Autonomous Emergency Braking Control Based on Hierarchical Strategy Using Integrated-Electro-Hydraulic Brake System

摘要

Highway traffic safety has been the most serious problem in current society, statistics show that about 70% to 90% of accidents are caused by driver operational errors. The autonomous emergency braking (AEB) is one of important vehicle intelligent safety technologies to avoid or mitigate collision. The AEB system applies the vehicle brakes when a collision is eminent in spite of any reaction by the driver. In some technologies, the system forewarns the driver with an acoustic signal when a collision is still avoidable, but subsequently applies the brakes automatically if the driver fails to respond. This paper presents the development and implementation of a rear-end collision avoidance system based on hierarchical control framework which consists of threat assessment layer, wheel slip ratio control layer and integrated-electro-hydraulic brake (IEHB) actuator control layer. The threat assessment layer continuously calculates threat metrics associated with collision avoidance by braking control. The tire slip ratio control layer with radial basis function (RBF) neural network control based on robust compensation term (RCT) is designed to obtain a desired braking torque, which enabled the controlled vehicle to generate the highest possible deceleration. As for the I-EHB actuator control layer, a resembling pulse width modulation (PWM) control method is adopted to convert the regulation information of the upper controller into the PMSM torque, the valve status (open / closed), and the hydraulic pump status (enabled / disabled). Finally, simulation test is conducted via co-simulation platform of MATLAB/Simulink and AMESim under scenarios of the active emergency braking process on high adhesion coefficient road and low adhesion coefficient road. The results show that the proposed AEB system control scheme is verified.