一类非线性系统的故障诊断与实现

非线性系统的Volterra级数模型是系统的一种非参数模型,为非线性系统的故障诊断提供了一种新颖的方法.这里阐述了基于Volterra级数模型故障诊断方法的工作原理,介绍了使用单片机实现诊断系统的方法.     

非线性不确定系统的鲁棒虚拟传感器重组的设计

主要将非线性滑模观测器和虚拟传感器重组方法相结合,设计了具有鲁棒性的滑模观测器。把线性系统虚拟传感器重组方法推广到非线性,并针对传感器故障设计合适的滑模观测器,使改变后的系统能够等价于原来的非线性不确定系统。数字仿真证明了该方法的有效性,重组后的系统输出可以很好地跟踪正常工作系统输出。     

基于观测器的防滑刹车系统鲁棒故障诊断初探

将基于观测器的鲁棒故障检测的概念应用到飞机防滑刹车系统的故障诊断中 ,建立一种简化的飞机防滑刹车系统的二阶数学模型 ,考虑未知输入矩阵已知时 ,对防滑刹车系统可能的特定的故障进行检测研究     

一类非线性系统的执行器偏差故障检测与诊断

针对一类具有系统建模误差以及含传感器模型不确定项的非线性控制系统，本文提出了一种用于执行器故障检测与诊断的观测器方法。观测器中引入了自适应补偿项，当出现偏差后将对故障及建模不确定项进行补偿。自适应算法中采用了死区算子，增强了算法的鲁棒性。利用自适应阈值进行故障检测，同时利用自适应律进行偏差估计。仿真结果表明了该方法的有效性。     

基于SVR的非线性系统故障诊断研究

针对非线性系统辨识建模和故障诊断难的问题,利用回归型支持向量机(support vector regression,SVR)分别设计了非线性系统的辨识建模系统和故障诊断系统,最后以某一非线性系统为例进行了仿真试验研究,建立了该非线性系统的SVR辨识模型,在此基础上进行了三种典型故障的诊断试验,仿真试验结果验证了该方法的有效性和先进性。     

压电陶瓷执行器迟滞与非线性成因分析

从微观上系统分析了电致伸缩效应、逆压电效应和铁电效应的位移机理,表明:三种效应的位移机理是根本不同的;压电陶瓷执行器的位移主要是由逆压电效应、铁电效应所引起的,电致伸缩效应对位移的贡献极其微弱,可以忽略不计;单纯的逆压电效应是线性的,而铁电效应则是迟滞非线性的.指出了非180°电畴转向与转向的不完全可逆,分别是造成压电陶瓷执行器非线性和迟滞的根本原因.通过实验研究了驱动电压幅值、驱动电压频率、驱动循环次数及晶片厚度对压电陶瓷执行器迟滞和非线性的影响.     

基于鲁棒支持向量机的非线性系统辨识

支持向量机(SVM)是一种基于结构风险最小化原理的学习技术,该文利用鲁棒支持向量机对非线性系统进行黑箱建模,首先推导出鲁棒支持向量机的基本理论,给出了对偶优化问题,并结合一个具体的例子进行了仿真实验,结果验证了所提出的方法的正确性和有效性.     

基于改进粒子滤波的非线性系统故障诊断

粒子滤波在非线性系统的故障诊断中,存在着粒子样本退化和突变状态难以跟踪的问题。为此提出一种基于无迹变换和遗传变异改进的粒子滤波算法,通过无迹变换将粒子转移到高似然区域,遗传算法代替重采样消除粒子多样性退化的问题,再利用对数似然函数和作为评价指标来进行故障诊断。仿真实验结果表明,改进的算法可有效提高滤波精度,在连续搅拌反应器变量发生突变时,能够有效、准确地诊断出故障。     

基于数据驱动的电动执行器故障诊断方法

本文针对在流程工业自动化系统中大量使用的电动执行器,结合热工系统的应用背景,提出了一种基于数据驱动的电动执行器故障诊断方法.该故障诊断方法包括特征提取和故障识别两部分:采用主成分分析法提取故障特征信号;采用基于支持向量机的方法进行故障识别.构造多类支持向量机分类器,建立了电动执行器多故障诊断模型.仿真实验研究证明了该诊断方法的可行性和有效性.     

