Industrial control systems examples & Types & concept

Significance of Automatic Control System

Industrial Applications (robot, assembly line, . . .)
Military Purpose (tank, missile, …)
Exploration Purpose (New Continent, Moon, Mars, Pluto…)
Transportation (automobile, ship, aircraft, …)
Daily Common Life (washing machine, boiler, toys, air conditioner, … )

The significance of automatic control is rapidly increasing in various fields owing to the development of electronics, computer science and information technology

Final Goal : Why do you learn Automatic Control?

→ convenient, comfortable and safe life for human beings

History of Automatic Control

selected Historical Development

1769 : James Watt’s steam engine and governor ->

Father of Automatic Control

1800 : Eli Whitney’s concept of interchangeable

parts manufacturing -> The beginning of mass production

1868 : J.C Maxwell : formulated a mathematical model for a governor control of a steam engine

Late 1800s : A.Hurwitz, E.J. Routh : investigated the

stability of linear systems.

1913 : Henry Ford : assembly machine for automobile production

1927: H.W. Bode : analyzed feedback amplifiers

1932 : H. Nyquist : analyzed the stability of system

1948: Evans : introduced Root-Locus Method

1954 : George Devol : first programmed industrial robot

state-variable model and optimal control

1980 : robust control : adaptive control, H∞ control, sliding mode control

Industrial control systems examples

Types of Industrial Control System

Open-Loop Control Systems
Closed-Loop Control Systems (Feedback Control System)

Open-Loop Control Systems

plant (system, process) : Any physical object to be controlled(robot, car, classroom, population, … )

The output is not monitored for the purpose of control action. In other words, the output is neither measured nor fed back for comparison with the input.

Some Features

1) easy implementation
2) low cost of operation
3) weak to disturbances
4) The accuracy depends on calibration

Typical Examples

1) traffic control (time base open-loop control)

* Note : Nowadays, in traffic control, real time feedback control is realized using vision sensor system.

2) dryer (high, medium, off)
3) washing machine (soaking, washing, rinsing)

Some Features

1) complicated structures (implementation may be difficult)
2) The system instability may occur
3) high cost of operation
4) robust to disturbances

Open-Loop Control Systems Example

speed control of turntable

position control of missile launcher

Closed-Loop Control Systems (Feedback Control System)

Comparator: – : negative feedback + : positive feedback

The output is monitored for the purpose of control action. The term ‘closed-loop control’ always implies the use of feedback control action in order to reduce system error

Some Features:

1) complicated structures (implementation may be difficult)

2) The system instability may occur

3) high cost of operation

4) robust to disturbances