Conversão entre modelos de sistemas a eventos discretos para simplificação da síntese de controladores

Abstract

The Supervisory Control Theory (SCT) formally structures the synthesis of controllers for Discrete Event Systems (DES) based on Automata and Languages theory. In SCT, events are separated into two different sets to include controllable and uncontrollable, and the control synthesis is defined on these sets. Among the aspects that limit the practical application of this theory are modeling and synthesis problems. In recent years, some approaches have been proposed as a mean to deal with such limitations, such as Distinguishers and Extended Finite-state Automata (EFA). Distinguishers use the concept of refinements to associate contexts with certain system’s events, which leads the control problem to be solved using a new alphabet constructed from the initial one. An EFA implements a similar idea, but using variables and logical formulas to represent contexts. These approaches bring some improvements to SCT, including modeling and synthesis simplification. However, in general, each approach is proposed within a specific framework, so that their integration is not straightforward. This work introduces a method for converting Distinguishers to EFA, and vice versa, while preserving the same global behavior. It is shown that the proposal allows to combine advantages from both approaches when solving a given control problem. The conversion is illustrated by examples. In particular, it is used a manufacturing system with rework of materials. The system is initially modeled by an EFA, which brings modeling advantages. Afterwards, the system model is translated to Distinguishers and a local modular control synthesis is processed with computational economies.