Robot Strawberry Picker May Be On The Way
July 1, 2013 
Scientists at the National Physical Laboratory (NPL) in London, England, have developed imaging technology that may some day solve labor shortages, as it can identify the ripeness of strawberries before they are picked.
In an interview conducted via email, the NPL’s Science Area Leader for Electromagnetic Applications, Richard Dudley, says it is the first unit that uses a combination of micro-, radio, and far infrared waves to analyze fruit. “Others have used single point measurements to understand water and sugar, for watermelons for example,” he says, “but I think we have been the first to image and use the images for harvesting applications.”
The droid can measure the strawberry’s Brix using microwave technology because the material properties of a high-sugar content fruit is different than one with more water, says Dudley. That said, it’s not easy to get around the age-old problem of determining the ripeness of a given piece of fruit without damaging it. “Getting the accuracy of our technique in line with what can be achieved with handheld destructive Brix testing — refractometers for example — is challenging for a non-contact imager,” he says.
Field Tested
Dudley, who proved this vision concept and is the project leader, says he and his team have been working on it for about three years. One of the toughest obstacles they’ve had to overcome is making sure the robot works both in and out of the lab. The test sites have provided complex and often harsh environments, and the variability in leaves and coverage often provide difficulties. “Achieving the required accuracy in these environments is probably the toughest challenge,” he says. “Getting a false reading is not acceptable.”
If the robot passes all the tests, a new challenge awaits in making it available to growers. Taking the equipment to the product stage in an affordable and high-performance package is a tremendous obstacle. “Often each growing house or crop is significantly different and the redesign of deployment can pose a significant cost increase,” says Dudley.
Not only that, he emphasizes that his team is mainly focused on the robot’s imaging, which is essential to provide the robot with spatial information. Next would come providing the robot with “arms” to pick the fruit, though Dudley says that may not be as difficult as it sounds. Robots have the necessary precision. “Getting the right hand to pick each fruit then requires additional design, sensors, and approaches,” he says. “All of these are engineering problems which can be overcome IF you have accurate information on the position and cut point of the fruit.”
That said, growers shouldn’t expect to see the robot commercially available anytime soon. Just a year ago, Dudley said he thought they were coming close to hitting the market, but not now. “No, this is taking longer than we anticipated,” he says. “We are at the difficult stage where we have proved the concept but now need to move to a commercial system — it’s a difficult space for any invention.”
No Limits
Though the project has been more difficult to see through than he expected, Dudley says he has no doubt it will be a success. He thinks that such a robot could come close to the picking speed of a human initially, and faster is possible. “The limitation here is in imaging speed rather than robot speed,” he says, “but as extra data is gathered on the growth of the berries, knowing when to pick can be predicted.”
Even if the robot could only pick as fast as a human, its overall production would be much higher because it could pick fruit 24 hours a day, says Dudley, adding: “360 days a year if needed with just some maintenance time and service stops.”
That would be quite a boon to growers, because like the U.S., Great Britain has encountered some serious labor shortages in recent years. “Yes, no one wants to pick fruit it seems,” says Dudley. “We have had EU (European Union) migrant workers but these are in short supply — it is one of the drivers for automated harvesting for us.”
But there’s no reason for such a robot to be used only at harvest, says Dudley, not when it can also conserve in other areas. “Having robots imaging not just the fruit but the whole plant on a regular basis enables the plant’s growth cycle to be monitored and managed,” he says. “Greater information in these growing environments leads to better output with the use of less resources, such as water, nutrients, and pesticides.”
Not Limited To Strawberries
The use of the robotic vision technology is in no way limited to strawberries or even harvesting, says Richard Dudley. They are currently working on applications in the food processing/sorting stages, for example.
Besides getting an accurate Brix reading of numerous fruits and vegetables, they want to be able to detect sub-surface defects, such as black heart in potatoes. Their current target crops are citrus, potatoes, pear/apple, and avocado.
“However, a really important area we see is in biofuel crops where the sugar content is not just a consumer issue but a production efficiency requirement,” says Dudley. “In the field, method for measurement of the Brix in these crops using either a hand-held sensor or a distributed network within the fields would offer some incredible benefits for management of these high-value vast-area crops.”
Public/Private Partnership
It’s a familiar story in the U.S.: researchers lamenting the lack of government support for the land grant universities that have long provided the heartbeat of agricultural R&D. Today it’s often necessary for university researchers to secure private funding for their research. It turns out that such public/private partnerships exist in England as well.
Richard Dudley works at the National Physical Laboratory, the largest applied physics organization in the UK. Founded in 1900, the NPL was directed in World War II by Charles Galton Darwin, grandson of the author of “On the Origin of Species.”
While NPL is a government laboratory, it is operated by a commercial company, SERCO. However, that doesn’t mean that Dudley’s research is privately funded. “The work at NPL is funded by the UK National Measurement System, part of the Business Innovation and Universities department of the UK government,” he says.
But it’s not “pure” government research either. Dudley says they have worked with private companies in such areas as developing the camera for the robotic vision system, as well as making it applicable to harvesting. “These companies have some intellectual property invested in the product,” he says, “though some of the companies no longer work with us or exist.”
Dudley welcomes the interest of private companies. “We are looking for innovative collaborators to further develop solutions in the farming industry where knowledge below the surface of a product is required in a non-destructive test,” he concludes.
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