COMPUTER COMMUNICATIONS, vol.179, pp.35-49, 2021 (SCI-Expanded)
The traveling salesman problem is one of the most studied problems in combinatorial optimization. An
emerging variant of this problem, which is referred to as the traveling salesman problem with drone, focuses
on deploying a drone and a delivery truck for last-mile delivery. This problem coordinates the truck and
drone deliveries in both time and location because the drone requires the truck to refresh its battery and load
the next customer’s package on the drone. Previous studies assume that the drone battery is swapped with
a new/fully recharged battery at the end of each drone flight. In contrast, this study investigates a flexible
recharging policy. For this purpose, we develop a new mixed integer linear programming formulation into
which remaining battery level consideration is incorporated. A computational study is provided to compare
the recharging policy with the battery swapping policy in terms of delivery time. Due to the complexity of
the problem, a heuristic approach is proposed to solve medium-sized instances.