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remarked "I can't define a robot, but I know one when I see one."
How Robots Work If you consider all the different machines people call robots, you
can see that it's nearly impossible to come up with a
On the most basic level, human comprehensive definition. Everybody has a different idea of what
beings are made up of five major constitutes a robot.
You've probably heard of several of these famous robots:
• A body structure
• A muscle system to move the • R2D2 and C-3PO: The intelligent, speaking robots with
body structure loads of personality in the Star Wars movies
• A sensory system that receives • Sony's AIBO: A robotic dog that learns through human
information about the body and interaction
Photo courtesy NASA
the surrounding environment Like you, NASA's robonaut has • Honda's ASIMO: A robot that can walk on two legs like a
• A power source to activate the a movable body, brain, power person
muscles and sensors system and sensor system. • Industrial robots: Automated machines that work on
• A brain system that processes assembly lines
sensory information and tells the muscles what to do • Data: The almost human android from Star Trek
• BattleBots: The remote control fighters on Comedy Central
Of course, we also have some intangible attributes, such as • Bomb-defusing robots
intelligence and morality, but on the sheer physical level, the list • The Mars Pathfinder: NASA's exploration robot
above about covers it. • HAL: The ship's computer in Stanley Kubrick's 2001: A
A robot is made up of the very same components. A typical robot • Robomower: The lawn-mowing robot from Friendly
has a movable physical structure, a motor of some sort, a sensor Robotics
system, a power supply and a computer "brain" that controls all of • The Robot in the television series "Lost in Space"
these elements. Essentially, robots are man-made versions of • MindStorms: LEGO's popular robotics kit
animal life -- they are machines that replicate human and animal
behavior. HowStuffWorks has several articles on other types of robots:
In this edition of HowStuffWorks, we'll explore the basic concept • How Robotic Surgery Will Work
of robotics and find out how robots do what they do. • How Robonauts Will Work
• How Snakebots Will Work
What is a Robot? • How Rumble Robots Work
Joseph Engelberger, a pioneer in industrial robotics, once • How Stinger Missiles Work
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All of these things are considered robots, at least by some people. A robot needs a power source to drive these actuators. Most
The broadest definition around defines a robot as anything that a robots either have a battery or they plug into the wall. Hydraulic
lot of people recognize as a robot. Most roboticists (people who robots also need a pump to pressurize the hydraulic fluid, and
build robots) use a more precise definition. They specify that pneumatic robots need an air compressor or compressed air
robots have a reprogrammable brain (a computer) that moves a tanks.
The actuators are all wired to an electrical circuit. The circuit
By this definition, robots are distinct from other movable powers electrical motors and solenoids directly, and it activates
machines, such as cars, because of their computer element. the hydraulic system by manipulating electrical valves. The valves
Many new cars do have an onboard computer, but it's only there determine the pressurized fluid's path through the machine. To
to make small adjustments. You control most elements in the car move a hydraulic leg, for example, the robot's controller would
directly by way of various mechanical devices. Robots are distinct open the valve leading from the fluid pump to a piston cylinder
from ordinary computers in their physical nature -- normal attached to that leg. The pressurized fluid would extend the
computers don't have a physical body attached to them. piston, swiveling the leg forward. Typically, in order to move their
segments in two directions, robots use pistons that can push both
Robot Basics ways.
The vast majority of robots do have several qualities in common.
The robot's computer controls everything attached to the circuit.
First of all, almost all robots have a movable body. Some only
To move the robot, the computer switches on all the necessary
have motorized wheels, and others
motors and valves. Most robots are reprogrammable -- to
have dozens of movable segments,
change the robot's behavior, you simply write a new program to its
typically made of metal or plastic.
Like the bones in your body, the
individual segments are connected
Not all robots have sensory systems, and few have the ability to
together with joints.
see, hear, smell or taste. The most common robotic sense is the
sense of movement -- the robot's ability to monitor its own motion.
Robots spin wheels and pivot jointed
A standard design uses slotted wheels attached to the robot's
segments with some sort of actuator. Photo courtesy NASA
A robotic hand, developed by joints. An LED on one side of the wheel shines a beam of light
Some robots use electric motors and
NASA, is made up of metal through the slots to a light sensor on the other side of the wheel.
solenoids as actuators; some use a segments moved by tiny When the robot moves a particular joint, the slotted wheel turns.
hydraulic system; and some use a motors. The hand is one of the
The slots break the light beam as the wheel spins. The light
pneumatic system (a system driven most difficult structures to
replicate in robotics. sensor reads the pattern of the flashing light and transmits the
by compressed gases). Robots may
data to the computer. The computer can tell exactly how far the
use all these actuator types.
