含故障模式的值传递诊断及其完备性讨论

基于模型的诊断是人工智能领域一个活跃的研究方向.基于值传递的诊断是一种高效的故障诊断方法,但在一般情况下不完备,且系统模型仅描述元件的正常行为.扩充了基于值传递的系统模型,可以描述系统元件的多种故障模式;重新定义了诊断,明确了该模型下得到的诊断与一致性诊断和溯因诊断之间的关系;同时,指出了值传递与真实诊断的关系,为诊断测试提出了新的思路;最后,给出了值传递诊断方法的完备的充分条件,对推进值传递诊断方法的实际应用有积极意义.

Multi-fault Mode Diagnosing with Value Propagation and Its Completeness

Model-based diagnosis is an active field of artificial intelligence research. Diagnostic problem is characterized by a set of observations to account for the differences between the system’s actual behaviors and its expected behaviors. The classical method was built on the well-known consistency-based theory and it described the system’s structure and behaviors usually in the first-order language. But it is not efficient and therefore is difficult to be applied in actual systems. Different from the classical method, diagnosing with value propagation is an effective procedure-oriented method. For some special systems, the algorithm terminates in polynomial time. But it is not complete and the system model can only discribles normal system behavior. This paper presents an expanded system model based on value propagation, which can discrible multi-fault mode of the system behavior, redefines the system diagnosis and discusses the relation between consistency-based (abductive) diagnosis and value propagation-based diagnosis. Furthermore, the relation between value propagation and the actual diagnosis has been analysed, which is useful in diagnosis test. Finally, the sufficient condition of the algorithm’s completeness is given, which is valuable for promoting the application of value propagation-based diagnosis.