Research On Multi-Vehicle Routing Problem Of Parts Milk-Run With Unload Queuing Time

Inbound logistics costs,as the source of vehicle logistics,account for a large proportion in vehicle logistics costs,and also greatly impact on the costs and quality of the subsequent vehicle production process.At the same times,by faster vehicle upgrading,more parts assortment,and the characteristics of small batch and multiple frequency of vehicle parts inbound logistics,the application advantages of the milk-run mode are prominent.It is very urgent to research on the milk-run path of vehicle parts inbound logistics.The characteristics of milk-run mode of vehicle parts inbound logistics and the research status and development trend of vehicle routing problem(VRP)are analyzed.Considering diversity of vehicle models and unload queuing time of vehicles returned to the logistics center after pickup,a multi-vehicle routing optimization model for milk-run with unload queuing time is established,its objective function is to minimize the sum of vehicle startup cost,vehicle transportation cost,penalty cost for violating the time window and vehicle unload queuing cost.Comparing various algorithms of VRP,the improved whale optimization algorithm is selected to solve the model.introduce crossover operation of genetic algorithm(GA)for discrete VRP to update Whale’s position.Three local search operators such as exchange operator,reverse operator and insert operator are introduced.The mixed neighborhood operator makes the neighborhood search space larger and more directivity.Then,the idea of simulated annealing is introduced,the bad solution with a certain probability is accepted,and the balance between the global search ability and the local search ability of the algorithm is achieved.Finally,taking one day’s order data of SQ automobile company limited company as an example,the designed improved whale algorithm is programmed by Matlab to solve the milkrun route planning scheme with 20 suppliers and 3 vehicle types.The results show that:comparing with the traditional supplier direct delivery mode,the total transportation cost is saved by 72.03%,this proves the feasibility and superiority of the milk-run mode.When the unload queuing time cost is added into the total objective of milk-run mode,the total cost is decreased by 2.52%.It is proved that the proposed model with vehicle’s unload queuing time not only can obtain a better vehicle route planning scheme,but also significantly reduce vehicle’s unload queuing cost without significantly increasing enterprise’s operation cost,and greater corporation management benefits are obtained.