parameters in the kinematic structure of an ...
. Accuracy can vary with speed and position within the working envelope and with payload (see compliance).
*''Repeatability'' – how well the robot will return to a programmed position. This is not the same as accuracy. It may be that when told to go to a certain X-Y-Z position that it gets only to within 1 mm of that position. This would be its accuracy which may be improved by calibration. But if that position is taught into controller memory and each time it is sent there it returns to within 0.1mm of the taught position then the repeatability will be within 0.1mm.
Accuracy and repeatability are different measures. Repeatability is usually the most important criterion for a robot and is similar to the concept of 'precision' in measurement—see
accuracy and precision
Accuracy and precision are two measures of ''observational error''.
''Accuracy'' is how close a given set of measurements ( observations or readings) are to their ''true value'', while ''precision'' is how close the measurements are to each oth ...
. ISO 9283 sets out a method whereby both accuracy and repeatability can be measured. Typically a robot is sent to a taught position a number of times and the error is measured at each return to the position after visiting 4 other positions. Repeatability is then quantified using the
standard deviation of those samples in all three dimensions. A typical robot can, of course make a positional error exceeding that and that could be a problem for the process. Moreover, the repeatability is different in different parts of the working envelope and also changes with speed and payload. ISO 9283 specifies that accuracy and repeatability should be measured at maximum speed and at maximum payload. But this results in pessimistic values whereas the robot could be much more accurate and repeatable at light loads and speeds.
Repeatability in an industrial process is also subject to the accuracy of the end effector, for example a gripper, and even to the design of the 'fingers' that match the gripper to the object being grasped. For example, if a robot picks a screw by its head, the screw could be at a random angle. A subsequent attempt to insert the screw into a hole could easily fail. These and similar scenarios can be improved with 'lead-ins' e.g. by making the entrance to the hole tapered.
*''Motion control'' – for some applications, such as simple pick-and-place assembly, the robot need merely return repeatably to a limited number of pre-taught positions. For more sophisticated applications, such as welding and finishing (
spray painting
Spray painting is a painting technique in which a device sprays coating material (paint, ink, varnish, etc.) through the air onto a surface. The most common types employ compressed gas—usually air—to atomize and direct the paint particles.
...
), motion must be continuously controlled to follow a path in space, with controlled orientation and velocity.
*''Power source'' – some robots use
electric motor
An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...
s, others use
hydraulic
Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counte ...
actuators. The former are faster, the latter are stronger and advantageous in applications such as spray painting, where a spark could set off an
explosion; however, low internal air-pressurisation of the arm can prevent ingress of flammable vapours as well as other contaminants. Nowadays, it is highly unlikely to see any hydraulic robots in the market. Additional sealings, brushless electric motors and spark-proof protection eased the construction of units that are able to work in the environment with an explosive atmosphere.
*''Drive'' – some robots connect electric motors to the joints via
gear
A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic ...
s; others connect the motor to the joint directly (''direct drive''). Using gears results in measurable 'backlash' which is free movement in an axis. Smaller robot arms frequently employ high speed, low torque DC motors, which generally require high gearing ratios; this has the disadvantage of backlash. In such cases the
harmonic drive
Strain wave gearing (also known as harmonic gearing) is a type of mechanical gear system that uses a flexible spline with external teeth, which is deformed by a rotating elliptical plug to engage with the internal gear teeth of an outer spline. ...
is often used.
*''Compliance'' - this is a measure of the amount in angle or distance that a robot axis will move when a force is applied to it. Because of compliance when a robot goes to a position carrying its maximum payload it will be at a position slightly lower than when it is carrying no payload. Compliance can also be responsible for overshoot when carrying high payloads in which case acceleration would need to be reduced.
Robot programming and interfaces
The setup or
programming of motions and sequences for an industrial robot is typically taught by linking the robot controller to a
laptop, desktop
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
or (internal or Internet)
network
Network, networking and networked may refer to:
Science and technology
* Network theory, the study of graphs as a representation of relations between discrete objects
* Network science, an academic field that studies complex networks
Mathematics ...
.
