Nonlinear Integral Sliding Mode Control for Electromechanical Brake System with Friction and Disturbance Compensation

The performance of the electromechanical brake (EMB) at the wheel end is challenged by the system's nonlinear characteristics, while robust control can enhance tracking accuracy in its servo system. In this article, a nonlinear integral sliding mode control (NISMC) strategy with friction and disturbance compensation is proposed for the EMB braking system, which combines a nonlinear integrator to eliminate the steady-state control errors caused by insufficient feedforward compensation. Notably, friction asymmetry is analyzed in detail based on the unwrapped planar ball screw model. A switching extended state observer (SESO) is designed to achieve rapid estimation of uncertainties in the EMB system, such as time-varying parameters, external disturbances, and unmodeled dynamics. To evaluate the effectiveness of the proposed control strategy for EMB, both simulation and hardware-in-the-loop tests are conducted under various conditions. Experimental results demonstrate that the designed strategy enhances the servo system's overall stability, control accuracy, and dynamic responsiveness.