The Passive Fault-tolerant Control For Networked Control Systems

With the arrival of the information age, every area developed very rapidly. And they connect with each other by the advantages of themselves. Network control systems have been applied to various fields with the continued integration between control technology, computer technology, network communication technology and other academic field over the last decade. Compared with the tradition control systems, NCSs have man advantages, such as, flexible architectures, high efficiency, low installation and maintenance cost, convenient maintenance, well maneuverability. However, it will inevitably have problems, since the data transmits in the network, such as network delay, data loss and so on. Because of widely using of networked control systems, once faults happen, the consequence could bring enormous harm. Therefore, in order to improve the reliability and security of NCSs, this paper focuses on fault tolerant control for researching under the presence of time delay and measuring data lose. The main research works are shown as follow:(1) For a class of uncertain NCS with time delays, when actuator faults happen, a state feedback fault-tolerant controller is designed. The possible failure of each actuator is described by a variable varying within a given interval to establish the closed-loop networked control system with actuator faults. In terms Lyapunov stability theory and linear matrix inequality approach, the sufficient conditions are presented for the existence of the designed controller so that the closed-loop system meets with the exponentially mean square stability and passivity performance level. Finally, a numerical example is provided to demonstrate the validity of the method.(2) For a class of uncertain NCS with time delay, when actuator faults happen, a sliding surface is chosen such that the trajectories of states will lie in the sliding surface from the initial time. By means of Lyapunov stability theory and linear matrix inequality technique, a sufficient condition is derived to ensure the robust stability and strictly passive of the siding mode dynamics. A new robust passive sliding mode controller is designed to ensure the reachability of the sliding mode dynamics despite the effects of actuator faults. Finally, the numerical simulation results further show the effectiveness of the proposed method.(3) For a class of uncertain NCS with step delay, when actuator faults happen with a complete failure or a partial failure or a positive drifting gain, considering that the measurement data loss meets with the known probability Bernoulli distribution. Design the state feedback fault-tolerant controller so that the closed-loop system meets with the exponentially mean square stability with guaranteed mix H_∞ and passivity performance level. Through the application of Lyapunov stability theory and linear matrix inequality technique, a sufficient condition of existence of the controller is given. Finally, the numerical simulation results further show the effectiveness of the proposed method.