Performance and Effectiveness of the Passive-Compliant Citrus-Picking Manipulator

The application of citrus-picking robotic hands in orchard environments is constrained by the diversity in fruit size and shape, as well as the need to control fruit damage during harvesting. To address this issue, this study proposes a passively compliant citrus-picking robotic hand and experimentally evaluates its performance. The robotic hand employs a spring-assisted grasping mechanism, optimizing the gripping force range and adjusting spring parameters to achieve passive, compliant encapsulation of citrus fruits of varying sizes while preventing damage. Furthermore, to accommodate citrus fruits with varying ellipticity, the robotic hand incorporates a floating linkage mechanism, enabling each finger to move independently under the control of a single stepper motor, thereby enhancing adaptability to morphological variations. Experimental results indicate that the robotic hand can reliably grasp citrus fruits of various sizes and ellipticities, and complete the harvesting process by rotating four times without applying tensile force, with a damage rate of only 2.6%. The proposed passively compliant robotic hand features a simple structure and strong adaptability, offering a reference for enhancing the applicability of citrus-picking robots in complex orchard environments. Future research will focus on further optimizing the robotic hand’s structure, improving harvesting efficiency, and exploring its adaptability in various operational environments.