Robust disturbance rejection for a fractional-order system based on equivalent-input-disturbance approach

Abstract

This paper presents a disturbance rejection method that is based on the equivalent-input-disturbance approach for uncertain fractional-order (FO) systems. An FO observer is used to reconstruct the plant states and estimate the disturbances. A disturbance estimator is incorporated in the construction of the FO control system to actively compensate for the entire disturbance. A robust stability condition for the control system and the parameters of the controller are derived using an indirect Lyapunov method. The presented method effectively rejects disturbances and handles modeling uncertainties without requiring prior knowledge of the disturbance. Comparison simulations on both numerical and practical examples demonstrate the effectiveness of the proposed method.