Design, Fabrication, and Finite Element Drop-Impact Evaluation of a 3D-Printed Soft Robotic End-Effector for Strawberry Harvesting

Harvesting strawberries is labor-intensive and expensive, as the fruit must be gripped, detached and carried without bruising or mechanical damage. The fruit's size, ripeness, orientation, and position, along with the fruit stem's orientation and position, further complicate the development of reliable robotic harvesting systems. In this paper, a 3D-printed soft robotic end-effector for robotic strawberry harvesting is designed and fabricated, capable of coordinated cutting, collection, and impact reduction. The end-effector, designed in SolidWorks, consisted of a strawberry holder, a sliding tray, a structural plate, a support column, sliders and a cutting mechanism. The rigid parts were produced from polylactic acid (PLA), and the compliant part was made from thermoplastic polyurethane (TPU) for cushioning during fruit handling. A prototype was produced via fused deposition modeling, and the mechanical configuration's feasibility was investigated. The dynamics of strawberries interacting with the compliant tray during controlled drop events were studied using finite element analysis in ANSYS Mechanical. Three major variables were drop height, strawberry size, and fruit density, and 15 simulations were created to evaluate these three. The models tested were small, medium and large strawberries; densities from 917.4 to 1147.7 kg/m³; and dropping heights from 20 to 100 mm. The tray was secured on four sides, and strawberries were dropped from a known height under gravity. These are the main response parameters: equivalent stress, total deformation and internal energy. This approach is used to assess soft-robotic harvesting components before physical testing and system-level integration.