Braking pressure control in electro-hydraulic brake system based on pressure estimation with nonlinearities and uncertainties

•Drawback: The influence of friction is reduced by using chatter/dither compensation [13]. [14] employs the Stribeck friction model compensation through a linear-in-the-parameter model. In [15], the LuGre dynamic friction model is proposed to reduce the dynamic pressure error. The load-dependent friction model is seldom mentioned. Highlight: The position-dependent Coulomb + viscous friction model is adopted to represent the friction, and the average relative root-mean-square error (ARRMSE) is below 0.11, meeting the requirements of controller design.•Drawback: In [25], a cascade controller based on a nonlinear observer is presented to track the desired pressure for a pressure sensor unequipped EHB, which is the first time to conduct the discussion on the pressure control issue of the sensorless EHB. The pressure estimation based on the available position of master cylinder piston in the EHB hasn’t been discussed so far. Highlight: This paper presents an interconnected pressure estimator with nonlinearly parameterized perturbations, having realized a closed-loop pressure control without expensive pressure sensor (even without add-in sensors).•Drawback: The estimator-based hydraulic pressure control system hasn’t been verified. Highlight: This paper presents an adaptive sliding mode controller (ASMC) in EHB based on pressure estimator, improving the robustness of system.•Drawback: The previous analysis on the stability of the interconnected system just focuses on the stability of observer and controller separately. Highlight: The interconnected stability of the whole control system is analyzed based on the Lyapunov Theorem. Superior to the conventional brake systems, brake-by-wire (BBW) systems can produce faster response and better performance. This paper presents an adaptive sliding mode hydraulic pressure controller based on a hydraulic pressure estimator to track desired hydraulic pressure for ‘sensorless’ electro-hydraulic brake system (EHB) in the presence of both nonlinearities and uncertainties. There are no add-in sensors (i.e. pressure sensor, position sensor) equipped in the sensorless EHB. The rotation angle of the motor is available by the braking control unit, and it can be transformed to the position of the master cylinder piston via the kinematic relationship. The position is utilized as the input of the whole control system. The friction of the EHB is analyzed and the position-dependent Coulomb + viscous friction model is presented to repres