Research On The Packets Dropouts And Quantization Robust Issues For Uncertain Discrete-Time Systems

With the rapid development of the computer, internet and communication technology in the past ten years, networked control systems(NCSs) have gradually evolved into a mainstream control systems in place of traditional point-to-point control systems for their great advantages, such as ease of maintenance and installation, flexibility, and low cost. Moreover, NCSs have attracted much attention because of their successful applications in modern complicated industry processes, e.g., industrial automation, intelligent home appliance, pilotless automobile, etc. NCSs have brought unprecedented opportunity and challenge for the development of control theory. Due to inherent network-limited bandwidth, the problem of analysis and synthesis for NCSs is quite different from the traditional control systems, several practical factors, such as quantization, packets dropouts and communication delays, which constitute crucial issues in NCSs, would degrade the system performance or even cause instability and make the problem of analysis and synthesis for NCSs become complicated. The traditional control theory is no longer adapt to NCSs. Hence, how to design control systems with the effects of quantization, packets dropouts and communication delays has become one of the most significant research topic in the control area and received wide attention.Based on the previous work of other scholars, this dissertation futher studies the problem of network control for uncertain discrete-time systems. First, the problem of H_∞control for polytopic uncertain discrete-time systems with quantized state feedback has been investigated. Via giving a new control law and using parameter dependent Lyapunov function approach, new results on the quantized H_∞state feedback control are expressed in terms of linear matrix inequalities(LMIs). Second, the problem of output feedback control for discrete-time systems with norm-bounded uncertainties subject to quantization and packet dropouts has been studied. By using the decoupling method, new LMIs conditions for the existence of an observer-based H_∞controller and static output feedback H_∞controller are established. Third, the problem of H_∞filtering for polytopic uncertain discrete-time systems with quantized measurements and packet dropouts has been considered. Via introducing some slack variables and using parameter-dependent Lyapunov function approach, new conditions for the existence of an H_∞filter are expressed in terms of LMIs. At last, the work of the thesis is summarized and further research topics are pointed out.