Analysis And Simulation Of High-performance Automobile ABS

With the development of science and technology and the popularization of cars, human's requirements of vehicle security become higher and higher, especially the braking security. Anti-lock brake system (ABS) is a kind of device, which can regulate the wheels'braking force automatically, prevents the wheels from locking and acquires the best effect during braking. This device is significant to steering safety. At present, in the practical vehicle ABS productions, logic threshold control is most widely used. These thresholds which are obtained from plenty of experiments are important parameters in the control process. But in practical situation, some parameters such as vehicle speed and slip rate are very difficult to be measured. Usually these parameters are estimated from the wheel velocity, but the estimated control parameters often have great deviation from the actual value. Thereby, This paper proposed the control strategy based on braking time interval, the strategy need no to estimate vehicle speed and slip rate, also obtain better control effect, that provide a new concept for the research of high-performance vehicle ABS.First, this paper introduced working principle and basic theoretical knowledge of vehicle ABS, and then established a mathematical model which is based on the kinematics analysis of the braking process, and analysis and simulation are achieved by C language, simulated the whole braking process of vehicle without ABS, analyzed the influence of relevant factors such as initial braking speed, angle of pavement, adhesion coefficient of pavement and braking force on braking ability and evaluated the influence by the relationship of the factors, then it obtained important conclusions which provided important references for future research of vehicle safety.Second, this paper proposes a new ABS control strategy called time interval algorithm (TIA), the control process is based on the braking time interval. In the whole process, with the change of braking time interval, the average braking force changes so the strategy can adapt to the need of braking strength in different pavements and finally it achieves the purpose of preventing the wheels from locking. This strategy ensures the stability and maneuverability in the braking process and enhances the security of vehicle. The control strategy needs not to evaluate the vehicle velocity, and it has advantages of low costs, simple control strategy and great applicability.Finally, taking the proposed control strategy applied to some special conditions, such as when braking on the bisectional roads (the adhesion coefficient provided by the two sides of pavements are quite different), and propose a corresponding control method so that the vehicle can get a good lateral stability which highly improved the safety of braking. Taking the control strategy applied to the vehicle model with suspension, this paper proposes corresponding control method, and the expected safety and highly efficient were obtained.At the end of this paper, a conclusion of this research is given, from the results of simulation, it shows that the proposed control strategy has great theoretical signification to the vehicle ABS, it is a simple, safe and stable control method. Further research work needs to be continued to complete the control strategy.