Operation twins-driven human-centric replenishment-kitting synchronization for smart customized production logistics

Customized manufacturing mode is characterized by a wide variety of products and materials, mixed production volume, and order-driven operations. This study focuses on replenishment and kitting operations in a mass customization workshop under assemble-to-order (ATO) mode. Field investigation reveals that the lack of coordination between replenishment and kitting operations can increase the operation time and ergonomic risks of operators, thereby leading to low overall efficiency, increased operational costs, and reduced health levels. To address this issue, this paper proposes a novel operation twin driven human-centric replenishment-kitting synchronization framework (HCRK-Sync) for coordinated operations. The proposed operation twin framework consists of vertical twinning and horizontal twining, in which vertical twinning leverages Industry 5.0 technologies and human digital twin for real-time operational status perception and horizontal twining focuses on HCRK-Sync decision mechanism. The HCRK-Sync mechanism aims to minimize order operation time and human ergonomic risks, thereby achieving a harmonious balance between replenishment tasks and picking efficiency. Experiment results indicate that compared to traditional methods, HCRK-Sync shows significant advantages in improving picking efficiency and reducing ergonomic risks, with an average reduction of 9%-35% in total order operation time and 8%-50% in ergonomic risks, demonstrating stability and adaptability across different production scenarios.