Optimization and analysis of a robot-assisted last mile delivery system

The last mile of freight distribution is a critical part of the supply chain because of its significant costs and customers' increasing expectations from e-commerce and same-day delivery services. Automated technologies in freight transportation represent an opportunity to develop more efficient systems characterized by the integration of different and complementary modes. In this study, we focus on the possibility of implementing an integrated truck-robot system for the last-mile delivery. This typology of problem shares similarities with truck-drone problems, although robots are characterized by much slower speeds and can perform several consecutive deliveries. Based on these particular features, a heuristic that efficiently identifies solutions based on initial truck tours and corresponding joint robot operations is presented. This solution approach leverages a special version of the "Weighted Interval Scheduling Problem," which allows for a very efficient Dynamic Programming solution. The developed solution approach is adopted to analyze the influence on efficiency of different features concerning the robot's design and operation, and the surrounding environment. The results show that robot-assisted last-mile delivery systems are quite efficient if robots are employed in heavily congested areas and appropriately retrofitted to accommodate several compartments in the robot's storage.