A robot and a collection of machines or peripherals is referred to as a
workcell, or cell. A typical cell might contain a parts feeder, a
molding machine and a robot. The various machines are 'integrated' and controlled by a single computer or
PLC. How the robot interacts with other machines in the cell must be programmed, both with regard to their positions in the cell and synchronizing with them.
''Software:'' The computer is installed with corresponding
interface
Interface or interfacing may refer to:
Academic journals
* ''Interface'' (journal), by the Electrochemical Society
* '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics''
* '' Int ...
software. The use of a computer greatly simplifies the programming process. Specialized
robot software Robot software is the set of coded commands or instructions that tell a mechanical device and electronic system, known together as a robot, what tasks to perform. Robot software is used to perform autonomous tasks. Many software systems and framew ...
is run either in the robot controller or in the computer or both depending on the system design.
There are two basic entities that need to be taught (or programmed): positional data and procedure. For example, in a task to move a screw from a feeder to a hole the positions of the feeder and the hole must first be taught or programmed. Secondly the procedure to get the screw from the feeder to the hole must be programmed along with any I/O involved, for example a signal to indicate when the screw is in the feeder ready to be picked up. The purpose of the robot software is to facilitate both these programming tasks.
Teaching the robot positions may be achieved a number of ways:
''Positional commands'' The robot can be directed to the required position using a
GUI
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
or text based commands in which the required X-Y-Z position may be specified and edited.
''Teach pendant:'' Robot positions can be taught via a
teach pendant
An industrial robot is a robot system used for manufacturing. Industrial robots are automated, programmable and capable of movement on three or more axes.
Typical applications of robots include welding, painting, assembly, disassembly, pick a ...
. This is a handheld control and programming unit. The common features of such units are the ability to manually send the robot to a desired position, or "inch" or "jog" to adjust a position. They also have a means to change the speed since a low speed is usually required for careful positioning, or while test-running through a new or modified routine. A large
emergency stop
A kill switch, also known as an emergency stop (E-stop), emergency off (EMO) and as an emergency power off (EPO), is a safety mechanism used to shut off machinery in an emergency, when it cannot be shut down in the usual manner. Unlike a normal ...
button is usually included as well. Typically once the robot has been programmed there is no more use for the teach pendant. All teach pendants are equipped with a 3-position
deadman switch. In the manual mode, it allows the robot to move only when it is in the middle position (partially pressed). If it is fully pressed in or completely released, the robot stops. This principle of operation allows natural reflexes to be used to increase safety.
''Lead-by-the-nose:'' this is a technique offered by many robot manufacturers. In this method, one user holds the robot's manipulator, while another person enters a command which de-energizes the robot causing it to go into limp. The user then moves the robot by hand to the required positions and/or along a required path while the software logs these positions into memory. The program can later run the robot to these positions or along the taught path. This technique is popular for tasks such as
paint spraying.
''Offline programming'' is where the entire cell, the robot and all the machines or instruments in the workspace are mapped graphically. The robot can then be moved on screen and the process simulated. A robotics simulator is used to create embedded applications for a robot, without depending on the physical operation of the robot arm and end effector. The advantages of robotics simulation is that it saves time in the design of robotics applications. It can also increase the level of safety associated with robotic equipment since various "what if" scenarios can be tried and tested before the system is activated.
Robot simulation software provides a platform to teach, test, run, and debug programs that have been written in a variety of programming languages.
''Robot simulation'' tools allow for robotics programs to be conveniently written and debugged off-line with the final version of the program tested on an actual robot. The ability to preview the behavior of a robotic system in a virtual world allows for a variety of mechanisms, devices, configurations and controllers to be tried and tested before being applied to a "real world" system. Robotics simulators have the ability to provide real-time computing of the simulated motion of an industrial robot using both geometric modeling and kinematics modeling.
''Manufacturing independent robot programming tools'' are a relatively new but flexible way to program robot applications. Using a
graphical user interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
the programming is done via drag and drop of predefined template/building blocks. They often feature the execution of simulations to evaluate the feasibility and
offline programming in combination. If the system is able to compile and upload native robot code to the robot controller, the user no longer has to learn each manufacturer's
proprietary language. Therefore, this approach can be an important step to
standardize programming methods.
