Modelling Experimentation and Simulation of a Brake Apply System

This study presents the development and validation of an analytic dynamic model of the brake apply system of a vehicle. The brake apply system model includes the brake pedal, vacuum booster, master cylinder and proportioner valves; the interactions with the wheel brake system, the front and rear brakes are included by modelling the compliance of the caliper and the drum brakes. Laboratory experiments are performed on a bench setup of the base brake system and the experimental data are compared with the theoretical predictions. The model is formulated such that the inputs are the pedal force applied by the driver, the vacuum supplied by the engine and the physical parameters of the brake components. The simulation predicts apply and vacuum chamber pressures; the output force, and input and output travels of the vacuum booster. Furthermore, front and rear hydraulic line pressures, prop ortioner piston travel and proportioner valve hysteresis are also predicted.