苹果采摘末端执行器设计及分析

Design and Analysis of Apple Picking End Effector

人工采摘苹果的效率低、劳动强度大、安全性差。近年来,随着劳动力成本的上升,人工采摘苹果的成本也在增加。因此,苹果采摘机器人等自动化采摘装备和技术成为迫切需求。然而,采摘机器人的末端执行器往往成为影响采摘效率和质量的关键因素。因此,提出了一种绳驱动的苹果采摘末端执行器。该末端执行器由夹持机构、支承连接机构和驱动传动机构组成,主要用于直径在80~100 mm的苹果采摘。夹持机构由三根手指构成,每根手指有两个关节,分为近指和远指,手指内侧附有橡胶柔性材料和压力传感器。支承连接机构主要由基座圆盘、升降圆盘、支撑架和法兰圆盘组成,其中支撑架还起着升降圆盘的运动导向作用。驱动传动机构由步进电机、滚筒、牵引绳、升降圆盘、弹簧和推力连杆组成。通过步进电机驱动滚筒带动牵引绳控制手爪的开合。通过对采摘手指与抓取中心之间的距离、采摘压力阈值、推力连杆长度以及电机选型等问题进行优化分析,完成了末端执行器的设计。经过优化分析,最终确定采摘手指与抓取中心之间的距离为30 mm,采摘压力阈值为7 N,推力连杆长度为40 mm,并完成了步进电机的选型。该末端执行器能够实现对苹果的自动化抓取和拧断,可应用于采摘机器人等苹果自动化采摘装置。

Manual apple picking is inefficient,labor-intensive,and lacks safety.In recent years,with the increase in labor costs,the cost of manual apple picking has also risen.Therefore,there is an urgent need for automated apple picking equipment and technology,such as apple picking robots.However,the end effector of apple picking robots often becomes a critical factor affecting picking efficiency and quality.Therefore,this study proposes a rope-driven end effector for apple picking.The end effector consists of a gripping mechanism,a support connection mechanism,and a driving transmission mechanism,primarily used for picking apples with a diameter of 80-100 mm.The gripping mechanism consists of three fingers,each with two joints,divided into proximal and distal sections,with rubber flexible materials and pressure sensors on the inner side of the fingers.The support connection mechanism mainly consists of a base disk,a lifting disk,a support frame,and a flange disk,with the support frame also serving as a motion guide for the lifting disk.The driving transmission mechanism consists of a stepper motor,a drum,a traction rope,a lifting disk,a spring,and a thrust link.The stepper motor drives the drum to control the opening and closing of the claws through the traction rope.The design of the end effector is completed through optimization analysis of the distance between the picking finger and the gripping center,the picking pressure threshold,the length of the thrust link,and the selection of the motor.After optimization analysis,the final parameters were determined:the distance between the picking claws and the gripping center is 30 mm,the picking pressure threshold is 7 N,the length of the thrust link is 40 mm,and the selection of the stepper motor is completed.The proposed end effector can achieve automated gripping and twisting of apples.