Research On Communication Sequences And Controller Design For Networked Control Systems

A Networked control system (NCS) is a distributed control system in which a large number of sensors and actuators are connected to and exchange information with a controller or a number of controllers via a shared communication medium. In an NCS, the communication network usually has finite bandwidth constraints so that only a limited number of sensors and actuators can be accommodated at any one time. One of the critical issues that have received significant attention in the community of an NCS is the joint selection of a policy for managing sensor-controller and controller-actuator communication, and a feedback controller that enforces performance or stability requirements for the closed-loop system. Up to now, this task has posed a significant challenge.This dissertation proposes new design method for dynamic communication sequences and feedback control strategies based on switching systems theory and noval techniques of time-delay systems considering the combined effects of network-induced constraints such as time-varying delays and packet dropouts. The main parts are concluded as follow:As the theoretical analysis foundation of this paper, the problem of delay-dependent stability and control for general linear systems with multiple successive delay components in the state is provided. General results on the asymptotic stability and robust H∞performance of such systems are obtained by exploiting a Lyapunov-Krasvoskii functional and by making use of novel techniques for time-delay system, robust H∞performance conditions are utilized to investigate the problem of robust H∞control for networked control systems.Basing on the delay-dependent stability method and switching system theory, the problem of integrated design of controller and input communication sequences is addressed for networked control systems (NCSs) with simultaneous consideration of medium access limitations and successive time-varying delays, packet dropouts and measurement quantization. As a continuation, the issue of joint design of dynamic output feedback controller and network access assignment sequences of both input and output channels is investigated for networked control systems (NCSs) which has insufficient communication channels to simultaneously accommodate all the sensors and actuators, which are all operating independently with individual communication packets and subject to successive time-varying delays and packet dropouts.The integrated design of output feedback controller and medium access scheduling policy under which controllability and observability of a linear plant can be preserved is also addressed for networked control systems (NCSs). Specially, three types of network-induced time delays are investigated, namely, time varying delay, identically and independently distributed (i.i.d.) delay and Markovian delay.Finally, the results of the dissertation are summarized, and beneficial suggestions, instructive directions for future research on the topic of control and communication co-design are provided.