| The flexible assembly line has gradually replaced the traditional assembly line because it can assemble many kinds and small batch products at the same time,and was widely used in modern discrete manufacturing enterprises.Due to the increase of product types,not only will increase the complexity of the assembly line,but also increase the difficulty of the operator’s information acceptance and processing,which puts forward higher requirements for the operator’s labor load,and affects the assembly balance.In the balance problem of flexible assembly line,the operator is the main component of the assembly line.If the unbalanced labor load of the operator is ignored,the efficiency and product quality of the assembly line will be greatly affected,and even the physical and mental health of the operator will be damaged.Therefore,it is important to consider the labor load in the balance problem of flexible assembly line.This paper takes main work contents are as follows:(1)Experimental design of labor load data collection.This paper investigated the problems of H3 assembly line of enterprise A deeply,design the optimization scheme of the assembly line in view of the unreasonable distribution of operators and processes,unbalanced labor load and problems that the balance rate needs to be improved,and design and complete the labor load data collection experiment at the same time.EEG signal,heart rate and subjective fatigue score of 15 subjects were collected before,during and after work,and labor load data to be analyzed were selected.(2)Study on labor load evaluation model based on EEG signals and energy consumption.This paper for the acquisition of EEG signals,adopt the method of preprocessing and wavelet packet transform to extract the δ wave,θ wave,α wave and β wave rhythms signal,power spectral density for EEG features,analysis of 15 subjects EEG characteristics in the three stages of change trend,determine the characterization of mental load index,and the fitting method is adopted to characterize relationship analysis index and operation time,A mental load evaluation model based on EEG signals is constructed.At the same time,based on the physical energy consumption,the relationship between relative heart rate and maximum acceptable operating time is analyzed,and the threshold value of physical energy consumption is determined,and the physical load evaluation model based on energy consumption is established.(3)Research on Balance model establishment and algorithm design of flexible assembly line considering labor load.The mental load evaluation model and physical load evaluation model were introduced into the second type of assembly line balance model,and the flexible assembly line balance model considering labor load was established with the minimum beat,minimum labor load balance index and minimum smoothness index as the optimization objectives.Based on the characteristics of the multi-objective balanced model,a traditional second-generation Non-dominated Sorting Genetic Algorithm Ⅱ(NSGA-Ⅱ)was selected and improved in terms of population selection,crossover and mutation.Meanwhile,standard detection function is used to improve the performance test of NSGA-Ⅱ algorithm.(4)Case study.This paper combined with the actual data of H3 assembly line,the traditional NSGA-Ⅱ algorithm and the improved NSGA-Ⅱ algorithm are used to solve the multi-objective equilibrium model respectively.The results show that the improved NSGA-Ⅱalgorithm can solve the H3 assembly line problem better.Compared with before optimization,it is found that after optimization,the labor load of each station is more balanced,and the balance rate is increased by 8.13%. |
PDF Full Text Request