时间交替ADC通道失配误差的LS法估计

提出了一种基于最小二乘法的时间交替ADC通道失配误差估计方法。将时间交替ADC系统中的某个通道作为参考通道,利用参考通道的输出数据,通过滤波器插值获得非参考通道的理想输出数据。利用最小二乘法分别对非参考通道理想和实际的采样点进行拟合,结合时间交替ADC系统采样模型,对通道失配误差进行估计。仿真表明,即使在测试信号中含有谐波信号以及采样通道存在其他随机误差时,利用该方法仍然能将失配误差的计算准确度控制在±5%以内。最后,通过对实际高速数字化仪通道失配误差的测量证明了该方法的实用性。     

基于多时间尺度的锂离子电池状态联合估计

荷电状态(SOC)和健康状态(SOH)估计是锂离子电池管理系统的关键技术。针对SOH退化情况下电池模型参数和容量参数发生改变影响SOC长期估计性能的问题,提出了基于多时间尺度的锂离子电池SOC-SOH联合估计方法。建立多时间尺度状态空间方程,构建SOC-SOH与电池模型参数间多维度空间插值曲面,基于无迹粒子滤波算法实现锂离子电池状态联合估计。根据SOH估计结果更新用于SOC估计的电池模型参数和容量参数,在SOH估计中以在线健康因子作为系统观测量实现在线联合估计。实验结果表明,在锂离子电池全寿命周期中,相较于未考虑SOH退化情况,方法在SOC估计的最大误差、平均误差和均方根误差方面有明显降低,较好地提升了SOC的长期估计性能。     

平行分度凸轮机构凸轮轮廓设计误差估计

介绍了平行分度凸轮机构凸轮工作轮廓的解析方程,介绍了非结点边界条件三次样条插值的原理,提出了基于MATLAB的平行分度凸轮机构凸轮轮廓设计误差的估计方法.     

数据采集系统通道间延迟时间差的精确评价

本文介绍了数据采集系统通道间延迟时间差的一种简单实用的精确评价方法,即加数字滤波器的正弦波拟合法。设计实现了单频数字滤波器的时域实现过程及频域表达式,讨论了评价过程的误差来源,以及减小其评价误差的几种对策;同时,给出了评价过程的几个典型实验结果。     

插值改进EKF算法在组合导航中的应用

为了提高GPS/DR组合导航定位的精度和稳定性,提出一种基于插值公式的EKF（扩展卡尔曼滤波）改进算法。插值滤波算法继承了EKF实时递推结构,利用基于Stirling插值公式的差分方法代替EKF中非线性函数导数的计算。将插值公式展开的一阶项和二阶项作为函数近似分别得到DD1、DD2（一阶、二阶差分）滤波算法。插值滤波不必计算函数稚可比矩阵,大大降低了计算的复杂度,并改善了EKF算法中泰勒展开线性化造成的较大误差。根据GPS/DR组合系统的状态和观测方程,采用EKF、DD1和DD2滤波算法分别估计目标的状态信息。对比分析表明,插值滤波的精度和稳定性好于EKF算法,应用范围更为广泛。     

基于国产 ADC 芯片的 TIADC 系统时间误差 自适应校准算法

武器及其测试系统的高精度与国产化是我们国家现在不得不面对的严峻问题,当数据采集系统的采样率达到 GSPS 量 级时,目前的国产 ADC 芯片很难达到,因此在不降低采样精度的前提下,提出多片 ADC 进行阵列化采样的方法提高系统的采 样率。 针对 TIADC 系统存在的通道失配问题,提出了基于一阶统计量的自适应误差估计算法与改进 Farrow 时延滤波器的校正 方法,并对 4 通道 TIADC 系统的时间误差估计提出新的估计策略。 仿真与实验结果表明,该算法能够对时间失配误差进行精 确估计,同时能够有效地抑制杂散分量,相比校正前的数据,无杂散动态范围提高 20 dB,对解决高速高精度数据采集装备国产 化问题具有重要的现实意义。     

2GSPS数字存储示波器插值算法

数字存储示波器在快时基档位工作时,由于实时采样率不够,仅能采集信号的少数样点,为了重构信号,必须进行插值。通过编程和仿真比较了三次样条插值、分段线性插值、三次插值、最邻近插值对几种不同波形的恢复结果,并计算和分析了相关的均方误差。考虑实际待测的信号的不可知性和复杂性,并权衡精度与速度,当待插信号的点数小于100点时,选用三次样条插值;当待插信号的点数不小于100点时,采用三次插值法。Matlab仿真表明,设计结果的各项性能指标均达到指定要求,设计过程简便易行。     

