Simulation And Studying Hydraulic Anti-lock Braking System Of Vehicle ABS Models

As a typical active safety component for automotives, the main goal of antilock braking system (ABS) is to prevent wheel lockup, to maintain steerability and stability, to reduce the vehicle’s stopping distance, and to improve the performance of the brake system effectively during emergency braking.On the basis of the achievement of predecessors, automobile hydraulic system control algorithms of ABS and the theory of single chip are mainly discussed in this paper. The idea is to establish a useful way to research, design and update the ABS. The main content in the dissertation is dealt as followed:(1) Research on ABS-used basic principle and control channels. First of all, the theory of ABS was expounded which include working theory and basic structure. Most of the control methods in the application of ABS including logic threshold control and control method based on wheel slip ratio are introduced, and their advantages and disadvantages are analyzed respectively. On the basis of familiarity of two sensors and the characteristic of signal, this article introduces their circuits’principles, structures and functions, analyses and compares the advantages and disadvantages of two methods of processing the wheel speed sensor. This paper discusses possible control channels of Anti-lock Braking System and their effect on directional stability and redirection-manipulative quality, and analyses the adaptability between control channels and automobile braking system and transmission system.(2) Research on ABS control algorithm method and the application of MATLAB. The paper builds the simulation model on the basis of analysis. The simulation model takes fully into account dynamic model of vehicle, mechanical model of wheel, model of hydraulic braking system. In order to unify the feasibility and reliability of simulation, the paper simplifies the model. A common logic controller is designed with toolboxes of MATLAB/SIMULINK according to the simplified automobile model and it can get good effect as the result of simulation test shows. And the direct control, logic control, Fuzzy control and PID control are chosen for establishing model in this paper. Simulate by direct control, switch control, PID control, Fuzzy control at the whole module, rectify the parameters time after time, the compare the four methods by data, simulation curve, and whether they are easy to carry out. By means of logic control expresses boost, decompress and dwell of hydraulic system, then analyses the coefficient of adhesion and braking efficiency under Fuzzy control and PID control, combine with the relation of coefficient of adhesion and slip rate, we can get the conclusion:in order to get good braking efficiency we can control the slip rate. And the paper fits the curve of distance, time of different road and muzzle velocity under PID control, gets the relation of distance, time and muzzle velocity.(3) Develop ABS-used single chip microcomputer and calculative simulation software. Among the widely-adopted electro-controlled ABS, single chip microcomputer is its kernel. It is important for ABS to make adequate use of their external ports, internal memories, interrupts and operating speed. A scheme is put forward to develop a special software of the data picking up and calculations simulation. The software gives prominence to quick data picking up, wheel speed calculation and filter, the calculations of reference speed and slip portion, the calculation of wheel acceleration and logic analysis of Anti-lock Braking control, which are convenient for the test, research and development of ABS.