A Milp of the Joint Order Batching, Sequencing and Picker Routing Problem Considering Pick-Face Blocking

In manual and semi-automated order picking systems, one of the challenges consists in minimizing picker blocking. One of the ways to prevent picker blocking is to have wide-isles warehouses. Although this solution solves part of the problem, pick-face blocking remains a challenge. Technological systems locating pickers in real-time have been proposed to minimize or eliminate picker blocking. Alternatively, finding the right combination of order picking policies may be more cost effective for less modernized warehouses. However, finding the right combination is not always easy given the multiple features and rules involved that sometimes cancel out the benefit of each other. The goal of this paper is to evaluate the effects of combining order picking policies on the performance of the order picking system. The evaluation sheds some lights on how order picking planning problems interact with each other and why, considering the pick-face blocking. We first formulate a Mixed Integer Linear Programming problem considering the pick-face blocking. Second, we propose a Simulated Annealing solution to the problem. Finally, we demonstrate, using full factorial ANOVA, that combining order batching, storage location assignment and picker routing policies significantly influences the order picking system