Fuzzy logic control and industrial applications

ABSTRACT FUZZY LOGIC CONTROL AND INDUSTRIAL APPLICATIONS TORUN, Yunis M. Sc. in Electrical and Electronics Eng. Supervisor: Assist. Prof. Dr. İlyas EKER July, 2004 Increasing demands for flexibility and fast reactions in modern process operation and production methods result in nonlinear system behaviour of partly unknown systems and this necessitates application of alternative control methods to meet the demands. Fuzzy logic (FL) control can play an important role, because knowledge-based design rules can easily be implemented in systems with unknown structure and it is going to be a conventional control method, since the control design strategy is simple and practical, and based on linguistic information. Computational complexity is not a limitation any more because computing power of computers has been significantly improved even for high-speed industrial applications. This makes FL control an important alternative method to conventional PED control method to use in nonlinear industrial systems. This thesis presents a practical implementation of the FL control to an electrical drive system. Such drive systems used in industry are composed of masses moving under the action of position and velocity dependent forces. These forces exhibit nonlinear behaviour. For a multi-mass drive system, the nonlinearities, like Coulomb friction and dead zone, significantly influence the operation of systems. The proposed FL control configuration is based on speed error and change of speed error. The feasibility and effectiveness of the control method are experimentally demonstrated and the results are compared with the traditional PJD control in dynamic responses of the closed-loop drive system. Keywords: fuzzy logic control, experimental application, electrical drive system, conventional control. iii