广义双线性系统的残差产生器设计

针对具有不可测外界干扰和有界控制输入的广义双线性系统,提出了一种用于故障检测的未知输入残差产生器的设计方法。首先,通过非奇异线性变换,将广义双线性系统分解成动态和静态两个子系统,设计了未知输入残差产生器,给出了未知输入残差产生器存在的充分必要条件,并基于Lyapunov稳定理论,分析了所设计的未知输入残差产生器的指数稳定性。然后,针对未知输入残差产生器中的待定参数,基于线性矩阵不等式技术和广义逆理论,给出了未知参数的求解过程,该求解方法不需要对待求参数进行参数化的过程,易于计算。     

基于UIOs的风力机传动系统多故障诊断

风力机故障诊断通过对机组运行数据进行提取、估计,以辨别出故障并获得故障信息.但目前风力机故障检测大多考虑单个故障发生的情况,而实际工程中无法避免多故障同时发生.通过设计未知输入观测器组,解决了风力机传动系统执行器和传感器的多故障诊断及隔离.针对不同故障类型各设计一组未知输入观测器.观测器组中的每个未知输入观测器产生一个残差信号,该残差不敏感于相应故障,但敏感于其他故障.通过对比观测器组中的残差信号可实现单一或多故障诊断.建立风力机传动系统故障模型,仿真分析得出该方法具有可行性.     

线性时滞系统故障检测滤波器设计H∞优化方法

研究一类线性时滞系统的基于观测器的故障检测滤波器设计问题.通过对线性时滞系统进行广义坐标变换,得到了只包含输入、输出时滞,无状态时滞的新的系统表达形式.在此基础上,选用基于观测器的故障检测滤波器作为残差产生系统,使得到的残差动态方程为仅包含未知输入时滞和故障时滞的线性时不变形式,进而可应用已取得的线性时不变系统故障诊断研究成果设计故障检测滤波器.同时给出一种线性时滞系统故障检测滤波器设计的H∞优化设计方法,并通过算例验证了所提方法的有效性.     

风力机系统基于H_/H∞未知输入观测器的故障诊断

针对实际工程中风力机传动系统未知输入难以完全解耦的问题,提出基于H_-/H_∞未知输入观测器(unknown input observer, UIO)故障诊断方法.首先,利用未知输入观测器的等式条件将未知输入分解为可解耦与不可解耦两部分,且将可解耦部分从估计误差中消除.其次,利用H_-/H_∞性能指标设计未知输入观测器的残差产生器,使残差对未知输入中不可解耦部分具有鲁棒性并对故障信号具有敏感性,并通过引入松弛矩阵解决观测器参数设计过程中的保守问题.考虑残差信号的随机特性,采用统计理论确定故障检测阈值.经仿真验证,该方法可对风力机传动系统传感器加性故障和乘性故障进行有效诊断.     

采样数据系统故障检测的H∞方法

提出一种对采样数据系统进行故障检测的H∞方法.首先构造离散时间故障检测系统,分析残差产生器的动态特性.然后从故障检测的角度引入算子,定量考察连续时间未知输入信号和故障信号对离散时间残差信号的影响.最后优化残差产生器的参数,使得故障检测系统对未知输入具有较强的鲁棒性,同时对故障具有较高的灵敏度.     

一类时滞LPV 系统的鲁棒故障检测

研究一类具有参数依赖时滞的线性参数变化系统的鲁棒故障检测问题，使残差信号和故障信号之问的误差最小，同时提高残差信号对控制输入和未知输入信号的鲁棒性．基于依赖于时变参数的滤波器构造残差产生系统，利用H∞控制理论将故障检测滤波器的设计归结为H∞滤波问题，应用线性矩阵不等式技术得到了此类系统鲁棒故障检测滤波器存在的充分条件．数值仿真表明所提方法是可行的．     

变采样周期和多包传输的非线性NCS故障检测

研究具有多包传输、时变采样周期和未知干扰输入的Lipschitz非线性网络控制系统的故障检测问题;利用主动变采样周期的方法将多包传输的非线性连续网络控制系统建模为离散切换系统,设计基于观测器的鲁棒故障检测滤波器构造残差产生系统,运用Lyapunov稳定性理论和线性矩阵不等式(LMI)技术,给出了使闭环系统渐近稳定的充分条件及故障检测滤波器的增益矩阵;最后运用仿真算例说明了故障检测滤波器的残差产生系统对故障具有敏感性,同时对外部扰动输入具有鲁棒性。     

