Abstract
Keeping the workload balanced between zones is critical to the performance of zone-picking systems. However, with zone-picking systems, even if they are designed with workload balance in mind, once they are running, it can be difficult to keep the workload balanced. Furthermore, their no-zone-crossing constraint refrains pickers of neighbouring zones from helping each other. As a result, nothing can be done when workload imbalance occurs. In this paper, we focus on solving the workload imbalance problem in parallel zone-picking systems. We propose a new parallel zone-picking system that allows pickers to help each other by setting up cooperation area between neighbouring zones and study its design and cooperation problems. We propose different methods for each problem and conduct simulation experiments to test them. The simulation results give us not only the performance of the proposed methods, but also several important findings. For example, setting up cooperation area between neighbouring zones benefits the system’s performance. However, this does not mean having lots of cooperation between zones is the best. In fact, our study shows the always-help method performs as poorly as the no-cooperation method. And cooperation-area designs that create more adjacency in the cooperation area of neighbouring zones will perform better.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
The data that support the findings of this study are available from the corresponding author upon request.
Additional information
Notes on contributors
Ying-Chin Ho
Ying-Chin Ho is a professor in the Institute of Industrial Management at National Central University (NCU) in Taiwan. He received his B.S. degree in industrial management from National Cheng Kung University (Tainan, Taiwan) in 1987, and M.S. and Ph.D. degrees in industrial engineering from Purdue University (Indiana, U.S.A.) in 1991 and 1995, respectively. Dr. Ho joined the faculty of NCU in 1995. His research and teaching interests include facilities design, material handling, logistics management, supply chain management, operations management, and the design and control of manufacturing systems.
Jia-Chyun Chen
Jia-Chyun Chen is a Ph.D. student in the Institute of Industrial Management at National Central University (NCU) in Taiwan. He received a M.S. degree in industrial and systems engineering from the Ohio State University in U.S.A. in 1997 and a B.S. degree in industrial engineering from National Tsing Hua University in Taiwan in 1995. His primary research interests include facilities layout design, material handling systems and the design, analysis, operation, and control of production and logistics systems.
Shih-Chou Kao
Shih-Chou Kao is an associate professor in the Department of Business Administration at Kao Yuan University in Taiwan. He received a Ph.D. in Industrial Management from National Central University in Taiwan in 2006. His current research interests include statistical process control and supply chain management.