A robot is a mechanical or virtual, artificial agent. It is usually a system, which, by its appearance or movements, conveys a sense that it has intent or agency of its own. The word robot can refer to both physical robots and virtual software agents, but the latter are usually referred to as bots to differentiate^[1].

While there is still discussion about which machines qualify as robots,^[2][3][4] a typical robot will have several, though not necessarily all of the following properties:

• is not 'natural' i.e. artificially created
• can sense its environment, and manipulate or interact with things in it
• has some ability to make choices based on the environment, often using automatic control or a preprogrammed sequence
• is programmable
• moves with one or more axes of rotation or translation
• makes dexterous coordinated movements
• appears to have intent or agency (See anthropomorphism for examples of ascribing intent to inanimate objects.^[5])
  

Defining characteristics

The last property, the appearance of agency, is important when people are considering whether to call a machine a robot, or just a machine. In general, the more a machine has the appearance of agency, the more it is considered a robot.

KITT has:

• a clockwork car is never considered a robot^[7]
• a remotely operated vehicle is sometimes considered a robot. ^[8] (or telerobot).
• a car with an onboard computer, like Bigtrak, which could drive in a programmable sequence might be called a robot.
• a self-controlled car, like the 1990s driverless cars of Ernst Dickmanns, or the entries to the DARPA Grand Challenge, which could sense its environment, and make driving decisions based on this information would quite likely be called robot.
• a sentient car, like the fictional KITT, which can make decisions, navigate freely and converse fluently with a human, is usually considered a robot.

Physical agency
However, for many laymen, if a machine looks anthropomorphic or zoomorphic (e.g. ASIMO or Aibo), especially if it is limb-like (e.g. a simple robot arm), or has limbs, or can move around, it would be called a robot.

For example, even if the following examples used the same control architecture:

• a player piano is rarely characterized as a robot^[9]

• a CNC milling machine is very occasionally characterized as a robot.
• a factory automation arm is almost always characterized as a robot or an industrial robot.
• an autonomous wheeled or tracked device, such as a self-guided rover or self-guided vehicle, is almost always characterized as a robot, a mobile robot or a service robot
• a zoomorphic mechanical toy, like Roboraptor, is usually characterized as a robot.^[10][11]
• a humanoid, like ASIMO, is almost always characterized as a robot or a service robot.

Interestingly, while a 3-axis CNC milling machine may have a very similar or identical control system to a robot arm, it is the arm which is almost always called a robot, while the CNC machine is usually just a machine. Having a limb can make all the difference. Having eyes too gives people a sense that a machine is aware ("the eyes are the windows of the soul"). However, simply being anthropomorphic is not sufficient for something to be called a robot. A robot must do something, whether it is useful work or not. So, for example, a rubber dog chew, shaped like ASIMO, would not be considered a robot.

Official definitions and classifications of robots

There are many variations in definitions of what exactly is a robot. Therefore, it is sometimes difficult to compare numbers of robots in different countries. To try to provide a universally acceptable definition, the International Organisation for Standardisation gives a definition of robot in ISO 8373, which defines a robot as "an automatically controlled, reprogrammable, multipurpose, manipulator programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications."^[12] This definition is to be used when comparing the number of robots in each country.^[13]

In spite of the ISO definition, countries, such as the USA and Japan have different definitions of robots. Japan, for example, lists very many robots partly because more machines are counted as robots. Since both Japan and the USA are important players in the development of robotics, the definitions used in these countries will be mentioned.

