Fault modeling on complex field using least‐square circle fitting for linear analog circuits

A new fault modeling method using least‐square circle fitting (LSCF ) for linear analog circuits is proposed in this paper. In this method, Monte Carlo simulation is used to obtain the output voltage values when the parameter of one faulty component is changed while those of the other components vary within their tolerance limits. All the output response voltage values for every faulty circuit statue are decomposed into real and imaginary parts on a complex field. Then, LSCF method is adopted to match these data, yielding a corresponding circular curve on complex plane, which also can be expressed with a circular function. Its center coordinates and radius are established as the fault features. During measurements, by calculating the distance from one real output to each circular center coordinate and comparing the distance with each circular radius, a faulty component can be diagnosed. The effectiveness of the proposed approach is verified by experiments. The results show that (i) the proposed fault modeling can accurately locate the fault component, and (ii) it can also simply be a fault dictionary. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

大规模容差模拟电路多故障诊断法

本文研究了大规模容差模拟电路的多故障诊断问题,针对交流、直流线性电路和非线性直流电路,考虑了测试点数目有限以及元件容差存在的情况下的电路故障诊断,采用了一种基于线性程序概念的子网络级故障诊断算法来确定元件的实际参数是否在容差范围内或者某些元件是否有故障.文中提及的几个测试方程在定义可能的故障元件中起了关键性作用,并详细阐述了二重故障的诊断原理,且给出了三重故障的诊断公式.该方法大大减少了大规模网络故障诊断计算量,快速有效的定位故障元件.最后用实例说明了该法的有效性.     

A method for fault diagnosis in linear electronic circuits

A method for fault location and parameter identification in linear AC and DC circuits with limited accessible terminals for excitation and measurement is developed in this paper. Fault location is based on a derived relationship having a general meaning. It requires analyses of the circuit with nominal parameters and distinct excitations as well as measurements of some node voltages in the circuit with perturbed parameters. The fault parameter is identified using a formula obtained on the basis of the Woodbury expression. A decomposition technique is suggested enabling us to apply the method for multiple fault diagnosis. Several numerical examples illustrate the proposed approach and show its effectiveness. Copyright © 2000 John Wiley & Sons, Ltd.     

Non‐linear analog circuit fault diagnosis with large change sensitivity

Large change sensitivity has been proved efficient at, but restricted to, generating a linear circuit fault dictionary. This paper discusses the extension of large change sensitivity to non‐linear analog circuit fault diagnosis. The fault dictionary is divided into d.c. and a.c. sections. In the d.c. domain, non‐linear components are approximated with piecewise linear models. By relating the operating region of each piecewise linear model to the magnitude of a single fault in a procedure termed preconditioning, it is shown that large change sensitivity can efficiently compute the response of a faulty non‐linear circuit. Results presented of an analysis of computational complexity show a significant reduction in the cost of simulating single linear resistor faults in a non‐linear circuit using this method. In addition, after establishing that the resistive portion of the circuit is fault free, a fault dictionary is constructed for dynamic components using large change sensitivity in the small signal a.c. domain. Included with a discussion on the issues of large change sensitivity based simulation‐before‐test, a small non‐linear circuit is used to demonstrate the effectiveness of the proposed fault diagnosis algorithm. Copyright © 2000 John Wiley & Sons, Ltd.     

Multiple catastrophic fault diagnosis of analog circuits considering the component tolerances

This paper deals with the diagnosis of multiple catastrophic faults, being cuts (open‐circuits) of some connecting paths and/or short‐circuits of some pairs of points in analog circuits. A method enabling us to detect and identify the faults, taking into account the deviations of the circuit parameters within their tolerance ranges, is developed. The method exploits an appropriate fault dictionary. The fault dictionary is used only for preliminary identification of the faults, because it is based on the analysis of the circuits with nominal parameters. The crucial point of the method is a verification procedure, proposed in this paper, based on the linear programming approach. It leads to the results considering the component variations within their tolerance ranges. In addition, a procedure for selecting appropriate test points, employing some evolutionary techniques, is developed. Although the approach presented in this paper is described in detail for linear circuits, it can be directly generalized to nonlinear circuits. Three numerical examples, including two linear and one nonlinear circuits, illustrate the proposed method and show its efficiency. Copyright © 2011 John Wiley & Sons, Ltd.     

