Adaptive sliding mode pressure control for an electro-hydraulic brake system via desired-state and integral-antiwindup compensation

Brake-by-wire (BBW) systems are electronically regulated actuators, which are capable of producing a desired braking torque to the vehicle's wheel. This paper focuses on the motor-type electro-hydraulic brake (EHB) system: an electric motor driven rotational-to-linear reducing mechanism that directly pushes the master cylinder to generate hydraulic pressure. A simple and practicable controller is developed to reduce the negative influence of system nonlinearities and uncertainties. Unlike the complicated stribeck-speed-detected and precise-parameter-identified friction model, a novel efficiency model is developed to describe the friction. Sliding mode control is used to reduce the non-parametric disturbances. Adaptation law based on non-smooth mapping is employed to weaken the parametric uncertainties. Desired-state compensation is applied to prevent the real pressure fluctuation weakening the performance of adaptation law. Anti-windup mechanism is adopted to compensate the integral windup action and tracking the desired pressure high-precisely. The stability of system is proved based on the Lyapunov function approach. The simulation and experimental results in the typical braking scenarios are conducted to verify the enhanced performance.