关键词: 并联平台;误差建模;视觉;运动学标定

Abstract: A step and gradual kinematic calibration method using vision-based metrology is proposed for a three-degree-of-freedom (3-DOF) planar parallel stage for screen printing, and it solves the kinematic calibration problem of this class of special planar parallel alignment stages. The mapping relationship between the errors of position and orientation and the errors of geometrical parameters is derived by a combination of vector method and analytical method. The Jacobian matrix is obtained. The vision-based and full-pose measuring device including two cameras is set up by taking into account both measurement costs and applicability, and the device is calibrated by a high accuracy lithography glass-board. By using precision vision-based metrology, based on the repeatability of the parallel alignment stage, a step and gradual kinematic calibration including step measurement, step identification and step compensation is designed. After calibration, the maximum position and orientation errors are reduced from 316 m and 3.510–3  to 9 m and 1.710–3 , respectively. The results show that the positioning accuracy after calibration is significantly improved and verify the effectiveness of the step and gradual kinematic calibration method.

Key words: parallel stage;error modeling;visual perception;kinematic calibration