模拟电路的马氏距离故障诊断方法研究

针对欧氏距离在模拟电路故障诊断中的不足,提出模拟电路的马氏距离故障诊断方法。利用MULTISIM对电路的软故障和硬故障进行仿真获取故障特征样本,在MATLAB中计算样本与故障类之间的马氏距离,并选择距离最小的故障类作为诊断结果。仿真结果表明:在20次不同特征维数的试验中,欧氏距离,正规化欧氏距离和马氏距离故障诊断方法的平均诊断准确率分别为:86.7%,87.1%和92.9%。马氏距离的诊断方法不受特征相关性的影响,能够正确诊断出欧氏距离和正规化欧氏距离诊断方法的误诊样本,在模拟电路的故障诊断中的准确率更高。     

基于小波神经网络的模拟电路故障诊断改进

在运用神经网络进行模拟电路故障诊断的过程中,代表着故障特征的网络输入至关重要,由于小波变换的时频局部化和多尺度分析等特性,将两者结合起来,通过小波变换对模拟电路的输出响应进行故障特征提取,同时解决PSPICE与MATLAB之间的数据通信问题,提出将蒙特卡罗分析产生的所有训练样本经过处理后输入到一个神经网络进行训练的方法,从而避免了训练多个神经网络。利用神经网络对各种故障模式进行分类,实现模拟电路的故障诊断,并进一步与传统的BP网络故障诊断法进行比较。仿真结果表明,该方法可以实现故障检测及定位,诊断的准确率显著提高,适用于模拟电路故障诊断。     

Global and local parametric diagnosis of analog short‐channel CMOS circuits using homotopy‐simplicial algorithm

The paper offers an algorithm for local and global parametric diagnosis in nonlinear analog circuits, including both identification of the faulty parameters and determination their values. The algorithm exploits a nonlinear algebraic type test equations which may possess multiple solutions, corresponding to different sets of the parameters values which meet the test. To find the solutions, the homotopy concept is applied. Since the test equation is not given in explicit analytical form, the simplicial method is used to trace the homotopy path. The proposed approach can be applied to a broad class of analog circuits, including the complementary metal–oxide–semiconductor circuits fabricated in nanometer technology. The developed diagnostic procedure has been implemented in DELPHI, whereas the required by the algorithm repeated circuit analyses are carried out using IsSPICE 4 and both environments have been joined together. For illustration, two numerical examples are given. Copyright © 2013 John Wiley & Sons, Ltd.     

容差条件下的模拟电路多故障诊断

针对容差模拟电路多故障诊断问题,提出了包括故障状态检测、故障粗糙集生成和故障元件定位的分步诊断方法。将有限测点的故障状态检测转化为容差约束下的线性规划问题;推导得到故障特征等式并生成故障粗糙集,证明了在容差条件下的故障特征等式中可选用标称参数电路的节点电压;对故障粗糙集中元件参数的偏差限值进行修正,对修正后的电路进行状态检测,实现故障元件定位,并估算故障参数偏差。仿真实例表明,该方法具有较高的诊断准确度和参数辨识精度。     

Frequency‐domain grouping robust fault diagnosis for analog circuits with uncertainties

A new frequency‐domain grouping robust fault diagnosis (GRFD) scheme, based on the design for both grouping‐robust estimation/evaluation of component variation rate and Boolean‐based decision process, is proposed for solving fault diagnosis of large‐scale analog circuits with uncertainties, including both component tolerances and measurement errors.In this scheme, first, grouping‐robust estimators for one partitioning of all component groups, designed by using grouping‐full‐column rank output measurement technique, are employed to estimate the component variation rate. Secondly, based on the faulty possibility judgment policy suggested in this research, grouping‐robust evaluators are employed for the careful evaluation of component variation rate in order to reduce the effect of both component tolerances and measurement errors on the diagnostic test result for one partitioning. Next, both repeating the same one‐partitioning GRFD for a variety of partitionings and combining Boolean‐based decision process, an overall GRFD scheme is proposed for achieving analog fault diagnosis. Finally, a fault diagnosis example of a large‐scale analog circuit is illustrated. The results indicate that without any a priori information about the type of component failure, a precise t‐diagnosable case for a large‐scale circuit with component tolerances and measurement errors is accomplished at the lowest measurement cost. Copyright © 2001 John Wiley & Sons, Ltd.     

