Analyse And Control Of Electro Hydraulic Braking System For Vehicle

The electro-hydraulic braking (EHB) system is a new kind of automotive brake system. Thebraking energy of EHB system is provided by high pressure oil instead of human force in thetraditional braking system. In recent years, EHB system has been received more attention in thevehicle active safety research aera, due to its advantages, such as simple structure, fast response, easyto control, and energy saving.In this paper, the working principle of EHB system was analyzed. From its principle and thedesign requirements, the structure of EHB system was determined, including electromagnetic valve,power module, hydraulic control unit and high pressure oil pipe. Then, the solenoid valve and powermodule were selected on the performance requirements of EHB system. And the three-dimensionalmodel of Hydraulic Control Unit (HCU) and its lid of EHB system body were designed using UGsoftware. Also, the security of high pressure oil pipe was checked.Taking the couple among the electric, fluid and mechanical movement into consideriation, thenon-linear model of EHB system was established using bond graph modeling method. And the bondgraph model was transformed into mathmatical model based on the theory of power flow. Thendynamic characteristics of EHB system were analynized using Matlab/Simulink software. And the themodel of EHB system was verified by comparing the simulation.results by Matlab/Simulink softwareand AMESim software respectively. From the mathmatical model, the influence of some keyparameters on the performance of EHB system was analyzed during the process of pressure increasingand decreasing, including electromagnetic valve parameters, accumulator parameter and wheelcylinder parameters. The results could be used to design EHB which will performance better.Finally, to improve the dynamics characteristics of EHB system, four controllers were designed,including BANG-BANG controller, PID controller, fuzzy controller and robust controller for themodel. At the typical brake condition, the effect between the range of parameters of BANG-BANGcontroller’s dead zone and the precision of EHB system was simulated. Also, the effect betweenproportion, differentiation, integration of PID controller, weight function of H∞robust controller andthe control accuracy of EHB system were analyzed. Then the simulation results of the four control algorithm were compared to each other. To optimize the weight function of robust H∞controller, thegenetic algorithm was used in this paper. The results show that the optimal robust controller canimprove the ability of EHB system to deal with parameters uncertainty, as well as anti-jammingperformance significantly.