Evaluation And Experimental Study On Human Fatigue During Hedge Pruning Based On Dynamic Bayesian Network

Hedge pruning is an open-air dynamic process,which is affected by time,weather and other uncertain factors.In the process of hedge pruning,workers always have to work in a certain posture with heavy load,and are continuously affected by the load of working posture and equipment weight,vibration,noise and so on.These complex and uncertain conditions will make workers fatigue,and even lead to occupational musculoskeletal disorders,leading to the occurrence of occupational accidents,but there is still a lack of attention in the field of human fatigue in hedge pruning at home and abroad.Therefore,it is necessary to evaluate human fatigue in hedge pruning,which is of great significance to improve the productivity of garden workers,reduce the probability of accidents,and ensure the safety and health of garden workers.This paper took garden workers as the research object,using dynamic Bayesian network and physiological experimental measurement tools to study the multiple factors of human fatigue in hedge pruning,determine the quantitative effects of working posture factor and working duration factor on human fatigue,and put forward a protection scheme for human fatigue in hedge pruning.The main points are as follows:The characteristics of hedge pruning were analyzed by observation,video recording and questionnaire,the formation mechanism and mechanism of human fatigue in hedge pruning were discussed,the main influencing factors of human fatigue were analyzed and summarized,and a multi-index evaluation system was constructed;The weight indexes were calculated by entropy method and analytic hierarchy process,and the quantitative model of human fatigue is established.Aiming at the problems of complexity and uncertainty of human fatigue in hedge pruning,based on the calculation result of a human fatigue quantitative model and expert experience,high-weight influencing factors are appointed as Bayesian network nodes,a static Bayesian network structure was established,on the basis,the adjacent time slices were modeled,and a human fatigue evaluation model of hedge pruning with transient fatigue was established.The model was used to evaluate the human fatigue data in hedge pruning,and the risk probability of labour fatigue caused by work duration and posture was analyzed in depth.Aiming at the key factors affecting human fatigue in hedge pruning,a multi-level synchronous experiment scheme including motion capture test,EMG test and EEG test was proposed.The kinematics data of subjects in different working conditions were collected by motion capture test,and the simplified force model of human body was established using the biomechanical method.The surface electromyography technique was used to record the signals of trunk muscles,and the activities and functions of different muscles in different working postures and the changes of muscle load in different periods were analyzed.Electroencephalogram signals were recorded,and the changing trends of four rhythm waves and the ratio R of α wave and β wave were analyzed during continuous operation.The effects of working duration and posture on mental fatigue were discussed.The experimental results are used to compare with the reasoning result of the fatigue evaluation model.According to the characteristics of human fatigue in hedge pruning and the requirements and principles of fatigue protection design,a human fatigue protection scheme was proposed.A three-dimensional digital model was established.Using the Lower Back Analysis,RULA and OWAS modules of Jack software,the human factors of different working postures after the digital man wearing the protection design scheme were analyzed respectively.In summary,this study has a high reference value for human fatigue evaluation of landscaping,agricultural and forestry labor.It provides a theoretical basis for the design of hedge pruning fatigue protection product,the improvement of awkward working posture,the reduction of working fatigue,the reduction of the probability of working accidents,the prevention of occupational musculoskeletal disorders,and the protection of the safety and health of gardeners,and provides a new idea and solution for the measurement and evaluation of human fatigue in many fields.