基于光栅相位法三维重构技术研究

投影光栅相位法（PMP）是一种基于光栅投影和相位测量的光学三维轮廓测量技术,可实现物体表面三维轮廓的自动测量。提出了结合投影仪移轴技术的平行光轴系统,利用计算机编程生成具有高对比度和高亮度、有相差的正弦光栅,用数字投影仪LCD将这些条纹依次投射到被测物体表面,由CCD摄像机获取受物体表面面形调制的变形光栅像,根据数字相移算法计算出相位分布再通过相位展开恢复出连续相位分布,由相位．高度关系最终求出物体轮廓的三维数据信息。针对该原理进行了阐述,并给出了详尽的算法及实验结果。通过MATLAB实验仿真,对条纹图像进行处理和轮廓重构。模拟实验证明,这种测量方法快速高效、分辨率高,且易于实现。     

三灰度编码相位展开方法条纹投影轮廓术

为了通过减少条纹投影轮廓术所需投影和采集的条纹图像数量,提高三维测量速度,提出了一种用于条纹投影轮廓术的三灰度编码相位展开方法.投影仪投射5幅条纹图像到被测物体表面,包括三幅正弦相移条纹图像和两幅三灰度编码图像,由相机采集经物体表面调制的变形条纹图.通过相机采集到的三幅变形正弦相移条纹图像计算包裹相位.通过相机采集的三...     

基于双频彩色光栅投影测量不连续物体三维形貌

为减少多频条纹相移法进行三维形貌测量时的投影条纹数量,提高测量速度, 提出了采用双频四步相移彩色条纹投影技术来准确测量具有台阶状不连续或孤立物体表面三维形貌的方法。利用计算机将高低两种不同频率的正弦条纹分别输入彩色图像的红色和蓝色通道合成为彩色条纹,由数字视频投影仪将四步相移彩色条纹投影到被测物体,然后利用彩色CCD或CMOS相机采集4幅彩色条纹图并存储于计算机中。基于色彩分离技术得到8幅两种不同频率的四步相移条纹图并由图像灰度算法获得1幅反映背景的灰度图像;由低频条纹确定台阶状的物体边缘,高频条纹计算物体的形貌,并通过背景图像的二值化定位阴影和不连续区域。提出的方法仅用4幅彩色图像完成了台阶状不连续或孤立物体三维形貌的准确测量。与现有的多频4步相移条纹投影形貌测量技术需要8~12幅图像相比,该方法有效地减少了条纹投影与图像采集的数量。     

用变形光栅条纹自迭加法测曲率

用变形光栅条纹自迭加法测曲率谭吉春（国防科技大学应用物理系）０引言应用莫尔条纹原理测量物体三维尺寸时，实验装置中通常有两块光栅。第１块称作物光栅。用投影光学系统将物光栅图案投射到被测物表面，生成变形光栅图案。此图案含有物体表面高差信息。第２块光栅称作...     

正交调制复合光栅投影的三维测量机理及仿真

介绍了采用复合光栅来进行快速测量获取物体三维信息的方法。该方法通过投影由载频光栅携带与其正交的相移光栅而形成的复合光栅来进行三维面形测量。建立了基于复合光栅方法的三维测量理论模型,运用复合光栅完整模拟物体恢复的过程,模拟结果证明了该方法的可行性。该方法具有祛噪功能,由于只需投影一幅复合光栅图像和采集一幅变形光栅图像就实现了物体的重建,因此适用于物体三维面形的快速实时测量。     

任意相移最小二乘法迭代的在线三维检测

为了简化采用满周期等相移算法的在线相位测量轮廓术(PMP)在实际测量过程中系统装调环节的繁杂程度,同时避免栅线方向和运动方向不严格平行引入附加相移降低解相精度,提出了基于最小二乘法迭代的在线三维检测方法。在测量过程中,任意栅线方向的正弦光栅被投影于物体表面,采用像素匹配技术获得不同时刻拍摄到的变形条纹图的等效相移条纹图,其相移量由投影系统和物体位移共同决定且为任意值。最后,采用最小二乘法迭代计算相位。实验结果表明:在不断改变投影到参考面上光栅栅线方向的情况下,该系统的测量结果稳定,均方根误差均不高于0.169 9mm。由于该方法放宽了测量系统空间位置的约束条件,提高了测量的灵活程度,使在线PMP更具普适性。     

一种基于相移技术的物体表面三维轮廓测量方法

提出一种将阴影莫尔条纹法与相位测量技术相结合的物体表面三维轮廓测量方法 ,该方法利用电磁铁和精密机械部件对光栅进行定位控制以实现精确相移 ,并采用三步相移技术对CCD摄像机采集的物体表面形貌莫尔条纹进行相位解调 ,可有效实现物体表面三维轮廓的高速、高精度自动测量。     

微小高度检测系统设计

高度信息是分析物体三维形貌的最重要信息。为了研究微小焊点的三维形貌,需要对焊点高度进行测量。针对传统测量技术的缺点,设计了一种检测系统。系统应用白光平行照射条纹板,将其像投影到被测物体上,受到物体高度轮廓的调制作用,形成变形的亮暗相间的条纹。该条纹图携带着焊点的三维信息,再用照相系统把变形的条纹图拍摄在CCD上,通过对CCD上像的处理,可以还原出高度信息。该方法可将条纹板的像等间距地投射到被测物体的表面上,避免了由于投影条纹宽度不同所带了的图像处理过程的误差。实现了测量范围大、重复性好、图像处理简单的优点,为微小高度的测量提供了新方法。     

快速离焦投影三维测量技术

随着数字投影技术的发展,基于投影的三维面型测量技术在多种场合得到广泛应用。基于相移的结构光投影测量技术以其算法简便精度较高得到较快发展。但投影仪为非线性仪器,会影响强度变化,进而影响相位测量精度;此外由于投影仪工作原理的投影速度受到限制。离焦投影技术的出现为高速测量和高精度测量提供了新的方法。总结了目前国内外对离焦投影技术的研究现状;从投影工作原理、相移算法、解包裹算法、误差补偿、条纹调制、标定技术及离焦投影技术的相关技术细节进行全面介绍,为数字离焦投影三维测量工作的研究提供参考。     

位相测量技术中系统参数的选择与测定

位相测量轮廓术（PMP）是将被测物体表面投影光栅条纹的灰度分布变换为位相分布，从而求得被测物体高度分布的轮廓测量技术。本文讨论PMP测量系统参数：抽样间隔X、Y；光栅周期p、q；最大系统噪声nmax以及光瞳位置参数d、L的选择和测定。这些参数的合理选择与精确测定，将提高位相测量以及位相-高度转换的精度。     

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...     

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.     

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.     

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。     

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.     

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....     

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.