现代测控平台动态测试系统研究

利用已有设备 ,以通用的 D/A、A/D转换和数据 I/O卡为硬件 ,以振动台、功率放大器、电荷放大器、信号发生器等设备产生信号 ,结合虚拟仪器概念与技术 ,组建了一套完整的动态测试实验系统。该系统可以进行动态信号采集与处理 ,可对动态信号进行多种信号分析。同时结合虚拟仪器技术开发了便于应用的用户界面。在开发系统的同时 ,还对一些动态信号分析方法作了深入研究     

位移传感器动态精度实验系统的研制

根据传感器动态精度理论研究的要求 ,研制了能反映不同速率动态信号激励下系统动态响应的位移传感器动态精度实验系统。该系统可实现动态输入信号速率的无级调速 ,由计算机采集输出信号并进行数据处理。     

系统动态校准中输入阶跃信号过渡时间参数分析

分析了阶跃信号过渡时间参数对动态校准结果－系统频率响应函的影响，得到了系统频率响应函数误差与过渡时间参数误差的关系，最后对典型的斜坡型负阶跃信号进行了分析。本文对采用阶跃信号动态校准系统的误差分析具有重要的意义。     

基于现代信号处理方法的动态测量误差分析

动态测量误差信号是包含多分量的非平稳信号,成分的复杂性决定了对动态测量误差的分析和处理需要结合多种信号处理方法.如傅里叶变换、小波变换和神经网络等.分析了各种信号处理方法的原理及其在非平稳信号处理中的应用,建立了一个动态测量误差分析仿真系统,对系统输出的动态测量误差进行分析,将总误差进行分解,找出引起此总误差的各组成单元带来的单项误差,为进一步更精确的进行动态精度评定、动态误差诊断与控制,提供了科学的理论依据.     

旋翼传感信号采集系统的指标评价体系构建研究

直升机旋翼地面试验完成旋翼传感信号的采集与处理,而旋翼传感信号的采集系统特性直接影响采集信号质量和气动特性分析准确性。经传感信号预处理后,针对旋翼传感信号采集系统性能评价问题和影响因素,给出参数指标定义及分析方法,建立传感信号采集系统的综合能力指标评价体系,研究采集系统增益精度、误差限、相位通道匹配、无杂散动态范围等指标与传感信号特征的关系,并在旋翼风洞地面试验基础上完成风压信号采集与指标评价体系验证。结果表明,传感信号采集增益精度达到0.01%,相位通道误差为0.01%,无杂散动态范围为75dBc,误差限为0.033%,线性度为0.0448%,表面压力信号误差小于0.0155%。该指标评价体系优于传统评价方式,能够全面地、准确的从静态与动态角度完成对多通道采集系统的指标评价,使采集的旋翼传感信号质量满足旋翼压力信号采集与处理要求。     

基于DASYLab软件的虚拟仪器设计与应用

结合虚拟仪器的构成特点与优势,利用DASYLab软件设计了动态应变信号采集分析系统,用于采集组合梁模型在运动小车作用下的应变值,并对采集信号进行拟合与输出显示。在桥梁工程检测中应用该系统进行动态应变测试,取得了比较满意的效果。     

数控机床主轴系统性能退化评估方法

为了揭示数控机床主轴系统性能退化规律,准确评估主轴系统性能退化程度,采用动态模糊神经网络建立主轴系统性能退化模型.采用小波包对信号进行分解与重构,实现小波包去噪和频段分解,以小波包功率谱作为信号特征.通过融合振动信号、电流信号和声发射信号,利用动态聚类的数据预处理方法简化数据,采用滑动窗遗忘法与梯度下降法相结合训练评估模型,改善评估动态特性.仿真结果表明,性能退化评估结果准确,满足制定备件计划和主动维护的需要,具有工业推广价值.     

动态测试与信号分析系统研究与应用

本文介绍了动态测试与信号分析系统的特点和功能,介绍了该系统连续大样本采集功能,实例说明小波分析等信号分析方法在机械故障诊断中的应用.     

