Authors

Abstract

This paper presents the design of a linkage-based underactuated end-effector for sweet pepper harvesting. The end-effector employs a single motor to drive a spring differential system, enabling two three-phalanx fingers to sequentially and adaptively envelop the fruit in a proximal-middle-distal order, coupled with a pneumatic cutting mechanism for peduncle separation. Biomechanical tests on sweet peppers established a safe grasping force threshold range of 0.72 N to 33.56 N. The phalanx dimensions were optimized using a genetic algorithm, ensuring the workspace covers the fruit diameter range of 70–103 mm. Static analysis determined that the push rod inclination angle should be maintained between 5°–10° to avoid dead points. Adams simulations verified the effectiveness of the enveloping sequence, with a peak contact force of 15.89 N remaining within non-destructive range. Prototype tests demonstrated that at a rotational speed of 90 r/min, the harvesting success rate reached 89.34%, the single-fruit harvesting time was 21.70 s, and the damage rate was 0%, confirming the effectiveness and feasibility of the proposed mechanism for low-damage sweet pepper harvesting.

Abstract in Chinese

本文设计了一种基于欠驱动原理的连杆式甜椒采摘末端执行器，通过单电机驱动弹簧差动系统，实现两指三指节按序自适应包络果实，并配合气动剪切机构分离果柄。通过甜椒生物力学试验获得夹持力安全阈值为0.72N至33.56N，利用遗传算法优化指节尺寸，使工作空间覆盖70–103 mm果径范围。静力学分析确定推杆倾角宜控制在5°–10°以避免死点。ADAMS仿真验证了包络时序合理，接触力峰值15.89 N处于无损范围内。样机试验表明，在90 r/min转速下，采摘成功率达89.34%，单果耗时21.70 s，损伤率为0，验证了机构在甜椒低损采摘方面的有效性与可行性。