Control of discrete event systems modeled as hierarchical state machines

Discrete-event systems (DESs) are systems in which state changes take place in response to events that occur discretely, asynchronously, and often nondeterministically. A class of DESs modeled as hierarchical state machines (HSMs), a special case of the statecharts formalism introduced recently, is considered. An efficient algorithm is provided for solving reachability problems in the HSM framework. It utilizes the hierarchical structure of HSMs. This efficient solution is used extensively in control applications, where controllers achieving a desired behavior are synthesized online.>