Picklist generation algorithm with order-consolidation consideration for split-case module-based fulfilment centres

This paper serves as an initial study on order-consolidating time for a module-based order-picking system. In this system, items are stored in modules, and order picking is performed in waves that comprise more than one customer order. Picked items from multiple modules are conveyed to the packaging department for sortation based on customer orders. The order-consolidating time is the main focus as well as the performance measure in this paper. Order-consolidating time is the time difference between the arrival time of the first and the last item at the packaging department that belong to the same customer order. We proposed a heuristic control strategy, namely a pick-list generation algorithm, which will reduce the order-consolidating time. We named our proposed algorithm the push algorithm, which is an improvement algorithm. The push algorithm is compared with the basic algorithm to evaluate its performance. This comparison is extended under different environment settings to provide a robust conclusion. The experimental results indicate that the proposed algorithm consistently out-performs the basic algorithm in every tested environment with at least 17% improvement.