Lettuce-picking robot could address farm labor shortage

Crops such as potatoes and wheat have been harvested mechanically at scale for decades. But many crops have resisted automation. Iceberg lettuce is one of those crops.

But the University of Cambridge is hoping to change that with Vegebot. The lettuce-picking robot has been tested in a variety of field conditions with G’s Growers, a local fruit and vegetable co-operative. Although the prototype is nowhere near as fast or efficient as a human, it’s another example of how collaborative robots could be used in agriculture in the future.

Vegebot has two main components: a computer vision system and a cutting system. An overhead camera takes an image of the lettuce field and identifies all the lettuces in the image. Vegebot then classifies whether each lettuce should be harvested or not. Finally, it cuts the lettuce from the rest of the plant without crushing it so that it is “supermarket ready.”

“Every field is different, every lettuce is different,” said 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.”

Vegebot’s machine learning algorithm was trained on example images of lettuces. Once it could recognize healthy lettuce in the lab, Vegebot was trained in the field in a variety of weather conditions on thousands of real lettuce heads.

Vegebot’s gripping arm holds the lettuce firmly enough not to drop it, but not so firm as to crush it.

In the future, collaborative robots could help address problems with labor shortages in agriculture. They could also help reduce food waste. At the moment, each field is typically harvested once, and any unripe vegetables or fruits are discarded.

Collaborative robots could be trained to pick only ripe vegetables. And since it could harvest around the clock, it could perform multiple passes on the same field, returning at a later date to harvest the vegetables that were unripe during previous passes.

“We’ve still got to speed our Vegebot up to the point where it could compete with a human, but we think collaborative robots have lots of potential in agri-tech.”