Structure design and advantage research for bidirectional synchronous force-increasing EMB actuator

Abstract

Electro-Mechanical Brake (EMB) can provide an ideal brake actuator for the active braking system of intelligent vehicles and the decoupled regenerative braking system of new energy vehicles. In order to solve the problem of large volume, weight， and axial size of the existing EMB actuator, a novel bidirectional synchronous force-increasing EMB (BSF-EMB) actuator scheme is proposed. Based on the maximum required braking force of the target vehicle under emergency braking conditions and the limitation of installation space in the wheel hub. The rotary motor and the ball screw are selected, the force-increasing mechanism parameters calculation and structure design are completed. In order to minimize the difference between the force-increasing ratio of the two-stage force-increasing mechanism and the lever force-increasing mechanism. The parameters of the force-increasing mechanism are optimized based on the weight adaptive particle swarm optimization algorithm. The three-dimensional model of the EMB actuator is established. In addition, when the required braking force is the same, the mass and volume of the BSF-EMB actuator can be decreased by about 43.4% and 55.8%, compared with the existing planetary gear force-increasing EMB (PGF-EMB) actuator scheme. Therefore, the BSF-EMB actuator can effectively decrease the unsprung mass of the vehicle and resolve the issue of limited installation space in the wheel hub of compact vehicles. The EMB models for two EMB actuator structures are built based on MATLAB/Simulink, and the EMB braking response speed and tracking performance of braking force are compared. The simulation results show that the braking response speed of the BSF-EMB actuator can be increased by 11%, 10.6%, 12.7%, and 14% compared to the PGF-EMB actuator under emergence braking condition and other three general service braking conditions, and the braking force adjustment is more precise. Finally, the effectiveness for the control strategy is verified by hardware in loop (HIL) experiment under sin wave input condition for braking force. The related research can provide reference for the design and application of EMB.