Research On Driving Safety Of Long And Complex Downhill Based On Driver-Vehicle-Road Cooperative Simulation

With the sustainable development of China's economy and the mature logistics industry,the total amount of transportation freight in the future will also show a gradual trend of increasing.Highway transportation as the main role of road freight transportation,its security sector will face more severe challenges.Unlike passenger cars,heavy-duty trucks have problems such as difficulty in shifting and braking in the complex downhill section,which make heavy-duty trucks become the main vehicle of traffic accidents.The existing research focuses on the temperature rise change,speed Prediction model and Accident section characteristics of the growing downhill,and lack the research of the coupling characteristics of driver's gear-shifting decision and driving safety.As the main body of vehicle control,driver's behavior is highly correlated with driving safety.Taking LAN Hai Expressway as an example,the accident section meets the standard of highway design and construction in the current period,and the cause of the accident was the failure of vehicle brake which was caused by the driver's wrong decision-making of gearing.Therefore,it is of practical significance for improving road traffic safety to study the driver's shift decision-making and driving safety of heavy haul trucks on long and complex downhill sections.The main contents of this paper are as follows:Research on velocity change characteristic of heavy duty Truck's downhill gear.on the basis of Driver-Vehicle-Road collaborative simulation system,the characteristics of downward speed change of heavy-duty truck with heavy downhill was studied.The relationship and influence between load weight,gear position,road slope,road adhesion coefficient and speed of trailer were analyzed.The range of speed change of different gear positions with different slope was obtained.The simulation results show that there is weak coupling between vehicle load and speed of trailer,and gear position is strongly coupled with the speed of the trailer.Therefore,it is necessary to consider the impact of driver's decision-making on the safety of heavy haul trucks in the form of long downhill.In addition,the key parameters of brake temperature rise model at running speed are given in this chapter.The stability values and variation curves of brake speed at different grades of heavy haul trucks are given,which can provide reference for the study of brake temperature rise of the same type of heavy trucks.The simulation study of long and complex downhill heavy haul truck driving safety based on Man-Vehicle-Road coordination.For the existing fixed speed cruise mode can not reflect the impact of driver's gear decision-making on driving safety in long and complex downhill sections.On the basis of Driver-Vehicle-Road collaborative simulation,truckSim and Simulink were used to design the simulation model of driving control.A virtual simulation experiment of introducing the characteristic spectrum of driver's maneuvering behavior at the level of vehicle speed was proposed.Finally,a long downhill was taken as an example to study the driving characteristics of long downhill vehicles under different driving modes.The simulation results show that compared with the constant speed cruise mode,the simulation results of the driving mode in this paper are more suitable for the long and complex downhill section of heavy trucks.Whether the road design scheme is to be constructed,or the long and complex downhill section is to be constructed or operated,the model could be used to simulate the three-dimensional road model.By analyzing the variation of vehicle speed,single wheel braking pressure amplitude and fluctuation frequency domain characteristics under different gears,the driver's shift decision and the design of safe Lane in this section could be optimized.Research on dynamic safety vehicle speed boundary of typical section of heavy duty truck.In the aspect of vehicle handing dynamics,the index parameters which can realtime characterize vehicle driving safety and stability were introduced.By changing the characteristic parameters such as road bend radius,road adhesion coefficient and slope,the changing law of Heavy truck driving safety was studied,and the coupling strength between each index and vehicle driving stability under different road conditions was compared,and the vehicle dynamic safety under different characteristic sections was solved.The simulation results show that the lateral acceleration threshold should be kept within 0.23 g and the tire load transfer rate should be kept within 0.4.When the curvedslope combination section runs steadily,the road gradient is weakly coupled with the driving characteristics of heavy-duty trucks,but the increase of road gradient will increase the risk of vehicle runaway.Compared with the running speed method and the side slip limit speed method,the dynamic stable boundary speed method in this paper has better applicability to various typical complex sections.The research results in this paper can provide theoretical basis for future road profile design,safety Lane design,driver's gear decision-making optimization and related vehicle early warning system design,and have important theoretical and practical significance for improving the driving safety of long and complex downhill sections.