基于延迟求和的输气管道泄漏声波定位方法

针对基于互相关分析的输气管道泄漏声波定位方法因声速和延时估计误差导致定位误差大的问题,提出一种基于延迟求和的泄漏位置声波定位方法。在泄漏位置上下游各增设一个声波传感器,使用延迟求和法对增设传感器信号进行延时估计并计算上下游方向声速;以泄漏位置表征各传感器间的延时,再利用延时表达式构造加权向量对线性阵列输出加权,搜索输出峰值点即可完成定位。在实验室进行了定位实验,结果表明:对泄漏信号的3.7 kHz分量使用延迟求和法进行延时估计能够获得更加稳定的输出,定位平均误差率由互相关分析法的9.09%降低至2.04%,声速计算环节的加入以及基于延迟求和的线性阵列定位方法能够有效提高声波法定位精度。     

面向零件平面度误差估计的空间泛克里金插值建模

机械加工零件表面平面度误差估计是零件质量控制的重要内容。三坐标测量机(Coordinate measuring machine,CMM)广泛应用于零件表面平面度误差测量,但是由于测量成本的限制,CMM获取的测量样本数量有限。因此需要采用空间插值方法,获取更准确的平面度误差估计。通过建立空间统计学的变异函数模型描述零件表面测量数据之间的空间相关性,并推导空间泛克里金插值方法预测零件表面未测量点的坐标高度值,最终将实际测量点和插值预测点通过最小二乘法建立平面度误差预测估计模型。实例研究的结果表明,球状变异函数模型较指数、高斯变异函数能够更有效地定量描述零件表面的空间相关性;同时,泛克里金插值方法提高平面度误差估计的准确程度,其估计精度优于传统方法 5%~10%。     

基于泄漏对消的电力谐波相角高精度估计算法

采用快速傅里叶变换(FFT)进行电力系统谐波分析时,受频谱泄漏和栅栏效应的影响,相角估计误差往往较大.为减小这类误差,提出一种基于频谱泄漏对消的谐波相角高精度估计算法,结合余弦组合窗时域和频域特性,综合考虑长、短范围频谱泄漏的影响,推导了基于余弦组合窗的插值FFT谐波相角计算式.该算法首先运用基于余弦组合窗的插值FFT方法获得频率偏差估计值,然后采用离散频谱泄漏对消方法进行信号谐波相角估计,实现简单,准确度高.非同步采样情况下,采用典型余弦组合窗(Hanning、Blackman、Blackman-Harris、Rife-Vincent(I)、Nuttall等)进行信号谐波相角估计的仿真实验与应用验证了本文算法的准确性和有效性.     

基于多级半带滤波器的超声相控阵聚焦延时

建立了基于多级半带滤波器的超声相控阵聚焦延时系统,以提高仪器延时精度。研究了聚焦延时原理与延时算法的实现。首先,采用内插滤波的方法,设计了半带滤波器作为内插滤波器;然后,对8倍内插结构进行了改进,通过多级半带内插滤波器合成技术,将合成后的滤波器分解为8个子滤波器进行同时滤波,使得内插与多相分解可同时进行。最后,通过对延时算法的仿真分析与现场可编程门阵列（FPGA）的实现,验证了此算法的可行性。实验结果表明：该系统在100 MHz采样率的条件下可实现1.25 ns延时精度,与同性能普通有限长单位冲激响应（FIR）内插滤波器相比,运算量最大可减少21.4%。此方案在运算量、计算速度、分辨率、性价比方面均具有较大优势,非常适合于实时性强、精度高的聚焦延时算法的实现。     

A novel curvature circle iterative algorithm for contour error control of multi-axis CNC machine tools

High-precision real-time estimation of contouring errors is a prerequisite for contouring errors control of multi-axis CNC machine tools. This paper focuses on developing a nearest point projection curvature circle iterative (NPP–CCI) algorithm to achieve real-time estimation of multi-axis contouring errors. It is found that the traditional curvature circle iterative (CCI) method has two major shortcomings. The first is that the iterative process may terminate incorrectly at the local contour position, and the other is that the actual tool position and local curvature circle are not necessarily coplanar in three-dimensional space, which would lead to inaccurate calculation of the delay time parameter and eventually affect the estimation accuracy. In order to address the problem of false termination, an index method is used to find the closest reference position with respect to the actual position. At the same time, the projection technology is proposed to overcome the problem met in extending the planar curvature circle iterative method to the spatial applications. The proposed NPP-CCI algorithm is more suitable for spatial contouring errors estimation in tracking complex trajectories and has higher estimation accuracy than the traditional CCI algorithm. Various experiments with different tool paths are conducted on an in-house developed multi-axis experimental platform to verify the effectiveness of the proposed algorithm. The experimental results show that the NPP-CCI algorithm can estimate the contouring errors with higher accuracy than the traditional CCI algorithm, and with the help of real-time computation and compensation, the contouring errors are reduced by more than 44% in terms of the MAX and RMS values.     