Robotics Institute of America

The Robotics Institute of America (RIA) defines a robot as:

A re-programmable multi-functional manipulator designed to move materials, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks.^[14]

The RIA recognizes four classes of robot:

• 1: Handling devices with manual control
• 2: Automated handling devices with predetermined cycles
• 3: Programmable, servo-controlled robots with continuous of point-to-point trajectories
• 4: Robots capable of Type C specifications which also acquire information from the environment for intelligent motion

Japanese Robot Association

Japanese Robot Association (JARA) classifies robots into six classes :^[15]

• 1: Manual - Handling Devices actuated by an operator
• 2: Fixed Sequence Robot
• 3: Variable-Sequence Robot with easily modified sequence of control
• 4: Playback Robot, which can record a motion for later playback
• 5: Numerical Control Robots with a movement program to teach it tasks manually
• 6: Intelligent robot: that can understand its environment and able to complete the task despite changes in the operation conditions

Other definitions of robot

There is no one definition of robot which satisfies everyone, and many people have their own. ^[16] For example, Joseph Engelberger, a pioneer in industrial robotics, once remarked: "I can't define a robot, but I know one when I see one."^[17]

Etymology

The word robot was introduced to the public at large by Czech writer Karel Œapek in his play R.U.R. (Rossum's Universal Robots), which premiered in 1921.^[18] The play begins in a factory that makes 'artificial people' - they are called robots, but are closer to the modern idea of androids or even clones, creatures who can be mistaken for humans. They can plainly think for themselves, though they seem happy to serve. At issue is whether the "Robots" are being exploited and, if so, what follows? (see lso Robots in literature for details of the play)^[19]

However, Karel Čapek himself was not the originator of the word; he wrote a short letter in reference to an article in the Oxford English Dictionary etymology in which he named his brother, painter and writer Josef Čapek, as its actual inventor.^[18] In an article in the Czech journal Lidovnoviny in 1933, he also explained that he had originally wanted to call the creatures laboři (from Latin labor, work). However, he did not like the word, seeing it as too artificial, and sought advice from his brother Josef, who suggested "roboti".

The word robot comes from the word robota meaning literally serf labor, and figuratively "drudgery" or "hard work" in Czech, Slovak and Polish. The origin of the word is the Old Church Slavonic rabota "servitude" ("work" in contemporary Bulgarian and Russian), which in turn comes from the Indo-European root *orbh-. Robot is cognate with the German word Arbeiter (worker).

History

Ancient developments

The idea of artificial people dates at least as far back as the ancient legends of Cadmus, who sowed dragon teeth that turned into soldiers, and the myth of Pygmalion, whose statue of Galatea came to life. In Greek mythology, the deformed god of metalwork (Vulcan or Hephaestus) created mechanical servants, ranging from intelligent, golden handmaidens to more utilitarian three-legged tables that could move about under their own power, and the robot Talos defended Crete. Medieval Persian alchemist Jabir ibn Hayyan included recipes for creating artificial snakes, scorpions, and humans in his coded Book of Stones. Jewish legend tells of the Golem, a clay creature animated by Kabbalistic magic. Similarly, in the Younger Edda, Norse mythology tells of a clay giant, Mistcalf, constructed to aid the troll Hrungnir in a duel with Thor, the God of Thunder.

In ancient China, a curious account on automata is found in the Lie Zi text, written in the 3rd century BC. Within it there is a description of a much earlier encounter between King Mu of Zhou (1023 BC-957 BC) and a mechanical engineer known as Yan Shi, an 'artificer'. The latter proudly presented the king with a life-size, human-shaped figure of his mechanical handiwork.

The king stared at the figure in astonishment. It walked with rapid strides, moving its head up and down, so that anyone would have taken it for a live human being. The artificer touched its chin, and it began singing, perfectly in tune. He touched its hand, and it began posturing, keeping perfect time...As the performance was drawing to an end, the robot winked its eye and made advances to the ladies in attendance, whereupon the king became incensed and would have had Yen Shih [Yan Shi] executed on the spot had not the latter, in mortal fear, instantly taken the robot to pieces to let him see what it really was. And, indeed, it turned out to be only a construction of leather, wood, glue and lacquer, variously coloured white, black, red and blue. Examining it closely, the king found all the internal organs complete—liver, gall, heart, lungs, spleen, kidneys, stomach and intestines; and over these again, muscles, bones and limbs with their joints, skin, teeth and hair, all of them artificial...The king tried the effect of taking away the heart, and found that the mouth could no longer speak; he took away the liver and the eyes could no longer see; he took away the kidneys and the legs lost their power of locomotion. The king was delighted.^[20]

