光通信粗瞄系统莫尔条纹信号正弦性补偿方法

为了保证光通信终端的精确对准,抑制编码器莫尔条纹正弦性偏差引入的细分误差,设计了基于经验模态分解(empir-ical mode decomposition,EMD)的正弦性修正方法。首先,介绍了卫星光通信终端跟瞄系统的组成与工作原理。接着,分析了莫尔条纹正弦偏差给系统带来的细分误差并给出满足工程需求的正弦性阈值。然后,在阐述EMD分解原理的基础上,给出了基于EMD的正弦性修正方法,该方法利用编码器自身粗码信息计算转速,从而确定精码莫尔条纹信号的基波频率值,并采用EMD分解在原始信号中提取与该值相匹配的基波分量。最后,对该方法进行了原理和转速自适应性仿真,并应用到去掉光学滤波镜片后的粗瞄回路编码器中。仿真及实验结果表明:在光通信终端的各工作转速下,修正后的莫尔条纹正弦性均小于0.85%,满足细分要求;修正后的精码译码结果精确,编码器测角精度维持在1″以内,满足终端对准精度的要求。     

小型光电编码器细分误差校正方法

为提高小型光电编码器精度,设计了精码莫尔条纹信号细分误差校正方法.首先建立存在直流分量、幅值误差、波形畸变的精码光电信号的波形方程,然后利用牛顿迭代法将两路精码细分信号校正至标准的正弦和余弦信号,最后建立两路信号间的正交性误差模型,通过最小二乘法求解出正交性误差校正参数.运用本文的细分误差校正法对某16位小型绝对式光电编码器进行误差校正处理,经测试,细分误差峰峰值由校正前的160″减小到校正后的48″.实验结果表明:研究的误差校正方法可以有效地减小细分误差、提高编码器精度,对于研制小型化、高精度光电编码器具有重要意义.     

莫尔条纹正交偏差的智能补偿方法

提出了一种新的编码器莫尔条纹正交偏差的补偿方法及实现方式。通过比较分析,采用相关函数分析法测量各精码周期莫尔条纹的正交偏差,并基于系统自身的粗码信息,构造一种智能采样算法,保证莫尔条纹采样均匀性;在工作中对所有精码周期的莫尔条纹实行数字式实时补偿,并可以通过模式间的切换自适应地更新正交偏差补偿参数,持续地保证补偿的精确性,降低编码器在各种恶劣环境下的误码率。实验结果表明,正交偏差10度以内时,补偿后的信号正交性提高了93%以上,保证了编码器测量精度。     

提高光栅莫尔条纹信号质量的滤波方法

针对莫尔条纹信号的质量问题提出一种相位差滤波法.将指示光栅上四场裂相方式中每场细分为多个不同相位的行组合,利用行组合间的不同相位排列关系来消弱高次谐波的分量,从而提高莫尔条纹信号的质量.首先,介绍了莫尔条纹的傅里叶级数表达式,对莫尔条纹的各次谐波特性进行了分析.然后,以指示光栅的图案设计为例,阐明该滤波方法消除二次、三...     

基于FPGA的新型数字锁相倍频方法

为了克服模拟锁相倍频电路在应用过程中易受温度和电压影响、锁相时间长、存在直流零点漂移及部件饱和等缺欠,以实现对被测信号的高速高精度采样,提出了一种基于FPGA的新型数字锁相倍频方法.该方法依据锁相倍频的基本原理,通过检测被测信号的边缘计算出频率值,找到相应的指针位置,再根据产生的分频因子来控制数控振荡器的输出信号,从而完成对被采集信号的锁相倍频.经过仿真分析,验证了该方法的可行性,证明了其具有精度高、锁相速度快等优点.     

锁相倍频细分中光栅位移跟踪速度与分辨率的关系

针对光栅传感器信号细分时普遍存在的分辨率提高、位移跟踪速度下降这一现象,基于锁相倍频细分方法研究了光栅位移跟踪速度与分辨率之间的关系.以50线/mm的普通光栅尺为例,利用FPGA芯片的底层嵌入模块74297实现了对光栅信号的锁相倍频细分.研究了锁相倍频细分电路的截止频率,推导出光栅跟踪速度与分辨率的数学关系.利用QuartusⅡ软件搭建了锁相倍频细分电路,利用Simulink工具箱对该电路进行了建模和仿真,验证了所得结果的正确性,为设计高分辨率、高位移跟踪速度的数字集成化光栅数显装置奠定了基础.     

莫尔条纹锁相细分误差补偿

<正> 一、绪言对于莫尔条纹的电子学细分、锁相技术的应用大约开始于六十年代初期。英国Goulder Mikron公司的齿轮单面啮合检查仪、齿距仪。苏联的БB—5058、БB—5059和БB—3244齿轮测量仪器等产品上均有锁相倍频技术的应用。我国成都工具研究所研制的单测头式齿轮整体误差测量仪及天津大学与天津第一机床厂研制的GYQ—80型光栅式齿轮误差检查仪,对光栅莫尔条纹的细分,也采用了锁相倍频技术。锁相倍频细分方法具有细分数高、对光栅     

一种光栅莫尔信号数字锁相细分方法

为了保证和提高光栅传感器在动态测量过程中信号细分结果的准确性和实时性,本文提出一种新型的莫尔信号数字锁相细分方法.该方法采用开环结构,根据光栅莫尔信号的实时频率,利用小数分频方法完成对光栅莫尔信号的细分功能;开发了基于现场可编程门阵列(FPGA)的数字锁相细分电路,并对细分实现过程中的电路关键环节进行详细分析;使用自制...     

非均匀采样莫尔条纹信号的分析与处理

为了动态、实时地测量光电编码器在变速转动情况下的细分误差,提出了一种莫尔条纹信号的非均匀采样分析与处理方法。利用傅里叶级数原理构造了实际情况下的莫尔条纹信号方程,根据编码器在不同转速下的实时采样,揭示了莫尔条纹信号的非均匀采样特征。鉴于信号采样的非均匀性,采用曲线拟合的最小二乘法重构莫尔条纹信号,利用离散傅里叶变换算法分析重构信号并求出波形参数。通过信号参数与细分误差的关系式,测量了编码器动态细分误差。采用该方法对21位绝对式光电编码器莫尔条纹信号进行了分析和处理,两次测试得到其动态细分极值误差为+3.21″、-4.69″和+3.45″、-4.81″。实验结果表明,该方法可以有效地分析和处理编码器在非匀速转动下产生的变频莫尔条纹信号,精确地测量编码器的动态细分误差,为工作现场编码器误差的实时检测与修正奠定了基础。     

空间精密位移信号软细分方法研究

为了解决高精度数控装备对位移传感器高分辨力反馈的需求,本文提出通过对空域信号特征的分析,从时空变换理论模型的角度去研究位移测量问题;利用光栅周期性栅线作为等空间位置触发位置采样建立空间序列模型;通过对光栅莫尔条纹信号自适应预测细分模型阶数与系数估计算法完成光栅莫尔条纹信号细分。实验结果证明此方法可以实现光栅莫尔条纹400倍细分,细分精度优于信号周期的±1%。此细分方法利用光栅刻划精度,信号细分精度与光栅信号波形质量无关,在不增加硬件的条件下实现光栅莫尔条纹精密细分,具有重要实际应用价值。     

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.