Fault Diagnosis of Nonlinear Analog Circuits Using Neural Networks with Wavelet and Fourier Transforms as Preprocessors

A neural-network based analog fault diagnostic system is developed for nonlinear circuits. This system uses wavelet and Fourier transforms, normalization and principal component analysis as preprocessors to extract an optimal number of features from the circuit node voltages. These features are then used to train a neural network to diagnose soft and hard faulty components in nonlinear circuits. Our neural network architecture has as many outputs as there are fault classes where these outputs estimate the probabilities that input features belong to different fault classes. Application of this system to two sample circuits using SPICE simulations shows its capability to correctly classify soft and hard faulty components in 95% of the test data. The accuracy of our proposed system on test data to diagnose a circuit as faulty or fault-free, without identifying the fault classes, is 99%. Because of poor diagnostic accuracy of backpropagation neural networks reported in the literature (Yu et al., Electron. Lett., Vol. 30, 1994), it has been suggested that such an architecture is not suitable for analog fault diagnosis (Yang et al., IEEE Trans. on CAD, Vol. 19, 2000). The results of the work presented here clearly do not support this claim and indicate this architecture can provide a robust fault diagnostic system.     

模拟电路故障诊断的小波包预处理神经网络改进算法

提出了基于小波包预处理的神经网络模拟电路故障诊断方法的两种改进方法:最优小波包变换(OWPT)预处理和不完全小波包变换(IWPT)预处理BP神经网络算法。首先对模拟电路的响应信号用这两种方法进行预处理,然后计算预处理后信号各个频段上的归一化能量,把归一化的能量作为训练样本送给BP网络进行训练,有效减少了BP网络的输入节点和隐层节点的个数,从而减小了神经网络的规模,降低了计算的复杂度,加快了网络的训练和收敛速度。仿真实验表明此方法能够快速有效的对模拟电路的故障进行诊断和定位。     

Classification of Defective Analog Integrated Circuits Using Artificial Neural Networks

This paper presents a new approach for detecting defects in analog integrated circuits using the feed-forward neural network trained by the resilient error back-propagation method. A feed-forward neural network has been used for detecting catastrophic faults randomly injected in a simple analog CMOS circuit by classification the differences observed in supply current responses of good and faulty circuit. The experimental classification was performed for time and frequency domain, followed by a comparison of results achieved in both domains. It was shown that neural networks might be very efficient and versatile approach for test of analog circuits since an arbitrary fault class or circuit's parameter can be analyzed. Considered defect types and their successful detection by the neural network; and a possible off-chip hardware implementation of the proposed technique are discussed as well. Moreover, optimized hardware architecture of the selected neural network type was designed using VHDL for FPGA realization.     

非线性容差模拟电阻电路故障诊断神经网络方法

将线性电路故障定位 l1 范数最优化算法推广到非线性电路的故障定位 ,由于测后计算是基于神经网络计算机环境 ,所需时间较少 ,能满足现代工业实时性需要。实例和计算机模拟结果表明所提方法是可行的     

改进的BP神经网络在模拟电路故障诊断中的应用研究

介绍了应用小波变换法与BP神经网络相结合实现模拟电路故障诊断的方法。应用小波变换法作为故障信号的预处理器,提取故障特征量,减小了BP神经网络的规模。该方法提高了神经网络收敛的速度以及故障类别识别的准确度,具有一定的应用价值。     

一种基于小波-神经网络的模拟电路故障诊断方法

小波分析具有数据压缩和特征提取的特性,神经网络具有非线性映射和学习推理的优点。结合两者的特点,提出了一种基于小波与神经网络的模拟电路故障诊断方法,该方法用小波变换对电路响应信号进行特征提取,从而简化神经网络的结构,降低计算的复杂度,加快了训练速度。对实例仿真表明,该法能有效地对模拟电路进行故障诊断。     

一种基于神经网络的模拟电路故障诊断方法

模拟电路故障诊断一直是一项富有挑战性的研究课题。文章在简要介绍BP神经网络基本原理的基础上,以差分放大电路为例,设计并实现了基于BP算法的模拟电路故障诊断方法,建立了模拟电路故障诊断BP神经网络模型。实验表明,该模型的辨识精度高,能实现对模拟电路故障的正确诊断。     

一种基于小波预处理的模拟电路故障诊断方法

文中提出了一种基于小波预处理的模拟电路故障诊断方法。由于小波分析具有数据压缩和特征提取的特性,我们利用小波变换对电路脉冲信号进行多尺度分解,提取特征向量输入神经网络进行训练。实验表明,该办法可以有效地减少神经网络的训练时间,提高模拟电路故障诊断的准确率。     

基于DSP的模拟电路诊断系统的实现

以现代测试技术、信号处理、信息融合等理论为基础,以神经网络在模拟电路故障诊断中的应用为主线,深入研究了模拟电路的故障特征提取和故障诊断方法。用TMS320F2812对选定的待测电路在元件存在容差的条件下,实现了模拟电路软故障诊断。验证了使用DSP实现模拟电路故障诊断系统的可行性。     

