With Network Latency And Packet Loss, Network Control System Stability Study

With the rapid developments of microelectronics, communication network and computer technology, the substance foundation of networked control systems (NCSs) supplied by the mergence of the diverse sensors, the intelligent actuators and the high-precision drive devices. The reliability and open issues of NCS have been solved by the sustained developments of high speed Ethernet and field-bus control technology which successful applications, and they also promote the extensive applications of NCS in the field of Aerospace, Equipment manufacturing, Telemedicine and so on. NCS can reflect resource sharing and the distribution of remote control, modular of system building, integrated, low cost, fault diagnosis and maintenance convenience, easy to expand, flexibility and other advantages. Due to the communication mechanism and the communication protocol, and the limited bandwidth of the network is shared by each node in the system, when each node's data transmitted over control network, NCS often meet data collision, network congestion and network connection interruption phenomenon. These make NCS produce data transmission delay and data packet dropout and other issues. These problems can reduce performance of control system, even lead the system to instability. Therefore, this paper studied the NCS that contain network-induced delay and packet loss and problems such as external disturbances. Based on service quality of control network, by using the performance index of NCS, this paper also studied the modeling of NCS, stability analysis and robust optimal control and design method of robust H_∞filter. The main results are as follows:Dynamic output feedback NCS with problem of the short network-induced delay and the disturbance of external limited energy is studied. Controller is a dynamic compensation function of dynamic output feedback control, so that it can improve performance of output feedback control system. By Lyapunov stability theory and linear matrix inequality processing method, this paper sought the existing conditions of NCS robust guaranteed cost control laws and summarized the design method of the robust guaranteed cost control laws.A class of state feedback NCS with problem of the long network-induced delay, packet dropout and the disturbance of external limited energy is studied. By the Lyapunov -Krasovskii theory and LMI approach, this paper began from the state feedback control problems, and proved robust controller design method and sufficient conditions of the stability system. In the stability conditions deduced process, this paper summarized the study of the more tight cross-term and got relevant state feedback controller design method. The simulation example calculated maximum of network induction time delay and data packet dropout.This paper dealt with the problem of robust H_∞filtering for a class of uncertain discrete systems, and the uncertainties that satisfied the so-called norm-bounded conditions exist in state matrices and output matrices. This paper design a linear filter with time-delay and packet dropout which can guarantee a prescribed H_∞performance level for the filtering error system and all admissible uncertainties. The sufficient conditions for feasible filter are derived. A LMI method for designing filters is given by matrix transformations. Finally, the simulation result shows that the method is very effective.