An integrated object-oriented Petri net paradigm for manufacturing control systems

A new manufacturing control software development methodology called IOPN (integrated object-oriented Petri net paradigm) is presented. The IOPN consists of four phases: (1) static analysis; (2) dynamic analysis; (3) integration; and (4) implementation. In the static analysis phase, all possible object classes required by the manufacturing control software, and the static relationships among these object classes are identified. In the dynamic phase, the object-oriented Petri net (OPN) control model is derived according to both the dynamic behaviour of shop floor operations and the desired control logic. After the control logic specified by the OPN model is analysed and there is proven to be no deadlock, the required control decision/knowledge (e.g. scheduling/dispatching knowledge) must be included in the OPN model. Finally, the manufacturing control system is implemented directly from the specification of the OPN model by applying a number of transformation rules. Since the IOPN approach not only possesses the characteristics of object-oriented methods and Petri nets, but also provides a straightforward mapping between the high-level specification of the control logic and the code of the control software, the time required for developing a new control software or modifying an existing control software to accommodate to the operational changes will be greatly reduced.