Robust fuzzy logic control of mechanical systems

An approach for the design of fuzzy control laws for tracking control of a large class of mechanical systems is proposed. The approach employs the framework of Lyapunov’s stability theory to formulate a class of control laws that guarantee convergence of the tracking errors to within speci3cation limits in presence of bounded parameter uncertainties and input disturbances. The proposed control laws possess a large number of parameters and functional relationships to be chosen by the designer according to a methodology developed in the paper. The large number of design degrees of freedom makes the approach suitable for fuzzy logic implementation. A number of fuzzy implementations of the proposed control methodology are provided. All implementations guarantee tracking error convergence to within prespeci3ed performance limits. An extensive simulation study using a model of a two-degree-of-freedom robot manipulator was conducted. Fuzzy and non-fuzzy implementations of the proposed methodology were compared to control laws designed using other design methods. Simulation study results indicate a superiority of the proposed control methodology compared to other approaches. The study also demonstrates better performance of the fuzzy control implementation compared to its non-fuzzy counterpart. c © 2002 Elsevier Science B.V. All rights reserved.