关键词: 聚焦区域选择, 聚焦搜索算法, 自动聚焦, 柱状零件, 显微视觉, 微装配

Abstract: On account of columnar parts in microscope vision system, an autofocus method of the real-time image characteristics detecting and feature area tracking is presented. Focus evaluation function, focus searching algorithm and focus area selecting is included in the proposed focusing algorithm. The system can achieve autofocus quickly and accurately, and the shortcomings of hill-climbing searching algorithm and local maximum of the searching result can be overcome. Meanwhile, it is important to select an appropriate focus area. The image feature area is used as focus area in the paper. The microscope vision system focuses after detecting the image feature. It can focus accurately at the columnar parts’ edge in the situations of the radius of the columnar parts is shorter than the depth of scope. The standard variance error is 205 μm for coarse focus, and 37 μm for fine focus. Experimental results prove the autofocus method can satisfy the request of the micro-assembly system for focus.

Key words: focus area selecting, focus searching algorithm, autofocus, columnar parts, micro-vision, micro-assembly