When most people think of a robot, they imagine a machine that looks and acts like a human. Most robots, however, look nothing like people. They can act only in the ways that humans program them to act. Still, robots are very useful machines. They do dangerous and repetitive work in factories, in hospitals, in the military, and in the space program. The word robot comes from the Czech word robota, which means “forced labor.”

How robots work

Robots are controlled by computers, which are controlled by humans. Humans write computer programs that tell the robot how to do certain physical tasks. The computer sends signals to the robot to make it perform each step of a task. An electrical system in the robot drives its movements.

Some robots can be “taught” to do jobs. For example, a human might guide the mechanical arm of a robot through the movements needed to complete a task. Sensors on the robot send signals about the movements to the computer. The computer stores the pattern of movements. Later the computer can retrieve the pattern and tell the robot what to do.

Uses

Robots are useful because they can go places where human beings cannot. Robots have no need for food or oxygen, so they can be sent underwater or into space. For example, robots have explored the surface of Mars. Robots can also handle dangerous materials such as radioactive waste or harmful chemicals. They can even dispose of bombs or do spy work for the military.

Robots can also replace humans who would otherwise have to do dull, repetitive tasks. For example, robots with a jointed arm work on assembly lines to build cars and appliances. Sections of the arm turn at several joints. The robot's “hand” can move in all directions. Those movements allow the robot to use such tools as welders and paint guns. Directed by a computer, this type of robot can keep an assembly line going constantly.

Medical robots help doctors to perform surgery. Robots allow doctors to see inside the body through tiny incisions. They can also position surgical instruments inside the body with great accuracy.

Robots can do work for humans on farms and in homes. Robots can milk cows and mow lawns. There are small robots that act as automatic vacuum cleaners. Some humans own small robots as toys or electronic “pets.”

History

Early types of robots, called automatons, date back to ancient times. Writings from ancient Greece and China tell of mechanical devices set in motion by steam, air, water, and falling weights. Later automatons were driven by springs, gears, pulleys, and levers. The most complex automatons appeared in the late 18th and early 19th centuries. Even these devices, however, were really just mechanical toys that did simple tasks. Some could toll the hours, others could play music, and some could write with a pen on paper.

During the Industrial Revolution people built more advanced and useful machines to help do repetitive work. Modern electronic robots, however, were not invented until after the invention of the computer. With computers, machines could be programmed to do tasks automatically, or without a human present.

Robots in science fiction

Although robots are becoming more complex, they still do not resemble the robots that are often presented in books, television shows, and movies. Many robots appear in science fiction, a type of story set in the future or in another world. Science-fiction robots can often think for themselves, listen, talk, and walk easily on two legs. Science-fiction robots that look exactly like humans are called androids. Two of the most famous science-fiction robots are R2-D2 and C-3PO in the Star Wars movies.