BDD-based supervisory control on extended finite automata

Abstract

In this paper, we settle some problems that are encountered when modeling and synthesizing complex industrial systems by the supervisory control theory. First, modeling such huge systems with explicit state-transition models typically results in an intractable model. An alternative modeling approach is to use extended finite automata (EFAs), which is an augmentation of ordinary automata with variables. The main advantage of utilizing EFAs for modeling is that more compact models are obtained. The second problem concerns the ease to understand and implement the supervisor. To handle this problem, we represent the supervisor in a modular manner by extending the original EFAs by compact conditional expressions generated from the monolithic supervisor. In order to, potentially, be able to handle complex systems efficiently, the models are symbolically represented by binary decision diagrams (BDDs). All computations that are performed in this framework are based on BDD operations. The framework has been implemented in a supervisory control tool and applied to industrially relevant benchmark problems.

Automatic generation of controllers for collision-free flexible manufacturing systems

“…To overcome the above problems, we perform the synthesis based on the approach proposed in [10]. In this framework, the synthesis is performed directly on the EFAs, rather than flattening them to ordinary automata.…”

“…Since the operations and SOPs are modeled by a new type of automata with variables called Extended Finite Automata (EFA) [9], the synthesis is also based on EFA. Applying a recently developed strategy [10], additional guards are then added to achieve the required closed loop behavior. The computations, including the guard generation, are based on binary decision diagrams (BDDs) [11], which means that large and complex systems can be handled efficiently, where small and comprehensible guards often can be achieved that correspond to a large number of states in a traditional supervisor implementation.…”

Process-theoretic supervisor synthesis framework with data

“…We note that in the deterministic case, all of the approaches actually converge to controllability of parameterized languages, or languages with data [6], [7]. Then, we can employ the tool Supremica [14], [4] to efficiently synthesize supervisors, relying on binary decision diagrams [11].…”

“…The extensions range over the most prominent models of discreteevent systems like finite-state machines [6], labeled transition systems [7], and automata [8]. In addition, depending on the model at hand, the notion of language controllability [1], [2] for deterministic systems is extended to controllability of parameterized languages [6], [7], whereas the notion of state controllability [9], [10], aimed at nondeterministic systems, is extended with data for extended finite automata [4], [11].…”

Supervisory control of extended finite automata using transition projection

“…Extended Finite Automata (EFAs) have been used in several research works and successfully applied to a range of examples such as [6], [7]. Beside a number of methods for synthesizing EFAs [8], [9], [10], the EFA framework in [5] has been implemented in Supremica [11], a verification and supervisory control tool.…”