The Evaluation of Driver's Distraction Load Based on Fixation Behavior Characteristics

In order to evaluate the impact of various behaviors of drivers operating mobile phones on driving safety, 19 drivers were organized to wear an eye tracker to carry out indoor simulation driving test, and the fixation data of drivers during normal driving, hands-free call and voice message in two typical traffic conditions of free flow and crowded flow of urban expressway were collected respectively. The driver's visual field plane is divided and classified into six visual interest areas with the hierarchical clustering method combined with mechanical division. Using descriptive statistics and variance analysis, a set of sensitive indexes (information entropy of fixation area, fixation duration, vertical fixation deviation and coefficient of variation of pupil area) was established to measure the characteristics of fixation behavior. Finally, the entropy weight method was used to construct the weight system of four indicators and propose the concept of distraction load index, and the TOPSIS method was introduced to verify the evaluation effect of distraction load index on the degree of distraction. The results show that most drivers are in the cognitive distraction state during hands-free call operation and in the visual distraction state during voice message operation. Compared with normal driving, except that there is little impact on distraction load during hands-free call operation in the free flow scenario, other mobile phone operations have a significant impact on the drivers' fixation behavior, resulting in a general increase in distraction load index. In addition, in the crowded flow scenario, the distraction load increases sharply when performing voice message operation, and the driving risk is much higher than that of hands-free call.