Study On The Influence Of Fog On Human Speed Perception

Speed perception is an important ability when people are walking,driving a vehicle and so on.This ability can ensure correct speed perception and safe driving.However,in certain conditions,people's perception of speed will deviate.Fog is a common weather condition that can result in misperception of speed.In fog weather,the change of fog's concentration reduces contrast,while the relationship is not clear between contrast and speed perception.In addition,further research is needed to investigate the factors that cause the speed perception deviation.Possible applications of our work could increase the safety of intelligent vehicles by considering these factors in the driving system.We analyzed factors in people's speed perception,in the hope to help decrease the traffic accidents caused by speed perception deviation.Therefore,it is necessary to study the human perception of speed in the fog.First of all,we introduced the related notions of speed perception,explained the characteristics of human vision and perception research of speed on neural cell level.Then we reviewed the impact of fog on speed perception in the literature and described how the other influence factors affect people's perception of speed.Based on predecessor's research results,this experiment used two different types of fog: Contrast Inconsistent(the real fog)and Contrast Consistent(the uniformed fog).UC-win/Road software was used as the virtual reality experiment platform to build the experimental environment,including five different fog concentration and speed level,and produced the experiment video of fog.Secondly,The sample entropy method was applied to analyze the experimental video of different type of fog,and according to the results analysised why people's speed perception generated deviation under the fog scene.Experimental method was applied using psychtoolbox toolbox,and MatLab software was chosen to control experiment process and store experimental data,then we observed the result of the experiment whether matching the results of sample entropy.Finally,we analyzed the experimental video's sample entropy and the results of the speed perception experiment,calculated the experiment video's sample entropy,which was consistent with the results of the speed perception experiment.The reason of the speed perception deviation could be the change of information on the road.The fog concentration was too small,human vision could receive more road information.The fog concentration was too large,human vision could receive much less road information,in these two types fog concentration human speed perception deviation was less.And when the fog concentration type was in the middle position,human vision received road information,which was also in the middle position.Now that human speed perception deviation was larger,the change of the amount of road information in the sample entropy can be well reflected,and showed that this method could be used to explain the influence of human speed perception deviation in the fog.We conclude that the variation of the amount of traffic information received by human vision has caused the deviation of speed perception judgment.In addition,we also analyzed the experimental data of two different types of fog,and the conclusions are as follows.In the real foggy weather,the subjects tended to overestimate speed,the perception of the same speed was different in different fog concentrations,the speed perception and fog concentration were non-linear related,during the first rise after the fall,presenting a peak value which was a maximum speed perception judgment deviation.In the global uniform foggy weather,the subjects underestimated speed,and the perception of the same speed was different in different fog concentrations,the speed perception and fog concentration were linear decrease related or general equal realted.It also showed that different ways and size of contrast would affect the judgment of human speed perception.