Research On Fault-tolerant Control For Networked Control Systems

Networked control system (NCS) is a kind of feedback control systems where the control loops are closed through real-time control network. As multi-discipline research fields, not only control process should be considered alone, but also the stability, scheduling mangagement and robustness of the whole networked control system should be considered too. Because of the complexity induced by network, this kind of automated control system is more vulnerable to faults. The consequence could be damage to technical parts of the plant, to personnel or the environment. A cost effective way to obtain increased availability and reliability in networked control system is to introduce fault detection and fault-tolerant control. Therefore, the research on fault detection and fault-tolerant control of networked control system has theoretical and applied significance, and it is a new research field at present.In this paper, we focus on the fault detection and fault-tolerant control, the following is the main work.The observer-based robust fault detection is studied for a kind of networked control systems with long random time-delays based on H∞robust control theory and LMI approach. The robustness of residual to unknown input and the sensitivity of residual to fault signal are reflected by l 2-gain. By augmented state approach, the observer-based robust fault detection is designed.The existence of real-time network in the feedback control loop makes analysis and design of an NCS complex. One of the most effective ways to reduce the negative effect of delays on the performance of networked control system (NCS) is to reduce network traffic. In this paper, adjustable deadbands are explored as a solution to reduce network traffic in NCS. A method to study the fault-tolerant control of networked control system is presented, which takes into account system response as well as network traffic. The integrity design for a kind of NCS with sensors failures and actuators failures is analyzed based on robust fault-tolerant control theory and communication constraints.Implementing a control system over a communication network induces inevitable time delays and data packet dropout. In this paper the networked control system with network-induced delay and packet dropout is modeled as asynchronous dynamical systems. The integrity design of an NCS is analyzed using hybrid systems technique based on robust fault-tolerant control theory. And the dropout probability is taken as a measure of the network quality of service (QoS). So a direct way of linking control system performance to the network's QoS is provided.Because the couple of the control and communication in the networked control system, the system performance of the closed loop system are not only depend on the characteristics of the control system, but also determined by the information scheduling approach imposed by network. In this paper, a kind of networked control system based on information scheduling is analysis. The fault-tolerant control design for a kind of NCS with actuators failures is analyzed based on robust fault-tolerant control theory and information scheduling. Parametric expression of controller is given based on feasible solution of linear matrix inequality (LMI). Asymptotical stabilization problem of networked control systems with time-varying delays under system information loss and noise disturbance is studied in this paper. A scheduling approach is also studied through the stability justification of the closed loop system for given sampling manner.Scheduling and control co-design for the robust fault-tolerant control of a typical networked control system is studied based on H∞control theory and real-time scheduling. Part of the information that calculated by controller may be discarded for heavy competition of network information transmission in a sampling period. Therefore, not all the information sent by the controller is received by the actuator, which will make system performance go worse or even destroy the stability of system. Considering the above factors, this paper give the parametric expression of controller based on feasible solution of linear matrix inequality (LMI) taking advantage of robust fault-tolerant control theory. The plant IAE (Integral-Absolute-Error) index is adopted to assign priority, therefore more control performance is considered while scheduling.