Modular supervisory control with general indecomposable specification languages

International audienceModular supervisory control of discrete-event systems (DES), where the global DES is composed of local components that run concurrently, is considered. For supervisory control of large-scale modular DES the possibility of performing control-related computations locally (in components) is of utmost importance to computational complexity. Recently we have treated the case, where the specification language is decomposable into local specification languages and is included in the (global) plant language. In this paper the case of general specification languages that are neither necessarily decomposable nor contained in the global plant language is studied. Sufficient conditions are found under which any manipulation with the global plant is avoided for the computation of supremal controllable sublanguages of (global) indecomposable specification languages

Supervisory Control Synthesis of Discrete-Event Systems using Coordination Scheme

Supervisory control of discrete-event systems with a global safety specification and with only local supervisors is a difficult problem. For global specifications the equivalent conditions for local control synthesis to equal global control synthesis may not be met. This paper formulates and solves a control synthesis problem for a generator with a global specification and with a combination of a coordinator and local controllers. Conditional controllability is proven to be an equivalent condition for the existence of such a coordinated controller. A procedure to compute the least restrictive solution is also provided in this paper and conditions are stated under which the result of our procedure coincides with the supremal controllable sublanguage.Comment: 29 pages, 11 figure

On Conditional Decomposability

The requirement of a language to be conditionally decomposable is imposed on a specification language in the coordination supervisory control framework of discrete-event systems. In this paper, we present a polynomial-time algorithm for the verification whether a language is conditionally decomposable with respect to given alphabets. Moreover, we also present a polynomial-time algorithm to extend the common alphabet so that the language becomes conditionally decomposable. A relationship of conditional decomposability to nonblockingness of modular discrete-event systems is also discussed in this paper in the general settings. It is shown that conditional decomposability is a weaker condition than nonblockingness.Comment: A few minor correction

Compositional synthesis of discrete event systems via synthesis equivalence

A two-pass algorithm for compositional synthesis of modular supervisors for largescale systems of composed finite-state automata is proposed. The first pass provides an efficient method to determine whether a supervisory control problem has a solution, without explicitly constructing the synchronous composition of all components. If a solution exists, the second pass yields an over-approximation of the least restrictive solution which, if nonblocking, is a modular representation of the least restrictive supervisor. Using a new type of equivalence of nondeterministic processes, called synthesis equivalence, a wide range of abstractions can be employed to mitigate state-space explosion throughout the algorithm