基于遗传算法的贴片机贴装顺序优化

元件贴装顺序是决定贴片机生产效率的关键问题。针对拱架型贴片机，采用了一种遗传算法。该遗传算法有其独特的染色体编码解码方式和交叉算子。算法中的染色体根据被贴装的印刷电路板由一条或多条子链组成，染色体的一个基因代表一个取贴循环。实验结果表明，该算法可以有效解决元件贴装顺序问题。同时，分析比较了三种传统交叉算子和该交叉算子的优化结果，表明这些传统交叉算子不能有效解决该问题。     

基于视觉定位的LED送料器

贴片机作为LED贴片领域中的重要组成部分,其部件送料器对其起着重要作用,通过研究LED的贴片流程以及送料器的结构,提出了一种双棘轮送料器。针对LED的定位问题,提出将机器视觉技术应用在送料器上,对LED工件进行图像采集,前期预处理,提取灯片的轮廓特征,利用四极点对灯片进行形心定位,通过对灯片轮廓的面积提取,对其进行污损检测。通过实验证明,实验所提出的方案能够在工件遗漏、工件污损情况下,准确的对合格工件进行视觉定位,保证贴片机吸嘴的吸取定位精度,提高贴片效率。     

FCS系统在贴片机的位置偏差校正中的应用

准确的定位技术是SMT表面组装生产线上主流设备贴片机的主要性能指标,贴片机的定位系统成为高性能贴片机最为关键的系统之一。以激光校准传感器作为贴片机的视觉定位检测系统,使贴片机自身具有识别贴片位置偏移的自动校正功能,满足小型元件的贴片精度要求,且提高对θ轴马达的强化,实现了面向大型元件的对应能力。结果表明:激光识别自动校正系统FCS在贴片头中的应用,通过非接触定心方式,LED激光多角度照射,光影宽度与切线数据的获取,使用最小二乘法准则完成元件形状分析,位置偏差校正,实现贴片元件精准定位的工艺要求。     

遗传算法解决多头动臂式贴片机的路径优化

贴片机贴装路径与表面组装生产线的装配效率紧密相关,多头贴片机现己成为市场的潮流。文中对多头动臂式贴片机进行分析,应用遗传算法实施贴装路径优化。通过实例计算和结果比较,该算法可以解决贴片机贴装路径问题,有效地提升贴装效率,减少贴装时间。     

高速高效贴片机控制系统设计与实现

介绍了高速高效贴片机的结构和功能划分,结合开发的高速高精度双臂多头贴片机样机,分析了其控制系统的要求。详细阐述了高速高效贴片机基于工控机+GT系列控制卡模式控制系统的软、硬件设计方法。针对贴片头多吸嘴同时吸贴的特殊结构的使用要求,在图像处理环节采用像素标记法对多元件目标进行图像分割处理,给出具体算法流程,并通过仿真说明了该方法具有较好的识别效果。样机的实际应用证明,控制系统及视觉处理满足了高速高效贴片机的使用要求。     

基于改进混合蛙跳算法的贴片机贴装顺序优化

元器件贴装顺序是影响贴片机工作效率的关键因素之一.针对拱架型贴片机,在建立贴装顺序数学模型基础上,采用改进混合蛙跳算法对贴装顺序进行优化,按照三角概率分布选择可能被改进蛙的策略,完成对基本混合蛙跳算法的改进.最后以3块PCB为例进行实验,实验结果表明,算法可以有效解决元件贴装顺序问题,并具有比基因遗传算法更高的准确性及效率.     

水平旋转贴片头的设计与运动学仿真

贴片头作为贴片机关键部件之一,是影响整个贴片机贴装速度的关键。为提高贴片效率,提出并设计一款水平旋转贴片头,介绍了水平贴片头的工作原理以及其具体的结构设计,并给出了相应的技术参数和设计要求,该贴片头适用于模组机,多个水平旋转贴片头共同工作。同时利用ADAMS仿真软件对水平旋转贴片头进行了运动学仿真,给出了贴片头在特定工作状态下吸嘴末端的位移、速度、角速度等特性曲线,为水平旋转贴片头的运动性能优化及控制策略提供一定的参考。     

基于改进混合遗传算法的贴片机贴装路径优化

贴片机的贴装路径是贴片机贴装速度提高的瓶颈。在深入研究了贴装路径优化问题的基础上,提出了一种三链的混合遗传算法。该算法根据拱架式贴片机的贴装数学模型,通过元器件拾取序列、贴放序列、喂料器排列三个子序列,设计了三链的染色体能同时解决贴装顺序优化问题和喂料器分配问题。计算结果表明,该算法能明显缩短PCB的贴装时间。优化效果较采用遗传算法和邻近算法更为明显。     

基于改进遗传算法的多直角贴装机器人路径协同规划

针对多直角机器人在大型复合结构板上协同贴片的问题,采用加入碰撞惩罚、分组进化、部分匹配交叉和自适应变异的改进遗传算法进行协同路径规划。利用MATLAB对3个直角贴装机器人进行了协同路径规划仿真实验,仿真结果表明：改进遗传算法规划出的路径更短、收敛速度更快,且无碰撞情况发生。     

贴片机系统中贴装头位置图像校准研究

贴装头位置校准是贴片机中元件贴装前关键的一步 ,目的是通过上照视觉系统检测贴装头中心以使其与之同心 ,从而保证元件贴装精度。研究出一种采用绕贴装头中心旋转、并等角度分布于圆周上的多幅图像信息 ,根据正多边形几心合一的特点 ,把贴装头中心定位到亚像素级精度 ,实现了高精度贴装头位置校准 ,同时分析了机械传动系统精度对校准过程的影响。     

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.