Global Sliding Mode Control for Nonlinear Vehicle Antilock Braking System

In order to further improve the braking performance of the nonlinear antilock braking system (ABS), an improved global sliding mode control scheme is presented. First, a nonlinear global sliding mode surface is designed. The method can eliminate the reaching phase compared with conventional linear sliding mode surface, and guarantee the system robustness during the whole control process. Then, a novel control law is proposed to satisfy the sliding mode reaching condition, and the theoretical proof is given. Simulation results demonstrate that the proposed global sliding mode control scheme enables the wheel slip-ratio to converge to optimal value quickly with the small oscillation, and has relatively short braking distance and braking time, which is very suitable to prevent the wheel from being locked during braking. The proposed global sliding mode control scheme is verified by joint simulation using MATLAB and CarSim, and shows good braking performance when the car is driving under extreme road conditions, which indicates the effectiveness of the proposed sliding mode control scheme.