Optimization of Storage Assignment in Robotic Mobile Fulfillment System by using the Ising Model

A proposal towards the realization of a sustainable logistics center, taking into consideration the workload on human workers

Abstract

The logistics industry has been confronting a severe shortage of labor, referred as “Logistics Crisis 2024 in Japan”. With the escalating e-commerce transactions, there exists a compelling necessity to enhance the productivity of logistics centers. The introduction of warehouse robots, operating in coordination with human workers tasked with activities such as ladder climbing, body movements and ladder setup/removal, constitutes a strategic initiative to improve picking operations. To ensure the sustainability of logistics centers, a critical need for productivity enhancement arises, considering the substantial workload on human workers. This study aims to reveal the existence of the optimal storage assignment plan by solving multi-objective non-linear optimization problem using the Ising model, in which the objectives include minimizing both the movement time of warehouse robots and the operation time of human workers. Additionally, shipping simulations on the proposed storage assignment plan were conducted to validate its efficacy in real-world logistics center operations.