What is A Robot


The term robot comes from the Czechoslovakian wordfor "forced labor,"
invented by Karel Capek. Karel Capek used robots in his plays and had them
look and behave like people.

Today, the word "robot" is harder to define because of new designs and
technology. The third edition of Websters's New International Dictionary
defines a robot as "a machine in the form of a human being that performs
the mechanical functions of a human being." However, today's robot makers
are not interested in giving their creations human forms. Most industrial
robots look like lobsters or oversized grasshoppers.

Around 1981, the members of the Robot Institute of America, held a
meeting to develop a definition of an industrial robot. Finally after long
debate, they came up with the definition:

"A reprogrammable, multifunctional manipulator designed to move
material, parts, tools or specialized devices, through variable
programmable motions, for the performance of a variety of

The key wor ds in their definition are "reprogrammable" and
"multifunctional." By "reprogrammable" they mean that if a robot gets a new
assignment, it will need new instructions, but its basic structure will not
change (except maybe a new mechanical hand). By "multifunctional" they
mean a robot is the mechanical counter part of a computer that can handle
various problems without any major hardware modifications. The only thing
that changes when a robot is reassigned is its program of instructions.

In modern robots, programmable microprocessors control all the robot's
movements and actions. Robots can be taught by using a teaching mode. An
operator moves the robot's hand through all of the desired motions manually
with his own hand. When the robot is activated, it will repeat those same
motions over and over again.

Most robots are equipped with one hand and one arm of several
articulated joints. Some of these joints swivel in smooth arcs mimicking
the behavior of the human shoulder, wrist, and elbow. Other robots move in
straight lines similar to a crane. Robots rarely have a pair of arms, and
are usually stationary. If a robot moves that is all it does. Examples
are delivery robots rolling down halls delivering mail or supplies.

The hands and arms of early robots were pneumatically powered (air
pressure) or hydraulically powered (fluid pressure). Flexible tubes
carried the pressurized substances to the joints. Now, electric motors
located at the joint give the robot greater precision and control, but slow
down its movements. All robot manufacturers dream of joints with
human-like tendons.

Most robots are blind and are insensitive to their surroundings. Some
have sensors triggered by light, pressure, or heat that can create a crude
picture of what is happening.


There are four types of robot arms that are used today. Degrees of
freedom are the axes around the arm in which it is free to move. The area
a robot arm can reach is its work envelope.

Rectangular arms are sometimes called "Cartesian" because the arm's
axes can be described by using the X, Y, and Z coordinate system developed
by Descartes. Descartes is a famous French philosopher, scientist, and
mathematician. If a pen were attached to the arm, it would draw a rectangle
which would be its work envelope. Imagine a graph where X would be side to
side, and Y would be in and out on the graph. Up and down would be Z which
runs through the graph and describes depth. Z also adds the third

A cylindrical arm also has three degrees of freedom, but it moves
linearly only along the Y and Z axes. Its third degree of freedom is the
rotation at its base around the two axes. The work envelope is in the
shape of a cylinder.

The spherical arm replaces up and down movements along the two axes
with a rocking motion of the arm. The spherical arm's work envelope is a
partial sphere which has various length radii.

The last and most used design is the jointed-arm. The arm has a trunk,
shoulder, upper arm, forearm, and wrist. All joints on the arm can rotate,
creating six degrees of freedom. Three are the X, Y, and Z axes. The
other three are pitch, yaw, and roll. Pitch is when you move your wrist up
and down. Yaw is when you move your hand left and right. Rotate your
entire forearm as if you are drilling a hole. Your arm would rotate around
an axis that goes through the center of your wristbone. This motion is
called roll.

What a robot