抄録
This paper considers an optimal tool assignment problem for automated two-machine flowshops such as FMS's (Flexible Manufacturing Systems) and FMC's (Flexible Manufacturing Cells) in order to improve their system efficiencies. This study is motivated by the fact that the system efficiency decreases as the imbalance of machine loads or the diversity of job processing times increases even under an optimal job schedule. Machine loads and job processing times on each machine are determined directly by assigning tools to two machines. Thus we adopt the weighted sum of two variances of machine loads and job processing times as the objective function. This is an extension of the traditional machine load problem. For this problem we propose an approximation algorithm based on simulated annealing technique, and strengthen it by strategically applying the optimal scheduling. Results of numerical experiments performed show that tool assignments and schedules by the proposed algorithm give quite high system efficiencies with small variances.
