| The manufacturing industry is the mainstay of the national economy and its lifeblood.The assembly line is an important production method in the manufacturing industry and an essential condition for enterprises to realize mass production.Two-sided assembly line is one of the layout methods of assembly lines,mostly used in the production process of large mechanical equipment,with the advantages of shortening the length of the assembly line,saving production space and improving equipment utilization.In assembly line production,product quality and output are affected by the quality and efficiency of the assembly,and a well-balanced assembly line can effectively improve the quality and efficiency of product assembly.Therefore,finding a feasible and effective assembly line balancing method is particularly important for related enterprises.Currently,research on two-sided assembly line balancing problem is mainly focused on the two-sided assembly line balancing problem with single product production and only considering the basic constraints.The methods used to solve the problem are relatively complex,resulting in the separation of theoretical research and practical production.In this study,the possible constraints on the two-sided assembly line are analyzed,and in addition to the basic constraints,several additional constraints are identified that have a significant impact on the assembly line balancing,including position constraint,synchronization constraint and zone constraint.To better apply theoretical research to production practice,this study conducts an in-depth investigation on the type Ⅰ two-sided assembly line balancing problem that integrates basic constraints and additional constraints,and for the first time applies the fruit fly algorithm with fewer parameters,simple solution process and strong global search capability to the solution of this problem.By briefly analyzing the type Ⅰ single-model two-sided assembly line balancing problem with multiple constrains,this study proposes reasonable model assumptions and constraint conditions.The mathematical model of the problem is constructed with minimizing workstations and paired workstations,as well as minimizing balance index for primary and secondary objectives respectively,and the solution of the problem is studied.A hybrid fruit fly algorithm for solving the type Ⅰ single-model two-sided assembly line balancing problem with multiple constrains is proposed,which combines the basic fruit fly algorithm with the variable neighborhood search algorithm.According to the characteristics of the solved problem,the generation process of fruit fly individuals in the algorithm is designed in detail.In this study,the generation process of fruit fly individuals is divided into three stages:encoding,decoding and assignment,and different encoding methods are used in different optimization stages.The detailed steps of the decoding process are given,and the task assignment method for all constraints is proposed.The principles that need to be satisfied by task assignment under different cases are given.In the optimization search stage,various operators are designed to construct neighborhoods for local search,and the minimization of weighted idle time as an adaptation function is proposed to assist in the optimization search.The feasibility of the proposed fruit fly individual generation method,the effectiveness of the proposed neighborhood construction method and the superiority of the proposed algorithm are verified by designing and implementing several comparison experiments.With the diversification of consumer demand,single-product production is no longer sufficient to meet consumption needs.Therefore,enterprises have to introduce mixed-model assembly line to improve their own competitiveness.In this study,through a brief analysis of the mixed-model assembly line balancing problem,a non-weighted treatment of the operating time of each operation for each product during mixed-model production is determined.Based on the characteristics of mixed-model production,the mathematical model of the type Ⅰ mixed-model two-sided assembly line balancing problem with multiple constrains is constructed based on the mathematical model of the type I single-model two-sided assembly line balancing problem with multiple constrains with additional relevant assumptions and modified objective function and constraints;and based on this,the hybrid fruit fly algorithm for solving the type Ⅰ single-model two-sided assembly line balancing problem with multiple constrains is improved and the hybrid fruit fly algorithm for solving the type Ⅰ mixed-model two-sided assembly line balancing problem with multiple constrains is proposed.The task assignment method in the process of fruit fly individual generation is redesigned,and the principle of task assignment adjustment is appropriately modified;the fitness function is modified to minimize the double weighted idle time to assist in the optimization search.The proposed algorithm is applied to solve the actual engineering case and a simulation comparison experiment is designed to construct the simulation model considering equipment failure and the uncertainty of workers’ operation time.The effectiveness,reliability and superiority of the proposed algorithm are verified by analyzing the operation of the model.This study integrates a variety of additional constraints in actual production and mixed-model production situations,and proposes an effective solution algorithm that is simple to apply and accurate enough to meet the actual production requirements,which enriches the research system of bilateral assembly line balancing problem and helps enterprises to plan and design assembly lines more scientifically and rationally,thus improving the efficiency of enterprises,and has certain significance for actual production. |
