起重机轨道测量激光光斑中心识别与定位算法

在轨道测量装置中,激光光斑中心检测算法的精度和速度直接影响轨道测量效果,传统的中心算法如灰度质心法、Hough变换等在检测精度或速度上存在不足。文中提出了一种基于高斯积分曲线拟合的光斑中心定位算法,在光斑降噪、特征增强的图像预处理基础上,插值拟合光斑灰度曲面,进行边缘计算、追踪及细化,得到光斑的像素级边缘点,计算其法向等距线及高斯积分拟合点,并通过贝塞尔曲面拟合其对应灰度值,再采用高斯积分曲线拟合得到亚像素级边缘点,对亚像素边缘点进行圆拟合方法最终确定光斑中心点。与灰度质心法、Hough变换椭圆中心法相比,此算法的拟合精度较高,抗干扰性好,达到了实验室环境下轨道测量的精度要求。     

视觉测量中椭圆特征亚像素提取方法的研究

椭圆是视觉测量中重要的基元特征。建立了三级灰度图像边缘模型的空间矩算子,利用LOG算子定位速度快的特点,确定图像像素级边缘,然后在包含边缘点的邻域内利用空间矩进行边缘的亚像素定位,由随机Hough变换提取椭圆边缘像素点,最后采用基于最小二乘原理的椭圆拟合边缘提取方法,得到亚像素级被检测椭圆。对像面椭圆亚像素提取算法的有效性和精度进行了实验研究,实验结果表明提出的基于空间矩亚像素边缘定位算法与像面椭圆亚像素提取算法具有较高的精度和稳定性。     

基于高斯曲面拟合的亚像素边缘检测算法

提出了一种基于高斯曲面拟合的亚像素边缘检测算法.该算法首先使用传统Canny算子进行边缘像素级的粗定位,再以粗定位边缘像素为中心取5x5窗口获取梯度幅值,对其进行高斯曲面拟合,在梯度方向上寻找局部极值点,从而达到边缘亚像素级的精细定位的效果.文中介绍了算法的理论依据,给出推导过程,并用螺旋测微器的标准间隙进行实例分析,...     

装配位姿视觉检测系统中红外靶点质心定位

结合装配位姿视觉检测系统的研发,为提高红外LED靶点质心亚像素定位精度与稳定性,对红外LED靶点图像的灰度分布模型进行了研究,提出了一种基于自由曲面拟合的质心定位算法以获取靶点图像的亚像素中心。根据靶点图像的灰度分布,该算法通过双三次样条插值生成靶点灰度分布曲面,利用拟牛顿法求取曲面顶点即靶点图像中心的亚像素坐标。实测实验显示该算法在图像噪声水平较低的高精度测量环境中,当靶点距离摄像机约5m和12m时,与高斯曲面拟合法和加权灰度重心法相比,该算法都能更准确地描述靶点的灰度分布,生成的灰度曲面更加接近靶点图像的真实分布,在高精度测量环境中具有更高的测量精度和稳定性。     

基于亚像素边缘检测的液位测量系统研究

针对化工、医药等领域中透明试剂的液位测量存在精度低、智能化水平达不到要求的问题。文中在线阵CCD测量技术基础上提出一种非接触透射式的高精度液位检测系统,采用一维图像亚像素边缘检测算法确定液位边缘,再进行阈值比较与直线拟合分析,确定液位像素点坐标,实现液位快速高精度测量。经过多次实验验证,测量范围为5～25 mm时,误差低于10μm,分辨率优于5μm。     

正交分光成像系统实时多光斑亚像素定位研究

正交分光成像系统在高频动态坐标测量中具有独特优势。针对其在高频测量条件下数据量大,光斑坐标难以实时提取的问题,提出了一种基于现场可编程门阵列(FPGA)的实时多光斑峰值位置亚像素定位算法。首先设计与光斑光强分布相近的模板,通过模板匹配解决了原始图像中因噪声导致的峰值抖动问题;其次对匹配后的图像进行阈值比较并生成窗口信号,对窗内像素进行高斯拟合,拟合中心作为光斑峰值亚像素坐标。计算中充分利用FPGA并行处理的特点,采用流水线设计实现了硬件加速。实验表明,该算法可实现对多光斑位置的实时提取,光斑重复定位极差小于0.1像素,标准差为0.014像素,分辨力达亚像素级别。     

图像测量中快速边缘亚像素定位研究

研究了一种图像测量中边缘点的快速亚像素定位的方法,采用先阈值分割再边缘提取进行粗定位,确定边缘点的像素级精度位置和边缘的方向,沿边缘点的边缘方向拓展像素,得到一定长度的灰度值向量,对向量进行处理实现边缘的亚像素定位。分别采用三次多项式拟合法、二次曲线拟合法和灰度矩法三种亚像素定位算法进行了理论分析和实验对比,结果表明,灰度矩算法具有较短的运行时间和较高的定位精度。     

改进Zernike矩的运动靶标高精度定位算法

针对目前运动靶标中心定位检测精度低、实时性差的难题,提出一种改进Zernike矩的亚像素边缘定位算法.该算法将Zernike算法和迭代法相结合,首先采用传统的Zernike算法计算图像的阶跃灰度矩阵,在阶跃灰度矩阵的基础上采用迭代法计算得到最佳灰度阶跃阈值作为边缘判据;最后从矩模板和灰度边缘模型两个角度对误差进行了分析和补偿.以靶标中心定位为实验研究对象,采用改进Zernike矩算法对靶标进行亚像素边缘定位,然后利用最小二乘法拟合圆心坐标,最后通过坐标变换得到靶标的空间位置,测试结果表明:该算法能够准确对运动靶标中心进行定位,算法的检测精度优于传统算法,同时最佳阈值的自动选取相比于人工手动调试具有更高的效率.     

数字图像相关中非迭代相关系数曲面拟合算法的研究

相关系数曲面拟合算法是数字图像相关中一种简单而有效的亚像素位移求解方法,具有计算效率高、实时性好等优点。在相关系数曲面拟合算法中,二元二次多项式曲面拟合算法和二元高斯曲面拟合算法可通过直接推导出的解析解获得亚像素位移量,无需迭代计算,且二元高斯曲面拟合算法无需对拟合后曲面函数求导获得极值点位置。因此对上述两种简单而非迭代的曲面拟合算法性能进行了研究。应用真实散斑图像从两种算法的计算精度与效率两方面进行了对比实验。实验结果表明,二元高斯曲面拟合算法具有较高的计算精度,且两种算法在相同的条件下的计算效率并无实质性的差异。     

齿形链链板视觉集成测量

构建了基于计算机视觉的齿形链链板的测量系统,对直线和圆的边缘定位,提出了新的亚像素算法,计算了齿形链链板的销孔直径及圆度误差、链板节距和两直边夹角,对测量结果进行了误差分析。将图像处理、参数计算、标定等整个测量过程集成起来,通过标准样件对被测零件图像进行坐标变换,确定待测区域并完成标定。实验表明,改进最小二乘直线拟合定位误差是常规最小二乘拟合误差的1/4。而圆的亚像素定位可使CCD的分辨率提高42倍,大大提高图像边缘的定位精度。利用亚像素方法测量时,销孔直径为2.563mm,链板节距为6.296mm,两直边夹角为60.453°,圆度误差为14.7μm。单一链板的整个测量过程不足1s。     

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...     

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.     

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.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.