Design of Multi-stage Production System Robust to Variance

这项研究考虑了在多阶段生产过程中利用多任务工人的方法。在设计生产系统时，重要的是通过有效地利用工人和生产设施来提高生产率。然而，操作时间的变化和不平衡的工作负载通常会降低系统的性能。该研究提出了一种MTW分配规则，利用时间缓冲区将MTW转移到工作量最小的前一站。研究表明，MTW能够有效地吸收作业时间的变化和工作负载的不平衡。它与看板系统的不同之处在于，时间缓冲系统使用剩余的加工时间来评估在制品(WIP)；然而，这些系统在多阶段生产过程中并不使用所有的库存信息。也就是说，当库存处于特定状态时发出生产指令。根据库存的不同状态，流量控制系统的性能会有所改善。在这项研究中，我们设计了一个利用多阶段生产过程中所有可用库存信息的最优流程控制系统。将在制品的状态空间作为库存的控制域，实现了详细的流程控制。

This research considers a method for utilizing multitasking workers (MTWs) in multistage production processes. In designing a production system, it is important to raise productivity by using workers and production facilities effectively. However, the variation in operation time and the unbalanced workloads generally decreases the system's performance. This study proposes a MTW assignment rule in which the MTW is shifted to the previous station of the minimum workload, using a time-buffer. It is clarified that the MTW can absorb the variation in operation time and the unbalanced workloads effectively.A flow-control system incorporating the concept of time buffer was proposed recently. It differs from the Kanban system in that a time-buffer system evaluates work-in-process (WIP) using the remaining processing time; however, these systems do not use all the inventory information in multistage production processes. That is, a production instruction is issued when the inventory is in a specific state. The performance of the flow-control system improves depending on the various states of inventories. In this study, we designed an optimal flow-control system that utilizes all the available inventory information in multistage production processes. Detailed flow control is achieved by treating the state space of WIP as a control domain of the inventory.