Adaptive Fuzzy Control For Non-strict Feedback Nonlinear Systems

More and more scholars begin to pay attention to the control design for fuzzy adaptive control of nonlinear systems,and have made some progress in recent years.The application of the theoretical knowledge and control methods in real life is the best way to cash in.Because the structure of non-strict feedback nonlinear system is different from strict feedback system,the research of nonlinear system with non-strict feedback structure has begun and gradually entered the field of vision of scholars.In this paper,the design of adaptive fuzzy controller and the stability of the closed loop system are analyzed by combining the adaptive backstepping technique and the Lyapunov stability theory.Main contents are as:(1)For a class of non-strict feedback nonlinear systems with single input and single output state,an adaptive fuzzy control design scheme is studied.The controlled system contains unknown nonlinear functions,partially measurable state and unknown input time delay.Based on fuzzy state observer design method and adaptive Backstepping design technology,the controller is designed.The Pade approximation principle is used to solve the input delay problem of the system and the Lyapunov function stability theory is used to prove the stability of the controlled system.The effectiveness of the proposed algorithm is verified by simulation of the motor system with input delay.(2)For a class of non-strict feedback nonlinear system with multi-inputs and multi-outputs states,an adaptive fuzzy control method is designed.For the unknown control direction in the controlled system,we use the Nussbaum gain function theory to solve it,and by constructing a dead zone compensator to solve the dead zone problem.Combined with adaptive Backstepping design technology,the controller is designed.Then we prove the stability of the controlled system.Finally,for the effectiveness of the proposed control scheme,a numerical simulation example is used to verify the effectiveness of the proposed control scheme.(3)For a class of interconnected with a non-strict feedback nonlinear interconnected systems,not all of the state can be measured under the condition of fuzzy state observer and were used to estimate the unknown nonlinear uncertain state identification system and function system of fuzzy logic system.By combining the adaptive Backstepping design technology and dynamic surface control technique,the problems of computational complexity control in the design process is solved and the controller design is completed.Then the stability of the controlled system is proved by the Lyapunov function stability theory.Finally,the feasibility of the design of the controller is verified by two simulation examples.