Nonsingular Integral Terminal Sliding Mode Control Design For Nonlinear Uncertain Systems

Sliding mode variable structure control theory is widely used in nonlinear system control.It has become the focus of research in the control community due to its strong robustness to uncertainties such as internal parameter perturbations and external disturbances of the system.The principle of variable structure control is to make the state trajectory of the system reach the phase plane by designing the switching function.The dynamic characteristics and stability of the system are determined by the switching function and the control law.Therefore,a well-designed switching function is the fundamental of control.Terminal sliding mode control is a classical control method in variable structure control,which can make any initial state of the system reach the sliding surface in a limited time,and gradually converge to the equilibrium point.However,due to the influence of uncertain parameters,the switching function is also prone to generate singularity problems and strong buffeting.Therefore,this paper mainly studies the above two aspects.The content is arranged as follows:In chapter one,referring to the related papers either in China or abroad,this paper first introduces the origin and development of sliding mode variable structure control.Among them,the main research directions of Terminal sliding mode variable structure,integral sliding mode variable structure and sliding mode variable structure control based on approaching law are summarized.In chapter two,the basic theoretical knowledge of sliding mode variable structure control is mainly introduced.First,it elaborates the definition of sliding mode variable structure and describes it in details.Even,Lyapunov stability theory are introduced.This chapter introduces how the equivalent control method of the sliding mode is produced,the existence condition and arrival condition of the sliding mode surface in the sliding mode variable structure,the common methods for designing the sliding mode surface of the sliding mode variable structure control,and the system control law for better control performance.In chapter three,the design of sliding mode surface and control law of traditional Terminal sliding mode control is described.It has limited time arrival and system stability.Next,the singular Terminal sliding mode controller can avoid singular problems in traditional Terminal sliding mode control.In this chapter,a new nonsingular integral Terminal sliding mode control is designed by improving the nonsingular Terminal slidingsurface function,which has a faster convergence to the equilibrium point than the nonsingular Terminal sliding mode control.In chapter four,compared with the Terminal sliding mode control,the global fast Terminal sliding mode control has a linear part,so it has faster convergence speed,but there is a singular problem.Therefor,a new global fast Terminal sliding mode control is proposed.Compared with the global fast Terminal sliding mode,the Simulink simulation of Matlab proves that it has faster convergence rate and a certain extent of weakening chattering.Finally,the content of this paper is summarized,and some issues to be noticed in the future research and the direction to be improved are proposed.