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joint has swiveled based on this pattern. This is the same basic step motors connected to each joint (some larger arms use
system used in computer mice. hydraulics or pneumatics). Unlike ordinary motors, step motors
move in exact increments (check out this site to find out how).
These are the basic nuts and bolts of robotics. Roboticists can This allows the computer to move the arm very precisely,
combine these elements in an infinite number of ways to create repeating exactly the same movement over and over again. The
robots of unlimited complexity. In the next section, we'll look at robot uses motion sensors to make sure it moves just the right
one of the most popular designs, the robotic arm. amount.
The Robotic Arm An industrial robot with six joints closely resembles a human arm
The term robot comes from the Czech word robota, generally -- it has the equivalent of a shoulder, an elbow and a wrist.
translated as "forced labor." This describes the majority of robots Typically, the shoulder is mounted to a stationary base structure
fairly well. Most robots in the world are designed for heavy, rather than to a movable body. This type of robot has six degrees
repetitive manufacturing work. They handle tasks that are difficult, of freedom, meaning it can pivot in six different ways. A human
dangerous or boring to human beings. arm, by comparison, has seven degrees of freedom.
Robotic arms are an essential part of car manufacturing.
The most common manufacturing robot is the robotic arm. A
typical robotic arm is made up of seven metal segments, joined by
six joints. The computer controls the robot by rotating individual
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Industrial robots are designed to do exactly the same thing, in a
controlled environment, over and over again. For example, a robot
might twist the caps onto peanut butter jars coming down an
assembly line. To teach a robot how to do its job, the programmer
guides the arm through the motions using a handheld controller.
The robot stores the exact sequence of movements in its memory,
and does it again and again every time a new unit comes down
the assembly line.
Most industrial robots work in auto assembly lines, putting cars
together. Robots can do a lot of this work more efficiently than
human beings because they are so precise. They always drill in
the exactly the same place, and they always tighten bolts with the
same amount of force, no matter how many hours they've been
working. Manufacturing robots are also very important in the
computer industry. It takes an incredibly precise hand to put
together a tiny microchip.
The Czech playwright Karel Capek originated the term robot in his
1920 play "R.U.R." In the play, machine workers overthrow their
human creators when a scientist gives them emotions. Dozens of
Your arm's job is to move your hand from place to place. Similarly, authors and filmmakers have revisited this scenario over the years.
the robotic arm's job is to move an end effector from place to
Isaac Asimov took a more optimistic view in several novels and
place. You can outfit robotic arms with all sorts of end effectors, short stories. In his works, robots are benign, helpful beings that
which are suited to a particular application. One common end adhere to a code of nonviolence against humans -- the "Laws of
effector is a simplified version of the hand, which can grasp and Robotics."
carry different objects. Robotic hands often have built-in pressure
sensors that tell the computer how hard the robot is gripping a Mobile Robots
particular object. This keeps the robot from dropping or breaking Robotic arms are relatively easy to build and program because
whatever it's carrying. Other end effectors include blowtorches, they only operate within a confined area. Things get a bit trickier
drills and spray painters. when you send a robot out into the world.
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Many mobile robots have a built-in balance system (a collection
of gyroscopes, for example) that tells the computer when it needs
to correct its movements.
Photo courtesy NASA
NASA's FIDO Rover is designed for exploration on Mars.
The first obstacle is to give the robot a working locomotion
system. If the robot will only need to move over smooth ground,
wheels or tracks are the best option. Wheels and tracks can also
work on rougher terrain if they are big enough. But robot
designers often look to legs instead, because they are more Photo courtesy NASA
adaptable. Building legged robots also helps researchers NASA's Frogbot uses springs, linkages and motors to hop
from place to place.
understand natural locomotion -- it's a useful exercise in biological
Bipedal locomotion (walking on two legs) is inherently unstable,
Typically, hydraulic or pneumatic pistons move robot legs back which makes it very difficult to implement in robots. To create
and forth. The pistons attach to different leg segments just like more stable robot walkers, designers commonly look to the animal
muscles attach to different bones. It's a real trick getting all these world, specifically insects. Six-legged insects have exceptionally
pistons to work together properly. As a baby, your brain had to good balance, and they adapt well to a wide variety of terrain.
figure out exactly the right combination of muscle contractions to
walk upright without falling over. Similarly, a robot designer has to Some mobile robots are controlled by remote -- a human tells
figure out the right combination of piston movements involved in them what to do and when to do it. The remote control might
walking and program this information into the robot's computer. communicate with the robot through an attached wire, or using
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radio or infrared signals. Remote robots, often called puppet
robots, are useful for exploring dangerous or inaccessible
environments, such as the deep sea or inside a volcano. Some
robots are only partially controlled by remote. For example, the
operator might direct the robot to go to a certain spot, but not
steer it there -- the robot would find its own way.
