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.
ROBOTIC ARMS.
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.
dimension.
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.