具有随机马尔可夫时延的网络控制系统H∞故障检测

针对存在随机时延的网络环境,研究了一类网络控制系统的H∞故障检测滤波器设计问题．考虑了可 由马尔可夫过程描述的随机时延,网络控制系统被建模成离散时间有限状态的马尔可夫跳变线性系统．基于此类模 型,构造了系统的残差发生器,相应的故障检测问题转化为H∞滤波问题．通过选择合适的滤波器增益,使得残差和 故障之间的误差尽可能地小,保证了残差对于未知输入的鲁棒性．以线性矩阵不等式的形式给出了故障检测滤波器 存在的充分条件,并运用锥补线性化方法完成了滤波器设计过程．数值算例表明,上述网络控制系统故障检测滤波 器不仅对故障敏感,同时对外界扰动具有鲁棒性．     

基于模型的闭环系统故障检测的一种新方法

针对在闭环控制系统中,如何取得产生残差的最佳信号的问题,通过对单输入单输出闭环系统各种故障的Matlab仿真研究及结果分析,提出了一种基于模型的闭环系统故障检测的新方法。该方法把控制器的输出残差和系统的输出残差结合起来检测故障,并且考虑到了在实际系统中控制器可能饱和的实际情况。这种检测故障的新方法对于实际系统可能发生的各种故障(如执行器,传感器故障)更为有效,可以提高系统检测故障的性能,减少了系统故障的漏报率。     

采样数据系统故障检测的H∞方法

提出一种对采样数据系统进行故障检测的H_∞方法. 首先构造离散时间故障检测系统, 分析残差产生器的动态特性. 然后从故障检测的角度引入算子, 定量考察连续时间未知输入信号和故障信号对离散时间残差信号的影响. 最后优化残差产生器的参数, 使得故障检测系统对未知输入具有较强的鲁棒性, 同时对故障具有较高的灵敏度.     

基于DSP的在线电容电流测量设备的开发

针对现有电容电流测量设备存在安全隐患的问题,文章提出了一种基于DSP的在线电容电流测量设备的设计方案,介绍了该设备的测量原理、硬件和软件的设计。该设备采用信号注入法测量电网电容电流:由消弧线圈二次侧在线注入20~80 Hz、步长为0.2 Hz、幅度相等的信号,通过DSP处理电网的反馈信号得到电网系统的谐振频率,间接计算得到电网电容电流。该设备解决了电容电流测量的安全性问题。     

Quantity,exchange, and shift components of difference in a square contingency table

A common task is to measure the difference between two maps that show the same spatial extent for the same categorical variable, such as land-cover type. One popular technique is to express the overall difference as the sum of two components called quantity and allocation. This article shows how to take an additional step to express allocation difference as the sum of two components called exchange and shift. Exchange exists for a pair of pixels when one pixel is classified as category A in the first map and as category B in the second map, while simultaneously the paired pixel is classified as category B in the first map and as category A in the second map. If there are more than two categories, then it is possible to have a component called shift, which is allocation difference that is not exchange. Our article shows how to compute all three components of overall difference: quantity, exchange, and shift. We show also how to compute the three components for each category and to reveal the category pairs that account for the largest exchanges. Our article applies the principles to characterize both temporal changes and classification errors using land-cover maps from suburban Massachusetts, USA.     

Nonlinear parameter estimation by weighted linear associativememory with nonzero interception

The method of linear associative memory (LAM) has recently been applied in nonlinear parameter estimation. In the method of LAM, a model response, nonlinear with respect to the parameters, is approximated linearly by a matrix, which maps inversely from a response vector to a parameter vector. This matrix is determined from a set of initial training parameter vectors and their response vectors according to a given cost function, and can be updated recursively and adaptively with a pair of newly generated parameter-response vector. The advantage of LAM is that it can yield good estimation of the true parameter from a given observed response even if the initial training parameter vectors are far from the true values. In a previous paper, we have significantly improved the LAM method by introducing a weighted linear associative memory (WLAM) approach for nonlinear parameter estimation. In the WLAM approach, the contribution of each pair of parameter-response vector to the cost function is weighted in a way such that if a response vector is closer to the observed one then its pair plays more important role in the cost function. However, in both LAM and WLAM, the linear association is introduced with zero interceptions, which would not give an exact association even if the model function is linear and so will affect the efficiency of the estimations. In this paper, we construct a theory which introduces a linear association memory with a nonzero interception (WLAMB). The results of our estimation tests on two quite different models, Van der Pol equation and somatic shunt cable model, suggest that WLAMB can still significantly improve on WLAM.     