挖掘机动态测试信号的微机采集与处理

本文主要介绍了大型挖掘动态测试信号的计算机采集与处理系统以及对应的软件设计，该系统的最大特色是具有信号采集的预处理功能。同时具有数据处理，图形显示及打印等功能，并在大型挖掘机的动态测试应用方面取得了良好的效果。     

动态测试信号模型及电能压缩感知测量方法

首先建立了动态测试信号统一模型,并给出两种实现形式。将动态测试信号分解为稳态信号和动态本征信号,根据动态本征信号先验结构信息构造压缩感知(CS)测量矩阵,推导了动态测试信号CS间接测量模型,解决了动态电能量值溯源和准确测量的理论问题;提出了动态测试信号电能量值CS间接测量新方法,并建立了智能电能表动态误差测试系统。最后,实验验证和不确定度分析表明,CS间接测量方法能够测试不同条件下智能电能表的动态误差。     

Static and dynamic test of high resolution DAC based on over sampling and low resolution ADC

The problem of the signal acquisition with high resolution and linearity for static and dynamic characterization of high resolution DACs is shifted into the problem of high speed signal acquisition at lower resolution. High speed low resolution ADC is used to over sample the signal sum of output voltage of the DAC under test and periodic reference voltage. Two different reference signals are used: sinusoidal for static test, and sawtooth for dynamic test. DAC output is reconstructed by means of the reference signal evaluated in the zero crossing sequence detected on the resulting signal.     

外界振动对精密离心机动平衡测试的影响

为从精密离心机动平衡测试信号中分离出外界振动的干扰信号,分析了惯导用精密离心机动平衡测试系统的测试信号,研究了静不平衡与偶不平衡作用下转子的回转中心,分析了来自地基水平方向的外界振动及外界角振动对精密离心机动平衡测试的影响。根据动平衡测试系统噪比对外界振动提出了要求。     

方位角测量跟踪系统设计及实验

为了使跟踪设备快速、准确地跟踪飞行目标并精确测量目标方位角,设计了一种测量跟踪系统,该系统根据跟踪设备发出的方位角偏差信号推动带有跟踪设备的伺服转台,驱动子系统采用H型双极模式PWM电路驱动伺服转台的直流电机以提高响应速度。使用测速机反馈速度信号以提高系统稳定性,使用高精度编码器输出目标方位角信号以提高测量精度。提出了系统动态传递函数,并对传递函数进行分析,给出了仿真动态曲线并计算动态参数。计算了电路的开关频率及延迟时间等关键参数。通过实验得到系统阶跃响应的位移曲线和速度曲线以及其他实验结果。实验结果显示,系统随动精度为0.1 (°)/s,最大跟踪速度为38.3 (°)/s,最大跟踪加速度为23.5 (°)/s²,满足了技术指标和设计要求。     

Floating clamping mechanism of PT fuel injector and its dynamic characteristics analysis

PT fuel injector is one of the most important parts of modern diesel engine.To satisfy the requirements of the rapid and accurate test of PT fuel injector,the self-adaptive floating clamping mechanism was developed and used in the relevant bench.Its dynamic characteristics directly influence the test efficiency and accuracy.However,due to its special structure and complex oil pressure signal,related documents for evaluating dynamic characteristics of this mechanism are lack and some dynamic characteristics of this mechanism can’t be extracted and recognized effectively by traditional methods.Aiming at the problem above-mentioned,a new method based on Hilbert-Huang transform(HHT) is presented.Firstly,combining with the actual working process,the dynamic liquid pressure signal of the mechanism is acquired.By analyzing the pressure fluctuation during the whole working process in time domain,oil leakage and hydraulic shock in the clamping chamber are discovered.Secondly,owing to the nonlinearity and nonstationarity of pressure signal,empirical mode decomposition is used,and the signal is decomposed and reconstructed into forced vibration,free vibration and noise.By analyzing forced vibration in the time domain,machining error and installation error of cam are revealed.Finally,free vibration component is analyzed in time-frequency domain with HHT,the traits of free vibration in the time-frequency domain are revealed.Compared with traditional methods,Hilbert spectrum has higher time-frequency resolutions and higher credibility.The improved mechanism based on the above analyses can guarantee the test accuracy of injector injection.This new method based on the analyses of the pressure signal and combined with HHT can provide scientific basis for evaluation,design improvement of the mechanism,and give references for dynamic characteristics analysis of the hydraulic system in the interrelated fields.     

