时栅传感器直驱式误差自动标定与修正系统

针对研制时栅位移传感器过程中的误差标定环节,常规光栅传感器精度不满足要求的问题,采用激光干涉仪作为误差标定基准,自主研制了基于激光干涉仪的直驱式时栅角位移传感器误差自动标定与修正系统。利用时栅角位移传感器的多测头结构与误差曲线等间距周期性分布的特性,以一个对极的误差曲线重构传感器整周的误差曲线,采用多项式拟合算法构建了时栅角位移传感器的误差修正模型。实验结果表明,误差自动标定与修正系统可以快速、准确地对时栅角位移传感器进行自动误差标定与修正,修正后的时栅角位移传感器的整周误差达到±0.43″。     

精密减速器角位移测量系统设计

为了实现对精密减速器输入端和输出端角位移的精密测量,建立精密减速器角位移测量系统。对该系统的机械结构、角度测量及标定方法、基于非线性最小二乘法的误差补偿模型进行研究。通过"立式筒状"结构和圆光栅角度传感器"前置"避免了传统检测仪的弱刚度结构和轴系形变对角度测量造成的影响。使用光电自准直仪与24面棱体结合的方式离散标定圆光栅角度传感器的角位移测量误差,研究基于谐波分析的误差补偿方法,对角坐标进行补偿,进一步消除误差。实验结果显示,通过优化检测仪的结构设计,角位移测量精度达到±7″;误差补偿后,角位移最终测量精度达到±2″,满足减速器角位移测量的高精度要求,对类似测角系统也有参考价值。     

基于单目视觉的激光光束方向标定研究

在由激光位移传感器组成的测量系统中,激光光束的方向是一个关键参数.方位角和俯仰角对于一条激光光束是最为重要的两个参数.本文中提出一种基于单目视觉的激光光束方向测量方法.首先,将CCD相机放置于基础平面上方,保持相机光轴与基础平面接近于垂直状态,并利用误差为10μm的圆孔型标定板建立单目定位模型.然后将激光光束发生装置放置在基础平面上并保持位置固定,同时在基础平面上放置特制靶块,使激光光束可以投射到靶块斜面上并形成一个激光光斑.在基础平面上方放置的CCD相机可以清晰的采集到激光光斑、靶块斜面的图像,应用相关算法提取出光斑质心的二维图像坐标.沿激光光束方向以相等间距移动靶块,通过CCD相机采集每移动一次靶块在当前位置下的光斑、靶块图像.利用相关的转换公式,结合靶块本身固有参数,将光斑质心图像二维坐标转换为基础平面下的空间三维坐标.由于靶块的移动,会得到靶块不同位置下激光光斑质心的三维坐标,将这些三维坐标拟合成空间直线表征待测激光光束.拟合直线得俯仰角即为待测激光光束的俯仰角.实验中,应用高精度仪器对靶块参数进行测定,并使用高精度标定板标定相机内外参数建立相应的定位模型.测量精度主要通过单目视觉定位精度、光斑重心提取精度来保证.结果显示,待测光束的俯角最大误差达到0.02°,光束间夹角的最大误差为0.04°.     

基于单目视觉的激光光束方向标定研究（英文）

在由激光位移传感器组成的测量系统中,激光光束的方向是一个关键参数。方位角和俯仰角对于一条激光光束是最为重要的两个参数。本文中提出一种基于单目视觉的激光光束方向测量方法。首先,将CCD相机放置于基础平面上方,保持相机光轴与基础平面接近于垂直状态,并利用误差为10μm的圆孔型标定板建立单目定位模型。然后将激光光束发生装置放置在基础平面上并保持位置固定,同时在基础平面上放置特制靶块,使激光光束可以投射到靶块斜面上并形成一个激光光斑。在基础平面上方放置的CCD相机可以清晰的采集到激光光斑、靶块斜面的图像,应用相关算法提取出光斑质心的二维图像坐标。沿激光光束方向以相等间距移动靶块,通过CCD相机采集每移动一次靶块在当前位置下的光斑、靶块图像。利用相关的转换公式,结合靶块本身固有参数,将光斑质心图像二维坐标转换为基础平面下的空间三维坐标。由于靶块的移动,会得到靶块不同位置下激光光斑质心的三维坐标,将这些三维坐标拟合成空间直线表征待测激光光束。拟合直线得俯仰角即为待测激光光束的俯仰角。实验中,应用高精度仪器对靶块参数进行测定,并使用高精度标定板标定相机内外参数建立相应的定位模型。测量精度主要通过单目视觉定位精度、光斑重心提取精度来保证。结果显示,待测光束的俯角最大误差达到0.02°,光束间夹角的最大误差为0.04°。     

