Anti-roll Control Of Vehicle By Hardware-in-the-loop Based On EHB System

The braking system is one of the most important factors that affect the safety of the car.The electronically hydraulic brake system has been widely used for its high brake pressure and rapid response.This paper takes the vehicle with EHB system as the research object,in order to research the roll stability.First,building the EHB system test bench,EHB system hardware on the ring platform;Second,establishing the vehicle dynamics model,EHB system actuator Dynamic model;Third,designing double-layer control strategy.The upper-layer control strategy is for anti-rollover control,the lower-layer control strategy is for the control of wheel cylinder pressure.Analyzing the roll stability of automobile under typical working conditions;finally,carrying out the breaking and hardware-in-the-loop experiments to verify the reliability and applicability of the control strategy.The main contents contributions are as follows.(1)Establishing the EHB system experimental bench and hardware-in-the-loop experimental platform.Establishing the EHB system experimental platform according to the principle of electronically controlled hydraulic brake(EHB)system,and carrying out verification experiments.Building hardware in the loop system of the EHB system with the XPC Target toolbox of Simulink based on the EHB system platform.Related hardware connection and software debugging are needed for the experimental platform.The main work of software debugging includes the establishment of target boot disk,communication setting between target machine and host machine,debugging and implementation of CAN communication,converting Simulink model to C code,etc.(2)Establishing dynamics models of the vehicle and the actuator of EHB system.A three degree and nine degree of freedom rollover dynamic are established respectively according to the vehicle dynamics equation.Some measure is taking to eliminate the algebraic ring in the nine degree of freedom rollover dynamic.The dynamic model is established according to the hydraulic characteristics of the EHB system actuator.The model is verified by the EHB system gantry.According to the nonlinearity and time-varying characteristics of the EHB system,the Unscented Kalman Filter(UKF)is used to track the pressure of the brake wheel cylinder of the EHB system,and the particle swarm(PSO)is used to optimize the parameters.(3)A two-layer control strategy is proposed.The upper control strategy is designed for anti-rollover control.The roll stability is selected as the control target,and white noise is introduced into the system at the same time.The PID control theory optimized by the Kalman filter is used todesign the anti-rollover control strategy based on the roll angle according to the principle of differential braking.The control strategy is verified under typical conditions and the results show that the algorithm can improve the anti-rollover performance of the vehicle and eliminate the influence of external noise on the system.The lower-layer control strategy is used to adjust the pressure of wheel cylinders.The fuzzy algorithm is used to adjust the duty cycle of the PWM so that control of the brake pressure,taking the difference between the target pressure and the current pressure as the control target.(4)Designing the experiments of braking and hardware in-the-loop.The performance of the EHB system platform and the reliability of the pressure control algorithm are analyzed by the braking experiments.The result shows that the pressure of the brake wheel cylinder is precise and the EHB system platform meets the requirements of braking.The hardware-in-the-loop experiments are carried out to verify the applicability of the anti-rollover control algorithm.It has been verified by experiments that the anti-rollover control strategy has good applicability.