Study On Job-shop Scheduling System Of The Discrete Manufacturing Enterprises

As market competition intensifies, enterprises are going towards the direction of multi-varieties and small-batch production. In discrete enterprises, especially those in the machinery industry, the case with multi-varieties and small-batch production and complex production organization, will cause long production period, mass work in process, inefficient use of machine tools and so on, thus affect the economic benefits of multi-varieties and small-batch production. The complexity of production organization particularly embodies in the great difficulty of enterprises' production planning, plan formulation based on subjective experience, and the poor timeliness and flexibilities of the plan. The research on Job-shop scheduling in the discrete manufacturing enterprises has important theoretical and practical significance.Based on the deep research of scheduling theory and a detailed analysis of the discrete manufacturing enterprises and its scheduling problems, a model for Job-shop scheduling with alternative operation routes is put forward in the paper. The alternative operation routes refer to flexibility of machine arrangement, that is, one operation arranged on which machine is not fixed and predetermined but alternative. This paper adopts the method combining genetic algorithm and heuristic rules to solve the Job-shop scheduling problem with alternative operation routes. So the solution to the problem is changed into optimizing two sub-problems, one is using genetic algorithm to select resources for process and the other is adopting heuristic rules to determine the sequence and start time of process on a machine.Moreover, by fully considering the uncertain factors in the production, a strategy by combining periodic scheduling and re-scheduling is adopted. According to the updated data in the dynamic database after disturbance occurs, the genetic algorithm can generate optimized production planning in response to the changes of the Job-shop. Meanwhile, in order to improve the visibility and legibility, a preliminary attempt has been done for the real-time monitoring of the workshop dynamic information in the scheduling system, with the application of virtual reality technology. By using of the virtual reality modeling language VRML, a simple model of the workshop equipment and workshop layout is set up and the expression of the equipment running station is done. Finally, a Job-shop scheduling prototype system, which combines the static scheduling and dynamic control and includes planning offline and dynamic scheduling, is developed.