Fault-Tolerant Control For A Class Of Networked Control Systems With Uncertain Time Delays

Networked Control System (NCS) is a feedback control system, wherein the sensors, actuators and controllers are connected as the network nodes through the computer network or field bus to accomplish the control tasks. Because NCS has many advantages such as reduced system wiring, lower cost, reduced weight and power, simple installation procedure and maintenance, etc., it is widely used in electronics, communications, transportation, aircraft, and automatic manufacturing. However, as the network bandwidth limits, it induced the following problems:network-induced time delays, data packet dropouts, multi-packet transmission, etc.. These problems affect the stability of networked control systems, and the network-induced delay is one of the most important problems, so network-induced delays cannot be ignored in the analysis and design of networked control systems. In the real engineering projects, the availability and reliability of networked control systems are strictly required, once the systems have faults, great damage can be caused, therefore, the fault-tolerant control research for networked control systems is of great theoretical and practical significance. Most fault-tolerant control research for networked control systems has only considered the uncertainty of system parameters and all ignored the perturbation of feedback gains, but this perturbation can affect the stability of the control system or even make the system unstable, at this point traditional robust fault-tolerant control showed high fragility. So the design of non-fragile controllers is given in this thesis. This thesis has systematically considered network-induced time delays, actuator or sensor failure, the uncertain perturbation of feedback gains, unknown disturbances etc., then propose the controller design of non-fragile state feedback and non-fragile static output feedback. The contents of this thesis are as follows:Firstly, networked control systems with uncertain time delays are discussed and the discrete models of networked fault-tolerant control systems are established against actuator or sensor failure. The design of the fault-tolerant controller, guaranteed cost fault-tolerant controller, H∞fault-tolerant controller is proposed adopting non-fragile state feedback control strategy. Finally, numerical examples are given to illustrate the validity of the results.Secondly, networked control systems with both uncertain time delays and uncertain parameters are discussed and the discrete models of networked fault-tolerant control systems are established against actuator or sensor failure. Because the state of the systems cannot be easily detected, the design of the robust fault-tolerant controller, robust guaranteed cost fault-tolerant controller, robust H∞fault-tolerant controller is proposed adopting non-fragile static output feedback control strategy. Eventually, numerical examples are given to demonstrate the effectiveness of the proposed methods.