EE2253CONTROL SYSTEM

PRESENTED BY S.S.KARTHIKA, AP/EEE

Objective

A control system consisting of interconnected components is designed to achieve a desired purpose.

Modern control engineering practice includes the use of control design strategies for improving manufacturing processes, the efficiency of energy use, advanced automobile control, including rapid transit, among others.

Introduction

System – An interconnection of elements and devices for a desired purpose.

Control System – An interconnection of components forming a system configuration that will provide a desired response.

Process – The device, plant, or system under control. The input and output relationship represents the cause-and-effect relationship of the process.

Introduction

Open-Loop Control Systems utilize a controller or control actuator to obtain the desired response.

Closed-Loop Control Systems utilizes feedback to compare the actual output to the desired output response.

History

History18th Century James Watt’s centrifugal governor for the speed control of a steam engine.

1920s Minorsky worked on automatic controllers for steering ships.

1930s Nyquist developed a method for analyzing the stability of controlled systems

1940s Frequency response methods made it possible to design linear closed-loop control systems

1950s Root-locus method due to Evans was fully developed

1960s State space methods, optimal control, adaptive control and

1980s Learning controls are begun to investigated and developed.

Present and on-going research fields. Recent application of modern control theory includes such non-engineering systems such as biological, biomedical, economic and socio-economic systems

The Future of Control Systems

Control System Design

UNIT I SYSTEMS AND THEIR REPRESENTATION

Basic elements in control systems Open and closed loop systems Electrical analogy of mechanical

and thermal systems Transfer function Synchros – AC and DC servomotors Block diagram reduction techniques Signal flow graphs

UNIT II TIME RESPONSE

Time responseTime domain specifications Types of test input – I and II order

system response Error coefficientsGeneralized error series Steady state error P, PI, PID modes of feedback

control

UNIT III FREQUENCY RESPONSE

Frequency response Bode plot Polar plot Determination of closed loop

response from open loop response

Correlation between frequency domain and time domain specifications

UNIT IV STABILITY OF CONTROL SYSTEM Characteristics equation Location of roots in S plane for

stability Routh Hurwitz criterion Root locus constructionEffect of pole, zero additionGain margin and phase margin Nyquist stability criterion.

UNIT V COMPENSATOR DESIGN

Performance criteria Lag, lead and lag-lead networks Compensator design using

bode plots

 TEXT BOOKS

1. I.J. Nagrath and M. Gopal, ‘Control Systems Engineering’, New Age International Publishers, 2003.

2. Benjamin C. Kuo, Automatic Control systems, Pearson Education, New Delhi, 2003. 

REFERENCES

1. K. Ogata, ‘Modern Control Engineering’, 4th edition, PHI, New Delhi, 2002.

2. Norman S. Nise, Control Systems Engineering, 4th Edition, John Wiley, New Delhi, 2007.

3. Samarajit Ghosh, Control systems, Pearson Education, New Delhi, 2004

4. M. Gopal, ‘Control Systems, Principles and Design’, Tata McGraw Hill, New Delhi, 2002.