Preface

Abstract

Networked control systems (NCSs) are control systems where the control loops are closed via communication channels. With the rapid development of networking communication technologies, NCSs have received increasing attention in the past decade. Compared with traditional point-to-point control systems, NCSs have a number of advantages, such as low cost, easy maintenance, and increased system flexibility. More recently, much attention has also been paid to design the suitable communication scheme to save the limited communication resource for NCSs. The study of NCSs can be twofold: designing controller over a preselected network and designing appropriate communication scheme for satisfying the requirement of control. In the first designing controller over a preselected network field, Internet Protocol (IP) networks are commonly preselected in NCSs due to their well-developed infrastructure, wide acceptance, simplicity, and affordability. The IP-based network delays display a nonuniform distribution character with small delays being dominant while large delays being exiguous, which implies that the probability of small delays is bigger than the one of large delays. However, this feature has not been well used in the analysis and synthesis of NCSs. Therefore, how to effectively use nonuniform delay distribution character in NCSs has stimulated the first research line of this monograph. In the second designing appropriate communication scheme field, communication bandwidth is a scarce resource in NCSs. If signal transmission only occurs when the relevant information from the sensor-to-controller needs to be transmitted, then not only all of the transmitted signals from the controller-to-actuator are helpful to ensure the desired performance, but also the redundant information is possibly avoided in the transmission. Therefore, more limited network resources can be released to other communication tasks in need. Notice that time-triggered communication schemes are a common assumption in some existing results, which leads to inefficient utilization of the limited network resources. Therefore, how to design efficient communication schemes to save the limited communication resource while ensuring the desired performance of NCSs has stimulated the second research line of this monograph.