Operational flow of an autonomous sweetpepper harvesting robot

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Postprint

This is the accepted version of a paper presented at The 5th Israeli Conference on Robotics

2016, Air Force Conference Center Hertzilya, Israel, 13-14 April, 2016.

Citation for the original published paper:

Ringdahl, O., Kurtser, P., Barth, R., Edan, Y. (2016)

Operational flow of an autonomous sweetpepper harvesting robot

In:

N.B. When citing this work, cite the original published paper.

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Operational flow of an autonomous sweet

pepper harvesting robot

Ola Ringdahl

1*

_{, Polina Kurtser}

2

_{, Ruud Barth}

3

_{, Yael Edan}

2

1_{Department of Computing Science, Umeå University, SE-901 87 Umeå, Sweden}

2_{Department of Industrial Engineering and Management, Ben-Gurion University of the Negev, Beer Sheva, Israel} 3_{Greenhouse Horticulture, Wageningen University and Research Centre, Wageningen, the Netherlands}

*_{Corresponding author}_{ringdahl@cs.umu.se}

Advanced automation is required for greenhouse production systems due to the lack of skilled workforce and increasing labour costs [1]. As part of the EU project SWEEPER, we are working on developing an autonomous robot able to harvest sweet pepper fruits in

greenhouses. This paper focuses on the operational flow of the robot for the high level task planning.

In the SWEEPER project, an RGB camera is mounted on the end effector to detect fruits. Due to the dense plant rows, the camera is located at a maximum of 40 cm from the plants and hence cannot provide an overview of all fruit locations. Only a few ripe fruits at each

acquisition can be seen. This implies that the robot must incorporate a search pattern to look for fruits. When at least one fruit has been detected in the image, the search is aborted and a harvesting phase is initiated. The phase starts with directing the manipulator to a point close to the fruit and then activating a visual servo control loop. This motion approach ensures that the fruit is grasped despite the occlusions caused by the stems and leaves. When the manipulator has reached the fruit, it is harvested and automatically released into a container. If there are more fruits that have already been detected, the system continues to pick them. When all detected fruits have been harvested, the system resumes the search pattern again. When the search pattern is finished and no more fruits are detected, the robot base is advanced along the row to the next plant and repeats the operations above.

To support implementation of the workflow into a program controlling the actual robot, a generic software framework for development of agricultural and forestry robots was used [2]. The framework is constructed with a hybrid robot architecture, using a state machine implementing the following flowchart.

References

[1] Comba, L., Gay, P., Piccarolo, P., & Ricauda Aimonino, D. (2010). Robotics and automation for crop management: trends and perspective. In International Conference on Work Safety and Risk Prevention in Agro-food and Forest Systems, Ragusa, Italy. [2] Hellström, T. and Ringdahl, O. (2013), A software framework for agricultural and forestry robots, Industrial Robot: An International

Journal, Vol. 40, Issue 1, pp. 20-26.

Acknowledgements

This research was supported by the European Commission (SWEEPER GA no. 66313) and partially supported by the Helmsley Charitable Trust through the Agricultural, Biological and Cognitive Robotics Center and by the Rabbi W. Gunther Plaut Chair in Manufacturing Engineering, both at Ben-Gurion University of the Negev.