Direct adaptive fuzzy control design achieving H∞ tracking for high performance servo drives

This paper proposes a direct adaptive fuzzy control technique to achieve H-infinity tracking for high performance servo drives with external disturbances. The proposed methodology combines the attenuation technique, fuzzy logic approximation method, and adaptive control algorithm for the robust tracking control design of the nonlinear servo drives with unknown parameter variations and structures. The adaptive fuzzy approximation technique is used as rough tuning and the H-infinity disturbance attenuation technique is considered as fine tuning. Selection of suitable performance weights is the main problem in design of a robust H-infinity controller In this paper, a systematic and automated approach based on adaptive fuzzy logic algorithm is proposed. It gives elevation to the selection of optimal performance weights without any trial and error effort. Computer simulations show the effect of both the fuzzy approximation error and the external disturbance on the tracking error can be attenuated efficiently by the proposed method. The results illustrate desired upgrade on both H-infinity and fuzzy control design. Thus, the proposed technique is suitable for the control of the uncertain nonlinear servo drive tracking applications. To the best knowledge of the author, however, the H-infinity optimal control design has not yet been used for adaptive control or fuzzy control of high performance servo drives.