Unknown Disturbance Estimation and Compensation by a Discrete-Time Nonlinear Observer and Its Application to a Dual-Stage Actuator System

Abstract

AbstractIn the present paper, we propose a discrete-time nonlinear observer (DNO) design method and an unknown disturbance estimation and compensation procedure based on DNO. The proof of the boundedness of the estimated error is derived based on the Lyapunov stability theorem. The proposed unknown disturbance estimation method is applied to a dual-stage actuator system of a hard drive (HDD) system. The effectiveness of the proposed method is verified through numerical simulations. The obtained results indicate that the proposed discrete-time unknown disturbance observer provides sufficient estimation performance even for relatively low sampling frequencies. In addition, control input compensation using the estimated disturbance signal provides effective performance.