ABSOLUTE-CONTROLLABILITY OF PREDICATES IN DISCRETE-EVENT SYSTEMS

Abstract

The absolute controllability of predicates in discrete event systems is studied in this paper. A predicate is absolutely controllable if it is control-invariant and the states specified by it are mutually reachable via legal states. It is shown that there is a global state feedback such that the resultant closed-loop system is strongly connected if and only if the predicate is absolutely controllable. The weakest absolutely controllable predicate stronger than the given predicate is shown to exist with respect to the given initial state. Based on the notion of the dual automaton a graph-theoretic algorithm is given to compute the set of weakest absolutely controllable predicates stronger than the given predicate. Application of the concept of absolutely controllable predicate to a class of optimal control problem is discussed. Examples are given to illustrate the results.