Robot-assisted fruit harvesting has been a critical research direction supporting sustainable crop production. One important determinant of system behavior and efficiency is the end-effector that comes in direct contact with the crop during harvesting and directly affects harvesting success. Harvesting avocados poses unique challenges not addressed by existing end-effectors (namely, they have uneven surfaces and irregular shapes grow on thick peduncles, and have a sturdy calyx attached). The work reported in this paper contributes a new end-effector design suitable for avocado picking. A rigid system design with a two-stage rotational motion is developed, to first grasp the avocado and then detach it from its peduncle. A force analysis is conducted to determine key design parameters. Preliminary experiments demonstrate the efficiency of the developed end-effector to pick and apply a moment to an avocado from a specific viewpoint (as compared to pulling it directly), and in-lab experiments show that the end-effector can grasp and retrieve avocados with a 100% success rate.

翻译：机器人辅助水果采摘一直是支持可持续作物生产的关键研究方向。系统行为和效率的一个重要决定因素是末端执行器，它在采摘过程中直接接触作物，并直接影响采摘成功率。牛油果采摘带来了现有末端执行器尚未解决的独特挑战（即其表面不平整、形状不规则、生长在粗壮的果梗上，且附着坚固的花萼）。本文报道的工作提出了一种适用于牛油果采摘的新型末端执行器设计。开发了一种具有两阶段旋转运动的刚性系统设计，首先抓握牛油果，然后将其从果梗上分离。通过受力分析确定了关键设计参数。初步实验证明了所开发的末端执行器从特定视角采摘并对牛油果施加力矩（相较于直接拉扯）的效率，实验室实验表明该末端执行器能以100%的成功率抓取并回收牛油果。