Integrated Order Batching and Distribution Scheduling in A Singleblock Order Picking Warehouse Considering S-Shape Routing Policy

In this paper, a mixed-integer linear programming model is proposed to integrate batch picking and distribution scheduling problems in order to optimize them simultaneously in an order picking warehouse. a tow-phase heuristic algorithm is presented to solve it in reasonable time. the first phase uses a genetic algorithm to evaluate and select permutations of the given set of customers. the second phase uses the route first-cluster method to obtain an effective schedule for a given permutation of customers. computational experiments represent that integrated approach can lead to significant reduction in the makespan. moreover, empirical observations on the performance of the heuristic algorithm are reported.