Modeling and control of the FMS workstation level information flow by a modified Petri net

A flexible manufacturing system (FMS) has a traditional structure of three-levels: the unit, the workstation, and the machine levels. The design quality of the workstation level plays an important role in the overall FMS performance. This paper focuses on the information flow analysis and control of the FMS workstation level. In order to design a unified workstation level system structure, front-end interfaces are introduced into the system which communicate with the workstation level through standard interface. After analyzing the information flow in the FMS workstation level, a modified Petri net is presented which associates data structures with places and programs/procedures with transitions. Using the modified Petri net, the model is set up for the information flow of the FMS workstation level. The designed system has been implemented in a real manufacturing factory with satisfactory and stable performance.