基于虚拟仿真的龙门机器人板材智能分拣系统及方法

在木门加工生产线上,针对龙门机器人对不同尺寸板材分拣的需求,本文提出了一种基于虚拟仿真的龙门机器人板材智能分拣实验系统。该系统基于Unity3D软件平台开发,搭建了龙门机器人分拣任务虚拟仿真场景,并在虚拟仿真实验场景中完成了虚拟数据集采集、相机标定以及手眼标定。针对不同尺寸的板材分拣任务,本文提出了基于板材的矩形角点势自适应识别的智能分拣算法,首先利用目标检测模型在局部区域内对板材进行角点检测,由双目成像原理恢复出的角点三维坐标计算板材尺寸和目标板材的抓取位姿,以此完成木门的分拣。该方法在相机采集图像过程中出现板材被遮挡的情况以及在板材复杂纹理和复杂背景的情况中更为鲁棒。此外,该方法完全在虚拟仿真环境下进行开发测试,不仅节约成本、安全高效而且方便进行多种测试方案的改变,对于向真实场景进行算法迁移和开发具有积极作用。实验结果表明,本文提出的方法可以完成龙门机器人板材智能分拣任务,对设计木工家具制造过程中龙门机器人智能分拣系统具有指导意义。     

一种通用的工业机器人位姿检测方法

为满足带有不同末端执行器的工业机器人系统的绝对位姿检测需求,提出一种通用的检测方法。其基本原理是以激光跟踪仪测量固定在机器人末端的4个参考点从而间接测量机器人的绝对位姿,并与指令位姿比较实现机器人位姿准确度和位姿重复性检测;其中,参考点坐标及机座坐标系通过多姿态约束同步标定,并设计非线性标定算法。通过末端带有制孔执行器的KUKA KR210 R2700工业机器人的位姿检测实验表明：该检测方法的准确性可满足机器人位姿检测的需要,且无需特殊的机械工装,具有良好的通用性;基于多姿态约束的非线性标定方法具有良好的鲁棒性,可有效的减小因机器人运动模型不准确引起的标定误差。     

改进最小二乘法双目视觉位姿测量技术研究与测试

由于工件表面油污、光照等因素干扰导致工件图像提取的特征点偏离实际位置,对工业机器人的抓取定位带来较大误差。该文以视觉引导工业机器人抓取气缸盖为应用对象,对双目视觉高准确度位姿测量技术进行分析。首先探讨特定条件下的双目视觉定位引导机器人技术以及粗差点产生原因与解决方法情况;其次介绍视觉系统视觉坐标系和目标坐标系,然后在位姿测量数学模型的基础上提出改进最小二乘法的准确计算方法,并搭建双目视觉引导的工业机器人抓取气缸盖系统进行测试分析。测试表明:改进最小二乘法的位姿计算方法可实现双目视觉对目标物的全自由度位姿测量,满足工业机器人高准确度抓取操作。     

多传感信息融合机器人标定方法

该文提出一种基于多传感信息融合技术进行机器人运动学标定的方法。首先通过对机器人的指数积(POE)正向运动学模型取微分的方式建立末端执行器的误差模型,利用ROMER-RA7520绝对关节臂测量机和安装在末端工具上的多个传感器分别采集末端执行器的位置和姿态信息;随后根据坐标统一原理将测量机的位置测量数据和多传感器的姿态量测数据转换到机器人基础坐标系下,实现位姿数据的空间配准;接着运用自适应加权融合算法融合处理经过空间配准后的位姿数据,得到末端执行器位姿测量值;最后应用迭代最小二乘法求解出参数偏差。KR5arc机器人标定仿真实验表明:该方法可大幅度提升机器人在任意位姿下的定位、定姿精度。     

基于锥孔靶标的机器人末端位姿间接测量方法

机器人的位姿误差是衡量机器人性能的重要指标,因此位姿测量是机器人校准过程中的重要环节。为简化机器人末端位姿测量过程,提出一种间接测量方法。首先设计靶标并建立靶标坐标系、将靶标安装在法兰盘上、标定出两者之间的转换关系;然后利用绝对关节臂测量机测量靶标上的锥孔,采用最小二乘法并结合靶标坐标系与法兰盘坐标系之间的转换矩阵计算出机器人末端位姿,并分析测量误差对位姿误差的影响;最后对KR5arc工业机器人末端位姿进行测量。实验表明:该间接测量方法相较于直接测量方法的优点在于不仅可以保证测量结果的准确度,而且可提高测量结果的紧密度、大大简化测量过程。     

立体偏折术的高效标定及法线计算方法

法线计算和系统位姿关系标定是立体偏折术测量的关键技术。针对法线匹配,在立体视觉极线准则的基础上采用假设点的方法,将法线计算转化为一维搜索法线夹角最小值问题。通过查找两个相机对应同一采样点的法线夹角的最小值来获取镜面梯度,最终通过径向基插值函数从梯度数据中恢复镜面精确面形。针对系统位姿关系标定,提出采用将标定板和镜面相结合的位姿关系标定方法。将标定板的厚度纳入标定模型中,提高了标定精度。该方法只需一个镜面反射图像即可确定相机和显示屏幕的位姿关系,使标定过程更加自由和灵活。初步实验验证了所提方法的可行性。     

机器人定位精度标定技术的研究

机器人末端位姿的精度依赖于各连杆几何参数的精度。为了提高机器人的位姿精度，需要对机器人进行标定，为此必须研究机器人运动学模型的建立方法。基于MDH模型和微分运动学，识别出机器人的各个连杆几何参数误差对机器人位姿精度影响程度，并结合最小二乘算法，对机器人的定位精度进行修正。实验表明，该方法适合对机器人几何参数误差的标定，并且能够提高机器人的综合性能。     

基于视觉的工业机器人码垛系统设计与分析

目的 为提高企业工件的码垛效率,降低工人劳动强度,搭建工业机器人视觉码垛实验系统.方法 在对工业机器人运动学模型分析的基础上,通过相机坐标系和末端坐标系的坐标关系,得到工业机器人末端执行器的位置和姿态信息.结果 提出了基于工件位置坐标的图像剔除算法,实现了多余工件图像的剔除.通过旋转平移矩阵计算待码垛工件的实际位置,并将此位置作为视觉校正后的工业机器人抓取工件位置.结论 实验结果显示改进后系统的重复性定位精度在x,y方向上均有显著提高,验证了工业机器人视觉码垛系统模型的准确性.     

基于多目红外视觉的室内无人车导航系统研究

该文设计了一套基于视觉的室内无人车导航系统。首先,搭建多目红外相机运动跟踪系统实验场地;其次,使用一维标定法对相机参数和位姿进行求解;再次,根据相机成像模型对空间点进行三维重建,实现对空间点的定位;最后,基于STM32芯片设计一套无人车控制系统,实现对无人机轨迹的控制,并使用多目红外系统对无人车进行定位导航。实验结果表明,该系统成功实现了对无人车的运动跟踪,可用于无人车室内自动导航、机器人运动精度检测等领域。     

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.     

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.     

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.     

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.