Design and characterization of analog VLSI neural network modules

A systematic method for testing large arrays of analog, digital, or mixed-signal circuit components that constitute VLSI neural networks is described. This detailed testing procedure consists of a parametric test and a behavioral test. Characteristics of the input neuron, synapse, and output neuron circuits are used to distinguish between faulty and useful chips. Stochastic analysis of the parametric test results can be used to predict chip yield information. Several measurement results from two analog neural network processor designs that are fabricated in 2 μm double-polysilicon CMOS technologies are presented to demonstrate the testing procedure     

基于神经网络与证据理论的模拟电路故障诊断

论述了利用多类电量测试信息、应用神经网络与D-S证据理论实现模拟电路故障诊断的基本原理,提出了一种基于可测点电压与不同测试频率下的电路增益经决策层信息融合的故障诊断新方法.分别利用此两类测试信息,各用一个独立的改进BP网络对电路进行初步诊断,再运用所提融合诊断算法实现故障定位.模拟实验结果表明:所提方法对硬故障与元件参数偏移较小的软故障均适用,故障定位准确率高.     

一种基于神经网络的模拟电路故障诊断方法

提出了一种基于模拟电路故障诊断的神经网络方法。这种方法利用小波分解、数据标准化、主成分分析对输入数据进行预处理,采用k个神经元输出的前馈神经网络结构进行有效训练。该方法检测和识别故障准确率高,系统的鲁棒性和稳定性强。     

On minimal set of test nodes for fault dictionary of analog circuit fault diagnosis

A method is proposed to obtain a minimal set of test nodes of an analog circuit for isolating all faulty conditions in the fault dictionary approach. Relevant theorem along with the proof is also given. Proposed method is extremely fast. This method is illustrated with an active filter circuit example.     

现代模拟电路故障诊断新方法

介绍了模拟电路故障诊断技术的发展历史及现状，探讨了基于专家系统、神经网络、模糊理论、小波变换等理论的模拟电路故障诊断新理论和新方法。同时，重点介绍上述各种方法的基本原理和优缺点，分析存在的问题，最后指出了模拟电路故障诊断技术的发展趋势。     

基于PSpice与LM算法的模拟电路故障诊断方法

采用小波神经网络与Levenberg-Marquardt算法相结合的方法,对模拟电路进行故障诊断;用小波对冲击响应信号进行多尺度分解,进行归一化后,提取故障特征信息作为神经网络的输入而进行分类。将PSpice与Matlab结合不但能有效的诊断模拟电路,且在收敛性和故障准确性上有了大幅提高。实验仿真表明,通过该方法构造的样本集训练出的网络稳定性高于传统方法,适用于神经网络。     

模拟数字电路故障诊断新方法

利用小波变换与神经网络相结合的方法,采用能量分布特征提取方法和改进BP算法,给出了一种基于小波变换和BP神经网络相结合的模拟电路故障诊断方法.用正弦信号仿真模拟电路,应用小波变换对模拟电路的采样信号进行多尺度分解,再进行能量分布特征提取,然后利用神经网络对各种状态下的特征向量进行分类识别,实现模拟电路故障诊断.在用神经网络诊断模拟电路的基础上,进行了将神经网络用于数字电路单故障诊断的研究.对两者的实例电路仿真结果表明,神经网络可以有效、方便地实现电路的故障检测和定位,准确率高,为故障诊断的研究提供了一种新思路.     

容差模拟电路的软故障诊断的小波方法

给出了容差模拟电路软故障诊断的小波与量子神经网络方法,利用小波分析,取其能反映故障信号特征的成分做为电路故障特征,再输入给量子神经网络,不仅解决了一个可测试点问题,并提高了辨识故障类别的能力,而且在网络训练之前,利用主元分析降低了网络输入维数。实验证明了这种方法的可行性与适用性。     

基于GA-LMBP算法的模拟电路故障诊断方法

主要分析遗传算法和BP神经网络的特点和存在的一些缺陷,研究遗传算法和改进型的BP算法相结合的相关技术,设计并实现一个基于遗传算法和LMBP算法相结合的GA—LMBP算法。通过诊断实例．比较三种算法的模拟电路故障诊断,结果证明在相同精确度的要求下,基于GA—LMBP的算法可以大大提高模拟电路故障诊断准确率。     

A Combined Clustering and Neural Network Approach for Analog Multiple Hard Fault Classification

A new neural network-based fault classification strategy for hard multiple faults in analog circuits is proposed. The magnitude of the harmonics of the Fourier components of the circuit response at different test nodes due to a sinusoidal input signal are first measured or simulated. A selection criterion for determining the best components that describe the circuit behaviour under fault-free (nominal) and fault situations is presented. An algorithm that estimates the overlap between different faults in the measurement space is also introduced. The learning vector quantization neural network is then effectively trained to classify circuit faults. Performance measures reveal very high classification accuracy in both training and testing stages. Two different examples, which demonstrate the proposed strategy, are described.     

基于小波变换及马氏距离的电路故障定位方法

针对模拟电路中的硬故障,提出了一种基于马氏距离统计学原理的快速定位方法。利用Pspice电路仿真软件,对ITC'97基准电路集中的连续状态可变滤波器电路进行电路建模及故障注入仿真,用Pspice与Matlab软件的数据接口技术,将无故障及各故障状态的仿真数据导入Matlab中,进而在Matlab环境中进行小波变换处理及马氏距离的计算,并以马氏距离作为定位故障元件的依据。经检验,这种故障定位方法对模拟电路硬故障具有快速定位的能力,而且测点少、在线计算量小等优点。