Safety Model And Simulation Of Vehicles On The Long-Steep Downgrade Based On Carsim/Trucksim

The continuous development of highway transportation industry in China has put forward higher requirements for road traffic safety in China.However,compared with developed countries,the high road traffic accident rate in China is threatening people’s travel safety and goods transportation,which seriously restricts the sustainable development of society.Especially with the shift of the focus of China’s road traffic infrastructure construction from the east to the central and western regions,the traffic accidents along the long-steep downgrade are particularly serious.Group deaths and injuries often occur,which has become a "malignant tumour" that hampers China’s economic development.Therefore,with the development of the speed of cars and heavy trucks in road transportation in China,it is particularly necessary to make research on the driving safety of driving safety on the long-steep downgrade.Based on this,the paper mainly carries out research from the following aspects:(1)A long-steep downgrade model was constructed by weft road design software based on the relationship between road alignment index and traffic safety,combined with the technical index of typical long-steep downgrade accident-prone section.(2)The operation safety analysis model of the long-steep downgrade vehicle was built,including the lateral stability model of the vehicle and the temperature rise model.The temperature rise principle of the brake hub of the long-steep downgrade vehicle was analyzed,and the driving safety evaluation index of the long-steep downgrade vehicle was constructed.(3)A CAR/Truck Sim simulation platform was built,which includes vehicle model,driver model and road model.Great Wall Motor(GWM)Harvard H6 and a five-axle truck were used as real vehicles to build vehicle models.The road model was established based on the long-steep downgrade pile-by-pile coordinate table,and the driver model was established based on the preview trajectory control and steering wheel Angle control.A Trucksim-Simulink co-simulation model based on PID control algorithm was built to simulate the temperature rise of the braking hub of a heavy-duty truck at a constant speed downhill.In addition,Truck Sim and Simulink combined ABS system was built based on logic threshold control strategy under Simulink environment.(4)Based on the vehicle lateral stability model of the long-steep downgrade section constructed,the influence of typical road alignment indexes and external environmental conditions on the lateral stability of the selected typical SUV was simulated and analyzed.The single factor and multi-factor analysis were carried out,which show that the growing downhill with curves has the greatest influence on the lateral stability of the vehicle.The influence of 4% longitudinal slope on vehicle lateral stability is obviously different from that of 2.5%,3% and 3.5% longitudinal slope,which is consistent with the existing research conclusions on the relationship between accident rate and slope.The result also illustrates that the ultra high elevation at the long-steep downgrade bend has the strongest influence on vehicle lateral stability and the weakest influence on road adhesion coefficient.(5)Based on the temperature rise model of the vehicle brake hub on the long-steep downgrade section and the Trucksim-Simulink co-simulation model,the research results show that the truck load,downhill speed and slope have significant effects on the temperature rise of the brake hub.Moreover,based on the co-simulation model,the advantages of ABS system in improving the emergency braking efficiency of heavy-duty trucks on long and downhill sections are concluded.The result and conclusion have a certain reference value to the following researches on the site selection of the escape lane,the establishment of traffic signs and lines,and the design of the flat and longitudinal lines of the long-steep downgrade.