Concepts akin to a robot can be found as long ago as the 4th century BC, when the Greek mathematician Archytas of Tarentum postulated a mechanical bird he called "The Pigeon" which was propelled by steam. Yet another early automaton was the clepsydra, made in 250 BC by Ctesibius of Alexandria, a physicist and inventor from Ptolemaic Egypt.^[21] Hero of Alexandria (10-70 AD) made numerous innovations in the field of automata, including one that allegedly could speak.

Medieval developments

Al-Jazari (1136-1206), an Arab Muslim inventor during the Artuqid dynasty, designed and constructed a number of automatic machines, including kitchen appliances, musical automata powered by water, and the first programmable humanoid robot in 1206. Al-Jazari's robot was a boat with four automatic musicians that floated on a lake to entertain guests at royal drinking parties. His mechanism had a programmable drum machine with pegs (cams) that bump into little levers that operate the percussion. The drummer could be made to play different rhythms and different drum patterns by moving the pegs to different locations.^[22]

One of the first recorded designs of a humanoid robot was made by Leonardo da Vinci (1452-1519) in around 1495. Da Vinci's notebooks, rediscovered in the 1950s, contain detailed drawings of a mechanical knight able to sit up, wave its arms and move its head and jaw. ^[19] The design is likely to be based on his anatomical research recorded in the Vitruvian Man. It is not known whether he attempted to build the robot (see: Leonardo's robot).

Early modern developments

An early automaton was created in 1738 by Jacques de Vaucanson, who created a mechanical duck that was able to eat and digest grain, flap its wings, and excrete. ^[19]

The Japanese craftsman Hisashige Tanaka, known as "Japan's Edison," created an array of extremely complex mechanical toys, some of which were capable of serving tea, firing arrows drawn from a quiver, or even painting a Japanese kanji character. The landmark text Karakuri Zui (Illustrated Machinery) was published in 1796. (T. N. Hornyak, Loving the Machine: The Art and Science of Japanese Robots [New York: Kodansha International, 2006])

In 1898 Nikola Tesla publicly demonstrated a radio-controlled (teleoperated) boat, similar to a modern ROV. Based on his patents U.S. Patent 613,809 , U.S. Patent 723,188  and U.S. Patent 725,605  for "teleautomation", Tesla hoped to develop the wireless torpedo into a weapon system for the US Navy. (Cheney 1989) ^[23]

Modern Developments

In the 1930s, Westinghouse Electric Corporation made a humanoid robot known as Elektro, exhibited at the 1939 and 1940 World's Fairs.

The first electronic autonomous robots were created by William Grey Walter of the Burden Neurological Institute at Bristol, England in 1948 and 1949. They were named Elmer and Elsie. These robots could sense light and contact with external objects, and use these stimuli to navigate. ^[24]

Unimate's PUMA arm

It wasn't until the second half of the twentieth century, when integrated circuits were invented, and computers began to double rapidly in power (roughly every two years according to Moore's Law),^[25] that it became possible to build robots as we imagine them. Until that time, automatons were the closest things to robots, and while they may have looked humanoid, and their movements were complex, they were not capable of the self-control and decision making that robots are today.

The first truly modern robot, digitally operated, programmable, and teachable, was invented by George Devol in 1954 and was ultimately called the Unimate. It is worth noting that not a single patent was cited against his original robotics patent (U.S. Patent 2,988,237 ). The first Unimate was personally sold by Devol to General Motors in 1960 and installed in 1961 in a plant in Trenton, New Jersey to lift hot pieces of metal from a die casting machine and stack them.^[21]

Contemporary uses

Robots can be placed into roughly two categories based on the type of job they do:

• Jobs which a robot can do better than a human. Here, robots can increase productivity, accuracy, and endurance.
• Jobs which a human could do better than a robot, but it is desirable to remove the human for some reason. Here, robots free us from dirty, dangerous and dull tasks.