基于多目标线性规划的模拟电路软故障诊断方法

阐述了一种新的容差条件下基于多目标线性规划理论的模拟电路软故障诊断方法。通过灵敏度分析建立电路测试节点电压增量方程,并以元件参数变化量与标称值的百分比作为故障判据。采用多目标线性规划方法求解测试节点方程组来估算电路中各元件在一定故障情况下的参数变化百分比,将方程组的解与各元件容差范围相比较来定位故障元件。仿真结果表明,该方法兼顾故障元件的定位和故障元件参数变化量的估算,可以有效地实现模拟电路元件参数在一定容差范围内变化条件下的软故障诊断。     

Symmetry‐aware placement algorithm using transitive closure graph representation for analog integrated circuits

Recently several topological representations have been explored as alternatives to the conventional absolute‐coordinate representation for integrated circuit layout automation. Those topological representations, however, lack one or more aspects in capturing the solution space subject to symmetry constraints, which are abundant in analog layouts. In this paper, we explore the use of transitive closure graphs (TCGs) to represent analog placements, i.e. placements with symmetry constraints. We define a set of conditions so that a TCG satisfying these conditions, referred to as a symmetric‐feasible TCG, will correspond to a valid symmetric placement and vice versa. We then present an O(n²) algorithm, where n is the number of cells to be placed, to build a symmetric placement from a symmetric‐feasible TCG, a problem known as packing. We further describe a set of random perturbation operations on existing symmetric‐feasible TCGs to generate new symmetric‐feasible TCGs with time complexity of O(n) . This allows our TCG‐based symmetry‐aware analog placer to search only the symmetric‐feasible TCG solution space, leading to a substantial reduction of the search space and solution time. Experimental results on several analog circuits have confirmed the superiority of the TCG representation to the conventional absolute‐coordinate representation as well as several other topological representations in analog layout design. Copyright © 2008 John Wiley & Sons, Ltd.     

Elman神经网络在非线性模拟电路故障诊断中的应用

Elman神经网络把隐层输出反馈回输入层,是一种动态递归神经网络,改进的Elman网络能逼近任意动态非线性系统。本文研究了Elman网络的结构和学习算法,并把改进的Elman网络应用于非线性模拟电路故障诊断激励信号参数优化中,以提高故障正确诊断率。首先用改进的Elman神经网络建立故障电路和无故障电路系统模型,然后用遗传算法搜索电路故障诊断的最佳激励信号参数。     

容差条件下模拟电路软故障的数学规划诊断方法

为了诊断容差条件下模拟电路软故障,提出一种利用数学规划进行软故障诊断的方法。从电路灵敏度分析入手,建立节点电压增量方程。随后,将节点电压增量方程作为约束条件,将要处理的故障诊断问题转化成为数学规划(mathematical programming,MP)模型并且建立相应的数学规划方程。通过求解这些MP方程,估计待测电路中各元件参数的偏移程度。并由此判断待测电路中是否存在故障元件。     

An algorithm for multiple fault diagnosis in analogue circuits

The paper deals with multiple fault diagnosis of analogue AC or DC circuits with limited accessible terminals for excitation and measurement and brings an algorithm for identificating faulty elements and evaluating their parameters. The main achievement is a method enabling us to efficiently identify faulty elements. For this purpose some testing equations are derived playing a key role in identification of possibly faulty elements which are next verified using a test of acceptance. The proposed approach is described in detail for double fault diagnosis. Also extension to triple fault diagnosis is given. Although the method pertains to linear circuits, some aspects of multiple fault diagnosis of non‐linear circuits can be also performed using the small signal approach. Two numerical examples illustrate the proposed method and show its efficiency. Copyright © 2006 John Wiley & Sons, Ltd.     

