文档介绍：基于神经网络的模拟电路故障诊断专家系统研究
摘要
随着电子工业的迅猛发展,模拟电路故障诊断问题已经引起广泛的关注,而且是国内外专家在设计和使用电子系统的一大难题。一些已有模拟电路的诊断方法只适用于特定条件下(如开路、短路等)的电路诊断,却很难发现由电路中的电子器件的容差变化引起的软故障。迄今为止,文献中很少对软故障即容差电路的故障诊断给出系统而有效的方法,本文将这一问题进行了研究探讨。针对传统诊断技术的局限性,讨论了利用神经网络方法诊断模拟电路软故障的方案,通过小波变换提取故障特征,并利用神经网络的非线性映射特性逼近故障诊断模型。针对传统方法的局限性,本文提出了具体的故障诊断方法,研究了基于Levenberg-Marquardt算法和动量法相结合的神经网络诊断方法,用来自模拟实验的实例对神经网络进行了训练仿真。诊断结果表明本文提出的方法是快速而有效的。此研究将为复杂模拟电路故障诊断甚至集成电路提供新的理论依据和诊断方法。
此外,传统故障诊断专家系统存在不能进行自学****自适应,知识获取困难,推理匹配冲突等不足,本文将小波分析、神经网络技术融入到专家系统的构建当中,利用小波分析提取模拟电路故障特征,用神经网络的训练代替诊断专家系统知识获取部分,用训练好的连接权和阈值代替专家系统知识部分,专家系统推理部分则通过权值数据与输入数据的运算来完成。针对一低通滤波器电路,研究开发了基于神经网络的模拟电路故障诊断专家系统。系统采用MATALB的GUI编程实现了以下功能:一是特征提取算法的实现,用户根据需要可以选择三种特征提取算法提取故障信号特征。二是神经网络参数设置,如设置隐层神经元的个数、学****率的大小等。三是神经网络的训练和故障诊断。该系统在一定程度上改善了传统专家系统不能进行自学****自适应,知识获取困难,推理匹配冲突等不足,提高了诊断的自动化和智能化水平。
关键词模拟电路;故障诊断;神经网络;小波变换;专家系统
The Study of Expert System Based on work of Analog Circuit Fault Diagnosis
Abstract
Along with the rapid development of electronics industry, the analog circuit fault diagnosis question already aroused the widespread interest, moreover, it is a big difficult problem to the domestic and foreign experts when they design and use the electron system. Some analog circuit diagnosis methods which already existed are only suitable under the special condition, for example, opening, short circuit and so on. it is very difficult to discover the soft fault which causes by electronic device's tolerance change in electric circuit. Until now, very few literature gives the systematic and effective method to the soft fault, this paper research this question.
In view of the traditional limitation of diagnosis technology, we discussed the plan which use work to diagnose soft fault of analog circuit, use the ability of wavelet transformation to extract the circuit fault character and work which has misalignment mapping characteristic to approaches the failure diagnosis model. In view of the limitation of traditional fault diagnosis method, this paper proposed the concrete fault d