关键词: 自动调焦, 视觉检测, 区间搜索, 清晰度评价函数

Abstract: During measurement, the visual inspection system was influenced by factors such as production accuracy and assembly errors, leading to defocused and blurred images. Consequently, a rapid focusing method for the precision visual inspection system was developed based on YOLOv5s. This method employed a combination of coarse and fine focusing strategies. Initially, the trained YOLOv5s models were utilized to search for clear imaging depth ranges with an accuracy of 97.6%, completed the coarse focusing processes within 900ms. Subsequently, the clarity evaluation function and an improved search algorithm were applied for precise focusing, swiftly identified the optimal imaging plane within the depth range. Experimental results indicate that within a defocus range of ±4 mm, the focusing accuracy reaches 0.04 mm, with an average time not exceeding 1600 ms, which reaches a 47.6% reduction compared to existing methods. This method offers rapid speed, high accuracy, and strong adaptability, making it ideally suited for online precision measurements in visual inspection systems.

Key words: autofocus, visual inspection, interval search, clarity evaluation function