What is it Good For?
Mobile robots stand in for people in a number of ways. Some
explore other planets or inhospitable areas on Earth, collecting
geological samples. Others seek out landmines in former
battlefields. The police sometimes use mobile robots to search for
a bomb, or even to apprehend a suspect.
Photo courtesy NASA
Mobile robots also work in homes and businesses. Hospitals may
use robots to transport medications. Some museums use robots to The Urbie is an autonomous robot designed for various urban
patrol their galleries at night, monitoring air quality and humidity operations, including military reconnaissance
levels. Several companies have developed robots that will vacuum and rescue operations.
your house while you sleep.
Advanced robots use more elaborate versions of this same idea.
Autonomous Mobility Roboticists create new programs and sensor systems to make
Autonomous robots can act on their own, independent of any robots smarter and more perceptive. Today, robots can effectively
controller. The basic idea is to program the robot to respond a navigate a variety of environments.
certain way to outside stimuli. The very simple bump-and-go
robot is a good illustration of how this works. Simpler mobile robots use infrared or ultrasound sensors to see
obstacles. These sensors work the same way as animal
This sort of robot has a bumper sensor to detect obstacles. When echolocation: The robot sends out a sound signal or a beam of
you turn the robot on, it zips along in a straight line. When it finally infrared light and detects the signal's reflection. The robot locates
hits an obstacle, the impact pushes in its bumper sensor. The the distance to obstacles based on how long it takes the signal to
robot's programming tells it to back up, turn to the right and move bounce back.
forward again, in response to every bump. In this way, the robot
changes direction any time it encounters an obstacle. More advanced robots use stereo vision to see the world around
them. Two cameras give these robots depth perception, and
image-recognition software gives them the ability to locate and
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classify various objects. Robots might also use microphones and band of hobbyists has been creating robots in garages and
smell sensors to analyze the world around them. basements all over the world.
Some autonomous robots can only work in a familiar, constrained Homebrew robotics is a rapidly expanding subculture with a
environment. Lawn-mowing robots, for example, depend on sizable Web presence. Amateur roboticists cobble together their
buried border markers to define the limits of their yard. An office- creations using commercial robot kits, mail order components,
cleaning robot might need a map of the building in order to toys and even old VCRs.
maneuver from point to point.
Homebrew robots are as varied as professional robots. Some
More advanced robots can analyze and adapt to unfamiliar weekend roboticists tinker with elaborate walking machines, some
environments, even to areas with rough terrain. These robots may design their own service bots and others create competitive
associate certain terrain patterns with certain actions. A rover robots. The most familiar competitive robots are remote control
robot, for example, might construct a map of the land in front of it fighters like you might see on "BattleBots." These machines aren't
based on its visual sensors. If the map shows a very bumpy considered "true robots" because they don't have reprogrammable
terrain pattern, the robot knows to travel another way. This sort of computer brains. They're basically souped-up remote control cars.
system is very useful for exploratory robots that operate on other
planets (check out this page to learn more). More advanced competitive robots are controlled by computer.
Soccer robots, for example, play miniaturized soccer with no
An alternative robot design takes a less structured approach -- human input at all. A standard soccer bot team includes several
randomness. When this type of robot gets stuck, it moves its individual robots that communicate with a central computer. The
appendages every which way until something works. Force computer "sees" the entire soccer field with a video camera and
sensors work very closely with the actuators, instead of the picks out its own team members, the opponent's members, the
computer directing everything based on a program. This is ball and the goal based on their color. The computer processes
something like an ant trying to get over an obstacle -- it doesn't this information at every second and decides how to direct its own
seem to make a decision when it needs to get over an obstacle, it team.
just keeps trying things until it gets over it.
Adaptable and Universal
Homebrew Robots The personal computer revolution has been marked by
In the last couple of sections, we looked at the most prominent extraordinary adaptability. Standardized hardware and
fields in the world of robots -- industry robotics and research programming languages let computer engineers and amateur
robotics. Professionals in these fields have made most of the programmers mold computers to their own particular purposes.
major advancements in robotics over the years, but they aren't the Computer components are sort of like art supplies -- they have an
only ones making robots. For decades, a small but passionate infinite number of uses.
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Most robots to date have been more like kitchen appliances. consensus on whether a robot can ever
Roboticists build them from the ground up for a fairly specific be intelligent. AI in the Movies
purpose. They don't adapt well to radically new applications.
