水果尺寸在线测量的智能柔性手爪设计  

Design of an intelligent soft gripper for on-line measurement of fruit size

作　　者：季钦杰 卢伟[1,2] 宋爱国 王鹏[1,2] 丁宇 王玲 JI Qin-jie;LU Wei;SONG Ai-guo;WANG Peng;DING Yu;WANG Ling(College of Engineering,Nanjing Agricultural University,Nanjing 210031,China;Jiangsu Province Engineering Laboratory of Modern Facility Agriculture Technology and Equipment,Nanjing 210031,China;College of Instrumental Science and Engineering,Southeast University,Nanjing 210096,China)

机构地区：[1]南京农业大学工学院,江苏南京210031 [2]江苏省现代设施农业技术与装备工程实验室,江苏南京210031 [3]东南大学仪器科学与工程学院,江苏南京210096

出　　处：《江苏农业学报》2020年第2期455-462,共8页Jiangsu Journal of Agricultural Sciences

基　　金：国家自然科学基金项目(11604154);江苏省自然科学基金面上项目(BK20181315);江苏省农机三新工程项目(SZ120170036);Asia Hub南京农业大学-密歇根州立大学联合研究项目(2017-AH-11);扬州市重点研发计划项目(现代农业)(YZ2018038)。

摘　　要：针对目前水果自动化分级中手爪普遍缺少抓取力和水果尺寸信息而感知能力不足的问题,设计一种具有抓取力和水果尺寸原位动态检测功能的柔性手爪。首先,设计一种基于单气道多腔体结构的智能柔性三指手爪,其中一根手指通过悬臂梁力传感器竖直安装于手掌上用于检测力触觉,一根手指内嵌柔性弯曲度传感器用于检测手指的弯曲度,另一根手指直接固装于手掌上;设计力觉传感器和弯曲度传感器调理电路,并分别进行标定。其次,提出基于力觉传感器和弯曲度传感器融合的水果尺寸原位测量方法,推导基于手指弯曲度的水果尺寸测量公式,并通过有限元分析和试验进行验证。有限元仿真结果表明,基于手指弯曲度的水果直径测量误差小于5%;通过分别对不同直径(15 mm、25 mm、35 mm、45 mm)的3D打印圆柱和水果(杏子、冬枣、红提和龙眼等)进行抓取试验,表明力觉信号第一次突变时刻(手指刚接触到圆柱时)的手指弯曲度可用于被抓物直径的精确测量,误差小于5%。基于柔性手爪的力觉传感器和弯曲度传感器信息融合进行水果尺寸的在线快速测量是可行的。For improving the shortcomings of the existed gripper without grasping force and fruit size detection in fruit grading system,an intelligent soft gripper which could measure grasping force and fruit size on-line dynamically was developed.Firstly,an intelligent flexible three-finger gripper based on the multi-cavity structure and single airway in each finger was developed.One finger was vertically installed on the palm through a cantilever beam force sensor to detect the tactile sense,one finger was embedded with a flexible curvature sensor to detect the curvature of the finger,and the other finger was installed on the palm directly.Moreover,the conditioning circuits of force sensor and bending sensor were developed and calibrated,respectively.Secondly,an in-situ measurement method of fruit size based on the fusion of the force sensor and curvature sensor was proposed.In addition,the fruit size measurement formula based on finger curvature was derived and verified by the finite element analysis experiment and fruit picking experiment.The simulation results of finite element showed that the fruit diameter detection error based on finger curvature was less than 5%.The grasping experiments on 3D-printed cylinders(15 mm,25 mm,35 mm,45 mm)and different fruits(apricot,jujube,grape and longan,etc.)indicated that the finger curvature at the moment of the first mutation of force signal(the fingers just touched the object)could be used to accurately measure the diameter of the object with an error of less than 5%.It’s feasible to quickly measure the fruit size online based on the fusion information of force sensor and bending sensor.

关 键 词：力触觉 弯曲度 柔性手爪 原位测量 柔性机器人 

分 类 号：S225[农业科学—农业机械化工程] TP241[农业科学—农业工程]