抄録
A '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 had good repetition accuracy and positioning resolution on nanometer order. Applying simple position feedback and parallel observer that estimates the disturbance into the system increased the actuator's stiffness almost to be infinite and promoted the sharp step response without any drift and hysteresis.