| The driving safety issues of tractor semi-trailer combinations are more complex and serious compared to ordinary vehicles,especially on mountainous roads where the complex environment greatly affects their handling stability.When driving on combined curves and slopes on mountainous roads,the handling stability and safety of tractor semi-trailer combinations will be greatly reduced due to the influence of complex line shapes,icy roads,and crosswinds.Therefore,conducting research on the driving safety of tractor semi-trailer combinations under various conditions,such as combined curves and slopes,crosswind speeds,and low adhesion coefficients on icy roads,is of great significance in improving their driving safety.This dissertation takes tractor semi-trailer combinations as the research object and uses TruckSim software and simulation driving equipment to conduct simulations and experiments under different influencing conditions such as different combined curves and slopes,different adhesion coefficient road surfaces,and different crosswind speeds to analyze the driving safety of tractor semi-trailer combinations under various factors and explore the relationship between their safe driving speed and the above factors.This dissertation focuses on the impact of different combined curves and slopes,different adhesion coefficient road surfaces on icy roads,and different crosswind speeds on the driving safety of tractor semi-trailer combinations on various grades of mountainous roads.A dynamic model of tractor semi-trailer combinations is established to analyze their driving stability.Based on this,a tractor semi-trailer combination model,road model,and crosswind model are established using TruckSim software to carry out driving safety simulations and experiments under different conditions of combined curves and slopes,different adhesion coefficient road surfaces on icy roads,and different crosswind speeds on different grades of mountainous roads.The driving stability of tractor semi-trailer combinations is evaluated from two aspects: lateral slip and rollover.The lateral offset and lateral acceleration are selected as the evaluation indicators for lateral slip,and the lateral load transfer ratio is selected as the evaluation indicator for rollover.Regression fitting models are established for the maximum safe driving speed of tractor semi-trailer combinations under single influencing factor conditions,such as the relationship between the maximum safe driving speed and crosswind speed,and the relationship between the maximum safe driving speed and road surface adhesion coefficient.Regression fitting models are also established for the maximum safe driving speed of tractor semi-trailer combinations under multiple influencing factors conditions,such as the relationship between the maximum safe driving speed and combined curves and slopes,crosswind speeds,and road surface adhesion coefficients.Based on the results of the fitting regression models,a road model is established in TruckSim for a real mountainous road scenario.By comparing the lateral offset value,lateral acceleration,and lateral load transfer ratio in the simulation results of driving at the design speed and the regression fitting model speed,the effectiveness of the fitting model is verified.An experiment is also conducted on the same mountainous road scenario model using simulation driving equipment to analyze the safety of tractor semi-trailer combinations driving under the guidance of the speed fitting model,and the results are compared with the TruckSim simulation results to verify the effectiveness of the speed fitting model in actual scenarios.The simulation and experimental results show that the speed fitting model can fully consider the effects of the combined road section radius of circular curves,road surface adhesion coefficient,and crosswind speed in mountainous areas.The fitted speed can significantly improve the lateral offset distance,lateral acceleration,and lateral load transfer rate of tractor semi-trailer combinations traveling at speed,which has practical guiding significance for setting the driving speed of tractor semi-trailer combinations under complex conditions in mountainous areas. |
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