改进经验模态分解在动平衡信号提取中的应用

在变频结构干扰和强噪声背景下，传统方法从原始振动信号中提取动平衡信号的精度不高。本文采用经验模态分解可以根据实时振动信号的局部特征时间尺度，将其自适应分解为有限多个由高频到低频排列的、正交的本征模态函数；同时利用自回归预测模型延拓信号端点，以消除分解过程的边界效应对低频动平衡信号的影响；最后，根据功率谱密度可以快速、有效地判断出代表基频信号的本征模态函数。实验结果证明，该方法可以高精度提取动平衡信号，在相同测量条件下，能够获得较高的一次不平衡量降低率和较好的重复性能。     

基于EMD与分批估计的动态称量快速融合方法

活体动物动态称量在生物医学实验中具有举足轻重的作用。为实现活体动物快速、准确的称量,提出基于EMD与分批估计相结合的动态称量信息融合方法:首先利用经验模态分解(EMD)方法解析活体动物动态称量的采样信号,提取表征采样信号的趋势或均值的残余量,计算各阶本征模函数(IMF)与采样信号的相关系数,根据相关系数分辨虚假IMF,并将虚假IMF和原残余量之和作为新残余量;然后对新残余量进行分批估计,消除各种噪声、扰动对称量结果的影响,获得准确的动态称量值。通过建立动态称量系统的仿真模型,对基于EMD与分批估计相结合的动态称量信息融合方法进行了仿真实验,仿真结果表明该算法准确度高。为了验证基于EMD与分批估计相结合的动态称量方法的有效性,进行标准砝码的静态称量和小鼠的动态称量试验,实测结果表明该方法稳定、可靠,称量误差≤±0.5%。     

Dynamic characteristics of NC table with SVD

This paper employs the SVD (singular value decomposition) method to study dynamic characteristics of a numerical control (NC) table. Acceleration signals of the NC table at three directions are tested; the singular spectrum of the signals is acquired with SVD; principal components of the signals are found out; dynamic characteristics of the signals and their contributing factors are studied by extracting dynamic characteristics of principal components; and signals and principal components are quantitatively analyzed by calculating signal energy. Results indicate that signal characteristics of the previous two principal components are apparent, based on which dynamic characteristics of chaotic signal can be extracted. Signal at the perpendicular direction of the table is significantly correlated with that at the horizontal motion direction, which indicates that they are excited from the same vibration source. However, signals perpendicular to each other in terms of the motion direction at the horizontal level are rarely correlated; the total signal energy is maximum at the motion direction, minimum at the horizontal non-motion direction, and medium at the perpendicular non-motion direction. Bending vibration of the lead screw at the perpendicular direction is far more violent than that at the horizontal direction.     

Small diameter fiber Bragg gratings and applications

Small diameter optical fibers are preferred in sensing systems as they have less influence on mechanical performance of smart composite. The static and dynamic monitoring capabilities of the small-diameter fiber Bragg gratings (FBG) are experimentally studied in this paper. Firstly, a small-diameter FBG is used as a strain sensor. Secondly, a temperature sensor is fabricated using a specific FBG. Thirdly, a simple sensing system is proposed in order to discriminate temperature at sensing point. Finally, utilization of these small diameter FBGs for vibration monitoring is discussed. The experiments revealed that the central wavelengths of the small-diameter fiber Bragg gratings shift linearly with strain or temperature. The FBG is more sensitive than a thermocouple inside the thermostat. Acquisition and analysis of the dynamic signal indicates that the designed FBG can be used for dynamic signal monitoring.     

斜拉桥健康监测信号改进小波相关降噪

为提高斜拉桥健康监测动态信号的降噪效果,针对传统小波相关降噪算法的缺陷,提出一种改进小波相关降噪算法。该算法将各层小波系数的主要能量周期作为相关检测邻域范围,并根据斜拉桥动态响应信号特征设置降噪阈值,最后采用一种全新的信号重构算法,得到降噪后的信号。将该算法与传统小波相关降噪和小波默认阈值降噪算法进行仿真试验比较,结果表明,改进小波相关降噪算法具有较好的降噪效果,能够应用于斜拉桥健康监测动态响应信号的降噪处理。     

EMD技术在动态称重数据处理中的应用

介绍了一种新的振动信号处理技术—EMD(经验模分解 )。根据EMD的特点 ,将用此方法处理动态称重系统输出信号得到的余量看作重量的稳定值。本文建立单自由度和二自由度称重系统的模型来验证EMD在动态称重信号处理上应用的可行性。计算结果表明 ,使用EMD处理单谐波、多谐波及含噪声的信号时都能得到较理想的结果 ,因此EMD是种可行的动态称重信号处理技术。