A Hybrid NSGA2 For Facility Layout Problem Of Mixed Model Assembly Line

In the manufacturing industry with global competitive increasingly,the mixed model assembly line was applied widely and had remarkable performance in the trend that was Flexible Manufacture and Agile Manufacture.Due to the phenomenon that most of researchers focused on the sequencing of the mixed model assembly line and few specific study about the facility layout problem of that was developed in the world,meanwhile the facility layout played a decisive role in the production process as one of the important factors affecting the efficiency of production system in the mixed model assembly line,the multi objective optimization mathematical model of the mixed model assembly line was established and the hybrid NSGA2 was proposed for solving the problem in the paper.In theoretical study of multi objective optimization problems based on hybrid NSGA2,GT-NSGA2 was proposed for solving the problem of infeasible solution that wasn't calculated by the objection function.For the weak capability of NSGA2 to local search,NSGA2-TS was designed to combine the advantage of NSGA2 and TS in order to obtain the global optimum.The selection criteria was proposed for improving the satisfaction degree of the final target solution set and solving the problem that some target candidate solutions was missed in algorithm.In the process of practical application to solve the facility layout problem of mixed model assembly line,the mathematical model was built for optimizing logistics and production efficiency and applied for the booster assembly line L1 as the case,the result showed the validity of gene test when adopting GT-NSGA2 optimized the mathematical model.And the ability to jump out of the local optimum and the faster convergence speed of NSGA2-TS were verified by adopting NSGA2-TS optimized the model again.Meanwhile the result of this case showed the reliability of the mathematical model.For solving the extensive problem of more object and more facility about the mixed model assembly line,the mathematical model aiming at minimizing logistics costs,maximizing production balance efficiency and maximizing production capacity was established,the case including L1 and L2 where more station was equipped were studied by using the NSGA2 with the selection criteria,the result proved the expansibility of the mathematical model to solve extensive problem of the mixed model assembly line,and the selection criteria can prevent loss of the target candidate solution and simplify the process of candidate selection during the operation of NSGA2-TS.