Hierarchical Opacity And Fuzzy Pattern Diagnosis Of Discrete-Event System

The discrete-event systems(DES)is a kind of dynamic system in which states evolved by discrete events in accordance with certain running rules.It has been successfully applied in military defense,traffic control,computer integrated manufacturing systems,electronic communication networks,and robotics.Since the 1990s,many scholars at home and abroad have proposed a series of theories based on DES,including the diagnosability and opacity of DES.The opacity means that under the same observer mapping,the trace to the secret state in the system is always confused with another trace of the same mapping that does not reach the secret state.Diagnosability means that under the observer,after passing a trace of finite length,it is always possible to uniquely identify errors in the system.Diagnosability and opacity are two opposite properties of DES,that means the system with opacity is equal to the non-diagnostic system.In order to further study the two properties of the above DES,this paper proposes a HDES opacity theory based on hierarchical discrete-event systems(HDES)with hierarchical structure to study the opacity of the system;Based on fuzzy discrete-event systems(FDES),which may cause faults triggered by multiple events during the running time of fuzzy systems,we study the dianosability of pattern failures in FDES,and propose a theory of dianosability of the fuzzy pattern failure.In the process of discussing the opacity of HDES,we formalize the hierarchical DES,and introduce two concepts of the hierarchical DES,that is opacity and k-delay opacity.In order to verify the opacity of systems,we propose two corresponding verifiers respectively,opacity verifier and k-delay opacity verifier,after which the necessary and sufficient conditions were given,then anaylze the complexity of constructing opacity verifier.Compared to previous non-hierarchical opacity verifier,hierarchical verifiers have low complexity and can be applied to more complex discrete-event systems.In the process of studing the pattern failure dianosability in fuzzy discrete-event systems based on verifier-based,firstly,the notions of the S-type pattern failure and the T-type pattern failure are introduced in fuzzy systems.Then the diagnosability of S-type pattern failures and the T-types pattern failures of FDES are formalized.In order to verify the diagnosability of pattern failures of FDES,a verifier automaton is constructed,and a sufficient and necessary condition for the diagnosability of pattern failures is presented to achieve the diagnosis of fuzzy system pattern failures.