| 摘要 |
PROBLEM TO BE SOLVED: To suppress the saturation of an air spring actuator by providing a plurality or air spring type support legs supporting a vibration base and a feedback device having nonlinear gain elements to control them. SOLUTION: An XY stage 12 repeats the inversion of direction to generate its rotation in the direction of x-axis and around y-axis. At this time, air spring actuators 2a to 2d which suppress the swing of a vibrationproof base 1 and are supported in x direction tend to be saturated. Accordingly, nonlinear gain elements 30a to 30d are inserted in front steps of voltage current converters 7a to 7d which drive the air spring actuators 2a to 2d to eliminate the saturation. Consequently, it is possible to eliminate the saturation of the air spring actuators due to step and repeat operation of the XY stage mounted on the vibrationproof base. By eliminating the saturation, the suppression of the swing of the vibrationproof base due to the drive of the XY stage is immediately led to the shortening of positioning time of the XY stage so as to improve the productivity. |
