The Research Of Anti-lock Braking System Of Automobile Based On FPGA

Nowadays, the speed of the vehicle accelerates continuously with the developing of theautomobile industry, so the Requirement of the vehicle safe characteristics is higher thanbefore. Anti-lock braking system (ABS) is a kind of braking system to prevent a series ofnon-stabilizing factor such as sliding, deviation, loss of steering ability when the wheels arelocked in the braking process, thus it is used to avoid accident occur. The system can controlthe braking capacity effectively and maintain stability and steering the ability of direction, itis important for security driving.In this paper we put forward a improved design of the ABS system, which adopts theFPGA chip as ABS anti-lock system Electrical Control Unit (ECU), and the correspondingpart of the system hardware design is completed. In the forward path, the output wheel speedsignal from wheel speed sensor need pre-processing. In the A/D converter circuit converts thedigital signal sent to ECU for processing and computing. In the back path, the design of thesolenoid valve driving circuit is completed, which can convert the output signal from ECU todrive the solenoid valve, it also has a self-test function can real-time detect system failure andexcludes malfunction in time. In the part of software design, we adopt hardware descriptionlanguage Verilog to achieve. The main design contains two parts, the first part is thecalculation of the reference speed. In this system we first get the estimate of reference speedwith the maximum wheel speed method, and then create a reference speed of the Kalmanfiltering system state space model, using the adaptive method by the value of constantlyupdated to reflect the road conditions, which has been based on the reference speed adaptiveKalman filter algorithm to make the reference speed consistent with the vehicle speedapproximately. The second part is the logic threshold control design, in this system adoptcontrol strategy based on the slip rate is major and the wheel acceleration is supple. The basicprinciple is to choose the wheel acceleration threshold and slip ratio threshold control brakepressure booster, decompression or dwell so that the slip ratio can maintain optimum slipratio in the vicinity, resulting in better braking effect.In this paper makes simulation model in the Matlab/Simulink. At the same muzzlevelocity at different friction coefficient of the road on the braking simulation after set the appropriate simulated parameters, to gets the simulation curve of braking distance and thevehicle speed with wheel speed in the braking time under all kinds of road conditions. Theanalysis of the simulation results proves the system has good control effect.