''Others'' in addition, machine operators often use
user interface
In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
devices, typically
touchscreen
A touchscreen or touch screen is the assembly of both an input ('touch panel') and output ('display') device. The touch panel is normally layered on the top of an electronic visual display of an information processing system. The display is ofte ...
units, which serve as the operator control panel. The operator can switch from program to program, make adjustments within a program and also operate a host of
peripheral devices that may be integrated within the same robotic system. These include
end effector
In robotics, an end effector is the device at the end of a robotic arm, designed to interact with the environment. The exact nature of this device depends on the application of the robot.
In the strict definition, which originates from serial ro ...
s, feeders that supply components to the robot,
conveyor belt
A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more pulleys (sometimes referred to ...
s, emergency stop controls, machine vision systems, safety
interlock
An interlock is a feature that makes the state of two mechanisms or functions mutually dependent. It may be used to prevent undesired states in a finite-state machine, and may consist of any electrical, electronic, or mechanical devices or system ...
systems,
barcode
A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or o ...
printers and an almost infinite array of other industrial devices which are accessed and controlled via the operator control panel.
The teach pendant or PC is usually disconnected after programming and the robot then runs on the program that has been installed in its
controller
Controller may refer to:
Occupations
* Controller or financial controller, or in government accounting comptroller, a senior accounting position
* Controller, someone who performs agent handling in espionage
* Air traffic controller, a person ...
. However a computer is often used to 'supervise' the robot and any peripherals, or to provide additional storage for access to numerous complex paths and routines.
End-of-arm tooling
The most essential robot peripheral is the
end effector
In robotics, an end effector is the device at the end of a robotic arm, designed to interact with the environment. The exact nature of this device depends on the application of the robot.
In the strict definition, which originates from serial ro ...
, or end-of-arm-tooling (EOAT). Common examples of end effectors include welding devices (such as MIG-welding guns, spot-welders, etc.), spray guns and also grinding and deburring devices (such as pneumatic disk or belt grinders, burrs, etc.), and grippers (devices that can grasp an object, usually
electromechanical
In engineering, electromechanics combines processes and procedures drawn from electrical engineering and mechanical engineering. Electromechanics focuses on the interaction of electrical and mechanical systems as a whole and how the two systems ...
or
pneumatic). Other common means of picking up objects is by
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
or
magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nicke ...
s. End effectors are frequently highly complex, made to match the handled product and often capable of picking up an array of products at one time. They may utilize various sensors to aid the robot system in locating, handling, and positioning products.
Controlling movement
For a given robot the only parameters necessary to completely locate the end effector (gripper, welding torch, etc.) of the robot are the angles of each of the joints or displacements of the linear axes (or combinations of the two for robot formats such as SCARA). However, there are many different ways to define the points. The most common and most convenient way of defining a point is to specify a
Cartesian coordinate
A Cartesian coordinate system (, ) in a plane is a coordinate system that specifies each point uniquely by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in ...
for it, i.e. the position of the 'end effector' in mm in the X, Y and Z directions relative to the robot's origin. In addition, depending on the types of joints a particular robot may have, the orientation of the end effector in yaw, pitch, and roll and the location of the tool point relative to the robot's faceplate must also be specified. For a
jointed arm these coordinates must be converted to joint angles by the robot controller and such conversions are known as Cartesian Transformations which may need to be performed iteratively or recursively for a multiple axis robot. The mathematics of the relationship between joint angles and actual spatial coordinates is called kinematics. See
robot control
Robotic control is the system that contributes to the movement of robots. This involves the mechanical aspects and programmable systems that makes it possible to control robots. Robotics could be controlled in various ways, which includes using ma ...
Positioning by Cartesian coordinates may be done by entering the coordinates into the system or by using a teach pendant which moves the robot in X-Y-Z directions. It is much easier for a human operator to visualize motions up/down, left/right, etc. than to move each joint one at a time. When the desired position is reached it is then defined in some way particular to the robot software in use, e.g. P1 - P5 below.
