Research On Fixation Characteristics Of Tower Controller Under Fatigue State

In recent years,unsafe events such as “mistake,forgetting and missing” caused by the air traffic controllers’ fatigue have become an important factor affecting the safety of air traffic control in China.A study shows that fatigue will lead to a decline in the ability of information acquisition and processing,and will seriously affect controllers’ performance.Vision is the main way for the controller to obtain information,and visual fixation is the most direct and most important way for the controller to express cognitive processing.Therefore,from the perspective of eye movement,controllers’ fixation characteristics under fatigue state are studied.And the influence of fatigue on control tasks is explored through information processing,attention resource allocation and transfer process.It’s helpful to improve the fatigue level of control and to support controllers fatigue risk assessment to provide data support.In this study,a tower control experimental platform was built based on MP150 multiple-channel polygraph,Eyeso Glasses eye tracker and tower control simulation software.20 students who major in ATC were recruited to participate in the simulated tower control experiments.Subjective fatigue data(Karolinska Sleepiness Scale data),objective fatigue data(EEG data)and eye movement data were collected during experiment.Combined with the subjective and objective fatigue data,the status of the subjects were determined and verified.The percentage of fixation time,average fixation duration,and fixation frequency were calculated according to different tower control task area.The Discrete Time Markov Chain model and Nearest Neighbor algorithm were utilized to evaluate fixation one-step transition probability in different area and the whole Nearest Neighbor Index.The difference of the indexes between normal and fatigue states was compared.The effects of fatigue on control tasks were analyzed based on the characteristics of eye movement and operational performance.The conclusion of this study was as follows:1.Compared with the normal state,the total fixation time of subjects in the fatigue state increased.There was a significant increase in the percentage of fixation time of the airspace surveillance area A,the field surveillance area L,the flight progress bar area S and the command bar area C.2.Compared with the normal state,there was no significant difference in average fixation time of the airspace surveillance area A,the field surveillance area L,the flight progress bar area S and the command bar area C.3.Compared with the normal state,There was a significant increase in the percentage of fixation time of the airspace surveillance area A,the field surveillance area L,the flight progress bar area S and the command bar area C under fatigue state.4.Compared with the normal state,Subjects’ fixation one-step transition probability in the information input end increased significantly after fatigue,Subjects’ fixation one-step transition probability from an information input end to another information input end reduced significantly after fatigue.Subjects’ fixation one-step transition probability from an information input end to another information output end had changed but not significant after fatigue.5.Compared with the normal state,Subjects’ NNI index decreased significantly after fatigue.The fixations’ distribution was mainly clumped.The overall visual range narrowed.