Robust Optimization Method For Express Vehicle Routing Under Demand Uncertainty And Support System Design

Due to the large number of customers,scattered locations and large differences in service time and other demands of the express terminal delivery service,there have been problems such as high delivery cost and untimely delivery.Although the application of technologies and management methods such as smart cabinets and other people's collections has improved the success rate of one delivery.The courier company still has to maintain a certain capacity redundancy in order to respond to the dynamic changes of customer demand in a timely manner such as new pickup or change delivery time,which leads to high distribution costs.Therefore,express delivery companies are facing the dilemma of increasing express delivery volume,but the profit is declining due to the rising distribution costs.With the increase of the number of online shoppers and express delivery,the number of new returns,exchanges,pickup requests and changes in delivery information is also increasing.The increase of uncertain demand makes the implementation of the original distribution scheme difficult or even impossible,and increases the cost of distribution.Therefore,it is of great significance to carry out robust optimization on the express vehicle path and improve the executability of the delivery scheme under the uncertain demand for reducing the delivery cost at the end of the express delivery and improving the delivery efficiency.In this paper,robust optimization of express vehicle routing under uncertain demand is studied.In view of the new and changing dynamic customer demand,the robust optimization and delivery cost minimization of express delivery are realized under the condition of maximizing the utilization of freight capacity and rationalizing the insertion rate of new demand.At the same time,the express terminal distribution support system is designed and implemented.The main study work is as follows:Firstly,for the problem of uncertain customer demand may lead to the execution of original distribution scheme difficult or even impossible and deliveryman cannot deal with various uncertain dynamic customer needs scientifically and reasonably in the actual distribution process,the robust optimization model of express delivery vehicle routing is constructed with minimum distribution cost and penalty cost.In this model,the discrete robust optimization method proposed by Bertsimas is used to establish the uncertain travel time set.Transforming the model into a corresponding form of the robust optimization model under the uncertainty set makes it easy to solve the model.Then,a hyperheuristic algorithm based on genetic algorithm is designed to solve the robust peer-to-peer model.In this algorithm,genetic algorithm is used as the upper search strategy.The insertion method and local optimization method are used as the underlying heuristic strategies.The initial path scheme is obtained through the underlying strategy framework,and then the robust solution is obtained by selecting,crossing and mutating the underlying policy framework and the number of customers with the high-level strategy.In addition,the corresponding dynamic customer processing strategy is designed according to the various dynamic customer demands in the delivery process,which maintains the feasibility and optimality of the planned vehicle path scheme in the worst case of the uncertain set.Finally,the express terminal delivery support system is designed and implemented based on Android system and Baidu Map.The robust optimization model and algorithm are applied to the system.The courier can use the system to manage dynamic customer needs,route planning and route navigation,which provides scientific and reasonable support for courier.The system is tested with the relevant data of the terminal distribution station of an express company in Chongqing.Through comparison and analysis,the effectiveness of the robust optimization method and support system proposed in this paper is verified.