Adaptive Fuzzy Fault-tolerant Control For Nonlinear Faulty Systems

With the advancement of modernization,the actual industrial production market is gradually occupied by many large-scale engineering systems,and the reliability and security of operation need to be maintained.Fault-tolerant control is a control technology,which can guarantee the stability of the controlled system by using the relevant fault compensation method in the presence of the components failures.Therefore,the study on the fault-tolerant control problem of nonlinear fault system is of great significance.In the theoretical framework of fuzzy control,adaptive control,robust control and fault-tolerant control,and by combining with adaptive Backstepping design technique,the universal approximation property of fuzzy logic system and Lyapunov stability theory,several adaptive fuzzy fault-tolerant control strategies are proposed for several classes of uncertain nonlinear faulty systems,and the stabilities of the corresponding controlled systems are proved.The main content of this thesis is summarized as following:(1)A robust adaptive fuzzy state-feedback fault-tolerant control design method is proposed for a class of single-input-single-output nonlinear faulty systems with measurable states.The controlled systems contain the unknown nonlinear functions,actuator faults(lock-in-place and loss of effectiveness faults),switching signals and stochastic disturbances.Under the arbitrary switching rules,the universal approximation property of fuzzy logic system is utilized to model the controlled system,and by combining with adaptive Backstepping design technique,common Lyapunov function stability theory and stochastic stability theory,a stable adaptive fuzzy fault-tolerant control design strategy is designed.Simulation results are given to further validate the effectiveness of the control strategy.(2)An active adaptive fuzzy output-feedback fault-tolerant control design method is proposed for a class of multiple-input-multiple-output nonlinear faulty systems with partially measurable states.The controlled systems contain the unknown nonlinear functions,completely unknown control gain functions,unknown time-varying delay terms and actuator faults(bias and gain faults).First,based on the universal approximation property of fuzzy logic system,Nussbaum gain function theory,adaptive Backstepping design technique and fuzzy state observer design method,a fault detecton,fault isolation and fault accommodation algorithm-based fault-tolerant controller design strategy is given.Second,the stability of the controlled system is proved by using Lyapunov function stability theory and Lyapunov-Krasovskii functional property.Final,the comparative simulation results are provided to further validate the effectiveness of the proposed control strategy.(3)An adaptive fuzzy output constraint fault-tolerant control design method is proposed for a class of multiple-input-multiple-output nonlinear faulty(abrupt fault)systems with unknown compounded disturbances and partially measurable states.Based on the universal approximation property of fuzzy logic system,fuzzy state observer design method,nonlinear disturbance observer design method,Backstepping design technique and barrier Lyapunovfunction stability theory,a stable fault-tolerant control design strategy is developed.Numerical and applied simulation study and the comparative simulation results are given to further validate the applicability and effectiveness of the proposed control strategy.(4)A decentralized adaptive fuzzy output constraint fault-tolerant control design method is proposed for a class of interconnected nonlinear faulty(incipient fault and abrupt fault)systems with partially measurable states.Based on the fuzzy logic system universal approximation property,fuzzy state observer design method,robust fault compensation methodic,command filter technique and barrier Lyapunov function stability theory,a stable decentralized fault-tolerant control design strategy is developed.The comparative simulation study and results are provided to further validate the applicability and effectiveness of the proposed method.