Research On Job-shop Scheduling Problems Based On Ontologiesand Context-awareness For Cloud Manufacturing

In order to get rid of existing problems in manufacturing industry, such as low-end industry chain, low productivity, high energy consumption and a lack of innovation, Cloud Manufacturing, a new knowledge-based networked intelligent manufacturing model with features of service-oriented architecture, high productivity and low consumption, was proposed. Related researches have made the theory of Cloud Manufacturing become mature. Therefore, it is necessary to combine this theory with practical manufacturing processes to realize the conception of “Manufacturing as a Service”. This paper focuses on the job-shop scheduling problems based on ontologies and context-awareness for Cloud Manufacturing, and the main contents are as follows:Firstly, ontology techniques are introduced to satisfy the need of servitization and intellectualization of processing equipment. After analyzing the advantages and disadvantages of existing ontology languages, OWL(Web Ontology Language) is chosen to model the processing equipment. Then, Jena inference mechanism is introduced to realize the inference and query of ontology models for more extra information. The results of this study lay a foundation for the solution of event-driven job shop scheduling problems based on ontologies, and the realization of a context-aware system for workshop.Secondly, according to the features of job-shop floor scheduling for Cloud Manufacturing, event-driven manner is introduced and combined with ontology techniques to realize the detection, monitoring and matching for events in job shop floors. These measurements strengthen the capacity of dynamically awareness and real-time management for job shop scheduling. Such techniques are applied for the job-shop scheduling problem FT46, which allows the system to gain workshop information dynamically, and to match event patterns to optimize the job shop scheduling problem by rules library. Finally, the job shop scheduling problem is packaged as a service by using Web Services technology, so that customers can use the workshop processing services conveniently through networks in real time.Thirdly, a context-aware system framework for job-shop scheduling is proposed to satisfy the demand of servitization and intellectualization of workpiece process. The context-aware system is realized by using the C/S architecture, so that the collaboration of the devices in the workshop becomes more automatic and intelligent to meet the real-time need of new tasks being inserted. At last, the context-aware system is set up by Web Services techniques to realize the networked connection of distance systems. And clients can monitor and gain information of manufacturing process via Web.Finally, an experimental prototype platform is set up by RFID techniques to realize the proposed system. On the experiment in milling and turning, the feasibility of the system is verified.