A generic colored Petri nets model for the makespan optimization in flexible manufacturing systems

Abstract

This paper introduces an optimization method of the makespan in a Flexible Manufacturing Systems (FMS) while considering the whole system behavior (operation, transport and preparation). A formal specification model well-adapted to describe a large class of FMSs is presented. Based on such a model, a user may specify its manufacturing system in FMS-oriented terms (machines, storage, transport equipment, manufacturing process, …). The introduced specification is automatically transformed into a colored Petri net (CP-net) model. Hence, existing formal verification CP-net methods are exploited, and especially the state space generation and handling, in order to deduce the optimal makespan. This is obtained by determining the opeation sequence minimizing the execution duration of a given manufacturing process. An important advantage of the developed approach is that it is parameterized. Thus, it may be adapted to a large class of existing FMSs. The implementation of the presented methodology was integrated into an experimental environment, called MAC-FMS, allowing graphical specification, supervisory control and formal verification based on CP-nets.