Multi Objective Vehicle Scheduling For A Company’s Assembly Line Considering Simultaneous Pick Up And Delivery Based On NASGA-Ⅱ Algorithm

At present,the market demand for diversified products is constantly increasing,and the flexible production line,as a prominent feature of modern industrial manufacturing enterprises,puts forward higher requirements for the distribution of raw materials and semi-finished products.In the process of material distribution,distribution vehicles are used as the main means of transportation to meet the service needs of the production line.Their main characteristics are: single vehicle type,speed limit in the workshop,many service points,time window,etc.The material distribution and transportation system in the enterprise mainly includes two main parts: unloading finished products,returning materials and loading spare parts in warehouse,unloading parts,loading finished products and returning materials at each station of production line.This thesis takes company A as the research subject,conforms to the direction of logistics system optimization of company A.The purpose is to meet the service requirements of material distribution with the minimum cost,and effectively improve the punctuality of material distribution,so as to improve the profit margin of the enterprise.The research object of this thesis is company A,a bearing equipment manufacturing enterprise,whose production mode is order oriented flexible production.Through the communication and in-depth experience with the management personnel of the logistics department,we mainly found the following problems:(1)A lot of resources are wasted in the material preparation transit area;(2)The material distribution does not meet the requirements of just in time;(3)The return of materials and the recovery of finished products are not timely;(4)Low loading rate of material distribution vehicles.Considering that each station has a variety of service time windows,this thesis improves the traditional distribution vehicle service mode.The distribution vehicle is not a fixed station service,and all stations in the assembly line can share all the distribution vehicles.Ensure that any distribution vehicle can be put into the new distribution route as soon as possible when it is idle.In view of the above situation,this thesis constructs a multi-objective vehicle scheduling model considering simultaneous pick-up and delivery.One goal of the model is to reduce the holding cost of logistics transportation vehicles in the factory,and the other goal is to minimize the total operating cost.The penalty coefficient for violating the time window is quantified in combination with the actual situation of the factory,which is convenient for managers to make decisions.Then use MATLAB software to realize the solution design of NSGA-Ⅱ algorithm,and select the case data of a certain period to optimize the solution,analyze and screen the optimal Pareto solution set,and get the optimal number of vehicles.By comparing the data before and after optimization,it is found that it can not only reduce the direct expenses and total operating costs,but also effectively improve the material delivery on time rate and vehicle loading rate.