Investigation On Minimal Diagnosis Bases Of Discrete Event Systems

Discrete Event Systems(DESs)are a type of dynamic system driven by discrete events to incur the system state dynamic evolution.In real life,queue management system,traffic control system,computer software and hardware system,communication system and database system can all be expressed as DESs after the highly quantified and modeled abstraction.Since the 1990 s,many scholars at home and abroad have put forward a series of theories about DESs,including diagnosability,predictability,opacity,etc.,and on this basis,the Further derived theories such as sensor selection and layout,system optimization and minimum fault diagnosis base.Diagnosability means that DESs can accurately determine that the system has failed within a certain time delay after the system fails.The minimal fault diagnosis base refers to the minimal observable event set required to ensure the diagnosability of discrete event systems,and the minimum fault diagnosis base problem refers to how to solve the minimal observable event set of DESs under the premise of ensuring the diagnosability of DESs.In order to explore the nature of DESs more deeply,this paper studies the diagnosability of DESs for centralized and decentralized DESs,and proposes the diagnosability theory of DESs;and based on the above theory,for the problem of the minimal fault diagnosis base of DESs,the solving algorithm of minimal fault diagnosis base.minimum of DESs is proposed.In the research of the diagnosability of DESs,the two core concepts of diagnosability and codiagnosability of DESs were first introduced.Next,in order to verify the diagnosability of DESs,the test automaton and verifier were constructed respectively,the sufficient and necessary conditions for the diagnosability and codiagnosability of DESs were derived,and the complexity of the construction of test automata and the verifier were analyzed respectively.Compared with diagnoser proposed previous,test automata and verifiers have better complexity,and can be more widely used in offline and online DESs.In the process of studying the minimal fault diagnosis bases of DESs,the concepts of Minimal Diagnosis Basis(MDB)and Minimal Codiagnosis Basis(MCB)in DESs are introduced and proposed respectively.Then,the solution ideas of MDB and MCB are respectively elaborated,and then the corresponding solution algorithm is proposed based on the solution idea,and the verification of the validity of the algorithm and the analysis of the complexity have been completed,and the solution of the minimal fault diagnosis bases of DESs has been realized.