Robotics

Robotics is the science of designing and building machines that can be programmed to perform more than one function traditionally performed by humans. The word robot comes from a play written in 1920 by the Czech author Karel Capek. Capek's R.U.R. (for Rossum's Universal Robots) is the story of an inventor who creates humanlike machines designed to take over many forms of human work.

Historical background

The idea of a machine that looks and behaves like a human being goes back at least 2,000 years. According to Greek mythology, Hephaestus, the god of fire, constructed artificial women out of gold. These women were able to walk, talk, and even to think.

By the eighteenth century, scientists and inventors had created an impressive array of mechanical figures that looked and acted like humans and other animals. The French Jacquet-Droz brothers, Pierre and Henri-Louis, for example, constructed a doll that was able to play the piano, swaying in time with the music, and a young scribe who could write messages of up to 40 characters.

Many of these early accomplishments had little practical value. They were built in order to impress or charm viewers, or to demonstrate the inventor's creative and technological skills. That line of research continues today. Many modern robots have little function beyond demonstrating what can be done in building machines that more and more closely resemble the appearance and function of humans.

One function for such robots is in advertising. They are used to publicize some particular product or to inform the general public about the robots themselves. Robots of this kind are most commonly found at conventions, conferences, or other large meetings. As one example, a robot named Argon was used in April 1983 to walk a dog through a veterinary congress in London, promoting the "Pets Are Good People" program.

Robots at work: the present day

Robots have come to play a widespread and crucial role in many industrial operations today. These robots are almost always of the Jacquard type—with few human features—rather than the Jacquet-Droz, doll-like style. The work that robots do can be classified into three major categories: in the assembly and finishing of products; in the movement of materials and objects; and in the performance of work in environmentally difficult or hazardous situations.

The most common single application of robots is in welding . About a quarter of all robots used by industry have this function. In a typical operation, two pieces of metal will be moved within the welding robot's field and the robot will apply the heat needed to create the weld. Welding robots can have a variety of appearances, but they tend to consist of one large arm that can rotate in various directions. At the end of the arm is a welding gun that actually performs the weld.

Closely related types of work now done by robots include cutting, grinding, polishing, drilling, sanding, painting, spraying, and otherwise treating the surface of a product. As with welding, activities of this kind are usually performed by one-armed robots that hang from the ceiling, project outward from a platform, or reach into a product from some other angle.

There are some obvious advantages for using a robot to perform tasks such as these. They are often boring, difficult, and sometimes dangerous tasks that have to be repeated over and over again in exactly the same way. Why should a human be employed to do such repetitive work, robotics engineers ask, when a machine can do the same task just as efficiently?

That argument can be used for many of the other industrial operations in which robots have replaced humans. Another example of such operations is the assembly of individual parts into some final product, as in the assembly of automobile parts in the manufacture of a car. At one time, this kind of assembly could have been done only by a crew of humans, each of whom had his or her own specific responsibility: moving a body section into position, welding it into place, installing and tightening bolts, turning the body for the next operation, and so forth. In many assembly plants today, the assembly line of humans has been replaced by an assembly line of robots that does the same job, but more safely and more efficiently than was the case with the human team.

Movement of materials

Many industrial operations involve the lifting and moving of large, heavy objects over and over again. For example, a particular process may require the transfer of steel ingots onto a conveyor belt and then, at some later point, the removal of shaped pieces of steel made from those ingots. One way to perform these operations is with heavy machinery operated by human workers. But another method that is more efficient and safer is to substitute robots for the human and his or her machine.

Another type of heavy-duty robot is an exoskeleton, that is, a metallic contraption that surrounds a human worker. The human can step inside the exoskeleton, placing his or her arms and legs into the corresponding limbs of the exoskeleton. By operating the exoskeleton's controls, the human can magnify his or her strength many times, picking up and handling objects that would otherwise be much too heavy for the operator's own capacity.

Mobile robots are used for many heavy-duty operations. The robots operate on a system of wheels or legs, on a track, or with some other system of locomotion. They pick up a material or an object in one location and move it to a different location. The robots need not be designed to handle very large loads only. As an example, some office buildings contain tracks along which mobile robots can travel delivering mail to various locations within the building.

Hazardous or remote duty robots

A common application of robots is for use in places that humans can go only at risk to their own health or safety or that humans can not go at all. Industries where nuclear materials are used often make use of robots so that human workers are not exposed to the dangerous effects of radioactive materials. In one type of machine, a worker sits in a chair and places his or her hands and arms into a pair of sleeves. The controls within the sleeves are connected to a robot arm that can reach into a protected area where radioactive materials are kept. The worker can operate the robot arm and hand to perform many delicate operations that would otherwise have to be carried out by a human worker.

Robots have also been useful in space research. In 1975, for example, two space probes, code-named Viking 1 and Viking 2, landed on the planet Mars . These probes were two of the most complex and sophisticated robots ever built. Their job was to analyze the planet's surface. In order to accomplish this task, the probes were equipped with a long arm that was able to operate across a 120° radius, digging into the ground and taking out samples of Martian soil . The samples were then transported to one of three chemical laboratories within the robot, where they underwent automated chemical analysis. The results of these analyses were then transmitted by automatic telemetry to receiving stations on Earth .

How robots work

In order for a robot to imitate the actions of a human being, it has to be able to perform three fundamental tasks. First, it must be conscious of the world around it, just as humans obtain information about the world from our five senses. Second, the robot must somehow "know" what to do. One way for it to get that knowledge is to have a human prepare a set of instructions that are then implanted into the robot's "brain." Alternatively, it must be able to analyze and interpret data it has received from its senses and then make a decision based on that data as to how it should react. Third, the robot must be able to act on the instructions or data it has received.

