一种基于线扫描相机的手眼标定技术

提出一种以固定点变位姿的方法标定线激光扫描相机与机器人的手眼关系,该方法分为两步标定出手眼矩阵,采用直径已知的标准球作为固定点靶标,首先控制机器人以平移的方式运动至少3次,然后机器人任意位姿运动至少4次;每次运动后用机器人末端执行器上安装的线激光扫描器扫描靶球,获取靶球表面轮廓上一列点云,对点云进行空间圆拟合,进而求出靶球的球心空间坐标;最后根据约束关系可列出方程,用最小二乘法或者奇异值分解求解手眼关系。实验结果表明:该方法快捷有效计算量较小,标定精度在0. 2mm左右,可以用于线激光扫描相机与机器人现场手眼标定。     

激光线扫描测量系统中物像对应关系的建立

提出一种基于样本线建立物像对应关系的标定法。该方法采用三棱柱作为标定块,标定块在标定范围内运动,得到样本线上的点。样本点的像由三棱柱两个棱面上的光带中心线用最小二乘法拟合直线求取交点的方法计算,所得像点到拟合样本线的最大偏差小于 0.1 像素。样本线将标定空间划分为 4 个子域,每个子域用线性插值的方法建立各自的映射关系。在自行设计的激光线扫描测量系统中采用该标定法,实际测量标准平面与球面的误差小于±0.05mm。     

曲面复合材料缝合机器人自动路径规划技术

为提高复合材料预制件缝合机器人的灵活性与加工柔性,针对缝合机器人自动路径规划问题,研究了基于三维光栅扫描技术的曲面复合材料缝合机器人视觉接缝提取技术.针对三维扫描摄像机视场固定的特点,对摄像机进行标定实验,改进传统的手眼标定方法,提出一种用于求解手眼关系矩阵的四点标定新方法,建立了机器人坐标系与摄像机坐标系的位姿映射关系.经过手眼关系标定,三维光栅扫描仪采样得到的缝合预制件点云数据可转化为机器人坐标系下的点云数据坐标.进一步对采集的预制件点云数据进行接缝中心线提取,提出了一种缝合轨迹及姿态规划算法,采用三次多项式对接缝中心线进行空间曲线拟合,采用最小二乘法对缝合微切平面进行平面拟合,完成机器人操作空间前进矢量及接近矢量的计算.最后,将规划结果应用于缝合机器人的离线编程仿真与实验中.实验结果表明,该系统精度高,线迹成型良好,可以满足机器人缝合系统的要求.     

三维激光扫描法船舶液货舱容量标定及其不确定度评定

船舶液货舱计量准确性关系到贸易双方的切身利益,三维激光扫描仪应用在船舶舱容量标定具有快速、准确的优势。三维激光扫描法船舶液货舱容量标定包括现场扫描、点云后处理和舱容生成三个步骤,其相对扩展不确定度达到0. 06%(k=2)。     

异形热态锻件几何尺寸测量方法的研究

提出一种异形热态锻件几何尺寸测量方法。基于线激光器、CCD和伺服系统构建线激光扫描测量系统,通过提取图像上被锻件表面轮廓调制的激光条纹二维信息,经过坐标变换及点云三维重构得到锻件三维尺寸信息。针对被测异形锻件形貌特征,建立基于摄像机运动的扫描测量模型,并提出一种基于棋盘参考平面的摄像机光心轨迹求解方法。根据平面上特征点在CCD图像不同帧中的坐标拟合摄像机的运动轨迹,结合扫描测量模型实现对异形锻件完整轮廓尺寸的测量。通过实验对封头进行扫描测量,得到球冠部分截面测量直径误差小于4 mm,满足热态锻件测量要求,验证了该方法的可行性。     

基于激光轮廓扫描的核电站管道管径测量方法

核电站停堆检修维护中,需进行管道检测,管道检测机器人实现核电站管道检测自动化作业的时候需对管道管径进行测量,确定使用对应的产品工具。本文研究了一种基于激光轮廓扫描的核电站管道管径检测方法。该方法采用高精度激光轮廓扫描仪,对检测管道进行扫描,通过RANSAC优化算法,对扫描得到的点云进行圆拟合,得到管道的精确管径。实验表明,该方法能去除数据点云中的干扰和采样误差,能精确测量管道的管径,绝对误差小于±0. 1mm,满足核电站自动化检测的需要。     

面向机器人标定的单激光跟踪仪顺序多站式测量系统建模与分析

为实现大型串联工业机器人的高精度标定,搭建了一种单激光跟踪仪的顺序多站式测量系统。该系统仅需单台激光跟踪仪,先后在不同的基站位置对工业机器人的末端位置进行独立测量,并基于多边测量方法计算机器人的末端位置。计算过程中仅需激光跟踪仪的距离信息,有效地优化了末端位置的测量不确定度。首先,建立了该测量系统的仿真模型,深入地分析了测量点的数量与分布形状、测量距离以及工业机器人定位精度等因素对系统测量精度的影响;然后,依据分析结果确定单激光跟踪仪顺序多站式测量系统的搭建方案。实验结果表明:该系统在2.5m距离上的测量误差仅为0.023mm,优于激光跟踪仪的测量精度,满足大型串联工业机器人参数标定的测量精度要求。     

线结构光视觉传感器机器人手眼关系标定

为实现对工业机器人手眼关系的标定,提出一种基于线结构光视觉传感器的手眼关系标定方法。该方法在标定时,将一个平面靶标作为参考物固定在工业机器人工作空间内,控制工业机器人末端运动以带动线结构光视觉传感器作多组变位姿运动,获取在不同位姿状态下的平面靶标图像并对其进行图像处理。通过对图像上固定特征点的测量,以及建立线结构光视觉传感器模型和手眼关系模型实现对线结构光内参数和手眼关系的标定。用棋盘格标定板进行测量实验验证,实验结果表明该方法准确度为0.036 mm,即优于40μm,可用于工业机器人的测量应用。     

光学三维扫描仪自由曲面测量评价方法的研究

基于光学方法的三维扫描仪是获取自由曲面数据的最主要的技术手段.为了有效评价光学三维扫描仪的自由曲面测量能力,提出一种便于溯源的自由曲面标准器的设计方法.该标准器由不同高度的标准球球阵组成,标准球之间的相互位置由数学函数生成的曲面抽样点确定.通过比较各个球心之间的扫描数据与标准数据,实现光学三维扫描仪测量能力的评价.该标准器的校准可以利用三坐标测量机完成,易于实现量值溯源.     

激光三维雕刻中扫描算法的研究

采用分层制造原理研究激光三维雕刻技术.在对现有激光扫描方式进行分析的基础上,从算法实现的难易程度、扫描效率及对硬件性能的要求等方面综合考虑,确定将直线扫描作为激光三维雕刻的扫描方式.给出了激光三维雕刻中直线扫描的原理,详述了扫描线生成算法并实现阴刻及阳刻扫描.针对直线扫描中存在的不足,提出并实现了一种新的直线扫描算法.应用结果表明,该算法稳定可靠、效率高,完全满足激光三维雕刻中的扫描需求.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.