Using HGA to solve E/T scheduling problems with fuzzy processing time and fuzzy due date

This paper considers fuzzy single machine and flow shop earliness/tardiness scheduling problems with fuzzy processing time and fuzzy due date. Fuzzy processing time is denoted by a triangular fuzzy number and fuzzy due date is denoted by a trapezoid fuzzy number. We formulate two kinds of scheduling model of single machine and flow shop scheduling problems. When solving the first kind of model with exact processing time and fuzzy due date, we take minimum earliness/tardiness penalty as optimized object and use hybrid genetic algorithm to search the optimal scheduling sequence. As for single machine model, we still adopt heuristic rule to get optimum common due date. When solving the second kind of model with both fuzzy processing time and fuzzy due date, the maximum average agreement index according to fuzzy completion time and fuzzy due date is considered as optimized object. Some numerical examples are given to illustrate the effectiveness and feasibility of our proposed algorithm.