Preface

The main purpose of control engineering is to steer the regulated plant in such a way that it operates in a required manner. The desirable performance of the plant should be obtained despite the unpredictable influence of the environment on all parts of the control system, including the plant itself, and no matter if the system designer knows precisely all the parameters of the plant. Even though the parameters may change with time, load and external circumstances, still the system should preserve its nominal properties and ensure the required behavior of the plant. In other words, the principal objective of control engineering is to design and implement regulation systems which are robust with respect to external disturbances and modeling uncertainty. This objective may very well be obtained in a number of ways which are discussed and demonstrated in this book.

Book is divided into five sections. In section 1 selected aircraft, vehicle and automotive applications are presented. That section begins with a contribution on rotorcraft control. The first chapter presents input-output linearization based on sliding mode controller for a quadrotor. Chapter 2 gives a comparison of different advanced control architectures for transonic phase of space re-entry vehicle flight. Then chapter 3 discusses the problem of robust fault tolerant, vertical motion control of modular underwater autonomous robot for environment sampling. The last three chapters in section 1 present solutions of the most important control problems encountered in automotive industry. They describe the second order sliding mode control of spark ignition engine idle speed, new active suspension control method reducing the passenger's seat vibrations and advanced adaptive cruise control system design.

Section 2 begins with a chapter on H-infinity active controller design for minimizing mechanical vibration of structures. Then it focuses on robust control of mechanical systems, i.e. uncertain Lagrangian systems with partially unavailable state variables, and adaptive back-stepping control of electro-hydraulic actuators. The last chapter in that section is concerned with the control of active magnetic bearing suspension system for high-speed rotors.

Section 3 consists of three contributions on the control of distillation and multi-step evaporation processes. The first chapter, concerned with a generic double feed tworeactant two-product ideal reactive distillation and the methyl acetate reactive distillation systems, demonstrates the implications of the nonlinearity, and in particular input and output multiplicity, on the open and closed loop distillation system operation. The next chapter shows that the desirable closed-loop performance can be achieved for an ill-conditioned high-purity distillation column by the use of a decentralized PID controller and the structured uncertainty model describing the column dynamics within its entire operating range. Then the last chapter of section 3 analyses a complex multi-stage evaporation process and presents a new full order Kalman filter based scheme to obtain full loop transfer recovery for the process.

Section 4 comprises two chapters on the control of power plants and power systems. The first of the two chapters studies the problem of reducing environmental effects by operational control of nitrogen oxide and carbon monoxide emissions from thermal power plants. The second chapter is concerned with damping of inter-area oscillations in electric power systems. For that purpose a mixed H2/H-infinity output-feedback control with pole placement is applied.

Section 5 presents a number of other significant developments in applied robust control. It begins with a noteworthy contribution on networked control which demonstrates that robust control system design not only requires a proper selection and tuning of control algorithms, but also must involve careful analysis of the applied communication protocols and networks, to ensure that they are appropriate for realtime implementation in distributed environment. A similar issue – in the context of force bilateral tele-operation – is discussed in the next chapter of that section, where it is shown that H-infinity design offers good robustness with reference to network induced time delays. Then the section discusses selected problems in resource allocation and control. These include development of robust controllers for single unit resource allocation systems with unreliable resources and real world natural resource robust management with the special focus on fisheries. The monograph concludes with the presentation of H-infinity synchronizer design and its application to improve the robustness of chaotic communication systems with respect to delays in the transmission line.

In conclusion, the main objective of this book is to present a broad range of well worked out, recent engineering and non-engineering application studies in the field of robust control system design. We believe, that thanks to the authors, reviewers and the editorial staff of InTech Open Access Publisher this ambitious objective has been successfully accomplished. The editor and authors truly hope that the result of this joint effort will be of significant interest to the control community and that the contributions presented here will enrich the current state of the art, and encourage and stimulate new ideas and solutions in the robust control area.

> **Andrzej Bartoszewicz** Technical University of Łódź Poland
