Auto Focus and Leveling Control of Large-Scale High-Precision Scan-Stage Using Driving Force and Surface Shape of the Stage

Abstract

The large-scale high-precision scan-stage is industrial equipment for microfabrications. The scan-stage needs not only fast and precise positioning but also the attitude control of the stage. The attitude of the stage is disturbed by the stage thrust in scanning. However, the sampling time of output is much longer than the sampling time of control input by DSP because image sensors are employed in the output encoder. It is difficult to reject the disturbances by single-rate feedback system. In this paper, we proposed the attitude control based on PTC (perfect tracking control) using driving force and surface shape of the stage. Finally, simulations and experiments are performed to show the advantages of the proposed control system.