Title: Fast recognition of overlapping fruit based on maximum optimisation for apple harvesting robot

Authors: Weikuan Jia; Dean Zhao; Chanli Hu; Chengzhi Ruan

Addresses: School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China ' School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China ' School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China ' School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China; School of Mechanical and Electrical Engineering, Wuyi University, Wuyishan 354300, China

Abstract: In order to improve the recognition speed and accuracy, this study aimed at overlapping apples proposes a positioning method based on the maximum optimisation, for fitting of overlapping circles. Owing to the diversity of apple growth posture, the overlap and shade between the apples will influence the recognition efficiency of apple harvesting robot vision system. Firstly, using the K-means method to segment the captured overlapping apple image under the L*a*b* colour space, lead to the overlapping apple target, and carries on the morphological processing, extracting the outline of the overlapping apple. And then to calculate the minimum distance between the pixels in the circle and the edge of outline, to obtain the minimum distance function, and find the local maximum in these functions, that is the centres of two circles. Finally, the radius is determined by the minimum distance between centres to the edge of the outline and to realise the positioning of overlapping apple, in order to verify the validity of maximum recognition method for the overlapping apples, and comparing with corrosion method and the Hough transform method, using two overlapping images captured by different apple varieties to repeat experiments. The experimental results show that, for the recognition speed and accuracy, the maximum optimisation method is optimal.

Keywords: apple harvesting robots; overlapping apple recognition; K-means segmentation; maximum optimisation; overlapping fruit recognition; overlapping circles; robot vision; apple images; recognition speed; recognition accuracy; image processing.

DOI: 10.1504/IJCI.2015.071233

International Journal of Collaborative Intelligence, 2015 Vol.1 No.2, pp.124 - 136

Received: 18 May 2015
Accepted: 25 May 2015
Published online: 17 Aug 2015 *

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