Increased productivity, accuracy, and endurance

Pick and Place robot, Contact Systems C5 Series^[34]

Jobs which require speed, accuracy, reliability or endurance can be performed far better by a robot than a human. Hence many jobs in factories which were traditionally performed by people are now robotized. This has led to cheaper mass-produced goods, including automobiles and electronics. Robots have now been working in factories for more than fifty years, ever since the Unimate robot was installed to automatically remove hot metal from a die casting machine. Since then, factory automation in the form of large stationary manipulators has become the largest market for robots. The number of installed robots has grown faster and faster, and today there are more than 1 million robots in operation worldwide (Half of the robot population is located in Asia, 1/3 in Europe, and 16% in North America. Australasia and Africa each account for 1%.)^[35].

German KUKA Industrial robots doing vehicle under body assembly

Some examples of factory robots:

• Car production: This is now the primary example of factory automation. Over the last three decades automobile factories have become dominated by robots. A typical factory contains hundreds of industrial robots working on fully automated production lines - one robot for every ten human workers. On an automated production line a vehicle chassis is taken along a conveyor to be welded, glued, painted and finally assembled by a sequence of robot stations.
• Packaging: Industrial robots are also used extensively for palletizing and packaging of manufactured goods, for example taking drink cartons from the end of a conveyor belt and placing them rapidly into boxes, or the loading and unloading of machining centers.
• Electronics: Mass produced printed circuit boards (PCBs) are almost exclusively manufactured by pick and place robots, typically with SCARA manipulators, which remove tiny electronic components from strips or trays, and place them on to PCBs with great accuracy.^[36] Such robots can place several components per second (tens of thousands per hour), far out-performing a human in terms of speed, accuracy, and reliability.^[37]

HelpMate trackless pharmacy bot navigates autonomously to transport drugs, lab specimens, supplies and medical records.

• Automated Guided Vehicles (AGVs): Mobile robots, following markers or wires in the floor, or using vision^[38] or lasers, are used to transport goods around large facilities, such as warehouses, container ports, or hospitals.^[39] Early AGV-style robots were limited to tasks that could be accurately defined and must be performed the same every time. Very little feedback or intelligence was required, and the robots may need only the most basic of exteroceptors to sense things in their environment, if any at all. However, newer AGV's, such as the Speci-Minder^[40], ADAM ^[41], Tug ^[42], and PatrolBot Gofer ^[43] qualify under the JARA definition of intelligent robots. They use some form of natural features recognition to navigate. Scanning lasers, stereovision or other means of sensing the environment in two- or three-dimensions is combined with standard dead-reckoning calculations in a probabilistic manner to continuously update the AGV's current location, eliminating cumulative error. This means that the Self-Guided Vehicle (SGV) can navigate a space autonomously once it has learned it or been provided with a map of it. Such new robots are able to operate in complex environments and perform non-repetitive and non-sequential tasks such as carrying tires to presses in factories, delivering masks in a semi-conductor lab, delivering specimens in hospitals and delivering goods in warehouses.

Dirty, dangerous, dull or inaccessible tasks

The Roomba domestic vacuum cleaner robot does a menial job

There are many jobs which a human could perform better than a robot but for one reason or another the human either does not want to do it or cannot be present to do the job. The job may be too boring to bother with, for example domestic cleaning; or be too dangerous, for example exploring inside a volcano^[44]. These jobs are known as the "dull, dirty, and dangerous" jobs. Other jobs are physically inaccessible. For example, exploring another planet,^[45] cleaning the inside of a long pipe or performing laparoscopic surgery.^[46]

• Robots in the home: As their price falls, and their performance and computational ability rises^[47], making them both affordable and sufficiently autonomous, robots are increasingly being seen in the home where they are taking on simple but unwanted jobs, such as vacuum cleaning, floor cleaning and lawn mowing. While they have been on the market for several years, 2006 saw a great increase in the number of domestic robots sold. By 2006, iRobot had sold more than 2 million vacuuming robots.^[48] They tend to be relatively autonomous, usually only requiring a command to begin their job. They then proceed to go about their business in their own way. At such, they display a good deal of agency, and are considered intelligent robots.

