Research On The Collaborative Delivery Routing Problem Of Trucks And Drones In The Context Of Emergency Logistic

Natural disasters will not only cause damage to resources,the economy,and human safety but also produce secondary problems such as medical and health problems,which pose a great threat to the safety of life and property of the people.Therefore,the study of emergency logistics is urgent.Emergency logistics is the key link to connect the outside world and the disaster site,and the last-mile delivery to ensure timely relief materials to the victims is the most important.The traditional distribution mode of emergency supplies is usually single-truck distribution.However,the complex road conditions after the disaster will seriously affect the speed of truck distribution and the smooth implementation of rescue work.To improve the efficiency of material distribution and reduce the impact of disasters,this paper studies the material distribution problem under the joint distribution mode of trucks and UAVs under the condition of road damage.The main research contents are as follows.First of all,this paper establishes the mathematical model of truck-UAV joint distribution under the background of emergency logistics.Based on the background of emergency logistics,the objective of the model is to minimize the total distribution time and the number of vehicles(drones)used.In addition,according to the cooperative flight of truck and UAV in reality,a mathematical model is established considering the flexible landing mode of UAV,the path constraint of truck and UAV,the endurance constraint of UAV,and the time constraint.Then,aiming at the mathematical model,a two-step algorithm based on the Floyd algorithm and genetic algorithm is designed.The first step is the logistics network conversion based on the Floyd algorithm,that is,the incomplete map of the road network under the condition of road damage is changed into a complete map by using the Floyd algorithm,and the distance between impassable two points is replaced and the sequence is updated.The purpose of this operation is to reduce the difficulty of solving the problem and prepare for the genetic algorithm solution in the second step;In the second step,a genetic algorithm with a local search strategy is used to solve the problem.The local search algorithm is designed based on the characteristics of the UAV’s fast flight speed and the synchronization requirements of truck-UAV joint distribution mode to make up for the poor local search ability of the genetic algorithm.The elitist strategy is introduced to modify the genetic algorithm,the dynamic crossover and mutation probability are designed,and the crossover operator is designed for the joint distribution mode.The "islands" processing strategy is designed for the situation of "islands" existing.Finally,the test set of the example like Solomon’s test set is used in the experiment.The experimental results show that the truck-UAV joint distribution method has the advantage in delivery time,and the time is reduced by about 30% compared with the single truck distribution;It is also proved that the flexible UAV landing mode can slightly reduce the delivery time,and the designed algorithm can obtain better solutions than the general genetic algorithm.