Study On Chain Saw Operator's Attention In Logging Based On Human Factors Engineering

In order to protect the chain saw operator and increase operational efficiency, forestry researchers have carried out a lot of tests based on human factors engineering principles in recent years. They have proposed some practical guidance and theoretical basis for objective research. However, at present stage of chain saw logging operation research, there are a lot of summary about cutting methods and collaboration, while the quantitative research of chain saw operator's load condition, posture control and operational efficiency is relatively less. In general, the researchers lack awareness of reducing operator's body harm according to scientific theory. Attention is the most important psychological and physiological quality reflected by chain saw operator, which has direct relations with operation safety and operating efficiency, therefore, the attention research of chain saw operator based on human factors engineering has great significance.The logging operations with heavy labor intensity may lead to a series of mental and operational injury, such as decreasing wake level, reducing cognitive function and so on. The operator's attention differs mostly, including lower operational performance and slower response capacity, which increases the probability of security incidents occurrence. Based on the study summary of chain saw logging operations at home and abroad, related tests were designed combined with experimental psychology, and the chain saw operator's attention was studied in this paper according to human factors engineering. Firstly set three conditions including normal concentration of attention, distracted attention before operations and distracted attention in operations, then the significance effect of attention on operator's safety and performance is discussed respectively. Determine the focused attention grade and apply LSD test to comparatively analyze the results. Then the cutting tilt difference and cycle time are respectively measured under the slope of 0°,15°,30°, so as to determine the impact of physical and psychological load on one's attention. Finally the method of helping operators know their own attention solution is proposed, as well as several measures of preventing distraction.Based on the results of this study, further test was carried out in forestry area with more desirable homogenization. Through comparing differences before and after operations, the operation load model of four-hour continuous logging was established to induce the attention fatigue of 15 chain saw operators. Firstly the visual analogue scale table and the subjective fatigue symptom questionnaire were introduced before and after operation respectively for subjective assessment, which was compared with statistical methods. Then the operators were asked to participate in objective behavior test under the same condition, and the different states of attention characteristics before and after operation were obtained from test results. Finally, according to the subjective and objective evaluation results, the attention fatigue of chain saw operators was verified, and objective results were obtained.The main results and conclusions of this study are as follows:(1) When operators'attention was focused, they had better control ability of themselves in the implementation, and brain's cognitive ability was good. On the contrast, when their attention was distracted, their control ability decreased greatly and the distraction in operation had more significant effect than that before operation. The focused attention grade table was established, which could give operators intuitive evaluation criteria and certain reference in measuring their own attention level.(2) Under different slope conditions, the physical and psychological load has significant impact on operator's attention. It is more difficult for operators in steeper slope, and greatly affected by attention fatigue. When operating in high slope, the operator's ability of monitoring conflicted information declined, and the attention fatigue reduced their distribution capacity of attention, therefore the process of deep treating conflicted information was affected and cognitive attention declined.(3) Under the operating load condition set in tests, the chain saw operators had no subjective fatigue feeling, but according to the behavioral tests and operating performance results, their attention ability in emergency treatment, paying attention to operations and information analysis had shown damages in different degrees. This indicates that subjective assessment results could not always reflect their own clear understanding, which had certain limitations. Under some special critical conditions, the chain saw operators could not evaluate their own attention fatigue state objectively and accurately, and the decrease of attention level not only affected the efficiency of logging operations, but also led to security implications.In short, attention has an important impact on chain saw operations. In order to guarantee the operator's security and improve operational efficiency, the attention study needs more efforts of researchers, and the operator also needs continuous learning in cultivating attention. The study in this area still has a long way to go.