一种面向不完备数据的集对粒层次聚类算法

针对现有层次聚类算法难以处理不完备数据集,同时考虑样本与类簇之间的不确定关系,提出一种面向不完备数据的集对粒层次聚类算法-SPGCURE.首先,采用集对信息粒的知识对缺失值进行处理,不同于以往算法中将缺失属性删除或者填充,用集对联系度中的差异度来表示缺失属性值,提出一种改进的集对信息距离度量方法,用于考量不完备数据样本间的紧密程度;其次,基于改进后的集对距离度量,给出各个类簇的类内平均距离的定义,形成以正同域Cs(样本一定属于类簇)、边界域Cu(样本可能属于类簇)和负反域Co(样本不属于类簇)表示的集对粒层次聚类;SPGCURE算法在完备和不完备数据都适用,最后,选用5个经典的UCI数据集,与常用的经典及改进聚类算法进行实验评价,结果表明,SPGCURE算法在准确度、F-measure、调整兰德系数和标准互信息等指标上均具有不错的聚类性能.     

Optimal adaptive estimation of sampled stochastic processes

This work presents an adaptive approach to the problem of estimating a sampled, stochastic process described by an initially unknown parameter vector. Knowledge of this quantity completely specifies the statistics of the process, and consequently the optimal estimator must "learn" the value of the parameter vector. In order that construction of the optimal estimator be feasible it is necessary to consider only those processes whose parameter vector comes from a finite set of a priori known values. Fortunately, many practical problems may be represented or adequately approximated by such a model. The optimal estimator is found to be composed of a set of elemental estimators and a corresponding set of weighting coefficients, one pair for each possible value of the parameter vector. This structure is derived using properties of the conditional mean operator. For Gauss-Markov processes the elemental estimators are linear, dynamic systems, and evaluation of the weighting coefficients involves relatively simple, nonlinear calculations. The resulting system is optimum in the sense that it minimizes the expected value of a positive-definite, quadratic form in terms of the error (a generalized mean-square-error criterion). Because the system described in this work is optimal, it differs from previous attempts at adaptive estimation, all of which have used approximation techniques or sub-optimal, sequential, optimization procedures [12], [13], and [14].     

计算机硬件系统常见故障的分析处理

归纳总结了计算机用户在日常工作、生活中可能碰到的多种代表性的电脑软硬件故障和问题及解决方法。各种故障问题类型和故障排除思维习惯来编排,具体包括开关机故障、死机故障、显示故障、声音故障、存储设备故障、CPU故障、内存故障、主板故障。在碰到电脑故障时,能快速判断和解决一些有规律可循的常见故障,以及如何维护电脑、如何避免电脑故障。     

On the adaptive control of a class of systems with random parameters and disturbances

The adaptive control of discrete time parameter linear stochastic systems with random parameters is investigated. It is shown that systems whose (unknown) autoregressive parameters undergo bounded martingale difference disturbances may be stabilized by the application of the so-called Modified Least Squares adaptive control algorithm. Asymptotically, the sample mean square performance criterion is equal to the one step ahead minimum variance control loss (which equals the prediction error variance when the system parameters are known) plus a term which is bounded by a quantity proportional to the square of the bound on the parameter disturbance. This latter term may be interpreted as the increase in the prediction error variance due to the random parameter variation.     

一种网络数据包的有效分类方法

终端用户的各种网络行为都会产生大量的数据包，在没有其它任何先验知识的情况下，如何把数据包分成网络游戏包和非网络游戏包是一件困难的工作。通过对大量的数据包样本进行分析，发现用地址偶对和端口偶对的线性拟合斜率作为模式的两个特征，再构造出一个线性分类器，采用增量校正算法求解该线性分类器的权向量，进一步利用该线性分类器，可以对各种环境下新的数据包准确划分为网络游戏包和非网络游戏包，据此可以控制终端用户网络游戏行为。     

A calibration method for odometry of mobile robots based on the least-squares technique: theory and experimental validation

For a mobile robot, odometry calibration consists of the identification of a set of kinematic parameters that allow reconstructing the vehicle's absolute position and orientation starting from the wheels' encoder measurements. This paper develops a systematic method for odometry calibration of differential-drive mobile robots. As a first step, the kinematic equations are written so as to underline linearity in a suitable set of unknown parameters; thus, the least-squares method can be applied to estimate them. A major advantage of the adopted formulation is that it provides a quantitative measure of the optimality of a test motion; this can be exploited to drive guidelines on the choice of the test trajectories and to evaluate accuracy of a solution. The proposed technique has been experimentally validated on two different mobile robots and, in one case, compared with other existing approaches; the obtained results confirm the effectiveness of the proposed calibration method.     

基于PT100型铂热电阻的测温装置设计

介绍了基于PT100型铂热电阻的测温装置的软硬件设计,并进行了实验验证。该装置采用惠斯通电桥电路采集PT100型铂热电阻的阻值,并将其转换为电压差值;PIC单片机采用分段线性方式将电压差值转换为温度值。实验结果表明,该测温装置测量精度高,误差小,可以快速、准确地测量预埋入PT100型铂热电阻的大型动力设备的内部温度。