关键词: 智能采摘, 双目立体视觉, 重叠分割, 图像相似度, 三维空间定位

Abstract: Accurate identification and localization of fruit in the natural environment is one of the challenges faced by intelligent picking. Based on binocular stereo vision, this paper proposed a three-dimensional spatial positioning method for outdoor overlapping citrus. Firstly, the contours of overlapping citrus fruits from the left  and right camera  were extracted and Gaussian smoothing was performed. Through the curvature analysis, the abnormal contour pixel points were found. Secondly, the adjacent two abnormal pixel points were connected in turn, and the distance from the pixel points on the line segment to the citrus outline was analyzed, the overlapping citrus contour segmentation was completed at the intersection of two adjacent normal line segments, and the corresponding non-citrus contour pixels were eliminated by searching for the abnormal line segments. Thirdly, the least squares ellipse fitting method was used to reconstruct the contour of the citrus target and obtain the center of the citrus. Finally, according to the binocular line constraint and image similarity, the overlapping citrus center points were matched, and the depth value and three-dimensional space coordinates of the citrus center were calculated based on the parallax principle, and the occlusion relationship of overlapping citrus was obtained by combining the depth values. The results of outdoor experiments showed that the positioning error of this method was 6.38 mm, which met the positioning accuracy requirements of outdoor picking operations of citrus picking robots.

Key words: intelligent picking, binocular stereo vision, overlapping citrus, image similarity, three-dimensional positioning