Finite-time Stabilization For Several Classes Of Uncertain Nonlinear Systems

In the field of nonlinear control,finite-time stabilization is one of the most fundamental and challenging problems.The finite-time stabilization possess some appealing features such as faster convergence rates,high accuracies and good robustness against various uncertainties.And it can reflect the instantaneous performance of the systems.Therefore,it has strong applicability in practical engineering systems.In this paper,based on the theory of finite-time stabilization,the controllers are designed for several classes of uncertain nonlinear systems.The specific research contents are as follows:1.For a class of uncertain nonlinear systems,an adaptive event-triggered controller is designed to solve the problem of global finite-time stabilization.By using the symbol function technique,the event-triggered error is completely compensated,the adaptive technique and the back-stepping method are simultaneously applied to the controller design,and the new manner of designing controller is completed on the basis the theory of fast finite-time stabilization.Furthermore,taking Lyapunov stability theorem into account,the system stability is proved,and the system is demonstrated by contradiction to be non-Zeno.2.For a class of stochastic nonlinear systems with input saturation,an adaptive fuzzy tracking controller is designed to solve the problem of finite-time stabilization.By using fuzzy logic systems to approximate the uncertain nonlinearity of the system,the constraint on the linear growth condition of the nonlinear term is eliminated,and the scope of the stochastic systems for which this method is applicable is also extended.The influence of input saturation is offset by auxiliary system in the design process.A new stability criterion is used to draw the conclusion that the stochastic system is practical finite-time stable in mean square,and system output can be driven to track a given reference signal.3.For a class of uncertain stochastic nonlinear systems with unknown time-varying output functions and unknown nonlinearities,an output feedback controller is designed to solve the problem of global finite-time stabilization.By introducing the symbolic function technique,the power integrator method and the homogeneous dominant method in the construction of controller and observer,the direct use of unknown output functions and their derivatives are avoided,and the restrictions on nonlinear terms are relaxed.Thus,the designed finite-time convergent observer makes the closed-loop system states bounded and converges to zero in limited time.