Research On Description And Scheduling Of Operation Sequence Flexible Job-shop Problem

Job-shop scheduling is a kind of typical production scheduling problem, which has received wide attention of scholars both at home and abroad. Along with the enhanced unpredictable market environment and the customers’ demand for product diversity, the enterprises gradually adopted the production model of muti-varieties and small-batch, which makes there exists some flexibility in the actual production process, such as machine flexibility, operation sequence flexibility and so on. It has been proved that by considering the flexible factors in the manufacturing system, the enterprises not only can improve the production efficiency and reduce cost, but also can enhance their own competitiveness.This paper researches on the operation sequence flexible problem in the processing of jobs in Job-shop. Firstly, the description methods of operation sequence flexibility in Job-shop are summarized and analyzed, and in view of the insufficiency of them, a new description method which is complete and doughtily application is proposed. Secondly, the mathematical model of the flexible Job-shop is built according to the actual production environment, and the scheduling target of minimize the maximum completion time is optimized. Thirdly, one phase hybrid optimization algorithm is designed based on the discrete particle swarm and variable neighborhood search, of which the two-part coding method which is suitable for the scheduling of operation sequence flexibility is designed, two methods of initializing particles are given, and a update way of particles which can produce a feasible solution is designed, simultaneously, three different neighborhood search structure for the proposed coding method are designed. Finally, through comparing with other’s research results, the effectiveness and stability of the proposed algorithm are analyzed.The research results show that the optimization results of considering operation sequence flexibility is better than the results of not considering it; the optimization results of the proposed hybrid algorithm is superior to the IGA algorithm in literature four which also has good stability. The research results has certain guiding significance to the scheduling of operation sequence flexibility and the application of particle swarm optimization in Job-shop scheduling.