Based on Synchronized Timed Petri Nets for Emergency Vehicle Preemption Systems

2011 ◽  
Vol 291-294 ◽  
pp. 2775-2778 ◽  
Author(s):  
Yi Sheng Huang ◽  
Yi Shun Weng
Keyword(s):  
Control System ◽  
Petri Net ◽  
Discrete Event ◽  
Discrete Event Dynamic Systems ◽  
Emergency Vehicle ◽  
Two Phase ◽  
Timed Petri Net ◽  
Traffic Lights ◽  
Event Dynamic ◽  
Clear Presentation

Timed Petri net (TPN) has been utilized as a visual formalism for the modeling of complex discrete event dynamic systems. It illuminates the features on describing properties of causality and concurrency. Moreover, it is well-known that synchronized timed Petri net (STPN) allows us to present all of the concurrent states in complex TPN. In this paper, we propose a new methodology to design, analyze and implement an urban emergency vehicle preemption control system by using STPN. The applications of STPN to two-phase traffic lights and emergency vehicle preemption are illustrated. The advantage of the proposed approach is the clear presentation of traffic lights’ behaviors in terms of conditions and events that cause the preemption phases alternations. Finally, a two-phase traffic lights control system with emergency vehicle preemption will be realized by using STPN. To our knowledge, this is the first work that employs STPN to model a two-phase traffic lights control system with emergency vehicle preemption system.

scholarly journals Petri Net-Based Semi-Compiled Code Generation for Programmable Logic Controllers

2021 ◽  
Vol 11 (15) ◽  
pp. 7161
Author(s):  
Igor Azkarate ◽  
Mikel Ayani ◽  
Juan Carlos Mugarza ◽  
Luka Eciolaza
Keyword(s):  
Code Generation ◽  
Resource Sharing ◽  
Discrete Event ◽  
Transition Function ◽  
Discrete Event Dynamic Systems ◽  
Programmable Logic ◽  
External Software ◽  
Implementation Methodology ◽  
Event Dynamic ◽  
Step Transition

Industrial discrete event dynamic systems (DEDSs) are commonly modeled by means of Petri nets (PNs). PNs have the capability to model behaviors such as concurrency, synchronization, and resource sharing, compared to a step transition function chart or GRAphe Fonctionnel de Commande Etape Transition (GRAFCET) which is a particular case of a PN. However, there is not an effective systematic way to implement a PN in a programmable logic controller (PLC), and so the implementation of such a controller outside a PLC in some external software that will communicate with the PLC is very common. There have been some attempts to implement PNs within a PLC, but they are dependent on how the logic of places and transitions is programmed for each application. This work proposes a novel application-independent and platform-independent PN implementation methodology. This methodology is a systematic way to implement a PN controller within industrial PLCs. A great portion of the code will be validated automatically prior to PLC implementation. Net structure and marking evolution will be checked on the basis of PN model structural analysis, and only net interpretation will be manually coded and error-prone. Thus, this methodology represents a systematic and semi-compiled PN implementation method. A use case supported by a digital twin (DT) is shown where the automated solution required by a manufacturing system is carried out and executed in two different devices for portability testing, and the scan cycle periods are compared for both approaches.

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