Iterative learning control for the synchronization control system of the scanner

This paper presents an engineering design method of iterative learning control and its application to synchronization control system of the scanner. Firstly, the synchronization control scheme in the scanner is analyzed, and iterative learning control is introduced to reduce the synchronization errors based on the feedback control system. The method employs the time lead factor to compensate phase lag of the closed loop control system of the reticle stage around bandwidth in order to improve convergent domain of the system. Furthermore, a non-causal filter is introduced to enhance robustness of the system and improve convergent performance of the system. In addition, the convergent condition of the synchronization control system is given. Finally, simulated results are illustrated for validating the effectiveness of the proposed method.