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.