The Research of Automobile Electromechanical Braking System Based on FPGA
|School||Xi'an University of Engineering|
|Keywords||Electronic mechanical braking system Sliding rate PWM pulse widthmodulation Field programmable gate array fuzzy PID Brushless DCmotor|
Adding a large number of electronic control systems in the traditional hydraulicor air brake system, such as electronic stability control program (ESP), tractioncontrol system (TCS), anti-lock braking system (ABS), active collision avoidancetechnology (ACC), and so on. The structure and piping layout became more andmore complex, meanwhile, the hydraulic circuit of the hidden trouble also beenlarged, and the difficulty of the assembly and repair also increased. The relativelysimple structure, functional integration and reliable electro-mechanical brakingsystem (EMB) is much favored, meanwhile, the EMB have some advantages such assmall volume, fast response, the reliable performance, safety and environmentalprotection make ABS and other control modules can be easily realized and otherscontrol can be carry progressed the centralized management and sharing informationvia the CAN bus. Many experts predicted that EMB system will eventually replacethe traditional hydraulic or air braking control system and become the futuredevelopment direction of the automobile brake system.This paper mainly from the following aspects: first, it will introduce thedevelopment situation of the domestic and abroad about the EMB system as well asits composition and development trend. And then establish the road modeling aboutthe automobile and establish the mathematical modeling of wheels, vehicle, actuatorand arrester based on the vehicle dynamics characteristics in Matlab, and finallymake sure the size of the optimal slip ratio when the vehicle running on differentroads.Second, it will design the hardware for EMB system. The hardware designmainly divided into the electronic control unit (ECU) design and the periphery of thecontrol circuit of the BLDC design. The last part is designed the software andanalysised the algorithm. The EMB system adopts the fuzzy PID algorithm, themainly task is that established the fuzzy PID algorithm model in matlab, thenattained it by using the verilog language and the IP core of FPGA in the quartusiisoftware. The software design will program the control module and the dataacquisition module of the EMB system in the quartusii software. Given the flow chart of the braking system and using FPGA to realize the control, and then verifythe correctness of the program via the function simulation of everyone module in themodelsim software. And then generate the top-level file, it is the control module ofthe data acquisition and the BLDC to achieve the speed control of the BLDC. So wecan realize the vehicle brake via the adjustment of the BLDC speed.EMB system uses the three-loop control method, the fuzzy algorithm to controlthe wide range in order to inprove the speed of the dynamic effects of the system;thePID algorithm to control the small range in order to improve the accuracy of thesteady_state control; and last add a feedforward algorithm module to inprove theresponse speed of the input signal.