Preface

Abstract

Switched control systems have attracted much interest from the control community not only because of their inherent complexity, but also due to the practical importance with a wide range of their applications in nature, engineering, and social sciences. Switched systems are necessary because various natural, social, and engineering systems cannot be described simply by a single model, and many systems exhibit switching between several models depending on various environments. Natural biological systems switch strategies in accordance to environmental changes for survival. Switched behaviors have also been exhibited in a number of social systems. To achieve an improved performance, switching has been extensively utilized/exploited in many engineering systems such as electronics, power systems, and traffic control, among others. Theoretical investigation and examination of switched control systems are academically more challenging due to their rich, diverse, and complex dynamics. Switching makes those systems much more complicated than standard systems. Many more complicated behaviors/dynamics and fundamentally new properties, which standard systems do not have, have been demonstrated on switched systems. From the viewpoint of control system design, switching brings an additional degree of freedom in control system design. Switching laws, in addition to control laws, may be utilized to manipulate switched systems to achieve a better performance of a system. This can be seen as an added advantage for control design to attain certain control purposes. On the one hand, switching could be induced by any unpredictable sudden change in system dynamics/structures, such as a sudden change of a system structure due to the failure of a component/subsystems, or the accidental activation of any subsystems. On the other hand, the switching is introduced artificially to effectively control highly complex nonlinear systems under the umbrella of the so-called hybrid control. In both cases, an essential feature is the interaction between the continuous system dynamics and the discrete switching dynamics. Such switched dynamical systems typically consist of sets of subsystems and switching signals that coordinate the switching among the subsystems. In this book, we investigate the stability issues under various switching mechanisms. For a controlled switching, the switching signal is a design variable just as