基于末端开环视觉系统的机器人目标抓取研究

以MOTOMAN-SV3X机器人、摄像机和传动带为基础,构建了一个基于机器视觉的机器人目标抓取系统.本系统中摄像机和机器人分别布置在传动带两端,其工作原理为:利用视觉定位和系统标定结果,经过坐标系转换将位姿信息转化到机器人基础坐标系中,然后根据位姿信息进行运动学逆解得相应的控制文件,最终实现摄像机在一端拍摄,机器人在另外一端对目标进行抓取.抓取实验结果验证了此系统的可行性和实用性,为提高生产线的自动化程度提供了一种新的方法,对后续的相关研究做了铺垫.     

基于视觉的运动目标跟踪抓取和装配研究

为提高家电装配生产线自动化水平和生产节拍,提出采用基于机器视觉的跟踪抓取和装配系统代替人工进行分拣上料和装配工作。使用Open CV进行摄像机内外参数标定,运用基于1DPHT方法求取目标位姿,采用卡尔曼滤波算法对目标位置进行跟踪预测。并搭建基于SCARA机器人的视觉跟踪抓取平台和基于6R机器人的装配平台,实验表明该系统能够实现2D空间移动目标的有效抓取和装配,且工作效率和精度较高。     

基于机器视觉的机器人作业目标定位

为了满足生产制造过程中物料无序分拣的需要,设计基于机器视觉的机器人作业目标定位系统。利用Qt开发人机交互界面,实现图像采集处理、通信和机器人运动控制功能。对图像进行阈值分割等处理,得到理想工作区域。通过机器人视觉系统标定实现相机像素坐标和机器人基坐标之间的转换,得到机器人坐标系下的工件位姿识别。在机器人目标抓取平台上随机摆放一定数量的工件进行数据采样,结果表明：系统准确度以及速度具有优势。     

机器视觉主导的机械臂动态抓取策略研究

针对传统工业机器人在移动目标的抓取中存在灵活性和位姿适应能力差的问题,以开源机器人操作系统（ROS）为平台进行基于视觉反馈的动态抓取策略研究。在ROS中搭建UR5机械臂动态抓取系统,并对机械臂进行正逆运动学分析;提出基于RGB颜色空间和SITF算法结合的新型特征识别方法以提高识别效率;设计注视逼近的视觉反馈控制策略,实现机械臂对传送带上移动目标的抓取操作。结果表明：所提策略识别成功率达到99.6%,逼近抓取成功率达到98.33%,验证了机器视觉主导的反馈抓取算法基本满足工程实际应用,有较高的可行性和准确性。     

基于视觉引导的FANUC机器人抓取系统研究

针对目前工业机器人上料时大都采用预先示教的方式,一旦工作条件发生变化就会导致抓取失败的问题,研究了一种基于视觉引导FANUC机器人的抓取系统,提高了机器人柔性化抓取能力。系统采用单目视觉定位方法:将图像中的特征点通过相机标定参数、Eye-in-Hand手眼标定参数转换为机器人基坐标系下的位姿,利用FANUC Robot Interface实现上位机与机器人通信并把定位结果发送到机器人位置寄存器,引导机器人运动到相应位置并通过末端执行器完成对空心圆柱体工件的抓取。经过多次抓取实验数据分析,该系统定位误差在0.5mm以内,具有很好的实际应用价值。     

基于单目视觉的工业机器人拆垛系统设计与实验

基于单目视觉提出了工业机器人拆垛系统构想。为实现工业机器人视觉拆垛系统中机器人精确运动控制与工件位姿识别,运用D-H位移矩阵法建立了机器人运动学模型,得到机器人末端相对机器人坐标系的位姿信息。基于形状模板匹配法提出目标图像识别算法,得到各个目标图像在相机坐标系下的位姿信息;将三维视觉模型与机器人运动学模型进行信息融合,建立机器人视觉拆垛控制系统数学模型。基于CCD工业相机、4-DOF工业机器人搭建视觉定位抓取实验系统。通过对空间目标进行抓取的实验,验证基于单目视觉的工业机器人拆垛系统的正确性、精确性、鲁棒性。     

