Nonlinear Backstepping Control of Electro-Hydraulic Brake System Based on Bond Graph Model

EHB (electro-hydraulic brake system) can provide active and decoupled brake for electric intelligent vehicles. However, modelling and control of automotive electro-hydraulic brake systems are always challenging due to the complex and highly nonlinear dynamic characteristics of the braking process. In this paper, a nonlinear backstepping control algorithm for EHB based on the bond graph model is introduced. A nonlinear, single-wheel brake system model is constructed using the bond graph method, in which the capacitive effect of the hydraulic fluid and the damping and inertia effects of calipers are considered. Based on this nonlinear model, a backstepping controller with good robustness is designed, and the control signals of the inlet and outlet valves are described by a unified expression. Moreover, the effects of the controller parameters on brake-pressure control are discussed in details, and suitable design parameters are chosen. Finally, the proposed algorithm is verified by the simulation and hardware-in-the-loop tests. The results show that valves are properly regulated by the backstepping controller, and the brake pressure follows the desired value rapidly and accurately.