Fresh, frozen, and processed berries represent a multi-billion-dollar industry in the United States. In Arkansas alone, fresh-market blackberries contribute $24.3 million annually to the state’s economy. However, these delicate berries, typically sold in clamshells at supermarkets, must be harvested by hand, a challenge amid ongoing labor shortages. In response, researchers at the University of Arkansas have developed a new robotic gripper designed to automate blackberry harvesting.

The U.S. Patent and Trademark Office issued a patent in April for the invention titled “Soft Robotic Gripper for Berry Harvesting.” The technology was developed by Anthony Gunderman, then a Ph.D. student and now an assistant professor in the university’s Department of Mechanical Engineering, in collaboration with former U of A professor Yue Chen (now at Georgia Tech) and undergraduate student Jeremy Collins. The patent was secured through Technology Ventures, part of the university’s Division of Research and Innovation.

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The gripper features three soft, pliable fingers that mimic the natural motion of a tulip flower opening and closing, a concept inspired by biomimicry. Each finger is actuated by a tendon-like system using guitar strings to retract and grasp the fruit gently. Force sensors at the fingertips ensure the berries are plucked without being crushed, preventing damage and red drupelet reversion, both of which reduce consumer appeal and lead to USDA rejection.

To calibrate the appropriate harvesting force, the engineers partnered with Adrea Myers, then a graduate student, and Renee Threlfall, associate professor of food science with the Arkansas Agricultural Experiment Station. Sensors were attached to the fingertips of experienced blackberry pickers to record the optimal pressure required for damage-free harvesting.

While robust fruits like blueberries and pears are already harvested by machines, and automated systems are used for processed blackberries, fresh-market blackberries still rely on manual labor. Before this robotic gripper can be deployed on farms, it must be integrated with computer vision and positioning systems to locate and reach berries on the plant.

Gunderman believes the robotic hand could eventually outperform the human hand in this specific task. “When we’re talking about one specific task, it is certainly the case that you could design something better than the human hand for that one specific task,” he said. The gripper also offers consistency, which varies greatly between novice and veteran harvesters.

In addition to blackberries, the gripper could be adapted for other soft fruits like raspberries. It has been tested on a variety of items, from rigid objects like a jar of pears and a can of beans to soft items like a bag of potato chips and a T-shirt. Gunderman notes that the technology may also benefit individuals with limited mobility, suggesting its potential beyond agriculture.

For more information:
Andy Albertson
University of Arkansas
Tel: +1 479 575 6111
Email: [email protected]
www.arkansasresearch.uark.edu