Research On Robust Control For Networked Control Systems With Actuator Faults

With the continuous development and cross penetration of computer technology,automatic control theory and network communication technology,the traditional control technology is gradually replaced by network control technology.Compared with traditional point-to-point control systems,network control systems（NCSs）have the advantages of simple installation,low cost,ruggedness,natural reliability and so on.However,in the actual industrial production process,due to the aging of the components of the control system or human error operation and other factors,the sensor,actuator and other components in the system will fail,which will affect the system and cannot achieve the expected goal.Therefore,when the actuator faults,ensuring the stability of the system and the corresponding performance indicators becomes an important issue in the design of the control system.In this thesis,the robust control of NCSs in the case of actuator faults is studied.Meanwhile,considering that NCSs work under the condition of short time-varying delay,the nominal point method is used to model NCSs,and the continuous time system model is transformed into a time-varying discrete time model.Using Lyapunov’s stability criteria for discrete systems and linear matrix inequality（LMI）method.Firstly,the stability of NCSs with actuator faults is discussed.Secondly,the non-fragile guaranteed cost controller is designed for NCSs with actuator faults,and it is proved that the system is exponentially stable.Finally,the problem of NCSs optimal robust non-fragile H_∞control with actuator faults is discussed.The main contents of this thesis are as follows:（1）The stability of NCSs with actuator faults is analyzed,and the time-varying fault matrix that is more suitable for the actual environment is considered.The nominal point technique is used to decompose the exponential uncertainties with short time delay generated during modeling,and two methods are given to solve the supremum of the ₂L norm of the exponential uncertainties and the corresponding nominal point.It solves the problem of small application scope of general modeling methods.（2）The non-fragile guaranteed cost control problem of NCSs with actuator faults is studied.By using the nominal point method,combined with the time-varying fault matrix and the non-fragile controller to establish the system model.The Lyapunov function is constructed to prove the exponential stability of the system,and the upper bound of the guaranteed cost index is obtained.Under the LMI method,the solution method of the non-fragile guaranteed cost controller is given.（3）The optimal exponential H_∞control problem of NCSs with actuator faults is studied.Considering that the gain fluctuation of non-fragile controller is occur randomly,the state feedback controller is extended by the concept of fault matrix.The design method of exponential H_∞state feedback controller is proposed and the norm boundγ_min of the optimal H_∞ control is solved.