Research On Function Block-Based Reconfigurable Manufacturing Cell Control System

The performance of manufacturing cell plays a highly important role in the enterprises rapidly responding to the fluky market and increasing their competition power. Because most of the existing manufacturing cell control systems haven't the real-time dynamic reconfiguration performance, they can't implement rapidly real-time configuration or reconfiguration according to the changing running environment or the abnormity situation. The above-mentioned factor contributes significantly to the total cost of manufacturing enterprises. To address this issue, this paper proposes a new modeling and design method of function block-based reconfigurable manufacturing cell control system.When constructing the system model, to make the manufacturing devices have real-time dynamic reconfiguration performance, the novel concept of general Virtual Manufacturing Device (VMD) composite function block through combining International Electrotechnical Commission (IEC) 61499 function block standard with Manufacturing Message Specification (MMS) is proposed. Then, the manufacturing cell hybrid control architecture based on composite function blocks has been constructed. This architecture distinguishes manufacturing control flows into independent reconfiguration control flow and execution control flow, hence, it can achieve the concurrent implementation of reconfiguration control and execution control for the manufacturing cell. To increase the local autonomy ability of the various VMD composite function blocks, and provide the control system software with some excellent characteristics of modularity, reusability, open capability, integration performance and maintainability, service-oriented manufacturing cell control software architecture is constructed. Besides, to resolve the problem of the information transfer among the heterogeneous manufacturing devices, the manufacturing information transfer model based on MMS and Web Services is presented. When dynamic modeling, a dynamic modeling and analyzing method of object-oriented colored Net-Condition/Event-System (OCNCES) through combining object-oriented colored Petri net technology with NCES model is proposed. Firstly, the constructing methods for object-oriented Net-Condition/Event-Module (ONCEM) models of the various general VMD composite function blocks and the OCNCES model of the complete manufacturing cell control system are presented. Secondly, the deadlock detecting algorithms for detecting the corresponding ONCEM models of the various general VMD composite function blocks and the OCNCES model of the complete manufacturing cell control system are proposed.Utilizing the presented algorithms, the above-mentioned models are analyzed. Finally, the resolution strategy aiming at the conflict events may appear in the aforesaid models is presented and the input/output conflicts in the various models are analyzed. Based on constructing the system model and performing dynamic modeling and analysis for the presented manufacturing cell control system in this paper, this control system is designed, developed and evaluated. Under the research background of a manufacturing cell, Unified Modeling Language (UML) class diagram method is adopted to design the control system. On the basis of the above designs, the control system software is developed by means of Web Services technology. Though the simulation experiment, the information transfer performance between the diverse VMD composite function blocks and the reconfiguration performance of the control system at the different platforms are tested and evaluated. The running case of the prototype system and the performance evaluation validate that the real-time dynamic reconfigurable manufacturing cell control system in network environment can be realized by IEC 61499 function block standard, MMS protocol and Web Services middleware.