Study on precise control of braking pressure in an electro-hydraulic brake system

To improve the braking pressure tracking performance of the electro-hydraulic braking (EHB) system, this paper proposes a high-precision brake pressure control strategy. Considering the effects of nonlinear friction and external disturbances on pressure control, a master cylinder pressure dynamic model is established, and a hierarchical control architecture is constructed, consisting of an upper-level pressure servo loop and a lower-level motor current loop. An improved PINN–LuGre friction model is introduced to enhance the accuracy of nonlinear friction characterization, while an improved linear extended state observer (ILESO) is employed to estimate and compensate for external disturbances in real time. Based on this, the upper-level pressure servo loop adopts an improved super-twisting sliding mode control (ISTSMC) scheme to achieve robust pressure tracking, and the lower-level motor current loop achieves precise actuation based on feedforward decoupling. Hardware-in-the-loop (HiL) experimental results show that the proposed strategy improves pressure tracking accuracy under ramp and step conditions. For low- and high-frequency sinusoidal conditions, the RMS error is significantly reduced, validating its effectiveness.