数控直线电机进给定位误差补偿技术研究

介绍了应用双频激光干涉仪测试数控直线电机进给的定位误差方法,并利用最小二乘法分别建立定位误差的线性模型、分段线性模型、样条拟合模型,并对数控直线电机进给的定位误差进行补偿。研究结果表明,采用软件补偿的方法可以较大地提高直线电机进给的定位精度。     

空间离散点最小二乘法分段直线拟合的研究

简单介绍了最小二乘法基本原理,提出了空间点列的最小二乘法分段直线拟合的原理,给出了这种拟合方法的程序框架图。理论和实验结果表明,该方法对空间点列进行直线拟合是很有效的。     

[误差建模及精度保证方法]双五轴数控铣削机床旋转轴误差辨识方法

为了快速、系统地辨识双五轴数控铣削机床旋转轴几何误差,提出了一种基于R-test的误差测量辨识方法。根据R-test误差模型研究误差测量值与各项误差参数的关系,辨识旋转轴各个几何误差项以得到旋转轴的安装误差和运动误差;利用最小二乘法原理平面圆拟合和直线拟合的方法分别辨识出2项位移误差和2项垂直度误差;基于多体系统理论及齐次坐标变换方法建立刀具坐标系与工件坐标系的齐次坐标变换模型,并辨识出3项移动误差和3项转动误差;最后,根据所得辨识值对X向和Y向位移误差进行补偿。实验结果表明,补偿后X向和Y向位移误差明显减小,误差补偿结果验证了测量、辨识的准确性和有效性。     

双五轴数控铣削机床旋转轴误差辨识方法

为了快速、系统地辨识双五轴数控铣削机床旋转轴几何误差,提出了一种基于R-test的误差测量辨识方法。根据R-test误差模型研究误差测量值与各项误差参数的关系,辨识旋转轴各个几何误差项以得到旋转轴的安装误差和运动误差;利用最小二乘法原理平面圆拟合和直线拟合的方法分别辨识出2项位移误差和2项垂直度误差;基于多体系统理论及齐次坐标变换方法建立刀具坐标系与工件坐标系的齐次坐标变换模型,并辨识出3项移动误差和3项转动误差;最后,根据所得辨识值对X向和Y向位移误差进行补偿。实验结果表明,补偿后X向和Y向位移误差明显减小,误差补偿结果验证了测量、辨识的准确性和有效性。     

轴承滚子凸度轮廓的最小二乘拟合与误差评定

为了实现对轴承滚子凸度轮廓误差的精确评定,依据圆弧修正型轴承滚子凸度素线轮廓的几何特征和形状误差的定义,基于最小二乘原理,研究了轴承凸度轮廓(两段圆弧和一段直线)的最小二乘拟合和误差评定方法。首先利用各测量点的曲率差值确定了圆弧段与直线段的相切参考点;其次分别选取两个参考点临近的测量点作为辅助相切参考点,并与对应的圆弧段测量点一起拟合出一系列的最小二乘圆弧并计算拟合误差;然后基于直线与两段圆弧相切的原则确定出一系列的直线方程并计算对应的直线度误差;通过比较判断最终确定出圆弧修正型轴承滚子凸度轮廓的最小二乘拟合及误差评定。实例结果表明:圆弧修正型凸度轮廓曲线的总误差0.020 9mm与文中设定标准凸度轮廓曲线引入的法向误差0.02mm相差4.5%。本方法可以有效的实现轴承凸度轮廓的拟合与误差评定,为平面多段曲线的最小二乘拟合提供了一种新的思路。     

基于多体系统理论的数控铣齿机热误差综合建模

基于多体系统理论,以某种数控铣齿机为例,基于小误差假设,建立了包含34项热误差元素的热误差综合数学模型,并通过数控铣齿机的特殊运动状态和热误差补偿实验验证了热误差综合模型的可靠性。     

基于最小二乘法CNC无线测头智能检测控制系统设计

为提高CNC在机检测效率和质量，针对现有的接触式测头各种检测误差，研究一种基于最小二乘法曲线拟合插值方法的测量误差补偿模型，该算法通过最小二乘法分别对测头模型标定、系统测量误差补偿模型构建，设计了一套精度较高的CNC无线测头智能检测与控制系统，达到在机测量零件尺寸精度和误差补偿。生产结果证明该系统误差补偿算法的可行性、有效性与优越性较高，提高了生产效率、生产质量，降低了次品率、生产成本，能广泛适用于CNC数控铣削精密加工零件尺寸测量与误差补偿。     

基于最小二乘法的机床螺距误差补偿方法研究

为减小机床的定位误差、提高加工精度，提出基于最小二乘法的误差模型及其补偿方法。运用最小二乘法多项式拟合方法建立螺距误差补偿数学模型，并将模型应用到数控系统，根据模型形成的补偿曲线，通过激光干涉仪检测得到三轴加工中心进给轴的定位误差数据，利用校正周期插补坐标值的方法，对三轴加工中心的螺距误差进行补偿。结果表明，使用最小二乘法对机床进行补偿后，机床各进给轴的定位精度均提高80%以上，具有显著效果。     

基于LSSVM的直线电机进给定位误差补偿研究

误差补偿是提高机械加工精度的有效途径,在分析测试数控直线电机进给定位精度的基础上,提出基于最小二乘支持向量机的直线电机进给定位精度误差回归建模和预测方法.最小二乘支持向量机具有完备的统计学习理论基础和学习功能,它用核函数建立预测模型,再用已知数据为学习样本训练学习机,用检验样本进行验证、预测系统未来误差.采用径向基核函数的最小二乘支持向量机对不同速度加速度下的定位误差进行了预测,并进行误差补偿.研究结果表明,采用LSSVM的方法可以较大地提高直线电机进给的定位精度.     

直线电动机工作台神经网络误差场建模与补偿

研究了H型直线电动机工作台的误差测量、建模及补偿技术。首先分析了定位平台的误差来源。采用激光矢量测量方法测量工作台的定位误差;然后用最小二乘法分别建立工作台的分段线性。用BP算法建立神经网络误差模型,利用误差模型构造了各电动机的一维或二维误差校正表;最后。根据误差校正表进行误差实时补偿实验。实验结果表明,经过样本训练的神经网络模型对工作台的误差具有较强的预测能力,将工作台两个方向的定位精度都提高到1μm。     

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.     

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....     

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.     

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.