Adaptive Fuzzy Control For A Class Of Nonlinear Strict Feedback Systems With Time-delay

The nonlinear phenomenons and time delays exist widely in actual control systems. They not only deteriorate the stability and performance of systems, but also make the analysis and control of the system becomes more and more difficult. With the development of modern science and technology, the control systems become more and more complex. It is difficult for us to set up a mathematical model which can describe the system accurately. Based on the above observations, this thesis studies the problem of adaptive fuzzy control for a class of nonlinear strict feedback systems with time delay. The content of this thesis mainly include the following aspects:First, the problem of adaptive fuzzy control for a class of nonlinear strict feedback time delay systems is studied. The monotonicity of the bounding functions is used to develop the variable separation method to deal with the unknown system functions. Fuzzy logic system is used to estimate the unknown parts of the system, and Backstepping technology is combined with the adaptive fuzzy control to design the adaptive fuzzy controller.Second, the problem of observer-based adaptive fuzzy control for a class of nonlinear time-delay systems is studied. The monotonicity of system bounding functions is used to overcome the problems which are arising from the nonlinear term and time delay in the Backstepping control design process. State observer is constructed to estimate the immeasurable state variables. Fuzzy logic systems are used to approximate the unknown nonlinear functions, and adaptive technique and backstepping are utilized to construct the output feedback controller.Thirdly, a simulation example is used to verify the effectiveness of the designed controller.