Fast facts:
Blackberry tour presented research and extension updates on blackberry programs
More than 60 participants attended the tour at the Fruit Research Station
Arkansas Blackberry Growers Association sponsored the tour
CLARKSVILLE — Do robots dream of electric blackberries?
Doubtful. But they may one day pick fresh blackberries for the rest of us if Renee Threlfall’s graduate students have anything to say about it.
The students have built a prototype robotic blackberry picker. It was displayed Wednesday during the Summer Blackberry Tour at the Arkansas Agricultural Experiment Station’s Fruit Research Station near Clarksville.
The Agricultural Experiment Station is the research arm of the University of Arkansas System Division of Agriculture, which hosted the tour. The event was sponsored by the Arkansas Blackberry Growers Association and featured research updates and blackberry management presentations by the division’s researchers and Cooperative Extension Service specialists.
More than 60 blackberry growers, industry members, students and representatives from the Arkansas Department of Agriculture attended the tour.
“Fresh market blackberries are mostly hand harvested to maintain the quality of this delicate fruit,” said Threlfall, research scientist for the experiment station. “Labor shortages and costs, and the slow speed of hand harvesting creates a bottleneck for fresh-market blackberry industry expansion and market-ready supply.”
Automated harvesting options like shaking the plants, cutting the stems or using rigid grippers are used for other fruits, Threlfall said. “These options are not feasible for harvesting fresh-market blackberries because they might cause quality issues like berry leakage or red drupelet reversion.”
Soft robotics offer a novel option for automatic harvesting by using compliant grippers of rubber or silicone, said Anthony Gunderman, a mechanical engineering graduate student who designed a robotic “hand.” These materials allow grippers to grasp and manipulate delicate objects, like berries, with complex and varying shapes.
The robotic harvesting research group is comprised of food science graduate student Andrea Myers and mechanical engineering students Gunderman and J.A. Collins. Their faculty advisors are Threlfall from the department of food science and Yue Chen, assistant professor of mechanical engineering.
They set out to determine how the human hand grasps and plucks the berries so they could design a robotic gripper that could mimic the movements, touch and pressure.
Myers said the student team collected the mechanical data on human hands by wearing gloves fitted with sensors that measured the movements, which fingers are used, and the force required to harvest blackberries without damaging them. The data was used to design and construct the robotic “hand” with tendon-driven, soft grippers.
The prototype was used to harvest blackberries from a commercial fruit farm at three fingertip pressures, Threlfall said. The robot-picked berries were evaluated for quality attributes essential for acceptable market-ready blackberries.
“The prototype demonstrated the feasibility of using robotic grippers to harvest fresh-market blackberries,” Threlfall said.
Gunderman said more research and development will be necessary to build a robotic harvester that can locate and differentiate ripe berries from unripe berries on the plant. “We’ll have to use technology that can recognize color bands of light,” he said.