A literature review of drone-truck routing problems: challenges and future research directions

In recent years, new routing problems with high complexity have emerged in parallel with the diversification of collaborative operational activities carried out by drones with ground vehicles. There are two main factors that affect the complexity level of these new generation routing problems. The first factor is the synchronization of vehicles with very different characteristics to optimally perform operational tasks. The second factor is that unlike traditional routing problems such as transportation and logistics, healthcare, military and emergency operations, new generation problems have more complex objective and constraint spaces. In traditional routing problems, customers are represented by fixed points in a two-dimensional search space. In contrast, in agricultural spraying, which is a new generation routing problem, the areas to be sprayed are represented by irregular areas. The objective and constraint functions in next generation routing problems are specified as area-based rather than point-based because of this difference. This increases the geometric complexity of the objective and constraint spaces in next generation routing problems. This paper analyzes 108 publications on traditional and next generation routing problems published between 2015 and 2024. A comprehensive review of routing problems based on drone-truck cooperation is provided according to their application areas, mathematical models, and solution methods. Unlike the review studies in the literature, new routing problems in the field of agriculture are also included in this research and the mathematical complexity of these problems is presented for the first time. Current trends for future research on drone-truck based problems are discussed.