Not all robots have all of these functions. For example, some of the earliest "for fun" robots like the Jacquet-Droz doll and scribe "knew" what to do because of the instructions that had been programmed into them by their inventors. The inventors also gave their toys the mechanical means with which to carry out their instructions: arms, fingers, torsos, eyes, and other body parts that were able to move in specific ways.

Mechanical systems

The humanlike movements that a robot makes as it works can be accomplished with a relatively small number of mechanical systems. One of those systems is known as the rectangular or Cartesian coordinate system. This system consists of a set of components that can move in any one of three directions, all at right angles to each other.

Think of a three-dimensional system in which an x-axis and a y-axis define a flat plane . Perpendicular to that plane is a third axis, the z-axis. A rule can be made to travel along the x-axis, along the y-axis, or along the z-axis. Overall, the ruler has the ability to move in three different directions, back and forth along the x- and y-axes and up and down along the z-axis. A system of this type is said to have three degrees of freedom because it has the ability to move in three distinct directions.

Another type of mechanical system is the cylindrical coordinate system. This system consists of a cylinder with a solid column through the middle of it. The cylinder can move up and down on the column (one degree of freedom), and an arm attached to the outside of the cylinder can rotate around the central column (a second degree of freedom). Finally, the arm can be constructed so that it will slide in and out of its housing attached to the cylinder (a third degree of freedom).

A third type of mechanical system is the spherical coordinate system. To understand this system, imagine a rectangular box-shaped component attached to a base. The box can rotate on its own axis (one degree of freedom) or tilt up or down on its axis (a second degree of freedom). An arm attached to the box may also be able to extend or retract, giving it a third degree of freedom.

Many robots have more than three degrees of freedom because they consist of two or more simple systems combined with each other. For example, a typical industrial robot might have one large arm constructed on a Cartesian coordinate system. At the end of the arm there might then be a wrist-type component with the same or a different mechanical system. Attached to the wrist might then be a hand with fingers, each with a mechanical system of its own. Combinations of mechanical systems like this one make it possible for an industrial robot to perform a variety of complex maneuvers not entirely different from those of a human arm, wrist, hand, and finger.

Sensory systems

The component of modern robots that was most commonly missing from their early predecessors was the ability to collect data from the outside world. Humans accomplish this task, of course, by means of our hands, eyes, ears, noses, and tongues. With some important exceptions, robots usually do not need to have the ability to hear, smell , or taste things in the world around them, but they are often required to be able to "see" an object or to "feel" it.

The simplest optical system used in robots is a photoelectric cell . A photoelectric cell converts light energy into electrical energy. It allows a robot to determine "yes/no" situations in its field of vision , such as whether a particular piece of equipment is present or not. Suppose, for example, that a robot looks at a place on the table in front of it where a tool is supposed to be. If the tool is present, light will be reflected off it and sent to the robot's photoelectric cell. There, the light waves will be converted to an electrical current that is transmitted to the robot's computer-brain.

More complex robot video systems make use of television cameras. The images collected by the cameras are sent to the robot's "brain," where they are processed for understanding. One means of processing is to compare the image received by the television camera with other images stored in the robot's computer-brain.

The human sense of touch can be replicated in a robot by means of tactile sensors. One kind of tactile sensor is nothing more than a simple switch that goes from one position to another when the robot's fingers come into contact with a solid object. When a finger comes into contact with an object, the switch may close, allowing an electrical current to flow to the brain . A more sophisticated sense of touch can be provided by combining a group of tactile sensors at various positions on the robot's hand. This arrangement allows the robot to estimate the shape, size, and contours of an object being examined.

Microcomputer-driven robots

Probably the most important development in the history of robotics has been the evolution of the microcomputer. The microcomputer makes it possible to store enormous amounts of information as well as huge processing programs into the brain of a robot. With the aid of a microcomputer, a robot can not only be provided with far more basic programming than had been possible before, but it can also be provided with the programming needed to help the robot teach itself, that is, to learn. For example, some computers designed to carry out repetitious tasks have developed the ability to learn from previous mistakes and, therefore, to work more efficiently in the future.

See also Artificial intelligence; Automation.

Resources

books

Aleksander, Igor, and Piers Burnett. Reinventing Man: TheRobot Becomes Reality. New York: Holt, Rinehart and Winston, 1983.

Asimov, Isaac, and Karen A. Frenkel. Robots: Machines inMan's Image. New York: Harmony Books, 1985.

Cook, David. Robot Building for Beginners. New York: APress, 2002.

D'Ignazio, Fred. Working Robots. New York: Elsevier/Nelson Books, 1982.

Malone, Robert. The Robot Book. New York: Harvest/HBJ Book, 1978.

Metos, Thomas. Robots A to Z. New York: Julian Messner, 1980.

Reichardt, Jasia. Robots: Fact, Fiction, and Prediction. New York: Penguin Books, 1978.

Wise, Edwin. Advanced Robotics. Dover, DE: Delmar Learning, 1999.

other

Current Science and Technology Center. "Robotic Surgery" [cited April 2003]. <http://www.mos.org/cst/article/1623/>.

Honda, Inc. "Asimo Humanoid Robot Project," homepage [cited April 2003]. <http://world.honda.com/robot/>.

David E. Newton

KEY TERMS

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Degrees of freedom

—The number of geometric positions through which a robot can move.

Exoskeleton

—An external bodily framework; in the field of robotics, an exoskeleton is a metallic frame within which a human can stand or sit in order to manipulate the frame itself.

Tactile sensor

—A device that converts mechanical pressure into an electrical current.