不确定供应链非线性系统的模糊鲁棒H_∞控制

为解决系统不确定参数和外部不确定需求引起的供应链非线性系统运作波动较大的问题,研究了一种鲁棒控制方法。基于离散Takagi-Sugeno模糊系统,建立了一类不确定供应链非线性系统的模糊模型。通过在每个最大交叠规则组中构建一种离散型分段Lyapunov函数,并应用并行分布补偿原理,提出一种新的模糊鲁棒H∞控制方法,该控制方法可在减少求解线性矩阵不等式个数的同时,保证不确定供应链非线性系统的鲁棒稳定。结合某二级不确定供应链非线性系统的实例进行仿真实验,实验结果验证了所提方法的有效性。     

Observer-based reliable stabilization of uncertain linear systems subject to actuator faults,saturation, and bounded system disturbances

A matrix inequality approach is proposed to reliably stabilize a class of uncertain linear systems subject to actuator faults, saturation, and bounded system disturbances. The system states are assumed immeasurable, and a classical observer is incorporated for observation to enable state-based feedback control. Both the stability and stabilization of the closed-loop system are discussed and the closed-loop domain of attraction is estimated by an ellipsoidal invariant set. The resultant stabilization conditions in the form of matrix inequalities enable simultaneous optimization of both the observer gain and the feedback controller gain, which is realized by converting the non-convex optimization problem to an unconstrained nonlinear programming problem. The effectiveness of proposed design techniques is demonstrated through a linearized model of F-18 HARV around an operating point.     

故障诊断中参数相位耦合特征提取的研究

以滚动轴承为例,建立了反映观测信号相位信息的振动信号模型,证明滚道的形状变化会产生参数相位耦合现象,而通过检测信号频率成分间的非线性耦合特征可对故障信号进行检测。文中对传统的二阶积进行了修正,以反映参数耦合模式的相位关系,进而给出非线性耦合特征描述方法。最后通过实验验证了所提出模型、方法和特征的有效性。     

Fault diagnosis of complex system based on nonlinear frequency spectrum fusion

A novel fault detection and diagnosis approach is proposed for nonlinear complex systems by combining nonlinear frequency spectrum characteristics and evidence theory. In order to overcome the problem of calculated amount expansion of generalized frequency response functions, single-dimensional nonlinear output frequency response functions are used to obtain nonlinear frequency spectrum, from which, features of nonlinear frequency spectrum are extracted. The fault diagnosis model of multiple faults is given based on evidence theory. The mass functions of evidences are obtained according to the similarity among different modes. In order to solve the problem of evidence fusion in the situation of evidence confliction, a dynamic parameter conflicting evidence combination method is proposed based on the average credibility. Fault diagnosis of the transmission system of numerical control machine tool is studied through nonlinear frequency spectrum. Simulations indicate that the proposed approach has simple calculation and high recognition rate for faults.     

Adaptive observer design for nonlinear systems using generalized nonlinear observer canonical form

In this paper, we present an adaptive observer for nonlinear systems that include unknown constant parameters and are not necessarily observable. Sufficient conditions are given for a nonlinear system to be transformed by state-space change of coordinates into an adaptive observer canonical form. Once a nonlinear system is transformed into the proposed adaptive observer canonical form, an adaptive observer can be designed under the assumption that a certain system is strictly positive real. An illustrative example is included to show the effectiveness of the proposed method.     

Robust fault diagnosis algorithm for a class of Lipschitz system with unknown exogenous disturbances

A robust fault diagnosis scheme for nonlinear system is designed and a novel algorithm for a robust fault diagnosis observer is proposed in this paper. The robustness performance index is defined to ensure the robustness of the observer designed. The norm of most unknown input disturbances are assumed bounded at present. However, some systems are proved unstable under traditional assumptions. In the proposed algorithm, the external disturbances constraint condition that satisfies the system stability is derived based on Gronwall Lemma. The design procedure of the observer proposed is implemented by pole assignment. Adaptive threshold is generated using the designed observer. Simulations are performed on continuous stirred tank reactor (CSTR) and the results show the effectiveness and superiority of the proposed algorithm.     

Design and Analysis of Fault Diagnosis and Fault-tolerant Control for a Class of MIMO Nonlinear State Systems

This paper presents a fault diagnosis and fault-tolerant control algorithm,which can be used for a class of multi-input multi-output(MIMO)nonlinear state system...     

基于导纳矩阵分解的非线性电路故障诊断

提出了一种非线性模拟电路故障诊断新方法.利用矩阵理论的Woodbury公式分解扰动电路的导纳矩阵,推导出非线性元件端电压跨越其工作区间的上折点电压或下折点电压时,扰动元件参数的偏移量和可及测试节点的电压值.利用该方法对非线性模拟电路进行故障诊断,由可及测试节点的电压测试值,诊断出扰动元件参数的偏移量和非线性元件的工作区间.     

基于主流形识别的非线性时间序列降噪方法及其在故障诊断中的应用

提出了一种新的基于主流形识别的非线性时间序列降噪方法。新的降噪方法将一维时间序列重构到高维相空间,利用非线性降维方法找出动力学系统在相空间中具有全域正交坐标系的低维主流形,然后根据主流形反求一维时间序列,进而达到降噪的目的。对洛伦兹信号进行的数值试验证明,与奇异谱分解等现有非线性分析方法相比,基于主流形识别的降噪方法能更加有效地消除混沌时间序列中的高斯白噪声。将该方法应用于带有断齿故障的齿轮箱振动信号的故障分析中,成功地提取出了淹没在带噪信号中的冲击特征。