Vision Servo Motion Control and Error Analysis of a Coplanar XXY Stage for Image Alignment Motion

Abstract EN

In recent years, as there is demand for smart mobile phones with touch panels, the alignment/compensation system of alignment stage with vision servo control has also increased.

Due to the fact that the traditional stacked-type XYθ stage has cumulative errors of assembly and it is heavy, it has been gradually replaced by the coplanar stage characterized by three actuators on the same plane with three degrees of freedom.

The simplest image alignment mode uses two cameras as the equipments for feedback control, and the work piece is placed on the working stage.

The work piece is usually engraved/marked.

After the cameras capture images and when the position of the mark in the camera is obtained by image processing, the mark can be moved to the designated position in the camera by moving the stage and using alignment algorithm.

This study used a coplanar XXY stage with 1 μm positioning resolution.

Due to the fact that the resolution of the camera is about 3.75 μm per pixel, thus a subpixel technology is used, and the linear and angular alignment repeatability of the alignment system can achieve 1 μm and 5 arcsec, respectively.

The visual servo motion control for alignment motion is completed within 1 second using the coplanar XXY stage.