基于气动无损夹持控制的番茄采摘末端执行器设计与试验  

Design and experiment of tomato picking end-effector based on non-destructive pneumatic clamping control

作　　者：陈子文 杨明金[1] 李云伍[1] 杨玲[1] Chen Ziwen;Yang Mingjin;Li Yunwu;Yang Ling(College of Engineering and Technology,Southwest University,Chongqing 400715,China)

机构地区：[1]西南大学工程技术学院,重庆400715

出　　处：《农业工程学报》2021年第2期27-35,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：重庆市技术创新与应用发展专项重点项目(cstc2019jscxgksbX0109);中央高校基本科研业务费(XDJK2017B049)。

摘　　要：为实现类球形果实采收过程中稳定夹持和无损采摘,该研究以番茄为研究对象,设计了一款全气动吸-夹一体式无损采摘末端执行器。首先设计空间多连杆三爪机构,采用3个夹持爪单元空间轴向均布的方式构成空间多连杆末端执行器主体机构,实现中心吸盘回拉果实和夹持爪夹持果实两个动作由单一主动气缸驱动并实现顺序动作;其次,建立末端执行器夹持爪单元的数学模型,并确定满足夹持爪尖端张开最大范围156 mm和吸盘回拉移动最大距离38.7 mm条件下的末端执行器结构参数,通过ADAMS软件对其进行运动学和动力学仿真分析,获得各部件间运动速度和加速度的相对关系,以及夹持力与气动系统压力和果实尺寸的关系。最后,设计并搭建具有压力负反馈和气压连续调节功能的电气伺服控制系统,通过分析果实在拉动和转动两种情况的滑移试验,提出基于动态标准差波动上升节点的双阈值滑移判别算法和基于滑移判据及损伤极限压力的无损采摘控制策略。204个不同尺寸番茄果实的实地采摘试验表明,末端执行器采摘成功率为96.03%,采摘过程耗时5 s,采摘过程中的直接损伤率为1.58%,72 h褐变率为1.76%。结果表明该采摘末端执行器具有较好的采摘效果,可满足实际工作需求。Harvesting of fresh fruit remains heavily reliant on manual labor.It is the most time-consuming and laborious part of the whole fruit production process,which accounts for about 40%of the total workload.Therefore,automatic fruit harvesting technology and agricultural picking robots become a focus of research,and one of the key questions is how to design an end-effector of harvester suitable for specific fruits without damaging fruit during the picking process.A pneumatic sucking-gripping integrated non-destructive end-effector for tomato was developed and a non-destructive control method was proposed in this study.Firstly,an innovative multi-link 3-finger mechanism with spatial envelope was designed,which was arranged symmetrically on a 3-finger type slide guide air gripper and driven by it.The vacuum cup was fixed in the center of three claws and was hinged to claws through multi-linkage.Based on this structure,the degrees of freedom(DOF)of vacuum cup were limited to the axial direction of the air gripper,when three claws opened or closed.Thus,the two motions of pulling and gripping the fruit which was sucked by a vacuum cup were driven by a single active component in order.Secondly,the structural parameters of end effector with a maximum envelope range of 156 mm and the maximum moving distance of sucker 38.7 mm are determined by establishing of kinematic model.Meanwhile,the relative relation between the motion velocity and acceleration of each component was obtained based on ADAMS kinematics and dynamics simulation analysis,as well as the relative relation between the holding force and pneumatic system pressure and fruit size.Thirdly,an electro-pneumatic system of end-effector with pressure feedback and pressure continuous regulation function was built.The Arduino Due programmable controller was used as the controller to control the proportional pressure regulating valve,so that the clamping force can be adjusted continuously in real time.In addition,FSR-402 pressure sensors were placed inside the three gripper

关 键 词：机器人 末端执行器 设计 气动系统 滑移判断 

分 类 号：TP242.3[自动化与计算机技术—检测技术与自动化装置]