Chattering elimination via fuzzy boundary layer tuning

Chattering in the control signal is one of the most important problems met in sliding mode control applications, especially in motion control. The boundary layer approach is one of the many modifications proposed in the literature to avoid the chattering. In this approach, instead of the discontinuous sliding mode control, a high gain feedback control law is employed. The thickness of the boundary layer is an important design parameter. This paper proposes a fuzzy on-line tuning method to adjust the boundary layer thickness for the best system performance without chattering. The method features the measurement of the chattering in the control signal. Simulation results with a model of a three DOF articulated robot arm are presented.