A Washington State University-led research team has revealed a custom-built robotic arm similar to a waving arms inflatable advertising display, only it picks apples.
The research team behind the apple-picking robotic arm suggests the technology could be adapted to pick several other types of fruit and operate in environments or conditions too challenging for human pickers.
According to the WSU-led team, Washington state is the nation’s leading apple-producing state, generating more than $2 billion in annual revenue. However, the state’s fruit-growing industry has experienced ongoing shortages of critical laborers, including harvesters and pruners. The labor shortage has been compounded by an aging workforce and a decline in migrant labor.
Ming Luo, an Assistant Professor in WSU’s School of Mechanical and Materials Engineering and the corresponding author of the work, said a recent trip through the region showed the practical cost of the problem: orchards filled with apples rotting on the ground.
“It is just a waste,” Lou said of the unsettling sight.
Driven to search for low-cost, viable alternatives to human harvesters, Lou and his fellow WSU scientists turned to the idea of a robot that picks apples, removing humans from the equation. Although large-scale robotic systems already exist, the team noted that they are expensive and complex to use.
After exploring several designs, the team zeroed in on an inflatable concept they described as “similar to, but stronger than, the wacky inflatable arm-flailing tube men that are used in outdoor advertising.”
The concept led to a prototype that weighs less than 50 pounds, including a metal base, and utilizes a two-foot-long soft fabric inflatable arm to extend toward a tree and grab a piece of fruit. The device was then tested at Allan Brothers Fruit in Prosser, Washington.
In a video released by the WSU team, the robot arm that picks apples is shown “seeing” the apple with rudimentary sensors, extending to pick it, and retreating to deposit it. The team said this entire process typically takes about 25 seconds.
When describing the system’s safety profile, the research team noted that the robot arm used to pick apples is light enough to work safely alongside humans and won’t harm “delicate” branches or other apples during the harvesting process. They also note that they designed their apple-picking robot to operate in modern apple orchards, which are organized in a V-trellis or linear plane to aid growing and picking operations.
Ryan Dorosh, a PhD candidate and lead author on the study, said that the team’s “very low-cost, safe robotic platform” is ideally suited for operation in the orchard environment.
Although the prototype and demonstrations were considered a success, the WSU team conceded that their apple-picking robot is still much slower than human laborers, who typically pick an apple every 3 seconds. The researchers are already exploring ways to improve the “rudimentary” detection system, which they said slows the process more than the arm’s movements.
They are also exploring ways to expand their robotic arm to perform other orchard tasks, including spraying, pruning, and flower thinning. This effort has led to collaborations with researchers at the Prosser Research Extension Center and with Manoj Karkee at Cornell University, aimed at equipping the robotic arm with an automated moving platform to enable it to move seamlessly through orchards.
Although still in the prototype stage, the WSU is working with the university’s Office of Innovation and Entrepreneurship to patent the technology behind the robot arm that picks apples. They are also exploring ways to reduce the already low cost of the inflatable robot below its current $5,500 price tag.
When discussing the practical application of fruit-picking robots, Lou highlighted their simplicity, noting that “the uncomplicated nature of the design makes it low-cost, easy to maintain, and highly reliable for a soft robot.” The researcher also hinted that their long-term goals include “producing a cost-effective solution and having the robot arm be able to do several tasks.”
The work, which was funded by the National Science Foundation, the USDA National Institute of Food and Agriculture, and the Washington Tree Fruit Research Commission, was recently published in the journal Smart Agricultural Technology.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.