| At present,aging of population has become a more serious social problem in China,it affects the development of our society,economy and other aspects.At the same time,with the aggravation of the aging of the population,drivers in China will enter the ‘aging driving group’ also.However,older drivers physiology,memory and other characteristics may declineded with aging,it could cause the drivers’ decay in the accuracy of information collection,timeliness of thinking and decision-making,effectiveness of operational behavior,and increase the probability of driving errors,which lead to an increased risk of traffic accidents.Therefore,the study of the psychophysiology,risk perception and operation behaviors of elderly drivers in the risk driving environment will be helpful to evaluate the driving suitability of elderly drivers and provide a theoretical basis for the safe driving and improvement of the traffic environment for elderly drivers.Based on the analysis of the visual attention,psychophysiology,risk perception,operation behavior characteristics that affect the safe driving of elderly drivers,aimed to deeply explore older drivers behavior characteristics,the research idea of ‘Basic Theory Analysis-Experimental Design-Virtual Modeling-Experimental Testing-Correlation Analysis-Model Construction-Safety evaluation’ was determined.Cognitive ability testing technology,virtual reality technology,graph theory and technical methods such as gray fuzzy theory were applied in this paper,through the platform and driving simulation experiment,all kinds of behavior characteristics datum of elderly drivers in different risk situations were obtained,the test data was comprehensively analyzed,the change rules of visual,operation,risk perception and psychophysiology characteristics were studied,the driver’s behavior safety evaluation model was established and the safety of elderly drivers’ behavior was evaluated.In order to test the driver’s useful field of visual(UFOV)and behavior characteristic data in risk situation,the UFOV testing software was developed,and a comprehensive experimental system of driver behavior was built,static and dynamic virtual experiment scenario with 7 km length were constructed which include five different traffic risk situations.Nineteen young and middle-aged drivers and nineteen elderly drivers were recruited for the test,two groups of drivers’ physiological and psychological behavior data in static and dynamic environments wer extracted by experiments.Through the analysis of drivers’ test data in the static environment,it’s found that the elderly drivers’ dynamic vision,night vision and depth vision have deteriorated in varying degrees,this decline may increase the risk of older drivers failing to detect risks,misjudging distances and driving at night.At the same time,with aging,the visual cognitive ability and processing speed,distraction and selective attention ability of the elderly drivers were also deteriorated.These attenuating phenomena could reduce the ability of elderly drivers to acquire traffic information quickly and accurately.Based on the analysis of dynamic driving simulation test data,it was found that with the increase of risk level,drivers’ fixation duration,and heart rate growth rate,HRV frequency-domain index-LF,EDA related index and risk sensitivity index all increased,while scaning index,HRV time-domain index-SDNN,braking time and risk response time all decreased.Regular changes of these indexes suggest that the greater the risk,the greater the driver’s attention and sensitivity to it,the greater the psychological stress and the effort requirement,and the earlier the response.Through the comparative analysis of behavioral characteristics in risk scenarios shows that there are some differences between elderly drivers and young drivers.The scanning range,scanning speed and the entropy of gaze distribution of old drivers in eye movement behavior,and the HRV time-domain index-SDNN and frequency-domain index-TP,VLF,LF of older drivers in psychophysiological behavior all declined with aging.The growth rates of HR and EDA of elderly drivers were higher than those of young and middle-aged drivers,and the growth rate in the scenanio with the highest risk level was the largest,which indicated that elderly drivers were more nervous in the face of risk,and the higher the risk level,the greater the tension degree of driving.The old drivers’ braking response time is more than 1 second later than young and middle-aged drivers,older drivers have less steering avoidance operation behavior than young and middle-aged drivers.The average speed of old drivers is higher than that of young and middle-aged drivers,and the standard deviation and coefficient of variation of speed of old drivers are higher than that of young and middle-aged drivers in three scenarios,which indicates that the elderly drivers’ ability to operate under risk situation is reduced,and the speed control ability is poor.The risk response time and the threshold of risk judgment of the elderly drivers are higher than that of the young and middle-aged drivers,and the risk sensitivity is generally lower than that of the young and middleaged drivers,which indicates that the time of the elderly drivers to make risk judgment and response is later,and the elderly’s risk discrimination has declined.Two group drivers’ behavior graphs in five risk scenarios were constructed,and the image of the spatiotemporal change process of drivers’ various behavior characteristics in risk scenarios is displayed.It is found that the nodes of eye movement,operation behavior and vehicle movement behavior of middle-aged and young drivers appear earlier than those of elderly drivers.Generally,the change process of behavior nodes of two types of drivers in risk situation is a change process of eye movement discovery-operation response-vehicle response-psychophysiological change.The similarity calculation of the longest common sub-sequence reveals the large difference between two group drivers in different kinds of behavior trajectories.The evaluation index system of driver’s behavior safety in risk situation is constructed,and the multi-level grey fuzzy comprehensive evaluation model of driver’s behavior safety in risk situation is established by synthesizing various indicators.Taking a risk scenario as an example,the model was applied evaluate the behavior safety(including eye movement,driving operation,physiological reaction and risk perception behavior)of two group drivers under the risk scenario,and find that the behavior level of young and middle-aged drivers was evaluated to be safe and that of elderly drivers is general.According to the evaluation results,some improvement measures are put forward to ensure the safe travel of elderly drivers,such as traffic management,safety training and propaganda,traffic environment improvement,designs improvement of traffic facilities layout and vehicle system,etc. |