基于双空间的融合特权信息支持向量机模拟电路故障诊断

针对模拟电路故障诊断识别率较低的问题,提出了基于双空间特征提取的融合特权信息支持向量机的模拟电路故障诊断新方法。首先对采集的信号进行主成分分析(principal component analysis,PCA)——特征提取;并用融合特权信息支持向量机LUPI-SVM(SVM of learning using privileged information,LUPI-SVM)分类器和SVM-GA分类器进行预分类;对分类结果不同的样本进行独立成分分析(independent component analysis,ICA)—特征提取,并用LUPI_SVM进行分类识别,Sallen-Key滤波电路故障诊断仿真实验结果表明该方法有效提高了分类的性能,为模拟电路故障诊断提供了新的途径。     

A generalized fault diagnosis method in dynamic analogue circuits

Fault diagnosis of analogue circuits is essential for analogue and mixed‐signal systems testing and maintenance. A new method is proposed in this paper for multiple fault diagnosis of linear analogue circuits in frequency domain. The Woodbury formula is applied to the modified nodal equation to construct the fault diagnosis equation, which relates the limited measured circuit responses with the multiple faults inside the circuit in a linear way. A recently developed ambiguity group locating technique is modified here to identify the faulty parameters directly. Computation cost is reduced compared to combinatorial search in traditional fault verification methods. Only one node is needed for voltage measurement, but multiple excitations on accessible nodes are required for fault identification. Parameter evaluation can provide the exact solution to the deviated values of faulty parameters. The faulty parameter deviations can have any finite values. Example circuits are provided to illustrate the proposed method. Two other methods for multiple analogue fault diagnosis sharing the same mechanism as the method proposed in this paper are also briefly described. The proposed method is extremely effective for the circuit with very limited accessible nodes and is also computationally efficient. Copyright © 2002 John Wiley & Sons, Ltd.     

Finding all solutions of piecewise‐linear resistive circuits using the dual simplex method

An efficient algorithm is proposed for finding all solutions of piecewise‐linear (PWL) resistive circuits using linear programming (LP). This algorithm is based on a simple test (termed the LP test) for non‐existence of a solution to a system of PWL equations in a given region. In the conventional LP test, the system of PWL equations is transformed into an LP problem, to which the simplex method is applied. However, this algorithm requires a very large number of pivotings because the simplex method is applied on many regions. In this paper, we introduce the dual simplex method to the LP test, which makes the average number of pivotings per region much smaller (less than one, for example) and makes the algorithm very efficient. By numerical examples, it is shown that the proposed algorithm could find all solutions of large‐scale problems, including those where the number of variables is 300 and the number of linear regions is 10³⁰⁰, in practical computation time. Copyright © 2002 John Wiley & Sons, Ltd.     

采用模糊支持向量机的模拟电路故障诊断新方法

为了解决模拟电路故障诊断复杂多样难于辨识的问题,有效提高分类的准确度,提出了一种模拟电路故障诊断的新方法。首先对采集的信号进行时-频域联合特征提取并采用新的模糊隶属度函数确定训练样本的隶属度,消除噪声和野点对故障诊断的影响;然后将训练集输入模糊支持向量机分类方法训练获得故障诊断模型;最后将测试集输入训练好的模糊支持向量机分类模型,实现对不同故障类型的识别。将该方法应用于CTSV滤波电路进行故障诊断仿真实验,结果显示该方法不仅能正确分类单故障而且能有效分类多故障,平均故障诊断率达到98.2%,为模拟电路故障诊断开辟新的途径。     

多特征故障字典及其在模拟电路可测性分析中应用

提出一种新的模拟电路可测性分析模型——多特征故障字典模型。该模型首先获得输出端的阶跃响应输出波形,提取出波形的多个特征量,将所有特征量形成一特征向量,不同故障类别对应的特征向量组成一特征矩阵。然后由PSPICE软件中的Monte-Carlo分析的结果计算出阈值,在该阈值下将特征矩阵转换成整数编码表,从而计算可测性分析指标-检测率与隔离率。仿真与实测数据表明:与传统模拟电路可测性分析方法相比,提出的方法优点有:1)不需要传递函数,可以适用于复杂电路;2)仅需要一个输出测点,容易实现;3)对于容差模拟电路,同样可以取得较好的检测率与隔离率。