Aggregation and multi-level control in discrete event dynamic systems

Abstract

In this paper we consider the problem of higher-level aggregate modelling and control of discrete-event dynamic systems (DEDS) modelled as finite state automata in which some events are controllable, some are observed, and some represent events to be tracked. The higher-level models considered correspond to associating specified sequences of events in the original system to single macroscopic events in the higherlevel model. We also consider the problem of designing a compensator that can be used to restrict microscopic behavior so that the system will only produce strings of these primitive sequences or tasks. With this lower level control in place we can construct higher-level models which typically have many fewer states and events than the original system. Also, motivated by applications such as flexible manufacturing, we address the problem of constructing and controlling higher-level models of interconnections of DEDS. This allows us to "slow down" the combinatorial explosion typically present in computations involving interacting automata.

Logical models of discrete event systems: A comparative exposition

“…Considerable work has been done to extend concepts of conventional control to this domain in the synthesis of supervisors with full state feedback (Ramadge & Wonham 1987aWonham & Ramadge 1987;Ushio 1990;Willner & Heymann 1991) and also under partial observation (Heymann & Lin 1993;Kozfik & Wonham 1995;Takai et al 1995). Also work has been reported dealing with decentralized supervision (Lin & Wonham 1988bZhong & Wonham 1990;Ozveren & Willsky 1992c;Rudie & Wonham 1992), invertibility of DES (Ozveren & Willsky 1992a), tracking and restrictability (Ozveren & Willsky 1992b), diagnosability (Sampath et al 1995) etc. Work on the realisation of an FSM from a given input-output description has been reported by Kumar et al (1995).…”

Analysis, Estimation, and Control for Perturbed and Singular Systems and for Systems Subject to Discrete Events.

“…Our research [16,17,[29][30][31][43][44][45][46]48,[51][52]57] has dealt with systems modeled as finite-state automata in which control is effected by enabling or disabling particular events and in which observations consist either of state measurements or the intermittent information provided when any of a particular set of observable events occurs. Our work has had as its objective the development of stability, regulation, and servo theories for such discrete event dynamic systems (DEDS), described by automata and for other more powerful models.…”

“…In particular, many algorithms in [16,17,[29][30][31][43][44][45][46]] have computational complexity that is polynomial in the cardinality of the automaton's state space. On the other hand, in many cases a DEDS consists of an interconnection of many smaller DEDS so that the Cartesian product state space can be enormous.…”