• The Matrix
Like the term "robot" itself, artificial
This situation may be changing. A new company called Evolution intelligence is hard to define. Ultimate AI • Blade Runner
Robotics is pioneering the world of adaptable robotics hardware would be a recreation of the human • 2001: A Space
and software. The company hopes to carve out a niche for itself thought process -- a man-made machine Odyssey
with easy-to-use "robot developer kits." with our intellectual abilities. This would • Demon Seed
include the ability to learn just about • Bicentennial Man
The kits come with an open software platform tailored to a range anything, the ability to reason, the ability • The Terminator
of common robotic functions. For example, roboticists can easily to use language and the ability to • Short Circuit
give their creations the ability to follow a target, listen to voice formulate original ideas. Roboticists are
commands and maneuver around obstacles. None of these nowhere near achieving this level of
capabilities are revolutionary from a technology standpoint, but it's artificial intelligence, but they have had
unusual that you would find them in one simple package. made a lot of progress with more limited AI. Today's AI machines
can replicate some specific elements of intellectual ability.
The kits also come with common robotics hardware that connects
easily with the software. The standard kit comes with infrared Computers can already solve problems in limited realms. The
sensors, motors, a microphone and a video camera. Roboticists basic idea of AI problem-solving is very simple, though its
put all these pieces together with a souped-up erector set -- a execution is complicated. First, the AI robot or computer gathers
collection of aluminum body pieces and sturdy wheels. facts about a situation through sensors or human input. The
computer compares this information to stored data and decides
These kits aren't your run-of-the-mill construction sets, of course. what the information signifies. The computer runs through various
At upwards of $1,000, they're not cheap toys. But they are a big possible actions and predicts which action will be most successful
step toward a new sort of robotics. In the near future, creating a based on the collected information. Of course, the computer can
new robot to clean your house or take care of your pets while only solve problems it's programmed to solve -- it doesn't have
you're away might be as simple as writing a BASIC program to any generalized analytical ability. Chess computers are one
balance your checkbook. example of this sort of machine.
The Future: AI Some modern robots also have the ability to learn in a limited
Artificial intelligence (AI) is arguably the most exciting field in capacity. Learning robots recognize if a certain action (moving its
robotics. It's certainly the most controversial: Everybody agrees legs in a certain way, for instance) achieved a desired result
that a robot can work in an assembly line, but there's no (navigating an obstacle). The robot stores this information and
attempts the successful action the next time it encounters the
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same situation. Again, modern computers can only do this in very experience the world like a human is essential to developing
limited situations. They can't absorb any sort of information like a human-like intelligence. It also makes it easier for people to
human can. Some robots can learn by mimicking human actions. interact with the robots, which potentially makes it easier for the
In Japan, roboticists have taught a robot to dance by robot to learn.
demonstrating the moves themselves.
Just as physical robotic design is a handy tool for understanding
Some robots can interact socially. Kismet, a robot at M.I.T's animal and human anatomy, AI research is useful for
Artificial Intelligence Lab, recognizes human body language and understanding how natural intelligence works. For some
voice inflection and responds appropriately. Kismet's creators are roboticists, this insight is the ultimate goal of designing robots.
interested in how humans and babies interact, based only on tone Others envision a world where we live side by side with intelligent
of speech and visual cue. This low-level interaction could be the machines and use a variety of lesser robots for manual labor,
foundation of a human-like learning system. health care and communication. A number of robotics experts
predict that robotic evolution will ultimately turn us into cyborgs --
Kismet and other humanoid robots at the M.I.T. AI Lab operate humans integrated with machines. Conceivably, people in the
using an unconventional control structure. Instead of directing future could load their minds into a sturdy robot and live for
every action using a central computer, the robots control lower- thousands of years!
level actions with lower-level computers. The program's director,
Rodney Brooks, believes this is a more accurate model of human In any case, robots will certainly play a larger role in our daily lives
intelligence. We do most things automatically; we don't decide to in the future. In the coming decades, robots will gradually move
do them at the highest level of consciousness. out of the industrial and scientific worlds and into daily life, in the
same way that computers spread to the home in the 1980s.
The real challenge of AI is to understand how natural intelligence
works. Developing AI isn't like building an artificial heart -- The best way to understand robots is to look at specific designs.
scientists don't have a simple, concrete model to work from. We The links on the next page will show you a variety of robot
do know that the brain contains billions and billions of neurons, projects around the world.
and that we think and learn by establishing electrical connections
between different neurons. But we don't know exactly how all of
these connections add up to higher reasoning, or even low-level
operations. The complex circuitry seems incomprehensible.
Because of this, AI research is largely theoretical. Scientists
hypothesize on how and why we learn and think, and they
experiment with their ideas using robots. Brooks and his team
focus on humanoid robots because they feel that being able to