Study Of Networked Control Systems Based On Markov Jump Theory

With the development of the network technology, more and more control systems will run based on network. Then the concept of networked control systems (NCSs) is proposed. NCSs are a type of closed-loop systems, in which the communication networks are employed to transmit information and control signals (reference input, plant output, control input, etc.) among control system components (sensors, controllers, actuators, etc.). The use of the communication networks brings many advantages such as sharing resources, reduced weight, lower cost, greater agility in diagnosis and maintenance, simple installation and maintenance, as well as high efficiency, flexibility and reliability. However, the communication networks in control loops also have some constraints such as time delays, packet dropouts and limited bandwidth, which complicate the analysis and design of NCSs.In this dissertation, we address the modeling and unified model of NCSs with random time delays and packet dropouts under Markov jump theory and robust control theory. The stability and robust control problems are investigated by introducing kinds of performance indices. The networked quality and the inner relationship between performance indices are also established. In this paper, the modeling, stability and robust control problems of NCSs with random time delays and packet dropouts are investigated mainly by employing theoretical analysis and numerical simulation methods.This paper contains four parts.In the first part (Chapter 1), the research background and fundamental issues of networked control systems are firstly introduced briefly. Secondly, the research evolution of networked control systems are reviewed. Finally, the main work of this dissertation and the used notations are listed.In the second part (Chapter 2, 3) the random sensor-to-controller (S-C) and controller-to-actuator (C-A) data packet dropouts are modeled by two independent Markov chains. The modeling and stochastic stability of NCSs are studied based on the hidden Markov model (HMM). Then the design of the optimal controller is given. Considering the random data packet dropouts occurring in the S-C and C-A, the resulting closed-loop NCS based on the extended matrix method is modeled as a discrete-time Markov jump linear system with four modes. Sufficient conditions ensuring the stochastic stability for NCS are established based on stochastic Lyapunov functions and linear matrix inequality (LMI) approach. Finally, the simulation examples illustrate the validity and feasibility of the results. In the third part (Chapter 4), the robust control (guaranteed cost control?H?control?H 2 /H?control) for a class of discrete-time NCSs with Markov time delays is investigated. Networked control systems in the frame of Markov jump theory are modeled as multi-step Markovian jump linear systems. By introducing kinds of performance indices and co-considering the robustness and stability, the focus is on the design of the robust stabilization controller (guaranteed cost controller?H?controller?H 2 /H?controller) based on stochastic Lyapunov functional and LMI approach. Finally, the simulation examples illustrate the effectiveness of the results.In the last part (Chapter 5), the stability and stabilization problems for discrete-time NCSs with random S-C and C-A time delays and packet dropouts are investigated. Networked control system with S-C and C-A time delays and packet dropouts is modeled as Markovian jump linear system with Markov delays. Based on Lyapunov stability theory and LMI method, sufficient conditions of the stochastic stability and stabilization controller design method for NCSs with random time delays and packet dropouts are presented. Finally, the numerical examples are given to illustrate the effectiveness of the results.