Research On Fuzzy Adaptive Fault-Tolerant Control Of Several Classes Of Nonlinear Systems With Unknown Faults

With the continuous development of modern industrial production,engineering system is becoming more and more complex.People pay more and more attention to the safety and reliability of the system operation.The fault tolerant control method is also developing.Faulttolerant control means that if the system fails,it can pass the related fault compensation algorithm,so that the fault system can still run steadily.Because many engineering systems are often nonlinear,it is of great significance to study the nonlinear fault system.In this paper,several kinds of unknown nonlinear fault systems are studied.Based on adaptive backstepping design technology and related control theory,several fuzzy fault-tolerant control schemes are proposed,and the stability of the proposed schemes are proved respectively.The main work of this article is as follows:(1)For the single input and single output nonlinear fault system,the system contains actuator error gain fault and measurable state in the system.By combining with the fuzzy logic system,the universal approximation property of the controlled system,the adaptive backstepping design technique and Lyapunov stability theory.A stable adaptive fuzzy fault tolerant control design scheme is proposed,and the stability of the control design is proved.The effectiveness of the proposed scheme is further verified by the numerical simulation example.(2)For a single input and single output nonlinear fault system,the system contains unknown control directions,unknown time delays,actuator bias gain faults and unmeasurable state.Due to the state of the controlled system is unpredictable,so it is necessary to construct the fuzzy state observer is applied to the unknown state,using the observed information,combining the Nussbaum gain function theory,backstepping design method,designing a kind of fuzzy adaptive fault-tolerant control scheme.The stability of the system is verified by the MATLAB simulation example.(3)For the multi input and multi output nonlinear fault system with random disturbance,the system contains the actuator fault.The controlled system is studied in the case of the state of system is not measurable.It makes use of Fuzzy state observer to observe the unmeasurable state.The Nussbaum gain function theory disposed of the problem of unknown control direction in the controlled system.Based on the theory of stochastic stability and Lyapunov function stability theory,a fuzzy fault-tolerant control scheme is proposed in the framework of backstepping,and the stability of the scheme is proved by combining with the Lyapunov stability theory.The effectiveness of the proposed scheme is further verified by the numerical simulation example.(4)For a large scale nonlinear interconnected fault system with error constraints,the controlled system contains failure and deviation.In the system state can not be measured under the condition of fuzzy logic system,the approximation property of the fuzzy state observer design method,backstepping design technique and obstacle Lyapunov function based on the theory,design a control scheme for stable fault tolerance,and prove the stability of the scheme is proved.The effectiveness of the proposed control scheme is further validated by numerical simulation.