Pressure Tracking Control of Electro-Mechanical Brake Booster System 2020-01-0211
The Electro-Mechanical Brake Booster system (EMBB) is a kind of novel braking booster system, which integrates active braking, regenerative braking, and other functions. It usually composes of a servo motor and the transmission mechanism. EMBB can greatly meet the development needs of vehicle intelligentization and electrification. During active braking, EMBB is required to respond quickly to the braking request and track the target pressure accurately. However, due to the highly nonlinearity of the hydraulic system and EMBB, traditional control algorithms especially for PID algorithm do not work well for pressure control. And a large amount of calibration work is required when applying PID algorithms to pressure control in engineering. In this paper, a fuzzy adaptive PI pressure control algorithm based on feed-forward is proposed to a novel self-designed EMBB mechanism, which is utilized to overcome the nonlinear pressure control problem when EMBB is in active braking and improve the control effect of PID algorithm. First, the structure of the EMBB system used in the paper and its working principle is presented. Second, this paper designs a two-layer control algorithm to implement the pressure control of EMBB. The upper layer is a pressure control loop using fuzzy PI algorithm based on feedforward, and the lower layer is a motor control loop composed of position loop and current loop. Finally, to verify the proposed control algorithm, a series of pressure tracking tests were performed under multiple operating conditions based on a real vehicle platform equipped with EMBB. The experimental results show that the proposed control algorithm can effectively enhance the accuracy of EMBB pressure control and its response speed during active braking compared with PID algorithm. Therefore, the proposed algorithm can effectively improve the effect of EMBB pressure control.