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Kinematic Sensitivity Analysis and Dimensional Synthesis of a Redundantly Actuated Parallel Robot for Friction Stir Welding

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 94-103页

作者： Xinxue Chai Ningbin Zhang leiying he Qinchuan Li Wei Ye Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China

Friction stir welding(FSW)has been widely applied in many fields as an alternative to traditional fusion *** serial robots can provide the orientation capability required to weld along curved surfaces,they cannot adequately support the huge axial downward forces that FSW *** parallel mechanism architectures,particularly redundantly actuated architectures for FSW,are still very *** this paper,a redundantly actuated 2 UPR-2 RPU parallel robot for FSW is proposed,where U denotes a universal joint,R denotes a revolute joint and P denotes a prismatic ***,its semi-symmetric structure is ***,inverse kinematics analysis involving an analytical representation of rotational axes is *** analysis is also conducted,which leads to the formation of a Jacobian *** performance is evaluated utilizing level set and convex optimization methods,where the local sensitivity indices are unit consistent,coordinate free,and of definite physical ***,global and hierarchical sensitivity indices are proposed for the design ***,dimension synthesis is conducted based on the sensitivity indices and the optimal link parameters of the parallel robot are *** summary,this paper proposes a dimensional synthesis method for a redundantly actuated parallel robot for FSW based on sensitivity indices.

关键词： Parallel robot Actuation redundancy Sensitivity Optimization Friction stir welding

Dynamic characteristics of dwarf Chinese hickory trees under impact excitations for mechanical fruit harvesting

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International Journal of Agricultural and Biological Engineering 2015年第1期8卷 17-25页

作者： Du Xiaoqiang Wu Chuanyu he leiying Tong Junhua School of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Zhejiang Province Key Laboratory of Transplanting Equipment and Technology Hangzhou 310018China

Mechanical vibration is an effective fruit harvesting *** evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and attenuation of dynamic response,a new method was proposed based on acceleration admittance measurement on dwarf Chinese hickory trees in orchard environment under impact *** primary resonance frequencies of the tree can be determined based on the acceleration admittance *** effect of the tree structure on the vibratory transmission was quantified using the attenuation ratio of the acceleration admittance.A 5-year-old dwarf Chinese hickory tree sample was *** responses at three resonance frequencies(5,9 and 12 Hz)were analyzed because they were identified as the most effective bands of excitation for the main part of the tree *** results reveal that the variation of the dynamic response along the testing tree is greatly related to the Chinese hickory tree *** attenuation ratio of the acceleration admittance at the branch crotches indicates the leader top crotch may amplify the acceleration admittance no matter what the crotch angle and the branch diameter *** the crotches,the branch chain nodes generally have negative influence on the acceleration admittance along the branch chains which heavily depend on the branch chain *** branch chains with a chain angle no less than 150°and a wood diameter ratio close to 1.0 could produce little influence on the vibration *** those branches with chain angle less than 150°,the vibration was generally attenuated at their chain nodes at three resonance *** impose impact excitations on the tree,high mechanical harvesting efficiency could be achieved on those branch chains which are almost straight and uniform.

关键词： Chinese hickory mechanical harvest fruit acceleration admittance vibration transmission impact test

Design and Experimentation of Automatic Tidying and Sorting Mechanism for Blood Collection Needles in Stacking State

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Chinese Journal of Mechanical Engineering 2019年第4期32卷 73-84页

作者： Junhua Tong Yingpeng Zhu leiying he Chuanyu Wu Peilin Cheng Faculty of Machinery and AutoMation Zhejiang Sci-Tech University Hangzhou 310018China Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province Hangzhou 310018 China

Disposable blood collection needles become severely intertwined and hooked during stacking, and thus individually feeding disposable blood collection needles during mechanical packaging is di cult. Based on the physical characteristics of the blood collection needles during the stacking state, this study designed an automatic tidying and sorting mechanism by combining compound vibration, sorting, and conveying. During the feeding process, the compound vibration-type material-tidying mechanism tidies 20-30 blood collection needles first;then, the material sorting and conveying mechanism transports the tidied blood collection needles individually. The orthogonal testing of the automatic material tidying process shows that various experimental factors are ranked by the significance level of the e ect on the tidying process and the significance ranking is as follows: vertical vibration frequency > horizontal amplitude > vertical amplitude > horizontal vibration frequency. Experiments were performed after analyzing the optimal combination. The results demonstrate that when the horizontal vibration frequency is 1.7 Hz, the horizontal amplitude is 150 mm, vertical vibration frequency is 1.3 Hz, vertical amplitude is 30 mm, and material length after tidying is 265 mm. The automatic sorting and conveying experiment shows the e ect of various experimental factors on the feed rate of the material, where the significance level of the e ect is ranked as follows: vibration frequency > material quantity > channel dip angle. The experimental results show that when the number of materials is 25, the channel dip angle is 12°, and vibration frequency is 52.5 Hz. The material delivery e ciency reaches 0.51 s/root, meeting the requirement of five channels for 80000 root/day feeding e ciency. The study can provide reference for the realization of automatic feeding of large aspect ratio flexible materials in similar stacking state.

