Hierarchical Modular Fault Diagnostics for Complex Systems

Laci Jalics，德尔福研究实验室，giorgio Rizzoni，俄亥俄州立大学，andrea Serrani，俄亥俄州立大学，ahmed Soliman，俄亥俄州立大学复杂系统中的分层、模块化故障诊断。1)开发一种方法，允许设计模块化的、分层的、基于模型的诊断算法，这些算法可以产生可重用的软件模块，并且可以有条不紊地组织成一个完整的、自包含的监测系统；2)与行业合作伙伴合作演示该方法。由于在车辆中引入了“线控”系统，容错成为复杂汽车系统中的一个关键因素。“线控”系统通过驱动器输入产生电气命令，并将其传送到计算机控制的机电致动器。与传统系统相比，“线控”系统需要复杂的控制和诊断策略，以保证车辆正常运行并防止系统故障。对于安全至关重要的线控系统来说，一个重要的障碍是实现一个强大的故障诊断策略，该策略可以在有限的硬件或没有额外硬件的情况下快速完成。本项目分三个阶段解决这些问题：1)通过使用基于物理的系统模型来理解复杂系统中子系统之间的相互作用和依赖关系；2)残差发电机组设计，可局部诊断部件、传感器、执行器故障；3)使用层次结构，通过使用故障传播有向图将组件、系统和子系统连接起来。故障传播有向图包含关于系统内故障传播特征的可用知识的分层表示。层次结构中的每个级别包含一个或多个结构，这些结构共同表示特定粒度下的系统视图。视图的粒度随着级别的增加而增加。因此，当一个人向下遍历模型的层次时，视图的分辨率就会增加。如果不需要诊断的高分辨率，则故障分析可能仅限于层次结构的上层，从而防止由于过多的细节而减慢诊断速度。

Laci Jalics, Delphi Research LabsGiorgio Rizzoni, The Ohio State UniversityAndrea Serrani, The Ohio State UniversityAhmed Soliman, The Ohio State UniversityHierarchical, Modular Fault Diagnosis in Complex SystemsThe objectives of this GOALI project program are: 1) to develop a methodology that permits the design of modular, hierarchical, model-based diagnostic algorithms that can result in re-usable software modules, and that can be methodically organized into a complete, self-contained monitoring system; and 2) to demonstrate the methodology in collaboration with an industry partner.Fault tolerance is a critical element in complex automotive systems because of the introduction of "by-wire" systems in vehicles. "by-wire" systems generate electrical commands through driver input and transfer them to the computer-controlled electro-mechanical actuators. With respect to traditional systems, "by-wire" systems require complex control and diagnostic strategies to guarantee proper vehicle behavior and to prevent system malfunctions. A significant roadblock for safety-critical by-wire systems is the realization of a robust fault-diagnostic strategy that can be accomplished quickly and with limited or no additional hardware. This project addresses these issues in three stages: 1) through the use of physically based system models to understand interactions and dependencies among subsystems in a complex system; 2) with the design of residual generator units that can locally diagnose faults in components, sensors and actuators; and 3) using a hierarchical structure that links components, systems, and subsystems through the use of fault propagation digraphs. The fault propagation digraph contains a hierarchical representation of available knowledge about the characteristics of fault propagation within the system. Each level in the hierarchy contains one or more structures that together represent a view of the system under a particular granularity. The granularity of view increases with levels. Thus as one traverses down the levels of the model, the resolution of view increases. If a high resolution of diagnosis is not required, failure analysis may be confined to the upper levels of the hierarchy, thereby preventing a slowdown of the diagnosis due to excessive detail.