An integrated system for scheduling of processing and assembly operations with fuzzy operation time and fuzzy delivery time

This paper integrates the processing scheduling wi th assembly scheduling, aiming to s atisfy the requirements for jus t-in-time (JIT) production. Considering the unc ertai nty of time fac tors in actual produc tion, the operation time of the jobs were represented as triangular fuzzy numbers and the delivery time of the final produc t as trapezoidal fuzzy numbers. An extended job-shop scheduling probl em (JSP) considering abov e factors was proposed in this paper. A mathematical model was es tablished for processing and assembly scheduling, aiming to achieve the mean satisfaction degree on delivery time. In light of the complexity of the problem, a genetic algorithm (GA) was designed to realize the fuzzy integrated optimization of processing and assembly under uncertainty. The proposed algorithm i ncludes selection, c rossover, mutation operations, and reflec ts the spiri ts of two-sec tion real number encoding and elite protection strategy. Each part of the GA was designed in detail. Finally, the proposed model and algorithm were verified through a c ase study on processing and assembly scheduling. The model enjoys high prac tical value by taking the customer satisfac tion of the delivery period as the main goal. The results show that our scheduling strategy mirrors the actual production situation and provides a good reference for JSP scheduling under multiple unc ertainties. The best solution obtained by our model is more feasible than basic JSP in real production environment.