Mariagrazia Dotoli

A coloured Petri net model for automated storage and retrieval systems serviced by rail-guided vehicles: A control perspective

An Automated Storage and Retrieval System (AS/RS) automatically stores incoming material and retrieves stored parts with no direct human handling. This paper proposes a modular and unified modelling framework for heterogeneous automated storage and retrieval systems, comprising rail guided vehicles and narrow aisle cranes. We employ coloured timed Petri nets, representing a concise and computationally efficient tool for modelling the system dynamic behaviour, particularly suitable for real-time control implementation. Indeed, the model can be utilized in a discrete event simulation to apply control policies in order to solve scheduling problems, as well as to avoid deadlock and collision occurrences.

Fault Detection of Discrete Event Systems Using Petri Nets and Integer Linear Programming

Abstract The paper addresses the fault detection problem for discrete event systems on the basis of a Petri Net (PN) model. Assuming that the structure of the PN and the initial marking are known, faults are modelled by unobservable transitions. Moreover, we assume that there may be additional unobservable transitions that are associated with the system legal behaviour and that the marking reached after the firing of a transition is unknown. We propose a diagnoser that works on-line: it waits for the firing of an observable transition and employs an algorithm based on the definition of some integer linear programming problems to decide whether the system behaviour is normal or exhibits some possible faults.

Modeling and management of a hospital department via Petri nets

This paper addresses the management and performance analysis of the pulmonology department of the general hospital of Bari, Italy, focusing on the department workflow and drug distribution system. To this aim, we present a discrete event system model which can be employed as a support for taking decisions regarding the information and automation integration in order to improve the drug procurement logistics and management. The model employs a timed Petri net framework to describe in a concise and detailed way the workflow in the pulmonology department, while considering various ordering and management policies of the department drug storehouse.