Abs Simulation Based On Vehicle Model And The Analysis Of Logic Threshold Control

Automotive ABS, being short for Anti-lock Braking System, is a common automotive active safety technology. System takes the real-time control which is decided by the measured vehicle driving conditions to the braking torque in order to prevent the wheels from fully locked, by which way on one hand can reduce the braking distance as well as increasing the automobile braking performance and on the other hand can allow the cars to take effective avoidance action during the braking procedures, improve the cars’handling-stability as well as reduce the accident rate. At present, the main research work on it is to apply modern control theory approach to optimize the control strategy and improve the stability of the system.This paper at first made use of computer simulation software Matlab/Simulink and established the seven degrees of freedom vehicle model including the longitudinal motion, the lateral motion, the yaw motion and four wheels which were then used to simulate the vehicle’s driving under different conditions. Have used magic formula to express the tire model, and by using curve-fitting method based on the relation curve of the road adhesion coefficient and the slip ratio, introduced the road adhesion coefficient to the longitudinal magic formula after which the test has been done to verify the accuracy of the method. Have chosen the logic-threshold control method, a normally-used control strategy on ABS products, which is designed based on the reference slip rate, the wheel rotary acceleration and deceleration as the system control method. Then established the ABS control module by the software Simulink/Stateflow and docked it to the vehicle model. Then simulation experiment was done under the driving condition of emergent straight-line braking at a high speed to verify the effectiveness of the ABS control.The decision of the threshold is important to the logic-threshold control strategy. But as the control logic is complex and the variety of the threshold which is under different driving conditions is lack of very clear theoretical basis. In this paper, the established vehicle model with ABS control module was used so as to analyze the different parameters’ influences on the threshold, which was then verified by the simulation experiments. At last, gave some theory support to the method for choosing threshold.