Adaptive Tracking Control For A Class Of Uncertain Switched Nonlinear Systems

With the development of modern industry,ordinary linear system control methods and relevant theories cannot satisfy the demands of the control accuracy.In order to enhance the control accuracy,as a kind of hybrid systems,switched systems consisting of a family of linear time invariant subsystems and a switching law specifying the switching among them are introduced,which have many applications and are widely used in many fields.Switched systems not only provide modeling methods for systems with sudden environmental disturbances,component failures or repairs and abrupt variations of operating point in practice but also improve the control accuracy.The tracking control problem of two kinds of nonlinear switched systems is studied in this paper.We consider different situations.One of the problem is adaptive tracking control for switched nonlinear systems with time-delay and unknown functions under arbitrary switchings.Based on the adaptive backstepping technique and common Lyapunov function(CLF)approach a class of adaptive fuzzy controller is designed.The fuzzy logic system is used to approximate the unknown nonlinear functions.The proposed controller guarantees that the output can converge to a small neighborhood of the reference signal and ensure all the signals to be bounded.During the design procedure,the proposed method has less design parameters and adaptive laws.This makes it easier to implement.The other tracking control problem is investigated for a class of uncertain switched lower triangular systems with disturbances.A state-feedback controller is designed by using adaptive backstepping technique and the universal approximation ability of fuzzy logic systems.It is shown that the designed state-feedback controllers can ensure that all the signals remain bounded and the tracking error converges to a small neighborhood of the origin.Finally,a large number of simulation results demonstrate the effectiveness of the proposed method.