Preface

With the development of process industries to meet market demand, new efficient technologies have come up innovative ways to enhance production capacity by giving special effort to process intensification. Maximizing production by allowing optimal inputs to flow to the process has saved energy, raw materials, and utility in process industries. In order to reduce global warming, various measures and preventive actions are initiated around the world.

This book provides the most recent information about the theory, history, state of the art, and best practices in implementing precise controllers in modern industrial processes, financial sectors, and bio processes. Presently monitoring and controlling are not only limited to industrial systems, but also have been extended to bio-medical, financial market, and areas related to forecasting and control. The main purpose of writing this book is to create an understanding of theory behind PID controller, how to tune, and where to apply the controller. The concept of applying PID controller to various fields and to design or tune the controller for specific purposes by fulfilling closed-loop performance specifications is the objective of this book.

The book covers the general topic of PID control configuration and tuning as well as new requirements that originate from allied application areas. This book contains eight preliminary sections each of which has one or more chapters. Thus, a total of 11 chapters has been accommodated in this book. It is proposed that section one will have chapter one and two. Chapter one will introduce PID controller design methods under specified performance, especially, time-domain and frequency domain specifications, optimization of PID parameters using error criteria. Chapter two presents the general discussion on the family of PID controllers with a path to proceed for optimal control. The architecture (series, parallel, and cascade) and structure of PID controllers for first and second order processes are explained here. Chapter three describes the PID-like controller tuning for second order unstable systems with different model structures, relying on assignment of dominant poles, as well as time domain specifications, providing sufficient stability margins. The controller parameters are obtained in terms of process parameters, or by using iterative techniques. Chapter four introduces concepts of tuning of PID controllers based on magnitude optimum for integrating unstable and Smith predictor systems in the continuous domain. The technique is combined with the concept of movement for cases on set point tracking and disturbance rejection. Model based tuning criteria of PID controllers for conventional controllers (P, PI, PID, PD etc) for multi input multi output systems are described in chapter five. Features and methods of auto tuning of PID controller, and the method of calculating performance of individual loops are also stated here. Tuning methods, using subspace identification techniques, different types of multiloop controllers with their design methods, and tuning of those controllers, are discussed in this chapter. Chapter six describes robust decentralized controller design for MIMO systems. Performances of individual loops and for the overall system are discussed here. Application of Nyquist type design for robust stability and nominal performance is discussed here. Chapter seven accounts for various intelligent controllers, namely using fuzzy logic based on the Mamdani structure. A method to make a pseudo-equivalence between the linear PID controllers and the fuzzy PID controllers is given here. Chapter eight presents discrete PID controller tuning using piecewise linearization methods using neural networks. PID controller is used using pole assignment. Design method of fractional order PID controllers for fractional order process is addressed in chapter nine. The difficulties in designing fractional order PID due to presence of fractional derivatives is explained here. Application of PID controllers in financial sectors is described in chapter 10. In this chapter, a portfolio management model with the aim to obtain good returns and decrease portfolio risk through stabilization of returns, by means of the PID control applied to pure returns, has been illustrated. The possible extensions in practical application of PID controllers in other fields, for example, polymerization and production of bromelin are described in Chapter 11. Each of the above chapters contains applications of the respective theory presented in it.

I sincerely thank the publisher and book-process-manager for their cooperation in bringing this book to a presentable manner.

> **Rames C. Panda**  Scientist, Dept of Chemical Engineering, CLRI, Adyar, Chennai India
