Clustering-based order-picking sequence algorithm for an automated warehouse

This paper addresses the order picking sequence problem in an automated warehouse where parts of an order picker's travelling tour are fixed, the length of the layout is significantly longer than the width, and the picker can hold only one item at a given time. The problem is to find an optimal sequence with given vertical paths and so it is a special type of travelling salesman problem. A simple sorting-based heuristic and an efficient clustering-based algorithm are developed for this problem. In order to use the gantry robots more efficiently, a flexible drop buffer assignment is considered and the proposed algorithms are modified for the new operating condition. Experimental results indicate the efficiency of the proposed algorithms.