A Multi-Objective Approach for the Integrated Planning of Drone and Robot Assisted Truck Operations in Last-Mile Delivery

Supply chains are experiencing a major transition driven by changing customer expectations, environmen- tal concerns, and technological development. Considering the surge in e-commerce since the pandemic, the path forward for affordable, responsive supply chains is autonomous last-mile delivery. Drone and robot technologies complement the last-mile delivery’s operational requirements and hence should be in- corporated to assist truck deliveries. This study develops a bi-objective optimization framework for the integrated planning of Drone-And-Robot-assisted Truck (DART) delivery operations to minimize total delivery cost and maximize customer satisfaction considering a soft time window. Three models, includ- ing DART, drone-, and robot-assisted trucks are compared considering different operational situations. The results show that the DART delivery mode outperforms with an increase in the number of demand points. DART is particularly preferred when there is a moderate combination of high-density and distant demand points in last-mile delivery. Numerical experiments confirmed that the robot-assisted delivery model brings about cost-effectiveness in heavily populated areas. On the other hand, the drone-assisted truck model stands out in situations where there is a small number of demand points with high dispersity.