基于Newton-Rapson迭代法的NURBS插补算法的研究

一阶、二阶Taylor展开式求解NURBS曲线插补坐标点ui+1,存在计算量大、插补时间长等问题,该文提出了一种基于Newton-Rapson迭代法的NURBS插补算法。仿真和实验结果表明:该算法计算过程简单有效,具有可行性和实用性,可以减少插补计算量和插补时间,提高插补精度和加工效率,满足了数控系统实时、高速、高效率插补的要求,对其他数控插补的过程具有很强的借鉴意义。     

Adaptive filtering techniques for velocity estimation of tomographic electric capacitance signals of two-phase gas/oil flows

The development of adaptive real-time flow velocity estimation algorithms for two-phase flows can contribute to monitoring the pipelines of various complex processes, such as energy, chemical, petroleum and nuclear industries. Among the different non-invasive tomography techniques, electrical capacitance tomography (ECT) is gaining increasing attention for its potential use in real-time imaging and characterization of multiphase flow systems. The nature of ECT signals for two-phase flows can significantly degrade the velocity estimation process with cross-correlation approaches. We address the unique challenges of such signals and propose a preprocessing technique to improve the performance and robustness of the velocity estimation algorithm. Two adaptive filters are used to estimate the velocity of a two-phase type flow. A least mean square (LMS) and a fast block LMS (FBLMS) are used to model the time delay between the two signals captured by the twin sensor (ECT). Performance of the proposed technique is assessed by applying it to ECT data obtained from an experimental flow rig. The computed estimates are then compared with the calculated velocity from tracking motion of bubbles captured by a high speed camera monitoring the two phase flow in the pipe. Results show that the proposed technique provides consistent results across various flow patterns, and is advantageous compared to cross-correlation based techniques, specially for chaotic flow conditions. Furthermore, the proposed estimation algorithms can be applied to other electric based tomographic techniques.     

Adaptive tuning piecewise cubic Hermite interpolation with Wiener filter in wavelet domain for scanning electron microscope images

Image processing is introduced to remove or reduce the noise and unwanted signal that deteriorate the quality of an image. Here, a single level two‐dimensional wavelet transform is applied to the image in order to obtain the wavelet transform sub‐band signal of an image. An estimation technique to predict the noise variance in an image is proposed, which is then fed into a Wiener filter to filter away the noise from the sub‐band of the image. The proposed filter is called adaptive tuning piecewise cubic Hermite interpolation with Wiener filter in the wavelet domain. The performance of this filter is compared with four existing filters: median filter, Gaussian smoothing filter, two level wavelet transform with Wiener filter and adaptive noise Wiener filter. Based on the results, the adaptive tuning piecewise cubic Hermite interpolation with Wiener filter in wavelet domain has better performance than the other four methods.     

基于运动估计EPZS算法的优化

编码器中的运动估计、计算量非常巨大,消耗了整个编码时间的80%,严重降低了编码的实时性.为了高效节省运动估计时间和编码时间,在充分研究预测区域搜索算法(EPZS)的基础上,提出一种对H.264视频编码标准采纳的EPZS算法进行了初始中心点和搜索模板的优化方法.在H.264编码器的参考模型JM10.1中,对4个测试序列进...     

Adaptive blind gain correction of time-interleaved ADCs for wide-band communication applications

High spectral efficiency is essential in design of multimedia communication systems such as L-band mobile in addition to various requirements of transmission quality.Time-interleaved A/D converter (TI-...     

An adaptive real-time spectrum analysis architecture

An architecture for adaptive real-time spectrum analysis of multi-frequency waveforms is presented. The adaptation strategies implemented ensure that system performances are at any time optimal, or at least near-optimal, for the aim of minimising measurement time. A new measurement algorithm for high-accuracy analysis in the frequency domain, which provides the basis for efficient adaptation, is introduced and an assessment is given of its accuracy. The system, based on this architecture, provides high-accuracy results and near-minimum measurement delay for input frequencies up to 20 kHz.     

Robust stability and performance of time-delay control systems

Most of the optimal and adaptive regulators assume an a priori known time delay. The time-delay mismatch can cause unwanted instability. Influence of this uncertainty is investigated in connection with the required performance and robustness.