Analysis Of Comfort Simulation Experiment To The Interchange Ramps Based On Naturalistic Driving Study

With the improvement of the concept of life consumption and the dynamic performance of passenger cars.People expect higher driving speeds,paying more and more attention to the comfort and safety during driving.Therefore,many small-radius ramp currently designed and used are difficult to meet the driver's requirements for driving comfort and driving pleasure.In this paper,the speed characteristics,trajectory characteristics and acceleration characteristics of the vehicle during the interchange are obtained through the natural driving experiment on the road interchange,and establishing the driver model in Carsim.The vehicle model in Carsim is established according to the vehicle selected during the experiment.Getting the relevant parameters of the simulation interchange through the interchange design file,reproducing the interchange using the weft 3D road design software.Extracting the intersection parameter data satisfying the Carsim model format from the interchange model to establish the road model in Carsim.Finally,based on the speed law in the experimental process,adjusting the road preview parameters and the ramp import and export trajectories in the Carsim model.Then according to the Carsim simulation model,studying the driving comfort and driving safety of the passenger car on the interchange.By changing the parameters in the simulation model,studying the driving comfort of the passenger car passing through the ramp with different radius of curvature at different driving speeds.Further research on the driving comfort problem of braking with different braking forces at different positions of the ramp.At the same time,the effects of passenger car load and ground adhesion coefficient on driving comfort and safety are analyzed.During the driving of the passenger car,the radius of the ramp is too small and the running speed is too high,resulting in a certain offset of the center of mass during driving.At the same time,the position of the center of mass is constantly fluctuating due to the change of the line shape of the road and the frequent turning of the vehicle.The driving process of the passenger car deviates from the target trajectory and even slips.From the perspective of lateral acceleration values,When the speed of a passenger car on a small radius interchange is more than 50km/h,the lateral acceleration value can exceed 4.05m/s~2,and the driving process is extremely uncomfortable.The effect of the length of the longitudinal slope on the magnitude of the braking deceleration and the length of the braking distance is obvious.When the brake master cylinder pressure exceeds 2MPa,the braking distance length is mainly affected by the braking starting speed.When driving on a small radius ramp,the passenger car load and road adhesion coefficient have a great influence on driving safety.At the same driving speed,the increase in load and the decrease in road adhesion coefficient have a greater impact on the uphill ramp than on the downhill ramp.