Study On The Auxiliary Deceleration Lane In Long And Steep Downhill Sections On Mountain Road Based On The Vehicle Driving Safety Features

At current,the highway traffic safety situation is still grim on mountainous area in our country,especially the drving security problem in continuous long and steep downhill sections,and the more traffic accidents for heavy duty trucks in such sections due to brake failure or hot recession have caused people' huge personal and property losses and become the prominent problem restricting China's economic and social development.Aiming at solving this problem,relying on Gansu province science and technology plan support project(1504fkca001)“Research on the Key Technology of Continuous Downhill Road Auxiliary Deceleration Lane” and Xi'an science and technology plan transfer and promote project(CX12162)“Research on Heavy Commercial Vehicles Safety Assurance Comprehensive Technology”,the paper studies the drving speed of heavy duty trucks in continuous long and steep downhill sections.,(1)Study on setting position of auxiliary deceleration lane by establishing the thermal model and the speed loss prediction model of heavy duty truck in long and steep downhill sections.According to the analysis of vehicle system dynamics,road and ramp test,heating and cooling process are modeled separately,and the thermal models of heavy duty truck brake on flat and ramp road are established combing continuous braking device and the driving brake.The accuracy of the model is verified by the real vehicle test.According to operating characteristic of the engine brake,exhaust brake,eddy current retarder brake,engine brake and eddy current retarder brake,exhaust brake and eddy current retarder brake,omnibus brake and eddy current retarder brake jointed respectively with vehicle brake and on the basis of ramp brake drum temperature rise model,driving modes of safety brake drum temperature threshold value of different slope section are studied to analize the relationship between the speed and road slope,slope distance,and the speed loss prediction model of heavy duty truck in long and steep downhill sections is established and then setting position analysis model of auxiliary deceleration lane is deduced.(2)Study on the parameter matching of auxiliary deceleration lane based on tire-particle flow mechanics model.Through simulation,bench and road test,the influence of paving thickness and particle size of the auxiliary deceleration lane on the wheel drivingresistance is studied.Based on the primary discrete element theory and method,tire structure model and auxiliary deceleration lane aggregate model are established,and using the tire performance testing system developed independently indoor bench test is done for truck tire vertical characteristics to research tire feedback on different input conditions.Coasting test and deceleration lane real vehicle experiment have been carried out,and the influence of paving thickness and particle size on the driving resistance is studied by measuring driving distance,speed,rotating speed of the tire and subsidence displacement of different type,and tire-particle flow mechanics model is tested.Based on tire-particle flow mechanics model and considering the deceleration effect and construction cost,the parameter matching of auxiliary deceleration lane is studied to determine the key technical parameters.(3)Study on the influence of auxiliary deceleration lane on vehicle driving stability.According to the vehicle dynamics principle,14 degrees of freedom vehicle nonlinear coupling dynamics model is established.According to the tyre particles flow model,vehicle nonlinear coupling dynamic simulation model is established,and the accuracy of 14 degrees of freedom vehicle nonlinear coupling dynamics model is verified by comparing the real car test data and simulation data.The impact of pavement materials and speed on the vehicle pitch and tilt is studied through the model to provide a theoretical basis for optimizing the design of auxiliary deceleration lane.(4)Study on the traffic sign setting of the auxiliary deceleration lane based on the visual identity of the driver.Based on the characteristics of the driver's visual cognition and according to the characteristics of road alignment in long and steep downhill sections,the relational model between the drivers' visual cognition distance and the traffic sign size and speed is established;Based on the driver's visual cognition as well as the vehicle's braking deceleration characteristics,the front distance model of traffic signs is established,at the same time,considering the factors such as driver's visual short-term memory,the repeat distance model of traffic signs is established.Based on the road alignment in long and steep downhill sections and the driver's viewpoint height for heavy duty trucks the setting height model for traffic sign is establishedThe research results provide technical guidance for future design of auxiliary deceleration lane and has theoretical and practical significance to provide the heavy durytruck's driving safety in continuous long and steep downhill sections on mountainous area.