Modeling Of Automobile Braking System And Research On Pressure Control Method

With the continuous development of the automotive industry, people started topay attention to car driving safety issues. Most cars currently produced almost usehydraulic brake system, and hydraulic brake system for the car driving safety has animportant meaning. In order to further enhance braking performance, the switchvalve can not meet the control requirements, so far the flow valves are usuallychosen as the pressure control valve in some hydraulic braking systems. And thehydraulic braking effect is very complicated, if only we consider the staticcharacteristics, the analysis results with the actual situation there is a big error. Tothis end, the research on the modeling of the hydraulic braking system with flowvalves has great signification.This paper studies the hydraulic control units of brake system with the flowvalves, the main research contents is that the modeling of increasing and reducingpressure process; According to the measured data in hardware-in-the-loopexperiment platform, using the classic least squares paramenter identificationmethod to identify the model parament, and get the full mathematical model. Andwe do simulation in Matlab/Simulink, by comparing the simulation results andexperimental results verify the validity of the model. On this basis, for the obtainedmodel designed a muti-model predictive controller based on the principle of muti-model control and generalized predictive control. And do simulations study on thecontroller parameters and robustness, To illustrate the controller effect of thedesigned controller, compared with PID controller.In the process of the modeling of hydraulic control unit increasing andreducing pressure model research, according to the different workoing conditions of the flow valve analysis the spool stress state, and simplify the brake wheelcylinders, wo can get the mathematical relationship between cylinders pressure andflow of valve.Because of the physical structure parameters of hydraulic control unitunknownthat we can’t get the full mathematical model, so built the hardware-in-the-loop experiment platform based on the dsPACE, and test the currentcharacteristics and incresing and reducing pressure characteristic which procide areliable data for the identification of unknown paremeters. By comparing thesimulation results and experimental results verify the validity of the model.This paper finally discussed the problem of hydraulic control unit controller,for the particularity of the model, we use muti-model predictive control ideology.By linearizing the nonlinear system into a group of linear sub-model, the controllerof the sub-models is designed based on the principle of predictive control, and thefinal control input is get by the decision-making mechanism. As the car brakehydraulic control unit is unavoidable interference in actual work, so we studied therobustness of the controller.