Modeling and control of a flexible manufacturing system using deterministic finite capacity automata

A design methodology which can be applied to manufacturing shop-floor production systems for modeling and control is presented. The problems of model complexity, system flexibility, model robustness, and ease of model construction are considered. These problems have been targeted and resolutions presented for a design methodology. In order to reduce model complexity, in terms of the number of required control states by a significant order of magnitude, an extended finite state machine called a deterministic finite capacity machine (DFCM) has been developed to model the control of a flexible manufacturing system (FMS). The complexity growth function of a DFCM control model becomes linear in the number of synthesized FMS components. For a FMS, a method for constructing its DFCM control model has also been developed. By incorporating supervisory control theory into a DFCM, a structured adaptive supervisory control (SASC) model not confined to any specific control architecture has been created. The SASC model is compositionally and modularly integrated by three function layers: acceptance, adaptive supervision, and execution. Control under the SASC model of a FMS then guarantees that the behavior of the FMS satisfies the desired control specifications. The capability of a FMS (representing the inherent system flexibility of the FMS) has been considered as the input to the SASC design methodology. Thus, the inherent system flexibility of the FMS is included in the constructed SASC model. Finally, the correctness and usefulness of the SASC design methodology have been validated by applying the design methodology to modeling and control of the FMS in the CIM lab at Penn State. Results of this implementation are discussed as a sample implementation.