关键词： Packaging Automatic feeding Stacking state Automatic tidying Sorting and conveying

High-efficiency tea shoot detection method via a compressed deep learning model

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International Journal of Agricultural and Biological Engineering 2022年第3期15卷 159-166,F0003页

作者： Yatao Li leiying he Jiangming Jia Jianneng Chen Jun Lyu Chuanyu Wu Faculty of Mechanical Engineering&Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province Hangzhou 310018China School of Information Science and Technology Zhejiang Sci-Tech UniversityHangzhou 310018China

Achieving high-efficiency and accurate detection of tea shoots in fields are essential for tea robotic plucking. A real-time tea shoot detection method using the channel and layer pruned YOLOv3-SPP deep learning algorithm was proposed in this study. First, tea shoot images were collected and data augmentation was performed to increase sample diversity, and then a spatial pyramid pooling module was added to the YOLOv3 model to detect tea shoots. To simplify the tea shoot detection model and improve the detection speed, the channel pruning algorithm and layer pruning algorithm were used to compress the model. Finally, the model was fine-tuned to restore its accuracy, and achieve the fast and accurate detection of tea shoots. The test results demonstrated that the number of parameters, model size, and inference time of the tea shoot detection model after compression reduced by 96.82%, 96.81%, and 59.62%, respectively, whereas the mean average precision of the model was only 0.40% lower than that of the original model. In the field test, the compressed model was deployed on a Jetson Xavier NX to conduct the detection of tea shoots. The experimental results demonstrated that the detection speed of the compressed model was 15.9 fps, which was 3.18 times that of the original model. All the results indicate that the proposed method could be deployed on tea harvesting robots with low computing power to achieve high efficiency and accurate detection.

关键词： deep learning tea shoot detection model compression high-efficiency

基于双轮廓同步跟踪的果树枝干提取及三维重建

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农业工程学报 2014年第7期30卷 182-189页

作者：贺磊盈武传宇杜小强浙江理工大学机械与自动控制学院杭州310018 浙江省种植装备技术重点实验室杭州310018

自适应果实振动收获是利用机器视觉技术识别果树的几何参数,从而分析其动力学特性并用来自动调整振动设备的参数,达到高效低损伤的作业目的。该文以自然生长的无叶山核桃树为研究对象,根据果实自适应振动收获方式的需要,研究了一种基于... 详细信息

自适应果实振动收获是利用机器视觉技术识别果树的几何参数,从而分析其动力学特性并用来自动调整振动设备的参数,达到高效低损伤的作业目的。该文以自然生长的无叶山核桃树为研究对象,根据果实自适应振动收获方式的需要,研究了一种基于双轮廓同步跟踪提取果树枝干并利用双目视觉技术进行三维重建的方法。首先结合自适应阈值分割算法和轮廓跟踪技术提取果树枝干区域,细化后得到枝干骨架并用二叉树结构描述。然后根据极线约束和拓扑结构建立双视图中树枝的对应关系。考虑到果树树枝形状的连续性,在三维重建过程中引入了曲率约束,从而提高了重建的效果。最后利用植物学的营养管道输送模型,结合线性回归方法参数化树枝半径。试验结果显示,重建的三维果树枝干形态与真实果树在视觉上很接近,估计的半径与测量半径之间的相对误差小于9%。该研究可为果树动力学模型的创建提供树体的3D结构参数,从而为果实的自适应振动收获技术提供参考。

关键词：机器视觉模型线性回归三维重建轮廓跟踪二叉树结构曲率约束

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基于机器视觉的幼苗自动嫁接参数提取

农业工程学报 2013年第24期29卷 190-195页

作者：贺磊盈蔡丽苑武传宇浙江理工大学机械与自动控制学院杭州310018

为提高果蔬嫁接机器人的自动化水平,该文提出一种基于机器视觉用椭圆拟合的方法恢复幼苗叶面并提取用于机器人自动嫁接的参数的方法。俯视采集幼苗图像,提取叶面轮廓并根据轮廓上的拐点对组合相同叶面上的轮廓弧段。应用椭圆拟合的方法... 详细信息

为提高果蔬嫁接机器人的自动化水平,该文提出一种基于机器视觉用椭圆拟合的方法恢复幼苗叶面并提取用于机器人自动嫁接的参数的方法。俯视采集幼苗图像,提取叶面轮廓并根据轮廓上的拐点对组合相同叶面上的轮廓弧段。应用椭圆拟合的方法参数化叶面形状,提取幼苗的叶面参数,包括生长方向、生长点和叶面面积。再由生长点准确定位培育幼苗的穴孔位置,从而为砧穗配对和取苗定位提供依据。试验结果表明提出的算法能够克服叶面相互遮挡的问题,幼苗识别且定位的成功率达到97.5%,能满足嫁接机器人自动作业的要求。