A laparoscopic robotic surgery machine.

• Telerobots: When a human cannot be present on site to perform a job because it is dangerous, far away, or inaccessible, teleoperated robots, or telerobots are used. Rather than following a predetermined sequence of movements a telerobot is controlled from a distance by a human operator. The robot may be in another room or another country, or may be on a very different scale to the operator. A laparoscopic surgery robot such as da Vinci allows the surgeon to work inside a human patient on a relatively small scale compared to open surgery, significantly shortening recovery time.^[46] An interesting use of a telerobot is by the author Margaret Atwood, who has recently started using a robot pen (the Longpen) to sign books remotely. The Longpen is similar to the Autopen of the 1800s. This saves the financial cost and physical inconvenience of traveling to book signings around the world.^[49] At the other end of the spectrum, iRobot ConnectR robot is designed to be used by anyone to stay in touch with family or friends from far away. One robot in use today, Intouchhealth's RP-7 remote presence robot, is being used by doctors to communicate with patients, allowing the doctor to be anywhere in the world. This increases the number of patients a doctor can monitor.

• Military robots: Teleoperated robot aircraft, like the Predator Unmanned Aerial Vehicle, are increasingly being used by the military. These robots can be controlled from anywhere in the world allowing an army to search terrain, and even fire on targets, without endangering those in control.^[50] Many of these robots are teleoperated, but others are being developed that can make decisions automatically; choosing where to fly or selecting and engaging enemy targets.^[51] Hundreds of robots such as iRobot's Packbot and the Foster-Miller TALON are being used in Iraq and Afghanistan by the U.S. military to defuse roadside bombs or Improvised Explosive Devices (IEDs) in an activity known as Explosive Ordnance Disposal (EOD).^[52] Autonomous robots such as MDARS and Seekur are being developed to perform security and surveillance tasks at military facilities to address manpower shortages as well as keeping troops out of harm's way. The Crusher Unmanned Ground Vehicle (UGV) is being developed to perform military missions autonomously. ^[53]

• Elder Care: The population is aging in many countries, especially Japan, meaning that there are increasing numbers of elderly people to care for but relatively fewer young people to care for them.^[54][55] Humans make the best carers, but where they are unavailable, robots are gradually being introduced.^[56]
  

Unconventional Robots

Much of the research in robotics focuses not on specific industrial tasks, but on investigations into new types of robot, alternative ways to think about or design robots, and new ways to manufacture them. It is expected that these new types of robot will be able to solve real world problems when they are finally realized.

A nanocar made from a single molecule^[57]

• Nanorobots: Nanorobotics is the still largely hypothetical technology of creating machines or robots at or close to the scale of a nanometer (10^-9 meters). Also known as nanobots or nanites, they would be constructed from molecular machines. So far, researchers have mostly produced only parts of these complex systems, such as bearings, sensors, and Synthetic molecular motors, but functioning robots have also been made such as the entrants to the Nanobot Robocup contest.^[58] Researchers also hope to be able to create entire robots as small as viruses or bacteria, which could perform tasks on a tiny scale. Possible applications include micro surgery (on the level of individual cells), utility fog^[59], manufacturing, weaponry and cleaning.^[60] Some people have suggested that if there were nanobots which could reproduce, the earth would turn into "grey goo", while others argue that this hypothetical outcome is nonsense.^[61][62]
• Soft Robots: Most man-made machines are made from hard, stiff materials, especially metal and plastic. This is in contrast to most natural organisms, which are mostly soft tissues. Researchers at Tufts University recently developed robots with silicone bodies and flexible actuators (air muscles, electroactive polymers, ferrofluids). The control software emphasizes soft behaviors using fuzzy logic and neural networks.^[63]

Soft-bodied robots can look, feel, and behave differently from traditional hard robots, enabling new applications. Some of these robots are currently exhibited at the Museum of Modern Art (MoMa) in New York City.

