Page 28 - Modern Robotics Building Versatile Macines

8 Modern Robotics

Wiener was able to create a prototype gun-aiming device that could
predict a target plane’s location with enough accuracy to improve
considerably the chances of shooting it down.

Feedback

The ballistics work would help Wiener develop a key concept, feed-
back. As the plane moved, the tracking device had to readjust con-
tinuously according to the target’s changing position. Electronically,
this meant feeding a signal from a sensor (something that monitors
the environment) to an effector (something that makes a response,
such as moving the gun barrel). As soon as the effector acts, the
incoming information will also change (for example, the angle
between the gun and plane will change). This is feedback.
Feedback can be either negative or positive. In negative feedback,
the incoming information is used to correct the device’s action
continuously to minimize the difference between the incoming and
outgoing information. If this works properly, the shells from the gun
will converge on the position of the plane, destroying it. Positive
feedback, on the other hand, responds to an input by increasing or
diverging the output. An example is an amplifier that accentuates
(and thus amplifies) an incoming wave signal. The “feedback” that
sometimes makes an audio amplifier squeal when a musician gets
too close is positive feedback.

Computers and Controls

By the end of the war, the first electronic computers (such as ENIAC)
were coming into use. While Wiener was involved only indirectly in
computer development, he saw great potential for the computers as
controllers for sophisticated machines such as communications sig-
nal processors. In a classified mathematical paper distributed widely
to military researchers, Wiener pointed out that communications
operations “carried out by electrical or mechanical or other such
means, are in no way essentially different from the operations com-
putationally carried out by . . . the computing machine.”