Typical programming
Most articulated robots perform by storing a series of positions in memory, and moving to them at various times in their programming sequence. For example, a robot which is moving items from one place (bin A) to another (bin B) might have a simple 'pick and place' program similar to the following:
''Define points P1–P5:''
# Safely above workpiece (defined as P1)
# 10 cm Above bin A (defined as P2)
# At position to take part from bin A (defined as P3)
# 10 cm Above bin B (defined as P4)
# At position to take part from bin B. (defined as P5)
''Define program:''
# Move to P1
# Move to P2
# Move to P3
# Close gripper
# Move to P2
# Move to P4
# Move to P5
# Open gripper
# Move to P4
# Move to P1 and finish
For examples of how this would look in popular robot languages see
industrial robot programming.
Singularities
The American National Standard for Industrial Robots and Robot Systems — Safety Requirements (ANSI/RIA R15.06-1999) defines a singularity as “a condition caused by the collinear alignment of two or more robot axes resulting in unpredictable robot motion and velocities.” It is most common in robot arms that utilize a “triple-roll wrist”. This is a wrist about which the three axes of the wrist, controlling yaw, pitch, and roll, all pass through a common point. An example of a wrist singularity is when the path through which the robot is traveling causes the first and third axes of the robot's wrist (i.e. robot's axes 4 and 6) to line up. The second wrist axis then attempts to spin 180° in zero time to maintain the orientation of the end effector. Another common term for this singularity is a “wrist flip”. The result of a singularity can be quite dramatic and can have adverse effects on the robot arm, the end effector, and the process. Some industrial robot manufacturers have attempted to side-step the situation by slightly altering the robot's path to prevent this condition. Another method is to slow the robot's travel speed, thus reducing the speed required for the wrist to make the transition. The ANSI/RIA has mandated that robot manufacturers shall make the user aware of singularities if they occur while the system is being manually manipulated.
A second type of singularity in wrist-partitioned vertically articulated six-axis robots occurs when the wrist center lies on a cylinder that is centered about axis 1 and with radius equal to the distance between axes 1 and 4. This is called a shoulder singularity. Some robot manufacturers also mention alignment singularities, where axes 1 and 6 become coincident. This is simply a sub-case of shoulder singularities. When the robot passes close to a shoulder singularity, joint 1 spins very fast.
The third and last type of singularity in wrist-partitioned vertically articulated six-axis robots occurs when the wrist's center lies in the same plane as axes 2 and 3.
Singularities are closely related to the phenomena of
gimbal lock
Gimbal lock is the loss of one degree of freedom in a three-dimensional, three-gimbal mechanism that occurs when the axes of two of the three gimbals are driven into a parallel configuration, "locking" the system into rotation in a degenerate t ...
, which has a similar root cause of axes becoming lined up.
Market structure
According to the
International Federation of Robotics
The International Federation of Robotics (IFR) is a professional non-profit organization established in 1987 to promote, strengthen and protect the robotics industry worldwide.
Activities
The purpose of the International Federation of Robotic ...
(IFR) study ''World Robotics 2020'', there were about 2,722,077 operational industrial robots by the end of 2019.
[https://ifr.org/img/worldrobotics/Executive_Summary_WR_2020_Industrial_Robots_1.pdf ] This number is estimated to reach 3,788,000 by the end of 2021.
For the year 2018 the IFR estimates the worldwide sales of industrial robots with US$16.5 billion. Including the cost of software, peripherals and systems engineering, the annual turnover for robot systems is estimated to be US$48.0 billion in 2018.
China is the largest industrial robot market, with 154,032 units sold in 2018.
China had the largest operational stock of industrial robots, with 649,447 at the end of 2018. The United States industrial robot-makers shipped 35,880 robot to factories in the US in 2018 and this was 7% more than in 2017.
The biggest customer of industrial robots is automotive industry with 30% market share, then electrical/electronics industry with 25%, metal and machinery industry with 10%, rubber and plastics industry with 5%, food industry with 5%.
In textiles, apparel and leather industry, 1,580 units are operational.
Estimated worldwide annual supply of industrial robots (in units):
Health and safety
The
International Federation of Robotics
The International Federation of Robotics (IFR) is a professional non-profit organization established in 1987 to promote, strengthen and protect the robotics industry worldwide.
