Design Of Fuzzy Adaptive Control Based On Event Trigger Mechanism

With the rapid development of network communication technology,the amount of data transmitted on the network is getting larger and larger.The traditional time-triggered control method periodically transmits and updates the control signals at discrete time points within equal intervals,which will cause a large amount of unnecessary redundant information to be transmitted,thereby causing waste of limited network resources.How to effectively reduce the amount of data transmission and save the communication resources has become an important research topic.In this thesis,for a class of uncertain nonlinear systems,some adaptive control schemes are designed based on backstepping recursive technology,adaptive technology,and event triggering technology.The stability and convergence of the closed-loop systems are proved by using Lyapunov stability theory.The main contents of this article are as follows:(1)For a class of strict feedback nonlinear systems with uncertain parameters and actuator faults,a direct and simple event-triggered co-design method is proposed.By introducing a compensating term in a smooth function form of a conventional control law and certain positive integrable functions,the effects of actuator faults and event-triggered error can be compensated completely.Such a direct design method has the following features:(i)a direct compensation of the event-triggered error is achieved without introducing any extra design parameters;(ii)it is not necessary to know any bound information on the parameters of event-triggered threshold,and global asymptotic tracking control of the overall closed-loop system is achieved;and(iii)the resulting stability criteria of the proposed event-triggered control design are much simpler and easier to fulfill by virtue of the introduced co-design method.Simulations are then carried out to validate the proposed schemes.(2)For a class of non-strict feedback nonlinear systems,neural networks are used to approximate the unknown uncertain dynamics.By combining fuzzy adaptive control and adaptive backstepping recursive technology,a design method of fuzzy adaptive fixed-time controller is proposed.To guarantee closed-loop stability,a new semi-global practical fixed time stability(SPFTS)criterion is established.Based on the established SPFTS,it is proved that the proposed control method can maintain the tracking performance and closed-loop stability in a fixed time.The validity of the theoretical results is further verified by numerical simulation.(3)For the problem of finite-time control of a class of uncertain nonlinear systems with event-triggered communication,an adaptive event-triggered design method is proposed to construct the controller by combining command filter and backstepping technology,under which the effect of event-triggered error can be compensated completely.In addition,the proposed controller can avoid the “complex explosion” and “singularity” problems in the backstepping recursive design framework.Based on the finite-time stability criterion,it is proved that tracking performance and closed-loop stability can be guaranteed at the same time in a finite time.Finally,a simulation example of one-link manipulator is given to verify the effectiveness the proposed finite fault tolerant control scheme.