Event-based supervisor control for a cyber-physical waterway lock system

Abstract

An event-based supervisory control scheme, in the Ramdage–Wonham framework, will be proposed for the cyber-physical Waterway Lock system, known as Lock III, in Tilburg, the Netherlands. The proposed control scheme imposes desired behavior, by appropriately disabling controllable events, so as to avoid activation of actuator commands that may lead to undesired and potentially hazardous operating states. The discrete event model of the total Waterway Lock system, comprising 54 actuator and sensor automata, will be presented in analytic 6-tuple forms of its subsystems. The system's desired behavior, which is expressed using six rules, will be formulated as 84 regular and prefix closed languages that will be realized as appropriate supervisor automata. All supervisors are developed by a general two-state supervisor form, which facilitates their implementation. A distributed control architecture will be proposed, which organizes all supervisors in distinct groups, each of which controls one and only one distinct command event. The complexity of the proposed control scheme will be computed to be equal to (168,324,564), being reasonable, as compared to the large number of subsystems and the restrictive design requirements. The physical realizability of the 84 supervisors, with respect to the 54 subsystems of the waterway lock system, will be proved analytically. Also, it will be proved analytically that the proposed supervisor architecture guarantees the nonblocking property of the controlled automaton, including all subsystems. The establishment of these analytic proofs supports the extendibility of the results to other applications. To demonstrate the resulting large-scale controlled automaton's good performance, its marked behavior and simulation results will be presented.