The Controllability Of Fuzzy Discrete Event Systems

In this paper,the controllability of fuzzy language is discussed in fuzzy discrete event systems : On the basis of the theorem that fuzzy sublanguage is controllable with respect to fuzzy language generated by automaton and uncontrollable events,theorems of controllability are given about union of cut set of sublanguage with respect to fuzzy language generated by automaton and uncontrollable events;after that,the related theorems are given regarding fuzzy sublanguage and fuzzy language generated by composed automaton;fuzzy sublanguage generated by fuzzy automata under the monitor satisfying a certain condition can make monitor non-blocking.Next,the degree of control invariance of fuzzy predicates and the degree of accessibility of states in fuzzy predicates are defined by control invariance of predicates and accessibility of states about predicates in DES,then the relationship of them is proved,to any of states,in the case of uncontrollable factors,existing a state feedback controller,makes value of the degree of accessibility of states in fuzzy predicates is less than the degree of control invariance of fuzzy predicates.Last,by two requirements of controllability of predicates in DES--control invariance of predicates and accessibility of states in predicates,in FDES,combining conceptions of degree of control invariance and degree of accessibility,the definition of controllable index is given to show range of controllability.