Conditions for Hierarchical Supervisory Control under Partial Observation

The fundamental problem in hierarchical supervisory control under partial observation is to find conditions preserving observability between the original (low-level) and the abstracted (high-level) plants. Two conditions for observable specifications were identified in the literature -- observation consistency (OC) and local observation consistency (LOC). However, the decidability of OC and LOC were left open. We show that both OC and LOC are decidable for regular systems. We further show that these conditions do not guarantee that supremal (normal or relatively observable) sublanguages computed on the low level and on the high level always coincide. To solve the issue, we suggest a new condition -- modified observation consistency -- and show that under this condition, the supremal normal sublanguages are preserved between the levels, while the supremal relatively observable high-level sublanguage is at least as good as the supremal relatively observable low-level sublanguage, i.e., the high-level solution may be even better than the low-level solution

Model abstraction of nondeterministic finite state automata in supervisor synthesis

Blockingness is one of the major obstacles that need to be overcome in the Ramadge-Wonham supervisory synthesis paradigm, especially for systems of industrial size. Owing to the high computational complexity, synthesizing a nonblocking supervisor for a large scale system is never easy, if still possible. In this paper we attempt to solve this synthesis problem by using abstractions. We first introduce a new abstraction operation, which preserves the nonblocking property. Then we describe how to synthesize supervisors by using abstractions of relevant automata so that the high computational complexity associated with the synchronous product described in the Ramadge-Wonham supervisory control theory (SCT) may be avoided

A Survey of Decentralized Adaptive Control

Systems with multi inputs and multi outputs are in common controlled by centralized controllers, multivariable controllers or by a set of single input and single output controllers. The decentralized systems dominated in industry and can be found in a broad spectrum of applications ranging from robotics to civil engineering. Approaches to decentralized control design differ from each other in the assumptions ? kind of interaction, the model of the system, the model of information exchange and the control design. One of the useful approaches to decentralized control problems was the parametrization. During last years it was proven that it seems to be perspective to combine predictive and decentralized control, for example unconstrained decentralized model predictive control or adaptive decentralized control using recurrent fuzzy neural networks. Another task is to use automatic decentralized control structure selection. Adaptive control enlarges the area of usage at decentralized controllers. AdaptiveZ(MSM7088352101

Controller synthesis for parameterized discrete event systems

Les systèmes à événements discrets sont des systèmes dynamiques particuliers. Ils changent d’état de fa¸con discrète et le terme événement est utilisé afin de représenter l’occurrence de changements discontinus. Ces systèmes sont principalement construits par l’homme et on les retrouve surtout dans les secteurs manufacturier, de la circu- lation automobile, des bases de données et des protocoles de communication. Cette thèse s’intéresse au contrôle des systèmes paramétrés à événements discrets où les spécifications sont exprimées à l’aide de prédicats et satisfont une condition de similarité. Des conditions sont données afin de déduire des propriétés, en observation partielle ou totale, pour un système composé de n processus similaires à partir d’un système com- posé de n0 processus, avec n ≥ n0. De plus, il est montré comment inférer des politiques de contrôle en présence de relations d’interconnexion entre les processus. Cette étude est principalement motivée par la faiblesse des méthodes actuelles de synthèse pour le traitement des problèmes industriels de taille réelle.Discrete event systems are a special type of dynamic systems. The state of these systems changes only at discrete instants of time and the term event is used to represent the occurrence of discontinuous changes. These systems are mostly man-made and arise in the domains of manufacturing systems, traffic systems, database management systems and communication protocols. This thesis investigates the control of parameterized discrete event systems when specifications are given in terms of predicates and satisfy a similarity assumption. For systems consisting of similar processes under total or partial observation, conditions are given to deduce properties of a system of n processes from properties of a system of n0 processes, with n ≥ n0. Furthermore, it is shown how to infer a control policy for the former from the latter’s, while taking into account interconnections between processes. This study is motivated by a weakness in current synthesis methods that do not scale well to huge systems