Research On Pre-allocated Finite Time Tracking Of Two Types Of State-constrained Nonlinear Systems

Due to physical limitations,performance and safety requirements,the states of nonlinear systems are often constrained.Hence,the research of state-constrained nonlinear systems has application values.This paper considers the preassigned finite-time tracking control problems for two classes of state-constrained nonlinear systems.Main contributions are:1.Practical preassigned finite-time tracking of full-state constrained highorder nonlinear systemsIn this part,for full-state constrained high-order nonlinear systems,a practical preassigned finite-time tracking controller is constructed via modified high-order barrier Lyapunov functions(BLFs).Fuzzy logic systems are employed to approximate unknown nonlinear functions.New feasibility conditions are proposed to prevent full-state constraints violation.It is rigorously proved that the states of fuzzy systems remain within a specific compact set,on which fuzzy approximation is valid.Besides,all the signals in the closed-loop system are semi-globally bounded,and the tracking error converges to the prescribed small region around zero in a preassigned finite-time.2.Practical preassigned finite-time tracking of full-state constrained strictfeedback nonlinear systems without feasibility conditionsFeasibility conditions are sufficient conditions for the existence of BLF-based stateconstrained control.In this part,the practical preassigned finite-time tracking control problem of full-state constrained strict-feedback nonlinear systems is studied without involving feasibility conditions.Nonlinear transformed functions and error transformations are introduced to reconstruct the original system,and fuzzy logic systems are employed to approximate unknown nonlinear functions.It is shown that full-state constraints aren't violated,the tracking error converges to the prescribed small region around zero in a preassigned finite-time,all the signals in the closed-loop system are semi-globally bounded,and the states of fuzzy systems remain within a specific compact set,on which fuzzy approximation is valid.