PETRI-NET EXTENSIONS FOR THE DEVELOPMENT OF MIMO NET MODELS OF AUTOMATED MANUFACTURING SYSTEMS

In this paper, the development of multiple-input multiple-output (MIMO ) subnets is discussed. Hierarchical time-extended Petri nets (H-EPNs) , a form of extended Petri nets, allow the development of structured M IMO subnets to model complex system functionalities. In addition, H-EP Ns also provide a means to convert such a MIMO structure to a single-i nput single-output (SISO) net that can easily be integrated within a t op-down system decomposition. The activator are definition is instrume ntal in deriving this transformation. The activator are definition and the H-EPN subnet definitions are integrated with the SPNP (stochastic Petri net package)(1) for simulation and analysis purposes. The activ ator are extension allows a truly hybrid approach to Petri net (PN)-ba sed systems modeling, analysis, and development of complex PN models o f automated manufacturing systems. The case study emphasizes the usefu lness of this extension in studying important issues such as static pr iority scheduling, dynamic failure recognition, and rescheduling in ma nufacturing systems. The SPNP package, suitably modified to handle the H-EPN extensions, is used for analysis and verification.