Development Of Autonomous Emergency Braking System Controller For Electric Vehicle

In recent years,with the rapid increase of the number of cars,the problem of road traffic safety becomes more and more serious.The automatic emergency braking control system can effectively identify the potential rear-end accidents in the process of vehicle driving,automatically trigger the braking system in time to avoid accidents,which is conducive to the safety of passengers.This paper will focus on the research of vehicle emergency braking controller,using the information collected by sensors to detect the driving conditions.When the dangerous conditions come,the controller will replace the driver to trigger the braking system,obtain the shortest braking distance with the function of wheel anti-lock braking control,and finally achieve driving collision avoidance or reduce the impact of injury.First of all,we use Freescale DSP to develop the controller.The hardware part takes MC56F8346 digital signal processor as the core.On top of that,we designed the minimum system circuit of DSP,the CAN communication circuit of signal transmission between DSP and radar sensor,the SCI communication circuit of signal transmission between DSP and PC,the A/D signal conditioning circuit of collecting brake pedal position signal,the signal conditioning circuit of collecting wheel speed,and the solenoid valve of braking system.In the software of Altium designer,we drew the related circuits,and made complete controller circuit schematic diagram and PCB diagram.In the software part,the application program of the required module is developed in Code Warrior 8.0,including A/D signal acquisition program,capture program,SCI serial communication program,CAN communication program and PWM control signal output program.The controller has the basic function of signal input and output.Secondly,the relevant control strategies and algorithms are studied around autonomous emergency braking.By using the safety distance model to set the trigger conditions of autonomous braking,when the vehicle risk coefficient reaches the set threshold,the braking system will automatically trigger;based on the idea of weight analogy,the adhesion characteristic curve of typical pavement is used to identify the adhesion characteristic of unknown pavement,which is helpful to set the parameters in the braking control system.In order to prevent the wheel from locking in the process of braking,the fuzzy control algorithm is used to control the wheel braking torque,so that the slip rate is stable near the optimal value.Finally,the mathematical model of the control system is simulated in Simulink and d SPACE environment.Change the relative speed relationship between the self car and the front car,and observe the movement state of the two cars during driving.The simulation results show that the autonomous emergency braking system in this paper can achieve the function of self emergency braking and anti-collision in a variety of working conditions,and it has application value in the aspect of vehicle safety assistant driving.