基于机器视觉的Delta机器人分拣与跟踪系统设计

为了提高Delta机器人动态抓取的精度与速度,提出了一种基于欧姆龙NJ控制器的Delta机器人控制系统。通过采用欧姆龙NJ运动控制器和EtherCAT内部高速总线将Delta机器人的运动控制和外部运动逻辑控制进行无缝对接,实现一体化控制。同时为了提高抓取效率,利用Delta机器人视觉系统识别抓取目标的位置,去掉重复图像信息,进而提出一种动态的抓取算法,实现了机器视觉与机器人动态抓取的完美结合。通过对样机进行测试表明:该Delta机器人在分拣与跟踪目标过程中漏抓率小于2%,误抓率为0,表明该系统能够达到抓取系统的实时性要求,在实际工程中具有一定的应用价值。     

基于Sysmac自动化平台的Delta机器人控制系统设计

为了提高Delta机器人在自动化拾取作业中的控制精度、速度及系统的实时性和可靠性,提出基于欧姆龙Sysmac自动化平台对Delta机器人控制系统进行设计,采用NJ系列机器人控制器和控制用高速网络EtherCAT,将机器人的运动控制和周边运动的逻辑控制进行统一,实现一体化控制,并通过视觉系统判断抓取对象的位置偏差,实现精确定位,展现机器人与视觉系统的完美配合。验证工作基于Delta机器人的动态抓取实验平台展开,顺利地完成了"检测—跟踪—抓取—搬运"实验,实验结果充分证明了方案的可行性。     

基于机器视觉的工件分拣及上下料系统

为了解决传统工业机器人无法对多个不定位姿的工件进行分拣抓取的问题,搭建一套基于机器视觉的零件分拣及上下料系统。所搭建系统能够较准确地对铝件和有机玻璃件进行分拣,并对工件的位姿进行识别,最后将结果换算到机器人的世界坐标系下,对工件进行准确抓取和上下料。其中针对工件的分拣,提出了通过条形码进行识别分拣的方法,此方法简单有效,快速便捷。对与背景对比度不高的透明有机玻璃件的位姿识别,提出一种自适应调参线性变换方法,从而准确识别出透明件的位姿信息。经实验测试,所搭建系统具有较高的准确性。     

基于视觉的工业机器人离线编程系统的设计

针对传统离线编程系统通用性差、可靠性低和二次开发难度大等问题,开发一套基于机器视觉的工业机器人离线编程系统。基于模块化思想,将该系统划分为机器视觉模块、虚拟环境模块、运动学模块、轨迹规划模块、离线程序模块和外部通信模块。借助机器视觉模块解构视觉系统与机器人末端位姿的坐标映射关系,得到规划机器人运动所需的位姿数据;基于虚拟现实建模语言构建机器人虚拟仿真环境,基于运动学模块与轨迹规划模块将位姿数据转化为机器人的作业〖JP2〗指令;基于离线程序模块与外部通信模块实现控制器指令与虚拟仿真环境的无缝衔接。最后,以一种六轴工业机器人为测试对象验证了该离线编程系统的基本功能。实验结果表明:该系统定位误差最大为0.4 mm,精度高,可满足工业应用需求。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

FORMULAS OF TENSION OF CONTINUOUS ROLLING PROCESS

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.     

A Concordant Shift Model for Flow in Bulk Metallic Glasses

The homogeneous plastic flow in bulk metallic glasses(BMGs) must be elucidated by an appropriate atomistic mechanism. It is proposed that a so-called concordant shifting model, based on rearrangements of five-atom subclusters,can describe the plastic strain behaviour of BMGs in a temperature range from room temperature to the supercooled liquid region. To confirm the effectiveness of the atomic concordant shifting model, a comparative investigation between the vacancy/atom model and the concordant shifting model is carried out based on the estimation of the strain rate deduced from two models. Our findings suggest that the atomic concordant shifting model rather than the vacancy/atom exchange model can well predict the large strain rate in the superplasticity of BMGs.