Research On Control Method Of Vehicle Longitudinal Dynamics System

With the rapid development of high-speed vehicle, traffic jam and accident have become global problems. It is an efficient way to take the place of manual manipulation by using intelligent controller in order to realize automated control of the vehicle. Longitudinal dynamics system control is an important part of automated control of the vehicle. Longitudinal control is the speed control of an automobile on its running way.In this paper, the relationship between substrate system and superstratum system is studied based on analysis of the structure, function and characteristic of vehicle longitude dynamics system. First, the structure, function and working progress of components in braking system are discussed, meanwhile, the nonlinear characteristics of braking system which is caused by the response of the braking pedal force, braking hydraulic pressure is analyzed. Then, nonlinear mathematic model of braking system is presented. According to the data from engine experiment, the static model and the dynamic model of the engine is established. The model of driveline and dynamic equation of whole vehicle are established by analyzing the characteristic of hydraulic torque converter and automatic transmission, and the force-applying status of the vehicle. Furthermore, the brake system model, drive system model, engine system model and dynamics equations of whole vehicle are combined to finish the design of the substrate system. Superstratum system which is linkage between vehicle and the front one (navigation vehicle) is a system to realize vehicle longitude automated track. First, the parameters of longitude track between two automobiles are discussed, the realization of the logical switch between engine and main brake cylinder is also analyzed, and then considerable precise superstratum system model is presented.The structure, purpose and influencing factors of the longitude dynamics system control are studied. Based on analysis of the system characteristic, the different simulation results under different intelligent control methods is discussed according to analysis of the system characteristic. First, a two-input single-output fuzzy logic controller is adopted. According to control purpose and fuzzy control strategy, control parameters are adjusted to vary the output of the system, and vehicle's longitudinal automated control can be realized (i.e. running at specific speed). Then, the neural networks model is applied to identify and process input data, design suitable networks layer for the vehicle longitude dynamics system control. And then, the parametersadjusting fuzzy-PID method is used to realize longitude control by adjusting the three parameters in PID control under the rule of the fuzzy control.Eventually, the vehicle longitudinal dynamics stimulant control system is demonstrated with ADAMS. Furthermore, the advice is put forward how to equip experiment fixing and obtain information during the vehicle's running process.