Preface

Proportional-Integral-Derivative (PID) controllers are by far the most adopted controllers in industry owing to the advantageous cost/benefit ratio that they are able to provide. In the last century, a large number of researchers have considered them, and industrial products have improved their functionality significantly. Proposals for the design and tuning of PID based control systems have generated a really vast literature during the last decades. This sparked the special attention of the IFAC Workshop PID’00 Present and Future of PID control held in Terrassa, Spain, in April 2000. This event provided a state-of-the-art on many aspects of PID control, ranging from specialized theoretical research topics and tuning methods to interesting reviews of technological products, patents and software, confirming that the PID controller continues to generate deep interest and is a good augury for future research in the field of PID controllers. Starting from this special event, in the last ten years there has been a renewed interest in the research on PID controllers, as witnessed by a large number of papers published on this subject. This book gives an overview of the advances made for PID controllers during this last decade. The book is divided into four parts in which well-known experts and specialists address different topics (one for each chapter) in the following fields: (i) new approaches for tuning PID controllers; (ii) control structures and configurations for PID control; (iii) issues in PID control; (iv) non-standard approaches to PID control. The first part concentrates on tuning methods. It starts with a review provided by A. O’Dwyer of the extensive literature of proposals for PI and PID controller tuning rules based on First-order plus Dead-time models. The next chapters follow by concentrating on specific topics related to PID tuning. A. Leva and M. Maggio discuss the availability of a process model and its use for assessing the behavior and characteristics of the control loop with respect to its robustness and performance, therefore addressing the problem of determining which tuning method is best suited to the particular problem at hand. An exposition of tuning rules for integral and unstable systems follows. In this chapter, A.S. Rao and M. Chidambaram introduce different design methods for PI/PID controllers for these systems. Different approaches are considered. In particular, analytical, IMC, pole placement and optimization methods. The advantage of using a two degree-of-freedom controller will