Adaptive H∞ Observer-Based Sliding Mode Control for Uncertain Fractional-Order Nonlinear Systems

In this paper, the robust control problem is investigated for fractional-order nonlinear systems(FONS) with the unknown-butbounded parametric uncertainties and the external disturbances. First, an H-infinity adaptive observer is designed to estimate the system states and the unknown parameters. Then based on the observer, a fractional-order sliding mode controller is designed and the asymptotic stability sufficient condition is derived for the closed-loop system on the basis of Lyapunov stability criterion. The control strategy can not only realize the system stabilization, but also estimate the system unknown parameters and the system states. Moreover, a fractional-order power type continuous function is adopted to replace the traditional sign function in the switch control component, the proposed method can avoid the chattering phenomenon. Finally, the simulation results demonstrate the feasibility and effectiveness of the presented method. (c) 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.