Pii: S0360-8352(00)00032-2

A generic event control framework is presented for a class of modular ̄exible manufacturing systems (FMSs). A modular FMS is characterized as a set of ̄exible workstations inter-connected by a material handling system consisting of a transporter and a stocker. Many of the existing FMS implementations in industry fall into this class. Furthermore, the modularity also allows the capability to e€ectively model a complex FMS by decomposing it into several modular FMSs. In order to achieve recon®gurability of control system for various FMS implementations and control policies, the proposed control framework is de®ned as a set of distributed resource controllers and a central system supervisor coordinating them. The resource controllers are further classi®ed into workstation, transporter, and stocker controllers. As the controllers exchange a series of events according to pre-de®ned protocols, they are modelled as event handlers in which control actions are made based on the event occurrences. Speci®cally, for each controller, an event-based control structure speci®ed in terms of generic logical and performance control functions, is presented. Since the proposed framework is de®ned by the use of the interacting distributed processes with the well-de®ned protocols and computationally ecient algorithms, it is expected that the framework is easily implementable for most industrial FMSs. Finally, the performance and recon®gurability is demonstrated by the distributed simulation from which we can also verify the correctness of the proposed algorithms. 7 2000 Elsevier Science Ltd. All rights reserved.