Job shop scheduling optimization with flexible process route of customized workpiece

ZHOU Ke1, LV Min2, XIA Zi-xiang1,3, LI Xiao-dong1
(1.Department of Mechanical Engineering, Jining University, Qufu 273155, China;
2.School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China;
3.School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116, China)

Abstract: Aiming at the problem of job shop scheduling with flexible process route, the mathematical model of job shop scheduling with flexible process route was established. The constraint condition was the delivery time of normal parts. The optimization goal was to reduce the completion time of customized parts, total energy consumption and total cost. A hierarchical coevolution algorithm was designed. The first level initial population was generated based on the reverse search of customized parts processing time. The second layer initial population was generated based on load balancing. Coding rules between different levels were used to ensure the collaborative relationship. Pox crossover operator was used to guarantee the order constraint relationship. According to the conflict detection of workpiece, equipment and process, the invalid experimental individuals were corrected. On the basis of improving the global search ability, the convergence speed was accelerated. Three different strategies were used to solve the same scheduling problem. The results indicate that the algorithm is feasible and effective to solve the job shop scheduling problem with flexible process route, and the completion time of customized parts is reduced by 53%.

Key words: job shop scheduling; evolution algorithm; flexible process route; customized workpiece