How Robots Work

By: Tom Harris

Robot Image Gallery NASA's Urban Robot, Urbie, features software-controlled cameras and sensors that allow it to operate autonomously in many types of terrain. URBIE checks out areas that would pose potential risks to human investigators. See more pictures of robots.

On the most basic level, human beings are made up of five major components:

  • A body structure
  • A muscle system to move the body structure
  • A sensory system that receives information about the body and the surrounding environment
  • A power source to activate the muscles and sensors
  • A brain system that processes sensory information and tells the muscles what to do

Of course, we also have some intangible attributes, such as intelligence and morality, but on the sheer physical level, the list above about covers it.


A robot is made up of the very same components. A typical robot has a movable physical structure, a motor of some sort, a sensor system, a power supply and a computer "brain" that controls all of these elements. Essentially, robots are man-made versions of animal life -- they are machines that replicate human and animal behavior.

In this article, we'll explore the basic concept of robotics and find out how robots do what they do.

Joseph Engelberger, a pioneer in industrial robotics, once remarked "I can't define a robot, but I know one when I see one." If you consider all the different machines people call robots, you can see that it's nearly impossible to come up with a comprehensive definition. Everybody has a different idea of what constitutes a robot.

You've probably heard of several of these famous robots:

  • R2D2 and C-3PO: The intelligent, speaking robots with loads of personality in the "Star Wars" movies
  • Sony's AIBO: A robotic dog that learns through human interaction
  • Honda's ASIMO: A robot that can walk on two legs like a person
  • Industrial robots: Automated machines that work on assembly lines
  • Data: The almost human android from "Star Trek"
  • BattleBots: The remote control fighters on Comedy Central
  • Bomb-defusing robots
  • NASA's Mars rovers
  • HAL: The ship's computer in Stanley Kubrick's "2001: A Space Odyssey"
  • Robomower: The lawn-mowing robot from Friendly Robotics
  • The Robot in the television series "Lost in Space"
  • MindStorms: LEGO's popular robotics kit

All of these things are considered robots, at least by some people. The broadest definition around defines a robot as anything that a lot of people recognize as a robot. Most roboticists (people who build robots) use a more precise definition. They specify that robots have a reprogrammable brain (a computer) that moves a body.­

By this definition, robots are distinct from other movable machines, such as cars, because of their computer element. Many new cars do have an onboard computer, but it's only there to make small adjustments. You control most elements in the car directly by way of various mechanical devices. Robots are distinct from ordinary computers in their physical nature -- normal computers don't have a physical body attached to them.

In the next section, we'll look at the major elements found in most robots today.