Research On Human Factors And Flexibility Of Assembly Line

The uncertainty environment of manufacturing enterprises is becoming more and more complex with the increasing competition in the market.As a result,flexibility is playing more important role in the production and manufacturing system as an ability to adapt and respond to quickly environmental fluctuations.In the past,the consideration of flexibility mainly focused on the manufacturing process.However human is the most active factor of assembly line production especially in the line with manual work.Therefore,it is necessary to fully consider human factors and use human mobility to make the assembly line more flexible.On the other hand privious Assembly line improvements are mainly on based on hardware,or the research of resource allocation scheduling algorithm was emphasized,but the development of technology equipment was bound to encounter the bottleneck.As workers is an important part of assembly production.Differences in skills,fatigue,and the choice of working patterns can interfere with the worker’s operation,and thus affecting the production efficiency and flexibility of assembly line.The research on human factors,which the existing hardware resources do not change,can not only improve the production efficiency,reduce the failure rate of the machine and personnel,but also reflect the concept of human-oriented production of lean production.It is also possible to realize the equalization of labor load between workers through multi-skilled walking and mutual assistance,so that the flexible assembly line can be fully developed.The existing flexible research in assembly line focuses on the selection of layout and on optimization balance and sequencing of mixed-model Assembly.There are two aspects being ignored.One is that there are fewer human factors to be considered in the process of modeling and balancing.Although the balance results are optimized,they are not practical and can’t be applied in production.The other is the insufficient research on dynamic operation strategy and resource flow flexibility.To solve above problems,according to the production organization operation process,flexible study can be divided into three aspects.The basic flexibility is the premise and foundation of the flexible assembly line,the workers’ state is considered to establish the mathematical model in the balance.Dynamic flexibility is the way to improve production efficiency and operation flexibility by using the production organization of walking workers after the assembly line is balanced.Potential flexibility,from the perspective of structure,through the study of workers and material flow model,research the potential capacity of further load balance and fault response.the specific contents are as follows:First of all,Fatigue behavior was seledted as element among lots of human factors.the research object,in view of the work intensity and work time caused by physical fatigue and mental fatigue caused by the tedious job itself,fatigue model and mathematical model of assembly line balance were set up.Choose average relative heart rate as a measure,considerd the accumulation of fatigue and recovery process.Combining the subjective feeling of fatigue with objective data makes the model have objectivity and practical value.After the analysis of the human factors,the assembly line of a company was studied,and the heart rate data collection was conducted using the IOT data acquisition module.The average relative heart rate of each task was obtained by calculating relative heart rate according to the time interval set in the experiment,and then using average relative heart rate as judging index we studied its relation with labor intensity and fatigue.A fuzzy model of labor intensity and fatigue level was obtained,and fatigue recovery index of fatigue recovery was determined,then the fatigue-recovery model established.A mental endurance model was built based on the boredom of the job.The fatigue-recovery model and the mental endurance model used as part of the mathematical model,and the assembly line balanced according to these constraint conditions.Genetic algorithm used to solve the problem.The object is to minimize the deviation between each work station time and cycle time.The balance comparison between the constraint and unconsidered of human factors is presented.Experimental results show that the first results are more valuable although the other results are more optimized.Then,used the u-shaped layout and the advantages of walking workers,the assembly line has better flexibility.Walking walker was the premise for the establishment of a flexible structure in reality.Through simulation,we studied the relationship between worker sequencing and output,compared the production efficiency of fixed mode and chase mode,discussed the advantages and disadvantages of fixed mode and chase mode,the change in the number of workers when production changes and the application condition of fixed mode and chase mode was discussed.Finally,proposed a load balancing policy based on chain structure,studied the strategies and potency of developing a flexible structure,proposed the structure responding mechanism based on the principle of resource reconstruction.Evaluation model of system structure robustness was established.Based on the evaluation model,the robustness of different flexible structures was compared.