Pressure Tracking Control of Electro-Mechanical Brake Booster System 2020-01-0211
The Electro-Mechanical Brake Booster (EMBB) is a kind of novel brake-by-wire system, which integrates active braking, regenerative braking and other functions. It usually compose of servo motor, transmission mechanism, and hydraulic system. The EMBB system can greatly meet the development needs of vehicle intelligentization and electrification. For safety reasons, we usually requires the EMBB system to respond fast and accurately to braking requests during active braking. In engineering, the PID algorithm is often adopted for the pressure control of this actuator mechanism. However, since the EMBB is coupled with the hydraulic system, it is normally regarded as a nonlinear controlled object and therefore a large number of PID parameter tuning is required. In this paper, A fuzzy adaptive PID pressure control algorithm based on P-V characteristic of hydraulic system is proposed for the control of the self-designed EMBB to resisting its nonlinear characteristic. Firstly, the structure of the EMBB system used in the paper and its working principle are introduced. Secondly, a two-layer closed-loop control structure to control the EMBB is designed. The upper layer is a pressure control loop using fuzzy PID algorithm based on feedforward, and the lower layer is a motor control loop composed of position loop and current loop. Finally, we modified an electric vehicle platform and used the self-designed EMBB mechanism to replace the vacuum booster. Based on the modified vehicle platform, the pressure tracking test verification of multiple working conditions was carried out. The experimental results show that the control algorithm of this paper can effectively enhance the accuracy of EMBB pressure control and its response speed during active braking and could meet the practical requirements of intelligent vehicles.