抄録
This paper reports an active air linear guide that utilizes air films generated by ultrasonic oscillation. The films on eight bearing surfaces of a horn, which is a stator, lift and guide the carriage. Moreover, the oscillation that modulates the amplitude via the positioning signal varies the thickness of the air film. Thus, this bearing regulates the position of the carriage in z direction using a PI controller with a displacement sensor so that its motion error becomes zero. Furthermore, no pneumatic plant is needed in this bearing. The motion error were 1.28 μm p-p in z direction and 1.08 μm p-p in y direction without compensation. Nonrepetitive motion errors were 0.125 μm 2o in z direction and 0.048 μm 2σ in y direction. PI feedback control, in which a fiber optic displacement sensor measures the movement of a gauge block mounted on the carriage, was performed. The settling time for 0.2-μm step positioning was less than 0.1 seconds. The positioning resolution was less than 20 nm.
