Fuzzy operator allocation for balance control of assembly lines in apparel manufacturing

Production processes in apparel manufacturing typically involve hybrid assembly lines. In order to perform at predetermined production rates, careful balance control of the sewing operations on these assembly lines is very important. The right number of operators to be moved in and out of a sewing section has to be accurately determined. In this paper, the authors extend the literature on fuzzy logic applications to control systems by proposing a simple, yet effective, rule-based system that captures the knowledge of experienced supervisors in a set of fuzzy rules. These rules specify how balance control can be achieved based on the level of difference between; (1) the actual and target buffer level; and (2) the actual and target section performance. Since these parameters are normally expressed in linguistic terms, they are encoded in rules expressed with fuzzy logic. The number of operators to be moved in and out of a sewing section can, therefore, be determined by means of fuzzy inferences. To evaluate the effectiveness of the system, we compared its performance to the decisions made by experienced supervisors at a large shirt factory. The system was found to increase in production efficiency by 30%.