Research On Modeling And Simulation Of Running Speed ​​Based On Vehicle And Vehicle Control

With the development of highway transportation, traffic security problems have aroused the attention of people all around the world. As an important objective factor, the matching of highway alignment and its operating speed are getting increasing concern from researchers. Recently, the most widely used operating speed models are those constructed by regressing the experiment data. Those models can calculate the operating speed based on the specified highway alignment, but due to the limitation of sample size, those models can not include every specific road condition, which might lead to the lack of continuity and suitability of the models.According to the current operating speed model, a further analysis on operating speed was conducted by taking vehicle dynamic model and driver model in to consideration. With the analysis, a new operating speed model considering driver and vehicle responses was built. The model is constituted by a desired speed model, a longitudinal vehicle dynamic model and a driver speed control model.The desired speed model is based on the current operating speed model regressed by measured vehicle speed. The model output the operating speed according to the highway radius.The longitudinal vehicle dynamic model was constructed according to the vehicle’s mechanical equilibrium firstly, discussed the relationship between vehicle acceleration and throttle or brake pedal input. A functional relationship between engine effective torque and throttle percentage in different engine speed was figured out; and also, by regressing the measured data, the functional relationship between brake percentage and braking force was found. Finally by putting the engine model and braking model into the vehicle mechanical equilibrium, a vehicle model which input the percentage of throttle and brake and output the vehicle acceleration was founded.The driver model has two main components:an information collecting and calculating model and a speed control model. The first model comprehensively considering the road condition of the preview point and present vehicle location, outputs a desired acceleration using comfortableness as a standard. The speed control model determines the percentage of throttle and brake pedals on account of the error between desired acceleration and actual acceleration, making the vehicle speed getting close to desired speed.This paper completed the current operating speed model by bringing in the longitudinal vehicle model and driver vehicle speed control model; the model was reviewed and matured by analyzing driver’s preview. Compared to the current highway safety evaluation system, the new operating speed model can reveal the change of vehicle throttle and brake percentage when road radius changes, which can be used as a more intuitional evaluation index of highway alignment.