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Observer-based Adaptive Fuzzy Control For Nonlinear State Constraint Systems

Posted on:2019-02-15Degree:MasterType:Thesis
Country:ChinaCandidate:M Z GongFull Text:PDF
GTID:2428330545458745Subject:Applied Mathematics
Abstract/Summary:PDF Full Text Request
State observer is used to estimate the states of the systems,since the state variables of many nonlinear systems in practical engineering are unmeasurable.In many practical engineering systems,the inevitable constraints are also the main factors that restrict the performance of the system and affect the output precision of the system.Constraint control has become one of the hot issues in the field of control theory.This paper presents a fuzzy adaptive Backstepping control method combined with observer design theory for a class of unmeasured states with unknown function states of nonlinear and time-varying state constraints system.The fuzzy logic system is used to approximate unknown functions,and an adaptive observer is designed to estimate the unmeasured states.A new design method of output feedback controller is presented to guarantee all signals of the closed-loop system are semi-global uniform ultimate bounded.The contents are as follows:(1)This chapter presents an adaptive output feedback approach of nonlinear single-inputsingle-output systems with full state constraints and unmeasured states.A fuzzy state observer is framed to estimate the unmeasured states.To ensure that all the states do not violate their constraint bounds,the Barrier type of functions will be employed in the controller and the adaptation laws.In the stability analysis,the effect caused by the constraints for all the states can be overcome by using the Barrier Lyapunov functions.The tracking problem of such systems is resolved,all the signals in the closed-loop system are guaranteed to be bounded,and all the states are not transgressed their constrained sets.The effectiveness of the proposed control approach can be verified by setting a simulation example.(2)This chapter presents an adaptive output feedback approach of nonlinear multi-inputmulti-output systems with time-varying state constraints and unmeasured states.An adaptive approximator is designed to approximate the unknown nonlinear functions existing in state constrained systems with immeasurable states.To deal with the tracking problem of such systems,a state observer with time-varying Barrier Lyapunov functions is introduced in the controller design procedure.The backstepping design with time-varying BLFs was utilized to guarantee all the system state remain within the time-varying constrained interval.The proposed control approach guarantees all the signals in the closed-loop systems are bounded and the tracking errors converge to a bounded compact set,and all the time-varying state constraints are never violated.A simulation example is given to confirm the feasibility of the presented control approach in this paper.
Keywords/Search Tags:fuzzy adaptive control, state observer, full state constrains, time-varying state constrains, output feedback control, barrier Lyapunov function
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