The Control Algorithm And Simulation Study For Automotive ABS

With the development of automotive industry, vehicles become faster and faster, people pay more attention to the safety performance of vehicles. The vehicle anti-lock braking system (ABS) can automatically control the brake torque of each wheel to prevent it from getting locked in the process of braking, and maintain the wheel slip ratio near the optimal slip ratio. It improves the braking performance and directional stability of vehicle. Therefore, as an effective vehicle active safety device, ABS is applied wider and wider. But the logic threshold control method which is widely applied ABS products is not an ideal vehicle ABS control strategy, it is necessary to do further research on ABS control strategies.First of all, This paper analyzed the ABS working theory, and introduced the basic components, layout and several primary control strategies of ABS. Then using ADAMS/Car, a multi-body vehicle dynamic model was built, the model included front and rear suspension system, steering system, brake system, tire model, powertrain and vehicle body model. According to fuzzy control theory, the ABS fuzzy control system based on the wheel slip ratio was built by using MATLAB fuzzy toolbox, and the road identification system was designed for ABS. The ABS fuzzy control system, road identification system and multi-body vehicle dynamic model were integrated by the interface of ADAMS/Controls. Then the straight-line braking simulations were carried out on the different friction coefficient roads. The simulation results show that the ABS fuzzy controller can maintain the wheel slip ratio near the optimal slip ratio and significantly improve the braking performance of the vehicle. But by comparing the results, We can find that the controller has better effect on the road with high friction coefficient. When driving on the road with high friction coefficient to the road with low friction coefficient, the fluctuation of slip ratio is obvious, and transient locking phenomenon appears.To enhance the adaptive ability of ABS fuzzy controller, according to analyzing the affect of quantification and scaling factors, the quantification and scaling factors self-modified fuzzy controller was designed. The simulation results show that compared with traditional fuzzy controller, the self-adaptive fuzzy controller can better adapt to changes of road, and can further improve the braking performance of vehicle.