基于间歇测量的状态估计稳定性和精度研究*

针对分布式控制系统状态估计过程出现的测量值丢失问题,本文量化分析测量值丢失对估计稳定性和精度的影响。首先,根据随机测量模型重新推导带测量值丢失的卡尔曼滤波器,得到估计误差协方差迭代式。然后,将随机误差协方差迭代式建模为修正的黎卡提微分方程,提出了估计稳定性和精度分析方法。最后,列举不同的系统实例,证明临界包到达率的存在性,当测量值到达率大于临界值时,平均误差协方差从发散过渡到有界,进而得到估计精度与包达率之间的函数关系。     

基于硬件Kalman滤波器的航拍云台姿态获取

航拍云台姿态获取是航空摄影中相机姿态校正的基本依据,介绍了一种基于硬件Kalman滤波器的航拍云台姿态获取的实现方法。设计中采用MPU6050作为系统的姿态传感器,它提供三轴角速度和三轴加速度数据。根据系统特征建立Kalman滤波方程对这些数据进行数据融合处理,Kalman滤波过程中的加减乘除浮点数运算由FPGA实现,外部数据的采集和时序的控制也由FPGA完成。经过对实际数据的处理实验,得出该硬件模块可以获得较为准确的航拍云台姿态,输出结果误差在-1.5°~1.5°范围内。     

高效快速纤维球过滤器的应用

介绍了纤维球过滤器的特点、工作原理及其在脱盐水装置中的应用效果。     

Approach from physicochemical aspects in membrane filtration

In membrane filtration, solution environment factors such as pH and solvent density are important in controlling the filtration rate and the rejection of the particles and/or the macromolecules. The filtration rate and the rejection in membrane filtration have been investigated from physicochemical aspects. It was shown that the properties of the filter cake formed on the membrane surface play a vital role in determining the filtration rate in mem-brane filtration. It was clearly demonstrated that such filtration behaviors as the filtration rate and the rejection are highly dependent on the electrical nature of the particles and/or the macromolecules. Furthermore, it was shown that the solvent density ρ has a large effect on the steady filtration rate in upward ultrafiltration.     

在矿浆过滤预处理中表面活性剂的应用

针对钼矿的基本物性,筛选合适的表面活性剂,进行钼矿浆过滤条件的试验研究。结果表明,钼矿浆中加入合适的表面活性剂后,增加了滤饼厚度,降低了滤饼湿含量,提高了对矿浆的处理能力。     

Spline-based meshfree method with extended basis

In this work, an extension has been performed on the analysis basis of spline-based meshfree method (SBMFM) to stabilize its solution. The potential weakness of the SBMFM is its numerical instability from using regular grid background mesh. That is, if an extremely small trimmed element is produced by the trimming curves that represent boundaries of the analysis domain, it can induce an excessively large condition number in global system matrix. To resolve the instability problem, the extension technique of the weighted extended B-spline (WEB-spline) is implemented in the SBMFM. The basis functions with very small trimmed supports are extrapolated by neighboring basis functions with some special scheme so that those basis functions can be condensed in the solution process. In order to impose essential boundary conditions in the SBMFM with extended basis, Nitsche's method is implemented. Using numerical examples, the presented SBMFM with extended basis is shown to be valid and effective. Moreover, the condition number of the system is well-managed guaranteeing the stability of the numerical analysis.     

基于M估计的非线性鲁棒检测卡尔曼滤波算法

针对传统鲁棒非线性滤波在观测噪声为非高斯强干扰噪声情况下,滤波性能下降的问题,提出一种利用卡方检测法预判断的非线性鲁棒检测滤波算法。该算法通过卡方检测设置门限,剔除突变野值,利用M估计修正量测更新。仿真实验对比了几种典型非线性滤波方法在不同观测噪声环境下的性能。所提算法在非高斯强干扰噪声情况下,比传统鲁棒滤波算法估计精度平均提高了25.5%;估计方差平均减少了18.3%。实验结果表明:所提算法可以抑制观测量非高斯强干扰噪声的影响,提高滤波精度及稳定性。     

基于SR-UKF的OFDM频偏迭代估计算法研究

对高速运动环境下多普勒效应引起的大载波频偏引起的载波间干扰进行数学分析,建立带频偏的非时变和时变频偏OFDM动态状态空间模型,提出了基于平方根无迹卡尔曼滤波（square-root unscented Kalman filter , SR-UKF）的频偏估计算法。将非线性状态估计思想引入OFDM频偏估计中,实现了对频偏的有效跟踪和估计。仿真结果表明,在大频偏、高阶调制下,SR-UKF频偏估计算法较自消除算法、最大似然估计算法具有更好的误码率性能;在收敛精度、稳定度和对信噪比敏感度方面,性能较扩展卡尔曼滤波算法均有所提升。     

基于Kalman滤波的谐波电流实时检测仿真分析

谐波电流的实时检测是有源电力滤波器实现的关键,数字化的实现引入了一定的时间延迟,影响了其滤波效果。将三相谐波电流进行Clark坐标变换到两相正交坐标系中,利用Kalman算法对系统进行建模,检测出各次谐波电流的幅值和相角。通过选取合理的Kalman状态变量,运用简单的代数运算向模型中增加了一个相位补偿角,来消除延时的影响。最后,利用Matlab进行仿真实验,验证了该方法的有效性和正确性。     

多传感器集中式增量卡尔曼滤波融合算法

在单个传感器的状态估计系统中,标准的增量卡尔曼滤波方法可以有效消除量测系统误差。对于多传感器情况,标准算法失效。针对该问题,提出了多传感器集中式增量卡尔曼滤波融合算法,即:增量卡尔曼滤波的扩维融合算法和增量卡尔曼滤波的序贯融合算法。在标准增量卡尔曼滤波算法的基础上,结合扩维融合和序贯融合的思想来实现多传感器数据的融合。实验结果表明,当存在量测系统误差时,提出的集中式融合算法与传统的集中式融合算法相比,提高了滤波精度,并且能够成功地消除量测系统误差。