The Study Of Target Visibility Model With Driving Workload Under Mesopic Vision

Good road lighting is a guarantee for night driving safety.The road visibility must be enough to ensure that the driver can detect obstacles on the road within the safety distance.The present visibility models are based on simple psychophysical experiments,which cannot reflect the impact of real driving workload on visibility,including the Small Target Visibility(STV)model,which provides a link between lighting design and driving performance and is widely used to evaluate the road lighting quality.This thesis is dedicated in studying the visibility model with driving workload under mesopic vision.In order to simulate the real driving environment more truthfully and reliably,a virtual driving simulation system is designed.All parts of the driving simulation system are synchronized through the E-prime program.Based on the driving simulation system,different driving workloads are designed,including the reference scene and the simulated driving scene.The influence of the driving workload,target contrast,target distance and lane position on the small target visibility is studied.The experimental results show that all factors have significant effect on detection rate and reaction time.The effect of driving workload and target contrast is greater than other factors,and there is a significant interaction between different factors.In general,the smaller driving workload,the larger target contrast,the shorter target distance and the closer position to the middle lane lead to the larger target visibility.On this basis,the experimental design is further improved and the relationship between the visual power function(MVP)and various factors is studied.The experimental results show that MVP has a positive correlation with visibility.All factors including driving workload,target contrast,target distance and lane position have significant effect on MVP.The interaction between different factors is significant too.The most widely used VL model is validated at the same time.The results show that the current threshold criterion of VL=7 cannot predict the target visibility accurately with driving workload.According to our experimental results,the threshold criterion should increase to VL=10 or VL=33 according to different driving workload.On the other hand,comparing the virtual driving scene with the actual field experiments designed by other researchers,a similar VL thresholds is found generally.Finally,a new visibility model including the driving workload and the interaction between factors is proposed,which R~2 is as high as 0.98.