GIỚI THIỆU về hệ THỐNG điều KHIỂN tự ĐỘNG (cơ sở tự ĐỘNG SLIDE)

CHƯƠNG 1

GIỚI THIỆU VỀ HỆ THỐNG
ĐIỀU KHIỂN TỰ ĐỘNG


1769
• James Watt’s steam engine and governor developed.
The Watt steam engine is often used to mark the
beginning of the Industrial Revolution in Great
Britain. During the Industrial Revolution, great
strides were made in the development of
mechanization, a technology preceding automation.

Control Systems

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Control
• Control is a sequence of decisions aimed at the
attainment of specified objectives in an
environment of uncertainty and presence of
disturbances.


Control system
• A control system is an arrangement of
physical components connected or related in

such a manner as to command, direct, or
regulate itself or another system.



Input
• The input is the stimulus, excitation or
command applied to a control system.
• Typically from external energy source,
usually in order to produce a specified
response from the control system.


Output
• The output is the actual response obtained
from a control system.
• It may or may not be equal to specified
response implied by the input.


History of Automatic Control


Prior to World War II
A main impetus for the use of feedback in the
United States was the development of the
telephone system and electronic feedback
amplifiers by Bode, Nyquist, and Black at Bell
Telephone Laboratories.

Prior to World War II
The Russian theory tended to utilize a timedomain formulation using differential
equations.


World War II
Design and construct:
• automatic airplane pilots,
• gun-positioning systems,
• radar antenna control systems.


Sputnik and space age
The time-domain methods developed by
Liapunov, Minorsky, and others have met
with great interest in the last two decades.


Recent time
Recent theories of optimal control developed
by L.S. Pontryagin in the former Soviet Union
and R. Bellman in the United States, and
studies of robust systems, have contributed
to the interest in time-domain methods.


Terms and Concepts

Two Types of Control Systems
• Open Loop
– No feedback
– Difficult to control
output with accuracy

• Closed Loop
– Must have feedback
– Must have sensor on
output
– Almost always negative
feedback


Open-loop and closed-loop systems


Open-loop control
An open-loop control system utilizes an actuating
device to control the process directly without using
feedback.
A common example of an open-loop control system
is an electric toaster in the kitchen.



Closed-loop control
A closed-loop control system uses a measurement
of the output and feedback of this signal to
compare it with the desired output.

A person steering an automobile by looking at
the auto’s location on the road and making the appropriate adjustments.

Control Systems



Manual control system

Goal: Regulate the level of fluid by adjusting the output valve.
The input is a reference level of fluid and is memorized by operator.
The power amplifier is the operator.
The sensor is visual.
Operator compares the actual level with the desired level and opens or
closes the valve ( actuator).
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