An important consideration in control issues is control of nonlinear systems. Sliding control is among those nonlinear controllers that can control the system desirably in the presence of unstructured uncertainties of carelessness in specifying parameters of the system. In sliding control, also called Variable Structure Control, the main objectives of the controller are achieved by introducing a sliding surface. One of the fundamental problems which may occur in sliding control is the chattering phenomenon on unwanted oscillation around the sliding surface. Different solutions are introduced to eliminate chattering. One of the commonest solutions is using a constant boundary layer round the sliding surface. In this paper, efforts are made to reduce chattering and to increase stability of the system by varying the sliding controller with a constant boundary layer. Finally, the mathematical model of a pendulum/cart in the presence of uncertainty is developed and the result of the simulation of the introduced controllers are compared.

Keywords: Nonlinear Systems, Sliding Control, Lyapunov Theorem, Chattering, Pendulum/Cart.

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