Engineers at the University of Cambridge have created a vegetable-picking robot that uses machine learning to harvest iceberg lettuce.
Called the Vegebot, the system first identifies the target crop within its field of vision, then determines whether a particular lettuce is healthy and ready to be harvested, and finally cuts the lettuce from the rest of the plant without crushing so that it is supermarket ready.
The robot has two main components: a computer vision system and a cutting system. The researchers developed and trained a machine learning algorithm on example images of lettuces. Once the Vegebot could recognise healthy lettuces in a laboratory, it was then trained in the field, in a variety of weather conditions, on thousands of lettuces.
A camera is positioned near the cutting blade to help ensure a smooth cut. The researchers were also able to adjust the pressure in the robot’s gripping arm so that it held the lettuce firmly enough not to drop it, but not so firm as to crush it. The force of the grip can be adjusted for other crops.
Although the prototype is nowhere near as fast or efficient as a human worker, it demonstrates how the use of robotics in agriculture might be expanded, even for crops like iceberg lettuce which are particularly challenging to harvest mechanically, the researchers said. The results are published in The Journal of Field Robotics.
Crops such as potatoes and wheat have been harvested mechanically at scale for decades, but many other crops have to date resisted automation. Iceberg lettuce is one such crop. Although it is the most common type of lettuce grown in the UK, iceberg is easily damaged and grows relatively flat to the ground, presenting a challenge for robotic harvesters.
“Every field is different, every lettuce is different,” said co-author Simon Birrell from Cambridge’s department of engineering. “But if we can make a robotic harvester work with iceberg lettuce, we could also make it work with many other crops.”
“At the moment, harvesting is the only part of the lettuce life cycle that is done manually, and it’s very physically demanding,” said co-author Julia Cai.
According to the University of Cambridge team, robotic harvesters could help address problems in the future with labour shortages in agriculture, and could also help reduce food waste.
© FoodBev Media Ltd 2019
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