Chattering Elimination And Terminal Sliding Mode Surface Design For Sliding Mode Control

Sliding mode control is a particular type of variable structure control. Because of its predominant robustness, many scholars pay more attentions to it. After decades' development, it has possessed academic foundation and been widely applied in many kinds of projects. The sliding mode design approach consists of two components. The first involves the design of a switching function so that the sliding motion satisfies design specifications. The second is concerned with the selection of a control law which will make the switching function attractive to the system state. Although the theory of sliding mode shows exuberant vitality in decades'development, it still exists some drawbacks such as chattering, convergence time of sliding mode surface and so on. Some solutions have been proposed by some scholars, but the problems have not been resolved perfectly. For instance, some solutions only eliminate the chattering but loose the robustness of systems; the terminal sliding mode surface can convergence in finite time, but it has singularity problem. In this paper, the two components are discussed.To begin with, in chapter two, this thesis pays attention to frequent chattering, studies the causes of chattering and propose a solution to reduce it. A time-variable boundary layer reaching law is proposed to eliminate the chattering and the robustness is much stronger than other approaches.Then, in chapter three, two types of terminal sliding mode surfaces are proposed. The one named fast terminal sliding mode surface could save convergence time than the traditional terminal sliding mode surface. But neither the fast terminal sliding mode surface nor the traditional one could solve the singularity problem. Based on above reasons, another surface proposed in chapter three is a nonsingular terminal sliding mode surface.In chapter four, high-order terminal sliding mode control, which combine high-order sliding mode control law with terminal sliding mode surface, is introduced to variable structure control to eliminate the chattering and reduce the convergence time.The simulations approve the approaches above are feasible and available.