An Accelerated Iterative Learning Control Approach for X-Y precision plane motion stage

Abstract

X-Y precision plane motion stage is widely used in precision motion control fields such as lithography machine workpiece stage, CNC machine tool, Laser measuring system, etc., which requires high accuracy of the position control. The X-Y precision plane motion stage uses two permanent magnet linear synchronous motors (PMLSM) as drivers to drive the motion table to perform XY two-degree-of-freedom motion. An open-closed-loop PD-type iterative learning controller (ILC) approach based on accelerated convergence was proposed to improve trajectory tracking performance of PMLSM. The interval was changed by real-time correction of the exponential gain matrix in the interval to accelerate the convergence rate. According to the λ norm, the monotone convergence of the proportion differentiation(PD) was developed for the PMLSM. The controller consists of two terms: a PID controller which enhances robustness to disturbances and system parameter variability and an ILC which generally improves the performance in the repetitive tasks by using the information from previous iterations. The experimental results show that tracking precision and convergence speed of PMLSM can be effectively improved by the scheme.