Authors : Basil M. Al-Hadithi , Feranado Matia and Augstin Jimenez
Abstract: In this study, a fuzzy (FLC) based variable structure control (VSC) is presented. VSC is characterized by its ability to deal with non-linearities, uncertainties of control systems, invariance to parameters fluctuations and disturbances and its robustness. The main objective is to obtain an improved performance of highly non-linear unstable systems. Both the fuzzy controller and the controller system are represented by the Affine Takagi-Sugeno fuzzy model (T-S). The main aim of this research is to design a completely FLC-VSC, which means a one without an additional conventional VSC as usually done by several other researchers. This proposed, controller will also be able to solve the chattering problem which is considered the main drawback of the VSC control by introducing a boundary layer around the switching surface and applying the equivalent control method inside this layer. From implementation point of view, each fuzzy rule will have a unique fuzzy consequent part. The main feature of the proposed method is that the switching function s(x) is added as an additional fuzzy variable and will be introduced in the premise part of the fuzzy rules together with the state variables. The proposed method is explained by applying it on an inverted pendulum mounted on a cart. The results obtained show a robust and stable behavior without chattering.
Basil M. Al-Hadithi , Feranado Matia and Augstin Jimenez , 2008. Robustness of Fuzzy Variable Structure Controllers. International Journal of Signal System Control and Engineering Application, 1: 38-48.