Development of Pneumatic Servo Bearing Actuator for Nanometer Positioning
Masato Kadotani*1, Takakazu Kitagawa*1, Satoshi Katto*1, Tomoko Hirayama*2, Takashi Matsuoka*2, Hiroshi Yabe*3, and Katsumi Sasaki*4
*1Graduate School of Mechanical Engineering, Doshisha University
1-3 Miyakodani, Tatara, Kyotanabe, Kyoto 610-0394, Japan
*2Department of Mechanical Engineering, Doshisha University
*3Kyoto University, Osaka Electro-Communication University
*4Pneumatic Servo Controls Ltd.
The ‘pneumatic servo bearing actuator (PSBA)’ that consists of an aerostatic bearing and a servo valve was proposed and developed for ultraprecise positioning. In the actuator, pressurized air controlled by the servo valve moves an actuated spool ultra-precisely. Even under open-loop control, the PSBA provided accurate replication and positioning resolution on a nanometer order. Applying simple positioning feedback and parallel observation that estimates the disturbance into the system increased the actuator stiffness to be almost infinite and promoted a sharp step response without drift and hysteresis, and thus the minimum positioning resolution of prototype PSBA was about 1 nm.
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