Research On Ergonomics Application In Automobile Assembly Workers Muscle Fatigue

With the progressing of society and the development of science and technology,the quality of people's lives is improved continually,and the occupational diseases of work have been increasingly attracting emphasis.Operators will have muscle fatigue caused easily by high work load and poor posture,which lead to occupational disease during automobile assembly.These diseases can get in the way of production enterprises,and lead to low production efficiency.Therefore,the enterprises need to take some measures to reduce the operator's fatigue and prevent occupation diseases.The exhaust system installation station,which had high work load and more poor posture,was selected as the research object in this paper.The ergonomics theory and assessment tools were used to assess the station,took the improvement measures to reduce operator?s fatigue and musculoskeletal disorders,provide improvement ideas and methods for other stations in the process of automobile assembly.This paper researched the exhaust system installation station firstly to get each procedure and its time,then drew flow process chart,and found that there were too many move times of operator and serious round trip operation,which caused a lot of waste.The flow process chart was optimized by the "5W1H","ECRS" principles to shorten the working hours effectively and improve the efficiency of the operator.In order to evaluate poor operating posture and the situation of muscle fatigue of operator in the exhaust system installation process,operator's posture should be evaluated by the ergonomics evaluation standard of posture and load in the exhaust system installation process.Then the station model could be designed and simulated by ergonomics simulation software DELMIA.In the exhaust system installation process,the operator's poor postures can be provided by two evaluation results which combined the evaluation of RULA,NIOSH and biomechanical angle action analysis with the second evaluation for the process of former evaluation.Finally,in order to verify the reliability of the simulation,and reflect the operator muscle fatigue from several aspects,the sEMG experiment should be carried.The muscle fatigues of operator were got from the time domain,frequency domain and joint spectrum amplitude analysis in the exhaust system installation process.The result showed that the muscle activities of operator were reduced continually when 1.5 hours per work,which means the operator needed rest.The working contribution rate of brachioradialis,biceps brachii,deltoideus,and trapezius were predominant and reduced in turn.According to the results of DELMIA simulation and sEMG experiment,the facilities in the exhaust system installation station had been improved and designed in two aspects.Firstly,the material shelves of the front exhaust system were redesigned.According to face height suitable for standing posture,hand work scope,relationship between hands operated manipulator and human body sizes,visual features,and the best visual field in the vertical plane,the material frame the height and width of the control button size and color,and control the height of the plate could be determined.Secondly,according to the principles of motion economy,the sling was added,which can make operator brisk action during delivery back exhaust system.And the improved scheme could be given by the improvement of flow process chart,the improvement of the material shelves and the growing in number of the sling gave.In order to verify the rationality and validity of above improved points,the same DELMIA simulation and sEMG experiment with the original scheme should be carried.The comparison analysis between the results of simulation and experiment and that of the original scheme showed that operator's poor postures had improved effectively,and the operator's work was in a normal state within 2 hours,which did not cause muscle damage.