A NEW EFFICIENT SELF-ORGANISING FUZZY LOGIC CONTROL (SOFLC) ALGORITHM USING A DYNAMIC PERFORMANCE INDEX TABLE

Abstract

The “raison d'etre” of Self-Organising Fuzzy Logic Control (SOFLC) algorithms is the Performance Index table which normally issues the adequate corrections to the low-level control given certain performance criteria. In the standard SOFLC architecture, the Performance Index table is generic, fixed a priori, and is of a ‘grid-partition’ structure making the whole scheme inefficient in terms of computational complexity and performance. In this paper we propose a new SOFLC architecture whereby the Performance Index table is ‘dynamic', of a free structure, and starting from an empty table. The architecture includes 3 mechanisms for optimising the rules of the Performance Index table and enhancing the performance as well as the robustness of the algorithm in terms of disturbance rejection and noise. Results of experiments on a nonlinear muscle relaxation process showed that the proposed control scheme was superior to the standard SOFLC algorithm in terms of performance and robustness against parameter variations, stochastic activity, and sensitivity to the selection of scaling factors.