Design of a rule-based flexible manufacturing system controller using modified IDEF0 methodology

Abstract

This article proposes a new method to design a rule-based FMS controller. This approach adopts modified IDEFO (MI) diagrams as a graphical representation of the production rules. Initially, the material flows or functional requirements for the FMS are specified by synthesizing the MI diagram primitives. The control flows for the FMS are then created by a number of transformation rules. The manufacturing policy, e.g. deadlock avoidance policy, is also specified and attached. The MI diagrams are therefore transformed to the final MI (FMI) diagrams which can be directly transformed to the production rules. Thus, a concise rule-based FMS controller is developed. The fact that the production rules are created by systematic transformation eliminates any redundant, contradictory, or unnecessary rules. Two approaches can verify the consistency of the designed FMS controller. The controlled Petri net approach can be adopted for verifying a small system, while a simulation approach is preferable for verifying a large system. By iterating the process, a feasible rule-based FMS controller can be systematically developed. This method not only provides graphical representations to construct well-organized production rules, but also includes a systematic transformation of the control flows for an FMS controller.