Identification And Early-Warning Of Fatigue State Of Intercity Coach Drivers

Fatigue driving will affect the reaction ability,executive ability and judgment ability of drivers,and it will do great harm to road traffic safety.Identification coach drivers play a very important role in road transport,and their professional characteristics make them a frequent group of fatigue driving.The accidents caused by fatigue of intercityintercity coach drivers are usually serious accidents,which are easy to cause mass death and injury.Although the laws of various countries stipulate the duration of driving,fatigue may occur due to personal reasons even within the prescribed driving time.For coach drivers,even if they are aware of fatigue,they will have to continue driving in order to ensure the transportation task.Therefore,the study of identification and early-warning of coach driver is of great significance to the traffic safety of intercity coach.There were few studies on coach drivers.In order to screen out the effective characterization parameters,a questionnaire about fatigue symptoms was first conducted for the coach drivers,and the results of the questionnaire were analyzed by the improved analytic hierarchy process?AHP?.On this basis,the fatigue characteristic research test was designed,and the fatigue state identification research and early warning system development of intercity coach drivers were conducted.The specific research contents are as follows.1)Optimization process of driver fatigue parameters of interurban coach drivers.The steering parameters,vehicle side parameters and reaction capacity parameters were optimized by using two-factor anova.After statistically analysised the interaction effects of time and fatigue factors,selected the number of steering wheel holding?NMRHOLD?,steering wheel direction change?SWDR?,steering wheel angle velocity standard deviation?SWV_Std?and steering wheel zero speed percentage?PNS?as steering control parameters,Standard deviation of vehicle lateral velocity?LV_Std?as the characteristic parameter of vehicle lateral velocity,first reaction time?RT₁st_Mean?and standard deviation of reaction time difference?RT_Diff_Std?as the characteristic parameter of reaction capacity.And then the time domain and frequency domain law of the variation of each parameter with the fatigue level were analyzed,at the same time,the variation law of the parameter caused by individual difference was also studied.2)Construction of driver fatigue identification model for interurban coach drivers.Considering the characteristics of the time series of driver fatigue characterization parameters,the gaussian mixture hidden markov model?GM-HMM?was used to establish the driver fatigue discrimination model.The training samples of 7 fatigue characterization parameters,including NMRHOLD,SWDR,SWV_Std,LV_Std,PNS,RT₁st_Mean and RT_Diff_Std,were selected as the input variables of the model.A GM-HMM fatigue final judgment model based on fusion parameters was established for each driver,and the accuracy of the model obtained through cross identification was 90.63%.Considering that the response time test may interfere with driver error,a GM-HMM fatigue initial judgment model based on state parameters was established by using other parameters besides the response time.When judging the fatigue state of drivers,the initial judgment model is used to predict the fatigue,and the reaction time test trigger time is determined.If the possible fatigue state is detected,the GM-HMM fatigue final judgment model based on fusion parameters is used for the final determination of fatigue.3)Analysis on the regularity of driver's reaction ability under fatigue condition.The GM-HMM fatigue identification model was used to analyze the variation of the reaction time with the fatigue degree.Firstly,it is confirmed from the perspective of time domain that the overall reaction time parameters show an increasing trend with the increase of fatigue level,but it will follow the process of rapid rise after the fluctuation decreases.The above rules show that the fatigue degree represented by reaction time is intuitive,and prove the existence of pulse fluctuation effect of fatigue.In the frequency domain,the probability density functions of the reaction time parameters in different states are established.Finally,the analysis of driving duration shows that the driver's circadian rhythm will affect the upper limit of driving duration when the driver is awake.4)Research on the acquisition technology of driver fatigue state characterization parameters based on image recognition.Parameter acquisition technology realizes steering wheel angle recognition,road curvature calculation and vehicle lateral velocity calculation with the help of OpenCV.The above requirements are realized by two algorithms.First algorithm uses digital image processing technology to process the collected steering wheel image.After the image enhancement of region of interest selection,gray level processing,median filtering and histogram equalization,the rotation angle of the steering wheel is calculated by color point tracking algorithm and angle calculation method.The second algorithm adopts the image enhancement algorithm of region of interest?ROI?setting,gray level processing,median filtering and gamma transformation based on the theoretical speed,and finally uses the two-segment straight line Hough detection algorithm to calculate the road curvature and lateral motion parameters.5)Development of fatigue identification and early-warning system for intercity coach driver.Firstly,the whole system is designed according to the requirements of software and hardware.According to the requirement of portability,embedded ARM9 was selected,and the system was matched and operated considerting from both the perspective of hardware platform and software design.The Ubuntu system kernel,file import system,root file system and OpenCV were transplanted.Qt software was used to design the system interface.Finally,the system is tested on real vehicle.The portable equipment developed in this paper,fatigue identification and early-warning system,provides a new way to intercity coach driver fatigue early-warning achieved detecting the fatigue of intercity coach drivers on the way.