Integrated schedule of order picking and delivery for instant delivery

In this study, we introduce an integrated schedule of order picking and delivery for instant delivery. Order picking, including order batching and picking sequencing, is scheduled online under real-time order arrival, which integrates order delivery by depicting order location dispersion in an online order picking strategy. Order delivery, including delivery person assignment and route planning, is modeled to minimize the total duration of order fulfillment by considering the influence of the order picking completion time. A rule-based online order picking strategy is established, and a customized ant colony optimization (ACO) algorithm is proposed to optimize order delivery. Experiments on 16 simulated instances of different scales demonstrate that our online order picking schedule considering order delivery outperforms existing approaches and that the customized ACO algorithm for order delivery is effective.