Farmer holding a cucumber

Robots set to replace humans on ‘cucumber flyers’ on German farms

Image credit: Dreamstime

A lightweight dual-arm robot capable of autonomously harvesting cucumbers has been developed by researchers at the Fraunhofer Institute for Production Systems and Design Technology (IPK).

In Germany, most cucumber farms use ‘cucumber flyers’ to help gather their fruit. These vehicles have two large, covered, wing-like arms, on which farm hands lie on their stomachs side-by-side. In this position, they grab cucumbers from the ground as the vehicle trundles through the farm.

Not only is this approach to harvesting uncomfortable and labour-intensive, but since the introduction of the minimum wage in Germany in 2014, the cost of crop cultivation with seasonal labourers riding cucumber flyers is growing increasingly uneconomical.

Consequently, many of the pickles consumed by Germans are now grown in Eastern Europe and India.

In order to maintain native cucumber farming, researchers in Berlin have been working on an autonomous system for harvesting cucumbers through an EU-funded project: the ‘Cucumber Gathering - Green Field Experiments (CATCH)’ project. This also involves researchers from the Leibniz Institute for Agricultural Engineering and Bioeconomy and the Spanish Centre for Automation and Robotics.

The researchers aim to develop a dual-arm robot system consisting of lightweight modules which can pick cucumbers with gripper arms. There are two major challenges facing the team. Firstly, recognising randomly placed ripe green cucumbers amid green foliage in all types of conditions. Secondly, handling the cucumbers without damaging them or the crops.

Crucially, the device must be at least as efficient as human labour in order to prove beneficial to German cucumber farmers. An experienced cucumber picker can harvest nearly 800 cucumbers in an hour.

Consequently, the collaborators have developed multispectral cameras and smart image-processing techniques which can help detect ripe cucumbers with 95 per cent accuracy.

They are also working to equip the robot with arms with five degrees of freedom, sophisticated tactile perception and the ability to mimic some human movements

“The robot can, for example, push leaves to the side using symmetrical or asymmetrical movements, or congruent and incongruent movements. As a result, it can automatically change directions on the fly to approach and then grasp a cucumber,” said Dr Dragoljub Surdilovic, a Fraunhofer IPK researcher.

Initial field testing in July 2017, which used various types of cucumbers, demonstrated that the technology functioned well, and it has since moved into further testing in a greenhouse at Fraunhofer IPK. As the project continues, the researchers will attempt to raise the detection accuracy to 100 per cent.

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