Fuzzy Sliding Mode Control with Piecewise Linear Switching Manifold

Variable Structure Control (VSC) has been successfully established in control systems engineering in the past two decades. Recently, Fuzzy Sliding Mode Control (FSMC) techniques have drawn the attention of the scientific community, due to their effectiveness in reducing the typical chattering phenomenon arising in VSC. In this paper we present a novel FSMC technique for a class of second order dynamical systems based on a piecewise linear sliding manifold. The proposed approach enhances the effectiveness of VSC in the presence of a saturated control input. In addition, employing the proposed VSC with fuzzy rule based algorithms results in smooth dynamics when the trajectory is in the vicinity of the switching manifold, as opposed to the typical chattering arising under classical VSC. After illustrating the proposed strategy on a simple design example, the approach is applied to an inverted pendulum, a well-known benchmark for automatic control techniques. The effectiveness of the technique is shown both by means of simulation tests and experiments on a lab equipment. Future research directions include the extension of the technique in the presence of uncertainties in the plant model.