A Passenger Car Brake Pedal Feel Analysis Model Based on Integrated Brake by Wire System

The fully decoupled brake by wire system is a complex system consisting of mechanical components such as springs and rubber and hydraulic structural components coupled together. Compared to conventional braking systems, it is characterized by the full decoupling of the brake pedal from the brake wheel cylinders in normal braking mode, and the pressure fluctuations in the wheel cylinders do not affect the pedal feel. In order to predict brake pedal feel in a passenger car, a dynamic model was developed for both normal and backup braking modes, taking into account the variation of the volume modulus of the brake fluid and the frictional forces of the master cylinder pistons. The influence of different pedal input speeds on the pedal feel characteristic curve was analyzed using static vehicle tests and the related parameters of the braking system were identified in order to correct the design data. Subsequently, a dynamic test of the vehicle pedal feel was conducted to establish a quadratic graph of pedal stroke, pedal force, servo cylinder pressure and vehicle longitudinal deceleration. The accuracy of the dynamics model was verified using vehicle tests, and we believe that this new dynamics model of the decoupled brake system can accurately predict brake pedal feel and can be used for the design and optimization of the brake system.