Nonlinear electro-mechanical braking clamping force control based on improved barrier lyapunov function

Abstract To address the issues of slow braking response time and low clamping force control accuracy in Electro-mechanical braking systems (EMB), a constrained backstepping sliding mode control method based on a Barrier Lyapunov Function (BLF) is proposed. Firstly, considering the nonlinear characteristics of the EMB system, a state-space model in strict feedback form is established. Secondly, a time-varying tangent-type Barrier Lyapunov Function is constructed, where an exponentially decaying time-varying function is used as the constraint boundary, and an integral term is introduced to reduce the steady-state error caused by unmodeled dynamics. On this basis, the control law is designed by combining the backstepping method with nonsingular fast terminal sliding mode control to achieve fast and accurate tracking of braking clamping force. Finally, the stability of the system is proven based on the Lyapunov stability theorem, and experimental validation is conducted. The results indicate that under step conditions, the response time of the proposed control method is improved by 58%. In terms of control accuracy, the standard errors under triangular wave and sinusoidal wave conditions are reduced by 29.48% and 31.78%, respectively. This verifies the superiority of the proposed control method.