圧力微分計を用いた空気ばね式除振台の外乱補償制御(機械力学,計測,自動制御)

概要

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The purpose of this research is to suppress the inclination of the pneumatic isolation table caused by the relatively quick movement of the servo stage set on the isolation table. Pneumatic isolation tables are widely used in ultra precision machineries, such as steppers and precision measurement apparatuses. This is because they can support a high payload with a relatively low energy. Recently, pneumatic isolation tables for the semiconductor manufacturing devices have required higher performance as the line widths of semiconductors become finer. Therefore, the size of isolation table including the counter-mass is becoming larger, and the characteristics of the air springs are becoming softer. When the servo stage on a soft isolation table quickly moves, the table inclines and the recovery takes some long time. In this paper, a new compensation method of the inclination of isolation table using pressure differentiators is proposed. The pressure change in the air spring is detected with the pressure differentiator and it is positively fed back to realize higher pressure response. The performance of the proposed method is evaluated using an isolation table having 4 air springs in vertical direction, and a pneumatic driven servo stage on it. The effectiveness of the proposed method is demonstrated experimentally.
2010-04-25