Magnetically preloaded aerostatic guideway for high speed nanometer positioning

Abstract

Demands for nanometer positioning with a high resolution and a long stroke have increased in a variety of industries. Performance of guide elements is one of the most important issues for realizing such positioning systems. In general, an ultra-precision positioning system has aerostatic guideway which can restrain a moving table without non-linear behavior, i.e., friction and backlash. Characteristics of aerostatic guideway affect the performance of the positioning system. This study is aiming at developing an aerostatic guideway which can achieve a high speed nanometer positioning. The aerostatic guideway preloaded by magnetic attraction force can lead to provide a compact structure, and the characteristics can be easily controlled without increased driving force. However, the relative velocity between permanent magnets and the attracted surface causes the induced eddy current, which deteriorates the performance during high speed positioning. In this study, in order to minimize the eddy current loss, the magnetic attraction force is successfully added to a mechanism following the positioning table. In order to evaluate the proposed structure, a positioning system is developed by using the magnetic attraction force preloaded aerostatic guideway. The positioning system is constructed by a positioning table and a following table. Basic characteristics of the aerostatic guideway are experimentally evaluated. From the results, the magnetic attraction force-preloaded guideway can be designed so as to obtain high stiffness. By optimizing the magnetic force, the performance of the positioning system was evaluated. The experimental results of frequency response confirm that the response of the positioning system can be improved by applying magnetic attraction force. In addition, the results of stepwise positioning confirm that the proposed positioning system has high positioning resolution. These results confirm that the proposed guideway achieves high speed nanometer positioning capability.

A Design Method of Precise Positioning Stage in Vacuum Environment by Disturbance Observer with Position Dependent Parameter

“…It is the feedback control model of the output error to getX (t) that is the estimatedX (t). That model is shown in equation (6). Here, L is feedback gain matrix.…”

“…Positioning accuracy of XY stage (hereinafter called the stage) less than 3 nm is required by CD-SEM which inspects circuit pattern less than 10 nm. As well as known, semiconductor photolithography apparatus has been equipped with the stage using aerostatic bearing to get high accuracy [3]∼ [6]. However, it was hard to introduce it into CD-SEM which is working in vacuum environment due to high cost and technical difficulties.…”

Effect of solid–gas damping on dynamic characteristics of aerostatic guideway

“…The bearing will be in resonant state generated by the supported air flotation positioning table. The damping of the various components of the aerostatic guideway drive chain is an important factor affecting its resonance (Hanifzadegan and Nagamune, 2015; Mauro et al, 2015; Schmidt et al, 1999; Tsumura et al, 2014).…”

Identification and evaluation for the dynamic signals caused by pressure fluctuation of aerostatic slider

“…However, the relation between the air pressure and the instabilities of aerostatic sliders caused by the sudden small displacement has not been analyzed. Previous research focuses on static and dynamic performance of aerostatic guideway (Li and Ding, 2007;Hwang et al, 2010;Tsumura et al, 2014). Conventional aerostatic guideways are not designed considering the influence of small vibration which occurs by supplying air.…”