Molecubes in motion

• Reconfigurable Robots: A few researchers have investigated the possibility of creating robots which can alter their physical form to suit a particular task,^[64] like the fictional T-1000. Real robots are nowhere near that sophisticated however, and mostly consist of a small number of cube shaped units, which can move relative to their neighbours, for example SuperBot. Algorithms have been designed in case any such robots become a reality.^[65]

A swarm of robots from the Open-source micro-robotic project^[66]

• Swarm robots: Inspired by colonies of insects such as ants and bees, researchers hope to create very large swarms (thousands) of tiny robots which together perform a useful task, such as finding something hidden, cleaning, or spying. Each robot would be quite simple, but the emergent behaviour of the swarm would be more complex.^[67] The whole set of robots can be considered as one single distributed system, in the same way an ant colony can be considered a superorganism. They would exhibit swarm intelligence. The largest swarms so far created include the iRobot swarm, and the Open-source micro-robotic project swarm, which are being used to research collective behaviors.^[68] Swarms are also more resistant to failure. Whereas one large robot may fail and ruin the whole mission, the swarm can continue even if several robots fail. This makes them attractive for space exploration missions, where failure can be extremely costly.^[69]
• Evolutionary Robots: is a methodology that uses evolutionary computation to help design robots, especially the body form, or motion and behaviour controllers. In a similar way to natural evolution, a large population of robots is allowed to compete in some way, or their ability to perform a task is measured using a fitness function. Those that perform worst are removed from the population, and replaced by a new set, which have new behaviors based on those of the winners. Over time the population improves, and eventually a satisfactory robot may appear. This happens without any direct programming of the robots by the researchers. Researchers use this method both to create better robots,^[70] and to explore the nature of evolution.^[71] Because the process often requires many generations of robots to be simulated, this technique may be run entirely or mostly in simulation, then tested on real robots once the evolved algorithms are good enough.^[72]
• Virtual Reality: Robotics also has application in the design of virtual reality interfaces. Specialized robots are in widespread use in the haptic research community. These robots, called "haptic interfaces" allow touch-enabled user interaction with real and virtual environments. Robotic forces allow simulating the mechanical properties of "virtual" objects, which users can experience through their sense of touch.^[73]

References

General references

• Cheney, Margaret [1989:123] (1981). Tesla, Man Out of Time. Dorset Press. New York.
• Craig, J.J. (2005). Introduction to Robotics. Pearson Prentice Hall. Upper Saddle River, NJ.
• Flanagan, J.R., Lederman, S.J. Neurobiology: Feeling bumps and holes (Portable Document Format), News and Views, Nature, 2001 Jul. 26;412(6845):389-91.
• Hayward V, Astley OR, Cruz-Hernandez M, Grant D, Robles-De-La-Torre G. Haptic interfaces and devices (Portable Document Format). Sensor Review 24(1), pp. 16-29 (2004).
• Needham, Joseph (1986). Science and Civilization in China: Volume 2. Taipei: Caves Books Ltd.
• Robles-De-La-Torre G. & Hayward V. Force Can Overcome Object Geometry In the perception of Shape Through Active Touch. Nature 412 (6845):445-8 (2001).
• Robles-De-La-Torre G. The Importance of the Sense of Touch in Virtual and Real Environments (Portable Document Format). IEEE Multimedia 13(3), Special issue on Haptic User Interfaces for Multimedia Systems, pp. 24-30 (2006).
• Sotheby's New York. The Tin Toy Robot Collection of Matt Wyse, (1996)
• Tsai, L.-W. (1999). Robot Analysis. Wiley. New York.
• DeLanda, Manuel. War in the Age of Intelligent Machines. 1991. Swerve. New York.