改进的精密测角法标定面阵摄像机参数

改进了用于标定线阵摄像机的传统精密测角算法,标定用于面阵摄像机的参数。该算法利用两束平行光之间的夹角和投影在摄像机上图像点之间的对应关系,在给定一个预测摄像机主点的基础上计算它和实际主点之间的偏差以及摄像机焦距。分析了图像特征提取误差对于平行光夹角测量精度的影响,并给出一种基于平行光夹角误差最小的最优估计,从而进一步提高摄像机内部参数的标定精度。通过仿真实验分析了图像特征提取精度和平行光夹角测量精度对摄像机参数标定精度的影响。结果显示,当图像特征提取精度为0.1pixel,二维转台精度为0.5″时,主点标定精度可以达到0.56pixel,焦距标定精度可以达到0.06mm。利用精度为0.5″的二维转台对摄像机参数进行了实际标定,通过分析像点和标定结果所计算的平行光夹角和实际测量的平行光夹角的误差,可知本文算法的误差是经典精密测角法的68.6%,由此证明该算法对于面阵摄像机参数标定具有更好的结果。     

基于激光交线的结构光视觉传感器现场标定新方法

提出了一种可适用于未知环境的线结构光三维视觉传感器现场标定的新方法.与基于交比不变性求解特征点坐标来标定激光平面的方法不同,该方法可直接基于激光交线图像实现快速标定.通过拍摄一个与线结构光相交并以不同姿态随机自由移动的平面靶标的图像(至少3幅),就可同时实现三维视觉传感器CCD和激光平面的快速标定.该方法不必求解标定点坐标,方便、快捷、简单,可实现自动化,标定精度高,标定方法鲁棒性强.实验结果证明了该方法的方便和有效性.     

图像式角位移测量的光栅偏心度监测系统

图像式角位移测量装置中,光栅的安装偏心标定结果直接影响着角位移测量的精度。为此,本文设计了一种用于调试图像式角位移测量装置光栅偏心度的系统。首先,根据图像式角位移测量机理,提出了基于线阵图像传感器的标定光栅偏心度监测原理;然后,在图像传感器上建立了偏心调试监测信号的模型,并提出存在偏心时偏心监测信号的变化机理;最后,对某型号角位移测量装置进行了实验,并给出了调试建议。实验表明,经过调节误差均方差由1017″降低到12.8″。本文设计的偏心监测系统能够实现对标定光栅的高精度安装调试,提高了图像式角位移测量装置的批量生产效率。     

基于线结构光参考平面的多摄像机标定方法研究

多摄像机视觉测量系统中不同视觉传感器空间分布广,无公共视角,现场标定十分困难。针对多摄像机标定问题,研究了一种基于线结构光参考平面的灵活标定方法。标定过程中,以空间中同时覆盖相邻摄像机视角的结构光平面作为标定参考基准,在不同摄像机视角中,自由移动平面靶标多次,确保每次移动后靶标与结构光相交,并能在各自摄像机中清晰成像,摄像机拍摄靶标图像。提取靶标图像中角点坐标、激光光条特征点坐标。借助靶标平面与摄像机坐标系外部参数矩阵,求解激光光条特征点在对应摄像机坐标系中坐标。通过结构光基准平面内,不同摄像机坐标系中至少3组非共线特征点坐标信息,求解相邻摄像机外部参数。分别进行标定试验和精度验证试验,试验结果表明该方法切实可行。     

基于线结构光参考平面的多摄像机灵活标定方法研究

多摄像机视觉测量系统中不同视觉传感器空间分布广,无公共视角,现场标定十分困难。针对多摄像机标定问题,研究了一种基于线结构光参考平面的灵活标定方法。标定过程中,以空间中同时覆盖相邻摄像机视角的结构光平面作为标定参考基准,在不同摄像机视角中,自由移动平面靶标多次,确保每次移动后靶标与结构光相交,并能在各自摄像机中清晰成像,摄像机拍摄靶标图像。提取靶标图像中角点坐标、激光光条特征点坐标。借助靶标平面与摄像机坐标系外部参数矩阵,求解激光光条特征点在对应摄像机坐标系中坐标。通过结构光基准平面内,不同摄像机坐标系中至少3组非共线特征点坐标信息,求解相邻摄像机外部参数。分别进行标定试验和精度验证试验,试验结果表明该方法切实可行。     

薄板激光拼焊视觉检测系统标定方法研究

激光焊接是一种高质量、高速度、低变形的焊接方法,广泛应用于机械制造、航空航天、汽车生产、微电子等领域。为在进行薄板拼焊前获取焊缝轨迹,利用视觉系统焊接轨迹进行规划。使用了数控焊接机床,激光焊接头安装在数控机床的Z轴上,视觉检测系统安装在激光焊接头上。主要对焊缝检测系统中,CCD相机内参数和低功率激光器投影光平面标定方法进行了研究。相机内参数的标定使用了张氏标定法。投影光平面标定时,靶标放置在数控机床的X-Y平台上,低功率激光器投射结构光条纹在靶标上,视觉系统随Z轴移动并在三个位置拍摄靶标图像。在三个位置分别提取靶标上特征点及投影光条中心,应用交比不变性得到投影光条的空间坐标,拟合后可得到结构光平面。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.