High-Performance Position Control for Repetitive Tasks of Motor-Driven Servo Systems Based on Periodic Disturbance Observer

Abstract

Repetitive position control of the motor-driven servo system (MDSS) plays an important role in numerous industrial processing and production. In this article, based on the Euler–Lagrange equation, a dynamics model was established by analyzing the relationship of the energy conversion to describe the motion of an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> -degree-of-freedom MDSS. For repetitive position control tasks of the considered system, a robust controller was designed to improve the performance of the closed-loop system, where the disturbance observer was employed to approximate the periodic dynamics of the system to improve both the transient and steady-state performances. The stability of the closed-loop system was analyzed based on the Lyapunov method. Moreover, to validate the control effect of the proposed method, the coordinated contouring task was considered for a dual-linear-motor-driven gantry system, where a B-spline wavelet series was employed as the periodic disturbance observer. The results of the comparative experiment show not only the effectiveness of the designed control scheme but also the superiority of the B-spline wavelet series on the approximation of periodic functions.