微间隙焊缝磁光成像卡尔曼滤波跟踪算法

在激光对接焊过程中,实时控制激光束准确对中焊缝是保证焊接质量的前提。针对紧密对接激光焊,研究一种用于微间隙(不大于0.1 mm)焊缝位置识别及跟踪的磁光成像卡尔曼滤波算法。采用磁光传感器实时获取焊接区域的微间隙焊缝磁光图像序列,利用微间隙焊缝磁光图像的灰度梯度特征提取焊缝位置坐标。以焊缝位置及位移量构成状态矢量,建立描述焊缝位置的状态方程和测量方程。同时,假设系统动态噪声和测量噪声为零均值随机分布的高斯白噪声,建立噪声环境下的卡尔曼滤波跟踪算法,计算最小均方差条件下焊缝中心最优预测值,减小系统噪声和过程噪声对焊缝位置测量的影响。试验结果显示,该方法能有效实现激光对接焊微间隙焊缝位置的识别与跟踪。     

角点检测与光流跟踪的焊缝特征提取与定位研究

针对V型坡口中厚板对接焊焊缝特征点检测精度不高的问题,研究了一种基于激光视觉传感的角点检测与光流(LK)跟踪的焊缝特征快速提取与定位方法。根据三角测量原理,设计了能够实时检测焊缝特征图像的激光视觉传感器,并建立了由激光条纹特征点像素坐标到焊缝特征点三维坐标的数学模型;对焊缝图像进行了预处理,采用Shi-Tomasi角点检测提取了焊缝特征;最后使用光流法为后续帧匹配特征角点,实时计算出了图像中焊缝特征点的亚像素位置。研究结果表明:基于角点检测与光流法跟踪的焊缝特征提取与定位方法,其特征点检测精度较高,平均误差在±0.13 mm以内,可以实时、准确地识别焊缝特征。     

斜率表征与卡尔曼滤波的焊缝跟踪方法研究

针对V型坡口中厚板对接焊焊接过程中存在的系统噪声和测量噪声的问题,采用了斜率分析与卡尔曼滤波相结合的方法进行了焊缝跟踪。使用激光视觉传感系统采集了V型坡口的条纹图像,获取了测量系统内外标定参数,通过锯齿靶标建立了焊缝特征点坐标转换模型;提出了一种基于极值法的边界约束灰度平方加权重心法,提取出了激光条纹线的中心点,采用斜率分析法寻找到了激光条纹中心线拐点,对每一段条纹中心线通过最小二乘法拟合求交,提取出了焊缝特征点;利用卡尔曼滤波方法对系统噪声和测量噪声进行了优化;对V型坡口进行了厚板对接焊试验,焊炬能始终对准焊缝中心。研究结果表明:基于斜率分析法与卡尔曼滤波的焊缝跟踪方法能够减小系统噪声干扰的影响,实现了焊缝特征点的准确提取,提高了焊缝跟踪精度。     

激光焊接焊缝显微组织磁光成像研究

针对焊缝显微组织对焊件质量影响问题,对激光焊接焊件不同区域的焊缝显微组织特征进行研究,对不同焊接试验参数下的焊缝成形差异进行分析,提出了一种焊缝显微组织磁光成像检测方法,采用低碳钢平板对接焊,试验共分为4组,将焊缝显微组织磁光图像与扫描电镜图像相结合,分析恒定磁场下不同区域焊接接头的显微组织磁光成像差异和焊缝的晶粒组成及特征。研究结果表明,在磁光图像中焊件焊缝可以分为熔合区、热影响区和母材区,且这3个区域的晶粒组成、大小及形态有明显的差异,恒定磁场下焊缝磁光图的颜色、亮度及灰度值反映了焊缝的成形质量。     

基于结构光视觉的激光拼焊焊缝质量检测方法研究

在基于结构光视觉的激光拼焊焊缝表面质量检测系统中,需要准确获得焊缝结构光条纹中心线和特征点的位置.由于焊接过程中的各种噪声干扰,使得焊缝图像复杂多变,因此选择合理高效的图像处理算法是非常重要的.针对这一问题,对结构光视觉焊缝质量检测系统图像处理方法进行了深入研究.在图像预处理中,首先通过开窗处理来获得兴趣区域,采用中值滤波去除图像噪声.在结构光条纹中心线提取过程中,提出了一种新的模板法获得了条纹的边界并用几何中心法提取了条纹中心线;最后,使用斜率分析法提取了特征点.试验表明,该方法具有较高的特征点检测可靠性,并且运算速度快、抗干扰能力强,具有较高实用价值.     

