Merging Petri nets and database models for control and monitoring; requirements in FMS

This paper reviews an approach for real-time control and monitoring of discrete events systems like flexible manufacturing systems (FMS). This approach is based upon a philosophy of hierarchical and modular control. Each module of the structure has its own monitoring system based on detection, diagnosis and recovery functions. Different models are used, namely Petri nets with objects. Some limitations of this approach are discussed. A new approach is proposed using an information system. The requirements of the model used to represent this information system are exposed.