Networked Supervisory Control Synthesis of Timed Discrete-Event Systems

TL;DR

This paper develops a method to synthesize supervisors for timed discrete-event systems over networks with communication delays and disorder, ensuring correct control despite non-ideal communication conditions.

Contribution

It introduces a framework for networked supervisory control that accounts for delays and non-FIFO observation channels, enabling correct supervisor synthesis under realistic network conditions.

Findings

Synthesizes networked supervisors that are controllable and nonblocking.

Models plant behavior under communication delays and disorder.

Guarantees maximally permissive control satisfying system requirements.

Abstract

Conventional supervisory control theory assumes full synchronization between the supervisor and the plant. This assumption is violated in a networked-based communication setting due to the presence of delays, and this may result in incorrect behavior of a supervisor obtained from conventional supervisory control theory. This paper presents a technique to synthesize a networked supervisor handling communication delays. For this purpose, first, a networked supervisory control framework is provided, where the supervisor interacts with the plant through control and observation channels, both of which introduce delays. The control channel is FIFO, but the observation channel is assumed to be non-FIFO so that the observation of events may not necessarily be received by the supervisor in the same order as they occurred in the plant. It is assumed that a global clock exists in the networked control system, and so the communication delays are represented in terms of time. Based on the proposed framework, a networked plant automaton is achieved, which models the behavior of the plant under the effects of communication delays and disordered observations. Based on the networked plant, the networked supervisor is synthesized, which is guaranteed to be (timed networked) controllable, nonblocking, time-lock free, (timed networked) maximally permissive, and satisfies control requirements for the plant.