基于结构光视觉的激光拼焊焊缝质量检测方法研究

焊缝质量自动检测是实现焊接自动化的关键技术。文中在分析结构光视觉检测原理的基础上,建立了基于结构光视觉的激光拼焊焊缝质量检测系统并对检测系统的图像处理方法进行了研究。对原始图像进行了开窗处理和中值滤波,并使用迭代阈值法获得了结构光光纹。提出了一种简化的模板获得了光纹的边界点并使用几何中心法提取了光纹中心线。使用平均斜率法识别出光纹中心线的特征点。分析了激光拼焊焊缝截面轮廓的特点并建立了截面轮廓几何参数计算方法。实验结果表明该检测系统可以完成焊缝截面轮廓相关参数的计算。     

基于结构光的螺旋钢管埋弧焊焊缝跟踪系统研究

介绍了基于结构光的螺旋钢管焊缝跟踪系统,利用LOG滤波和二值化法消除图像中的噪声并把光带图像从背景中提取出来.采用边界取平均值法抽取光带的中心线,用斜率分析法检测出特征点.该图像处理方法处理速度快,能够满足跟踪系统的要求.     

焊缝缺陷检测现状与展望综述

针对焊缝表面成形缺陷检测存在的技术问题,对现有焊缝缺陷检测技术即磁粉检测、超声检测、涡流检测、渗透检测、磁光成像检测、红外检测以及结构光视觉检测法进行了深入研究。对检测原理、系统基本结构、各自的适用范围以及研究现状进行了论述;并分析总结了基于结构光视觉检测法的激光条纹图像采集、图像处理、特征提取和焊缝缺陷分类识别等技术相关的理论与算法;研究结果表明:为了满足焊缝缺陷全方位检测要求,可融合多检测技术,优势互补;随着人工智能技术的不断发展和焊件质量要求的提高,实现焊缝缺陷检测技术可视化、自动化是未来的发展趋势;人工智能技术是焊缝缺陷检测的关键技术,实现真正智能化检测需进一步研究。     

基于图像处理的爬壁机器人焊缝识别与跟踪

基于爬壁机器人移动平台和单目相机的图像采集系统,设计了一种焊后焊缝图像处理方法,将改进的自适应中值滤波算法与灰度形态学方法结合,实现从信噪比较高的图像中提取特征。采用基于边缘检测和Hough变换的焊缝位置提取算法,经测试识别准确率达70%,且单幅图像平均处理时间为200ms,能满足管道爬壁机器人行进过程中的实时焊缝跟踪,并提供了一种引导机器人沿焊缝前进的自主定向方案。     

基于结构光视觉的激光拼焊焊缝背面质量检测方法研究

在激光拼焊中,背面焊缝成形质量直接影响焊件的机械性能.文中在分析结构光视觉检测原理的基础上,建立了基于结构光视觉传感的焊后焊缝背面质量检测系统并对焊缝背面质量检测系统图像处理方法进行了深入研究.在图像处理过程中,首先通过开窗处理来获得兴趣区域,采用中值滤波去除图像噪声;其次使用迭代自动阈值法分割出结构光;在结构光条纹中心线提取过程中,提出了一种新的模板法获得了条纹的边界并用几何中心法提取了条纹中心线;然后,将斜率分析法引入到条纹中心线特征点检测中并获得了中心线上的一系列特征点.最后通过背面焊缝的图像序列,计算获得了背面焊缝不同位置处的几何参数及缺陷值.试验表明,该焊缝背面质量检测系统图像处理方法可靠性高、运算速度快、抗干扰能力强,具有较高实用价值.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.