Computer Interfacing

Motor drives

a motor

is

accelerating,

as it

does when

it is

racing

to-

wards

its new

position,

it

acquires momentum because

of

its

mass. Just because

it has

reached

its new

position

and

no

longer

has a

signal from

the

amplifier

to

drive

it,

doesn't mean that

it

will suddenly stop.

Far

from

it; its

momentum will carry

it

past

the

correct position.

As a

result

of

this overshoot,

a

feedback voltage will

be de-

rived from

the

wiper

of the

output potentiometer that

will apply

a

torque

to the

motor

in the

opposite direc-

tion.

The

motor stops

(too

late!), reverses,

and

heads

back

the way it

came, once more gaining momentum. This

time

it

overshoots fro ...