Activities
The purpose of the International Federation of Robotic ...
has predicted a worldwide increase in adoption of industrial robots and they estimated 1.7 million new robot installations in factories worldwide by 202
[IFR 2017] Rapid advances in automation technologies (e.g. fixed robots, collaborative and mobile robots, and exoskeletons) have the potential to improve work conditions but also to introduce workplace hazards in manufacturing workplaces.
Despite the lack of occupational surveillance data on injuries associated specifically with robots, researchers from the US
National Institute for Occupational Safety and Health
The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the C ...
(NIOSH) identified 61 robot-related deaths between 1992 and 2015 using keyword searches of the
Bureau of Labor Statistics
The Bureau of Labor Statistics (BLS) is a unit of the United States Department of Labor. It is the principal fact-finding agency for the U.S. government in the broad field of labor economics and statistics and serves as a principal agency of t ...
(BLS) Census of Fatal Occupational Injuries research database (see info fro
Center for Occupational Robotics Research. Using data from the Bureau of Labor Statistics, NIOSH and its state partners have investigated 4 robot-related fatalities under th
In addition the Occupational Safety and Health Administration (OSHA) has investigated dozens of robot-related deaths and injuries, which can be reviewed a
OSHA Accident Search page Injuries and fatalities could increase over time because of the increasing number of collaborative and co-existing robots, powered exoskeletons, and autonomous vehicles into the work environment.
Safety standards are being developed by th
Robotic Industries Association(RIA) in conjunction with the
American National Standards Institute
The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...
(ANSI
On October 5, 2017, OSHA, NIOSH and RIA signed a
allianceto work together to enhance technical expertise, identify and help address potential workplace hazards associated with traditional industrial robots and the emerging technology of human-robot collaboration installations and systems, and help identify needed research to reduce workplace hazards. On October 16 NIOSH launched th
to "provide scientific leadership to guide the development and use of occupational robots that enhance worker safety, health, and wellbeing." So far, the research needs identified by NIOSH and its partners include: tracking and preventing injuries and fatalities, intervention and dissemination strategies to promote safe machine control and maintenance procedures, and on translating effective evidence-based interventions into workplace practice.
See also
*
Automation
Automation describes a wide range of technologies that reduce human intervention in processes, namely by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machines ...
*
Domestic robot
A domestic robot is a type of service robot, an autonomous robot that is primarily used for household chores, but may also be used for education, entertainment or therapy. While most domestic robots are simplistic, some are connected to Wi-Fi ...
*
Intelligent industrial work assistant (iiwa)
*
Lights out (manufacturing)
Lights-out manufacturing is a manufacturing methodology (or philosophy), not a specific process.
Factories that employ "lights-out manufacturing" are fully automated and require no human presence on-site. These factories are considered to be able ...
*
Mobile industrial robots
*
Cartesian coordinate robot
A Cartesian coordinate robot (also called linear robot) is an industrial robot whose three principal axes of control are linear (i.e. they move in a straight line rather than rotate) and are at right angles to each other. The three sliding joi ...
*
Gantry robot
A Cartesian coordinate robot (also called linear robot) is an industrial robot whose three principal axes of control are linear (i.e. they move in a straight line rather than rotate) and are at right angles to each other. The three sliding jo ...
*
Workplace Robotics Safety
References
Further reading
*Nof, Shimon Y. (editor) (1999). ''Handbook of Industrial Robotics'', 2nd ed. John Wiley & Sons. 1378 pp. .
*Lars Westerlund (author) (2000). The extended arm of man. .
*Michal Gurgul (author) (2018). Industrial robots and cobots: Everything you need to know about your future co-worker. .
External links
Industrial robots and robot system safety(by
OSHA
OSHA or Osha may refer to:
Work
* Occupational Safety and Health Administration, a federal agency of the United States that regulates workplace safety and health
* Occupational Safety and Health Act (United States) of 1970, a federal law in the Un ...
, s
in the public domain.
International Federation of Robotics IFR (worldwide)Robotic Industries Association RIA (North America)BARA, British Automation and Robotics Association (UK)by National Institute for Occupational Safety and Health, NIOSH
Safety standards applied to RoboticsMachine Guarding - Why It's a Legal Requirement
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Industrial robots,
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Occupational safety and health