An Incremental Petri Net-Based Approach to the Modeling of Production Sequences in Manufacturing Systems

A crucial step in the logic-control design for flexible manufacturing systems is the modeling of the desired behavior in terms of production sequences. These are typically expressed as a series of informal specifications which are to be translated into a formal model. The present paper introduces a Petri net-based methodology for the modeling of production sequences conceived as an incremental process, which progressively adds subnets to a partial model until all specifications have been included. A formal verification of the model is performed at every stage, so that specifications, which are incongruent with the current model and can jeopardize its correctness, can be detected and rejected or modified. No unnecessary modeling constraints are imposed on the model class and behaviors characterized by complex alternative-parallel relationships between operations can be represented. A specific algorithm is provided for the automatic synthesis of complex connection structures in the model, allowing for greater flexibility and complexity in the design process.