The ‘Vegebot’ was initially trained to recognise and harvest iceberg lettuce in a lab setting. It is now being tested in a variety of real field conditions.

At the moment it is “nowhere near” as fast or efficient as human pickers, the developers say, although they hope they can improve this with further development time.

Crops such as potatoes and wheat have been harvested mechanically at scale for decades, but many other crops have resisted automation, such as iceberg lettuce which is too easily damaged and grows relatively flat to the ground.

“Every field is different, every lettuce is different,” said Simon Birrell, co-author of a paper on the robot. “If we can make a robotic harvester work with iceberg lettuce, we could also make it work with many other crops.”

The Vegebot first identifies the ‘target’ crop within its field of vision, then determines whether a particular lettuce is healthy and ready to be harvested, before finally cutting the lettuce from the rest of the plant without crushing it so that it is ‘supermarket ready’.

“For a human, the entire process takes a couple of seconds, but it’s a really challenging problem for a robot,” said co-author Josie Hughes.

The Vegebot has two main components: a computer vision system and a cutting system. The overhead camera on the Vegebot takes an image of the lettuce field and first identifies all the lettuces in the image, then – for each individual lettuce – classifies whether it should be harvested or not.

A lettuce might be rejected because it’s not yet mature or might have a disease that could spread to other lettuces in the harvest.

The researchers developed and trained a machine learning algorithm on example images of lettuces. Once the Vegebot could recognise healthy lettuces in the lab, it was then trained in the field, in a variety of weather conditions, on thousands of real lettuces.

A second camera on the Vegebot is positioned near the cutting blade and helps 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.

“We wanted to develop approaches that weren’t necessarily specific to iceberg lettuce, so that they can be used for other types of above-ground crops,” said Iida, who leads the team behind the research.

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

However, a robotic harvester 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.

Last month, a team unveiled a strawberry-picking robot that can pick and package ripe strawberries, bruise-free, every five seconds with its delicate clasping mechanism. 

The ‘Vegebot’ was initially trained to recognise and harvest iceberg lettuce in a lab setting. It is now being tested in a variety of real field conditions.

At the moment it is “nowhere near” as fast or efficient as human pickers, the developers say, although they hope they can improve this with further development time.

Crops such as potatoes and wheat have been harvested mechanically at scale for decades, but many other crops have resisted automation, such as iceberg lettuce which is too easily damaged and grows relatively flat to the ground.

“Every field is different, every lettuce is different,” said Simon Birrell, co-author of a paper on the robot. “If we can make a robotic harvester work with iceberg lettuce, we could also make it work with many other crops.”

The Vegebot first identifies the ‘target’ crop within its field of vision, then determines whether a particular lettuce is healthy and ready to be harvested, before finally cutting the lettuce from the rest of the plant without crushing it so that it is ‘supermarket ready’.

“For a human, the entire process takes a couple of seconds, but it’s a really challenging problem for a robot,” said co-author Josie Hughes.

The Vegebot has two main components: a computer vision system and a cutting system. The overhead camera on the Vegebot takes an image of the lettuce field and first identifies all the lettuces in the image, then – for each individual lettuce – classifies whether it should be harvested or not.

A lettuce might be rejected because it’s not yet mature or might have a disease that could spread to other lettuces in the harvest.

The researchers developed and trained a machine learning algorithm on example images of lettuces. Once the Vegebot could recognise healthy lettuces in the lab, it was then trained in the field, in a variety of weather conditions, on thousands of real lettuces.

A second camera on the Vegebot is positioned near the cutting blade and helps 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.

“We wanted to develop approaches that weren’t necessarily specific to iceberg lettuce, so that they can be used for other types of above-ground crops,” said Iida, who leads the team behind the research.

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

However, a robotic harvester 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.

Last month, a team unveiled a strawberry-picking robot that can pick and package ripe strawberries, bruise-free, every five seconds with its delicate clasping mechanism.