Research on Job-Shop Scheduling in Fuzzy Environment

摘要

Job-shop scheduling (JSP) is a difficult problem, both theoretically and practically. Although the job-shop scheduling problem has often been investigated, very little of this research is concerned with the uncertainty characterized by the imprecision in problem variable. But in reality, the processing time are often imprecise and this imprecision is critical for the scheduling procedure. In this paper, we develop a framework to solve and optimize JSP with uncertain processing times in which imprecise processing times are modeled as triangular fuzzy numbers (TFN). The resulting fuzzy framework is an extension of the original crisp problem. Therefore, we apply GA which used for solving the crisp job shop problem to optimize the fuzzy problem. We improved the simple GA in representation method, crossover and mutation operators, the computer simulations verify the effectiveness of this approach. Our work intends to extend the original job-shop scheduling problem into a more generalized problem that would be useful in practical situation.