Supervisor Localization of Timed Discrete-Event Systems under Partial Observation and Communication Delay

TL;DR

This paper develops a method for supervisor localization in timed discrete-event systems considering partial observation and communication delays, ensuring controlled behavior through decentralized supervisors and local controllers.

Contribution

It introduces a novel approach combining timed relative observability and coobservability to synthesize and localize supervisors under communication delays.

Findings

Achieved equivalent controlled behavior with local controllers and preemptors.

Modeled communication delays with channel models and bounded/unbounded delays.

Validated approach with a timed workcell example.

Abstract

We study supervisor localization for timed discrete-event systems under partial observation and communication delay in the Brandin-Wonham framework. First, we employ timed relative observability to synthesize a partial-observation monolithic supervisor; the control actions of this supervisor include not only disabling action of prohibitible events (as that of controllable events in the untimed case) but also "clock-preempting" action of forcible events. Accordingly we decompose the supervisor into a set of partial-observation local controllers one for each prohibitible event, as well as a set of partial-observation local preemptors one for each forcible event. We prove that these local controllers and preemptors collectively achieve the same controlled behavior as the partial-observation monolithic supervisor does. Moreover, we propose channel models for inter-agent event communication and impose bounded and unbounded delay as temporal specifications. In this formulation, there exist multiple distinct observable event sets; thus we employ timed relative coobservability to synthesize partial-observation decentralized supervisors, and then localize these supervisors into local controllers and preemptors. The above results are illustrated by a timed workcell example.