Vehicle Braking Performance Improvement via Electronic Brake Booster

Throughout the automobile industry, the electronic brake boost technologies have been widely applied to support the expansion of the using range of the driver assist technologies. The electronic brake booster (EBB) supports to precisely operate the brakes as necessary via building up the brake pressure faster than the vacuum brake booster. Therefore, in this article a novel control strategy for the EBB based on fuzzy logic control (FLC) is developed and studied. The configuration of the EBB is established and the system model including the permanent magnet synchronous motor (PMSM), a two-stage reduction transmission (gears and a ball screw), a servo body, reaction disk, and the hydraulic load are modeled by MATLAB/Simulink. The load-dependent friction has been compensated by using Karnopp friction model. Due to the strong nonlinearity on the EBB components and the load-dependent friction, FLC has been used for the control algorithm. The control concept focused on transforming the pressure control to position tracking control of the EBB, which enabled overcoming the nonlinearity in the hydraulic system and achieve the control process with the required precision and dynamics. The improvement on the vehicle braking performance was examined and demonstrated theoretically by comparing the EBB and the vacuum brake booster. The EBB model and its control strategy are integrated to a well-used verified seven degrees of freedom longitudinal-vertical vehicle model. The results showed that the position tracking control of the EBB perform well. The braking performance of the vehicle with EBB is better than the vacuum brake booster in terms of response time and stopping distance and time. Furthermore, the EBB has improved stability in its booster characteristics while maintaining consistency with vacuum brake booster.