Abstract:

For the functional requirements of advanced automatic driving， this paper proposes a brake-by-wire system， including two operating modes： conventional braking and redundant braking. The system decouples the brake pedal and brake pressure and realizes active braking by wire in both modes. And for the conventional braking that accounts for most of the working intervals， a variable equivalent piston cross-sectional area control method is used to ensure pressure control accuracy while reducing the performance requirements of hydraulic cylinder motor and extending its service life. Meanwhile， to achieve accurate pressure control， pressure control algorithms based on p-V characteristics of wheel cylinders and solenoid valve overflow characteristics are proposed respectively according to the different hardware structure characteristics of the two working modes. Finally， the simulation analysis and hardware-in-the-loop test are carried out. The results show the feasibility and effectiveness of the proposed brake by wire system and pressure control algorithms.

Key words: advanced automatic driving, brake-by-wire, variable equivalent piston cross-sectional area control, pressure control algorithm