A comparative study of order batching algorithms

In a man-on-board storage and retrieval system, orders are combined into batches and each batch is processed in a tour of the storage/retrieval (S/R) machine. Batching policy determines the way to combine orders to form batches. Since batching is an NP-hard problem, heuristic algorithms have been proposed. The major steps of these algorithms include seed selection and addition of orders to a batch. This paper is a comparative study of order batching algorithms composed of four seed selection rules and four order addition rules for order batching problems. Together, they constitute 16 algorithms. In addition, another method, namely the SL (small and large) algorithm, is also considered. The performances of these algorithms are compared along the three dimensions of shape factor, capacity of the S/R machine,and storage assignment policy. The results indicate that the economic convex hull algorithm has the best performance.