Research On The Vehicle Routing Problem With Three-Dimensional Loading Constraints And Soft Time Windows

Vehicle Routing Problem is a core problem of logistics operation system.It is used to optimize the vehicle distribution path,making the cost of logistics distribution minimum.Three-Dimensional Container Loading Problem is to find a reasonable solution to put all the little boxes into a container,required to satisfy some certain constraints and reach the highest utilization rate of the container.It is used in logistics transportation widely.In the logistics distribution system,Three-Dimensional Container Loading Problem effects on Vehicle Routing Problem,the former failure will lead to the latter be invalid.Therefore,they must be intergrated optimization,namely the Vehicle Routing Problem with Three-Dimensional Loading Constraints.The ntergrated optimization will help to improve the vehicle charging ratio and reduce the total shipping cost.And it is a hotspot issue of the integration of logistics distribution system.At the same time the real customers pursuit the timeliness of distribution service and ask the delivery time,it makes enterprise in a market time competition environment.So the reseach on Vehicle Routing Problem with Three-Dimensional Loading Constraints and Soft Time Windows not only has theoretical value,but also has a practical significance.The research object of this paper is a distribution network included a home-delivery center and multiple customers.Integrated optimization of Three-Dimensional Container Loading Problem and Vehicle Routing Problem to build the optimizing model of the Vehicle Routing Problem with Three-Dimensional Loading Constraints and Soft Time Windows,considering the customers' Soft Time Windows constraints,used minimizing the total distribution cost(including the vehicle fixed expense,the vehicle running costs,and the penalty cost if it can't satisfy the time obligation)as the goal.The model can definite the vehicles travel plan and objects packing proposal.Three-Dimensional Container Loading Problem and Vehicle Routing Problem belongs to NP problem.Therefor the Vehicle Routing Problem with Three-Dimensional Packing Constraint and Soft Time Windows is a NP problem,too.This paper aims at the complexity of the model designs a hybrid algorithm to solve the model,based on the Greedy Algorithm,Particle Swarm Optimization algorithm,Local Search algorithm and Packing Heuristic algorithm.The hybrid algorithm is divided into two layers.Firstly,the outer layer adopts Particle Swarm Optimization algorithm based on Greedy Algorithm to optimize the Vehicle Routing Problem to get a concrete path plan.It will call the inner algorithm and optimize the vehicle path plan according to the inner return value in the fitness function.Secondly,the inside layer uses Local Search algorithm nested Packing Heuristic algorithm to solve Three-Dimensional Container Loading Problem,judging its feasibility.If it is viable,the specific packing solutions should be given.Finally,through the concrete example simulation test,numerical example results show that the optimization model and algorithm are effective and practical.