关键词：机器视觉参数提取嫁接椭圆拟合叶面恢复拐点提取

一种可整周回转的新型3T1R并联机构运动学分析

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机械工程学报 2018年第11期54卷 151-160页

作者：贺磊盈涂叶凯叶伟李秦川浙江理工大学机械电子工程系

具有3移动1转动（3T1R）4自由度并联机构在工业领域具有广泛的应用潜力。然而绝大多数现有的3T1R并联机构的动平台转动范围小于90°。提出一种具有整周回转能力的3T1R并联机构。该机构动、静平台通过两根相同的混联分支（PRR）2RH相连... 详细信息

具有3移动1转动（3T1R）4自由度并联机构在工业领域具有广泛的应用潜力。然而绝大多数现有的3T1R并联机构的动平台转动范围小于90°。提出一种具有整周回转能力的3T1R并联机构。该机构动、静平台通过两根相同的混联分支（PRR）2RH相连接。通过两个共轴、反向的等螺距螺旋副来实现动平台的整周回转能力。运用李群理论分析了机构的自由度。建立闭环约束方程对机构进行了位置正、反解计算。通过速度分析建立了雅可比矩阵,并在此基础上对机构进行了奇异分析,找到了所有的奇异位形。分析了机构的工作空间,以条件数作为性能指标,绘制了机构在工作空间内的性能分布图。研究结果为该机构后续的优化设计、动力学建模提供了理论基础。

关键词：并联机构整周回转奇异分析工作空间

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基于视触觉感知的番茄尺寸和姿态解析方法

农业机械学报 2024年第1期55卷 223-232页

作者：马锃宏谭励曾伟贺磊盈杜小强浙江理工大学机械工程学院杭州310018 浙江省种植装备技术重点实验室杭州310018 农业农村部东南丘陵山地农业装备重点实验室(部省共建) 杭州310018

针对传统农业机器人抓取过程中视觉识别番茄果实尺寸和姿态存在枝叶遮挡的问题,提出了一种基于视触觉感知的番茄尺寸和姿态解析方法。在果实抓取过程中通过视触觉传感器得到果实外轮廓接触局部点云信息,然后通过相机参数标定以及各手指... 详细信息

针对传统农业机器人抓取过程中视觉识别番茄果实尺寸和姿态存在枝叶遮挡的问题,提出了一种基于视触觉感知的番茄尺寸和姿态解析方法。在果实抓取过程中通过视触觉传感器得到果实外轮廓接触局部点云信息,然后通过相机参数标定以及各手指关节变换矩阵,将不同传感器坐标系下的点云信息变换到同一基坐标系下,进而通过点云改进PCA算法和ICP算法解析抓取果实的尺寸和姿态信息。为了评估所提出解析方法的性能,在实验室环境下进行了番茄尺寸和姿态检测试验。通过游标卡尺测量和深度相机扫描分别获得番茄果实尺寸和姿态的真实值,并与本文方法解析结果进行对比。检测试验结果表明,本文方法获得的番茄横向尺寸和纵向尺寸平均相对误差分别为8.66%和11.08%,番茄果轴与视场投影面的水平夹角和垂直偏转角平均相对误差分别为10.03%和14.02%。本文方法解析的番茄果实尺寸与姿态信息,可应用于番茄果实抓取过程中的姿态调控,从而提高番茄果实抓取采摘的可靠性。

关键词：番茄采摘视触觉传感器尺寸与姿态解析 PCL点云库改进PCA算法 ICP算法

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鞋底曲面数据提取与喷胶轨迹的自动生成方法

机械工程学报 2008年第8期44卷 85-89,96页

作者：武传宇贺磊盈李秦川胡旭东浙江理工大学浙江省现代纺织装备技术重点实验室杭州310018

为快速有效地提取鞋底曲面信息和生成喷胶轨迹,提出一种基于线结构光扫描鞋底曲面的方法。利用线结构光三维测量原理,扫描套在鞋楦上的鞋帮底面,获得表示鞋底曲面信息的点云数据。用B样条曲线拟合出一系列的三维扫描线,生成封闭的鞋底... 详细信息

为快速有效地提取鞋底曲面信息和生成喷胶轨迹,提出一种基于线结构光扫描鞋底曲面的方法。利用线结构光三维测量原理,扫描套在鞋楦上的鞋帮底面,获得表示鞋底曲面信息的点云数据。用B样条曲线拟合出一系列的三维扫描线,生成封闭的鞋底轮廓线,计算鞋底轮廓线在鞋底曲面的偏置曲线得到喷胶轨迹。构建线结构光扫描鞋帮底面的试验装置,计算其在x、y和z轴方向上的测量误差分别为0.094、0、0.015 mm,满足系统精度要求。最后将生成的喷胶轨迹通过坐标变换应用于St(?)ubli机器人自动喷胶系统,验证了方法的有效性和可行性。

关键词：线结构光轨迹 B样条插值