基于FPGA的增量式编码器接口电路的设计

运动控制系统多数采用增量式光电编码器作为位置与速度的反馈测量元件。针对该编码信号特点,利用FPGA内部丰富的逻辑模块和IO模块灵活的可编程性,设计增量式编码器的接口电路,使之具有倍频、鉴相、计数等功能,并分析仿真结果验证设计的可行性,提高编码器的分辨率,进而实现高精度的位置伺服控制。     

用于位置与速度反馈测量的编码器倍频鉴相电路的设计与分析

针对用于位置与速度反馈测量的光电编码器信号的特点，介绍几种实用的倍频鉴相电路与防微振计数电路，同时介绍干扰信号检测与剃除的方法，它对提高编码器分辨率与实现高精度、高稳定性的信号检测及位置伺服控制具有一定的现实意义。     

基于FPGA的EnDat协议绝对式光栅尺通讯实现

为了满足高速精密运动控制对光栅尺信号的实时反馈的要求,设计了基于FPGA的EnDat 2.2协议接口模块和上位机。针对EnDat 2.2协议的通信传输方式及光栅解码要求,采用状态机设计了解码模块,并通过Modelsim仿真工具验证时序。利用FPGA和MAX485模块组成硬件电路,通过解码模块和CRC校验模块对光栅尺信号进行数据处理,最后把解码并验证成功的位置和参数信息通过串口发送到上位机显示。仿真与实测结果表明该数据采集系统位置采集周期小于40μs,能够满足25 kHz的控制要求,并且成功发送位置值到GUI上位机显示。     

基于FPGA的多通道高速数据采集系统

为了实时监测多轴运动控制单元,检测其性能及可靠性,设计了一种集FPGA与PCI总线于一体的多通道高速数据采集系统.该系统并行采集16通道控制信号,应用FPGA对采集的信号进行分析并提取检测信息和反馈信息;检测信息通过PCI总线传输给计算机,闭环控制反馈信息通过RS - 422串行通讯发送控制单元.信号采集实验表明:该系统能够并行采集工作频率＜ 100 kHz、控制电压＜32 V的多通道控制信号,采样精度为12bit、采样速率为6.4 MSPS,满足检测需要.     

基于CPLD的编码器信号处理电路设计

基于CPLD芯片,对增量式编码器输出信号进行处理,实现了编码器信号的整形滤波、倍频和鉴相。为了提高编码器的测量精度,设计了一种4倍频脉冲输出电路,提高了编码器的分辨率,并设计了鉴相电路,实现正反向的角度或速度测量。文中给出了Quartus原理图输入电路、时序仿真结果,以及试验测试结果。文中的研究在角度位移等测量领域有着广泛应用价值。     

基于FPGA的光栅信号处理电路设计

利用现场可编程门阵列(FPGA)提出了坐标测量机中光栅信号的处理电路。详细分析了四倍频辨向电路、计数电路的设计思想,运用VerilogHDL语言完成了整个电路的硬件设计。仿真结果表明,本设计不但达到电路预期指标,而且资源占用较小,程序易修改。     

ECT系统微小电容信号采集的研究

针对ECT系统微小电容检测中信号调理和完整性的问题,对基于FPGA的ECT数据采集系统进行了详细的研究,其中包括FPGA产生可调高频正弦信号的模块功能介绍,FPGA控制通道选择电路的原理及正弦数据变为激励信号的处理过程,保证了采集信号的准确性和完整性,提高了ECT系统的集成度,并提出了改进方案.     

基于FPGA的高精度磁编码器设计

磁编码器主要用于伺服电机系统的转角和转速测量,针对目前产品精度和分辨率相对较低的现状,提出一种基于FPGA实现的标定查表法细分方案。首先将三路磁头相差120°放置,使磁编码器输出3路相差120°的差分正弦信号,并通过FPGA进行卦限判断,选取线性度最好的一路信号进行信号处理,从而有效地避免了正弦信号的死区。同时利用FPGA对卦限信息和磁编码器输出信号的A／D转换信息进行处理,作为EEPROM的地址信息进行硬件查表,实现对磁编码器信号的倍频处理,从而提高了磁编码器的分辨率和测量精度,可实现每个周期4096份的倍频。     

光栅信号采集的分析与实现

光栅测量系统应用广泛,常用于高精度的数字信号检测系统中。本文首先分析了几种常用的光栅信号采集方案,然后针对高频于扰信号,提出了技术改进方案,最后介绍了光栅信号采集的PLD／FPGA实现。实验结果表明,使用PLD实现对光栅信号的采集,在很大程度上提高了系统的整体可靠性。     

超声波穿金属厚壁通信电路系统设计与实现

在分析超声波穿金属厚壁通信系统需要高频高压的基础上,设计了一种利用电感储能产生高压脉冲的发射电路.采用FPGA产生高精度高频控制信号,驱动IGBT开关元件.同时在对介质表面声波透射状况分析后,设计了接收信号放大和带通滤波电路,实现了超声信号的稳定接收.在接收信号包络检波和A/D采样转换后,通过FPGA处理实现了数据流的还原.该设计方案可实现密闭容器内信息的采集与高速传输,具有重要的应用前景.     

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.