A development methodology for heterarchical control of flexible manufacturing systems

This paper presents a methodology for development of a heterarchical control system in Flexible Manufacturing Systems (FMS) environment. A Petri net based model is applied for development of control software. A real-time scheduling methodology for the heterarchical system is also developed and it is used as a software entity in the overall architecture. The partition of generic and specific modules in control software development is emphasized. The control system performs its control tasks in two stages: (1) generation of generic control code and distribution of them to each controller entity prior to system execution; (2) generation of specific control code according to job arrival and its process plan. The control software and the scheduling algorithm are evaluated by a simulation program.