The mushroom-farming industry is currently experiencing labor shortages and rising labor costs. Engineers at Penn State’s College of Agricultural Sciences believe that mechanical or robotic picking can help alleviate those problems.
They have developed a robotics mechanism for mushroom picking and trimming and demonstrated its effectiveness for the automated harvesting of button mushrooms. The prototype designed to be integrated with a machine vision system can both pick and trim mushrooms growing in a shelf system.
“The mushroom industry in Pennsylvania is producing about two-thirds of the mushrooms grown nationwide, and the growers here are having a difficult time finding laborers to handle the harvesting, which is a very labor-intensive and difficult job,” said Long He, assistant professor of agricultural and biological engineering. “The industry is facing some challenges, so an automated system for harvesting like the one we are working on would be a big help.”
The robotic mushroom-picking mechanism included a picking “end-effector” based on a bending motion, a “4-degree-of-freedom positioning” end-effector for moving the picking end-effector, a mushroom stipe-trimming end-effector, and an electro-pneumatic control system. It uses a suction cup mechanism that latches onto the top of each mushroom’s cap then pulls upward.
To determine forces that needed to be programmed into the robotic picker, researchers took mushroom-picking-dynamics measurements using force sensors and an inertial measurement unit.
Engineers conducted bruise tests on the mushroom caps to analyze the influence of air pressure and acting time of the suction cup. The test results showed that the picking end-effector was successfully positioned to the target locations, and its success rate was 90% at the first pick, increasing to 94.2% after the second pick. They believe that an optimized suction cup for the task should improve those figures.
The team noted that the laboratory test results indicated that the developed picking mechanism has the potential to be implemented in automatic mushroom harvesting.