A Dual Stage Compliant Positioning System with Integrated Planar Optical Grating for Position Feedback

摘要

Assembly, handling and dispensing systems for small-scale parts play an essential part in reducing the cost of these products. These operations require both long coarse positioning for transfer between operations as well as dispensing as well as fine short range positioning on the submicron level for feature assembly. Typical prismatic rolling guide-way based positioning stages with ballscrew drives are to inaccurate for positioning in the submicron level which led to the development of dual stage positioning systems. One stage performs the coarse long-range motions whereas another stage provides small precise motions. One disadvantage of such systems is that each actuator requires individual motion feedback, which leads to higher system cost. Focus of this paper is the design of a positioning stage that uses a dual stage approach for coarse and fine positioning, but utilizes a single two-dimensional optical grating interferometer as position feedback for the resultant motion feedback. This results in significant reduction in error sources and measurement uncertainties due to misalignment and measurement system errors.