This study details the development of an ultra-precision air-bearing stage that integrates real-time motion error measurement and compensation features. The motion errors addressed include horizontal and vertical straightness errors, as well as roll, pitch, and yaw errors. These errors are measured by an embedded system that incorporates five capacitive sensors and a reference mirror within the stage. A key advantage of this stage is its capability to perform real-time compensation using the internal measurement system and on-stage pneumatic regulators, eliminating the need for external measurement and compensation devices. Experimental results show a significant reduction in motion errors, with horizontal and vertical straightness errors decreasing from 3.09 and 1.95 μm to 0.29 and 0.25 μm, respectively. Additionally, roll, pitch, and yaw errors were reduced from 3.18, 3.45, and 4.93 arcsec to 0.35, 0.41, and 0.49 arcsec, respectively. These results clearly demonstrate the effectiveness of the proposed approach.

In ultra-precision processes, such as aerospace parts and precision mold machining, the accuracy of a feed drive system should be secured to achieve sufficient form accuracy. Dual-Servo stages, which compensate for multi-DOF motion errors, are being developed depending on the applied processes. This paper deals with the fine stage of a dual-servo stage to compensate for 6-DOF motion errors of a linear stage. The proposed fine stage measured 6-DOF errors of the linear stage motion with capacitive sensors, a reference mirror, and an optical encoder. It compensated for the errors using the flexure hinge mechanism with piezo actuators. The error equations and the inverse kinematics were derived to calculate the 6- DOF errors and displacements of piezo actuators for 6-DOF motions, respectively. Performance evaluation was implemented to verify feasibility of the developed fine stage of the fabricated dual-servo stage. Through the step response test of the fine stage, compensation resolutions for the translational and the rotational motion were confirmed to be less than 10 nm and 1/3 arcsec, respectively. The 6-DOF motion errors in the verification test were reduced by 73% on average.