MILP Formulations for the Order Batching Problem in Low-Level Picker-to-Part Warehouse Systems

In this work we introduce Mixed Integer Linear Programming (MILP) formulations for the Order Batching Problem considering traversal and return routing policies. The proposed MILP formulations have been tested on randomly generated instances and compared with the well-known savings algorithm. According to our extensive computational experiments we can say that the proposed MILP formulations are quite useful to yield good upper bounds and hence, they can be used for benchmarking purposes.