Measurement of six-degree-of-freedom geometric errors of a translation stage using three absolute position encoders

Abstract

This paper presents an effective method for evaluating the geometric errors of precision translation stages. It quantifies the six degrees of freedom (6-DOF) absolute posture of a moving platform on the stage, where a phase-encoded binary scale is fixed. This evaluation is accomplished using multi-axis readings obtained from three absolute position encoders. The scale errors are compensated using a reversal method, and distances between the measurement points are obtained without the need for additional calibration processes. Therefore, the proposed method can achieve both high accuracy and efficiency, even when implemented for on-site calibration. The performance of the prototype measurement system was evaluated by measuring the 6-DOF geometrics errors of a translation stage over a 100 mm range, and the measurement results showed agreement with the reference data within ±0.3 μm and ±1.2″.