Research On Coordinate Scheduling Mechanism For Networked Manufacturing System

The networked manufacturing enables the enterprise to achieve better product quality;lower production cost and reduced manufacturing risk, so it has been the trend of modern manufacturing system. However, networked manufacturing also challenges the enterprises in many aspects such as planning and scheduling activities. Among these aspects, a crucial one is that the manufacturing operations of products and jobs must be carefully planned and scheduled in the networked manufacturing environment.The virtual job-shop might be an effective realization of networked manufacturing. It is a virtual manufacturing environment where several manufacturing resources, such as plants, job-shops or manufacturing cells, contract a manufacturing alliance for taking market opportunity. In a virtual job-shop, the collaborations among these manufacturing resources take place at the shop-floor level and they involve much more operational details of individual partner.In this paper, manufacturing scheduling problems in a visual job-shop have been researched. The main contents are as follows:At first, the statuses in quo of the researches and developments for the networked manufacturing system in modern world have been summarized, and the necessities to construct a virtual job-shop have been analyzed. Besides, the definition of virtual job-shop has been presented and the concept model, function model, and control model for the agent-based virtual job-shop scheduling system are also given out. The proposed models sustained alternation, negotiation and harmony at landscape orientation or portrait between agents, which satisfy the opening and agility demand.Then, market-based mechanism are discussed, and a virtual workshop coordinate scheduling method is established based on the market-based methods. Regarding the running environment of virtual workshop production scheduling system as a virtual economy body, and treating the task agent and resource agent as bargainers, the negotiation process of the economymodel have been expounded particularly. Added to these, the scheduling process were broken down to two parts in order to solve the complex scheduling problems in virtual job-shop, that are dynamic task distributing strategy and conflict resolution method, and then relevant scheduling strategies are designed and emulated by simulation experiments.At the end, the correlative theories and practice applications of agent knowledgebase are discussed. Based on logical knowledge express model, virtual workshop scheduling system knowledge base are established, and knowledge for scheduling are expressed in rule form. The rule's relationship is described based on the database conception, and a framework to gather expert's knowledge are conformed based upon attributes of manufacturing tasks, along with finishing time and manufacturing cost for the parts. Knowledge bases of scheduling strategies and task assigning rule are even been established.