Real-time order picking planning framework for warehouses and distribution centres

This paper proposes a dynamic-order picking (DOP) framework where batches and picker routes are continuously modified in response to urgent orders arrival and disruption events. In the proposed framework, we consider conflicts between pickers in narrow aisles to ensure a smooth replanning function. For this purpose, we first formulate a static joint-order batching and sequencing model (J-OBS) that takes into account congestion time. Then, we propose a replanning model (D-J-OBS) that utilises real-time input from multiple information systems. As a solution approach and due to the NP-hardness of the problem, we use a tabu search algorithm to solve practical sizes of the static and the dynamic problems. The results indicate that the DOP framework generates significant tardiness savings compared to online-order picking, especially for systems with high degree of dynamism.