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Journal of Intelligent & Robotic Systems

, Volume 95, Issue 1, pp 149–164 | Cite as

Evaluation of approach strategies for harvesting robots: Case study of sweet pepper harvesting

Category: (5)
  • Ola RingdahlEmail author
  • Polina KurtserEmail author
  • Yael Edan
Open Access
Article

Abstract

Robotic harvesters that use visual servoing must choose the best direction from which to approach the fruit to minimize occlusion and avoid obstacles that might interfere with the detection along the approach. This work proposes different approach strategies, compares them in terms of cycle times, and presents a failure analysis methodology of the different approach strategies. The different approach strategies are: in-field assessment by human observers, evaluation based on an overview image using advanced algorithms or remote human observers, or attempting multiple approach directions until the fruit is successfully reached. In the latter approach, each attempt costs time, which is a major bottleneck in bringing harvesting robots into the market. Alternatively, a single approach strategy that only attempts one direction can be applied if the best approach direction is known a-priori. The different approach strategies were evaluated for a case study of sweet pepper harvesting in laboratorial and greenhouse conditions. The first experiment, conducted in a commercial greenhouse, revealed that the fruit approach cycle time increased 8% and 116% for reachable and unreachable fruits respectively when the multiple approach strategy was applied, compared to the single approach strategy. The second experiment measured human observers’ ability to provide insights to approach directions based on overview images taken in both greenhouse and laboratorial conditions. Results revealed that human observers are accurate in detecting unapproachable directions while they tend to miss approachable directions. By detecting fruits that are unreachable (via automatic algorithms or human operators), harvesting cycle times can be significantly shortened leading to improved commercial feasibility of harvesting robots.

Keywords

Agricultural robotics Robotic harvesting Fruit approach Human-robot collaboration 

Notes

Acknowledgements

This research was supported by the European Commission (SWEEPER GA no. 644313) and by Ben-Gurion University of the Negev through the Helmsley Charitable Trust, the Agricultural, Biological and Cognitive Robotics Initiative, the Marcus Endowment Fund and the Rabbi W. Gunther Plaut Chair in Manufacturing Engineering.

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© The Author(s) 2018

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  1. 1.Department of Computing ScienceUmeå UniversityUmeåSweden
  2. 2.Department of Industrial Engineering and ManagementBen-Gurion University of the NegevBeer-ShevaIsrael

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