Research on Model-Based diagnosis of Dynamic Systems

在本研究计划中，基于模型的故障诊断方法的发展及其应用研究已经针对以下4类动态系统进行，（1）由状态空间模型描述的集总参数线性系统（2）具有黑盒型表示的过程（3）像发电厂这样的大规模系统（4）（1）采用并行卡尔曼滤波和广义似然比（GLR）检验方法，建立了一个可在线进行的分级诊断系统。此外，还提出了几种直接估计连续时间线性系统物理参数的方法，这些方法结合使用数值积分或无限脉冲数字滤波器方法和递归辨识算法。仿真结果也证实了该估计器对故障诊断问题的适用性 ...更多信息 n. (2)首先，为了研究现有的用于故障诊断的各种递推辨识算法的收敛性和数值不稳定性，在微机上研制了一个计算机辅助设计系统软件包。其次，针对自适应控制系统，提出了一种以Kullback判别信息为检测指标的在线诊断方法。此外，还提出了一种利用模糊推理来判断检测到的系统参数变化是否由故障引起的诊断方法。特别是，该方法可以被认为是一个新的，所谓的“知识辅助的基于模型的诊断”，它有效地结合了现有的知识，系统的运行行为和故障模式的基于模型的诊断。(3)提出了火电厂控制系统故障诊断的两种方法。一种是基于线性化扰动模型和GLR检验的方法，另一种是基于仿真器的小参数调整方法，并通过实际火电厂模型验证了其有效性。(4)对于抛物型和双曲型分布参数系统，已经提出了几种估计和识别状态变量、系统参数和未知边界条件的方法。另一方面，他们的诊断问题的适用性正在调查。少

In this research project, developments of model-based failure diagnosis methods and their application studies have been carried out for the following 4-types of dynamic systems,(1) Lumped parameter Linear Systems Described by State-Space Model(2) Processes with Black-Box Type Representation(3) Large-Scale Systems like an Electric Power Plant(4) Distributed Parameter Systems.Research results of the project obtained for each system are summarized as follows :(1) A hierarchical diagnosis system which can be performed on line has been developed by using parallel Kalman filter and generalized likelihood ratio (GLR) test. Furthermore, several methods for directly estimating physical parameters of continuous time linear systems have been proposed by a combinational use of the numerical integration or infinite impulse digital filter approach and the recursive identification algorithms. The applicability of the estimator to failure diagnosis problem has also been confirmed through the simulatio … More n.(2) First, in order to investigate the convergence and the numerical instability in many kinds of existing recursive identification algorithms, which are used for failure diagnosis, a soft-ware package of CAD system has been manufactured on the personal computer. Next, for adaptively controlled systems, a method of on-line diagnosis method has been proposed by using Kullback discrimination information as the detection index. Furthermore a diagnosis method using fuzzy inference to decide whether the detected system parameter changes are due to a failure or not tas also been developed. In particular, the method can be considered as a new one, so called "Knowledge Aided Model-Based Diagnosis", which effectively incorporates available knowledge about the system operating behavior and the failure modes into the model-based diagnosis.(3) Two diagnosis methods of controlled deaerator system in the thermal power plant has been developed. The one is a method using a linearized perturbation model and GLR test, and the other is a simulator-based method with small parameter adjusting scheme, and their effectiveness has been confirmed for the model of a practical thermal power plant.(4) Several methods for estimation and identification of state variables, system parameters and unknown boundary conditions have been proposed for parabolic and/or hyperbolic type of distributed parameter systems. On the other hand their applicability to diagnosis problems are on being investigated. Less