Study On ESC Hierarchical Control Strategy And Control Methods Of HCU For Passenger Car

With the continuous increase in the number of domestic car ownership and the number of drivers,car safety and accident prevention have become more and more important.Consequently,the Electronic Stability Control(ESC)has attracted widespread attention.ESC can effectively reduce the incidence of traffic accidents when the vehicle is in emergency avoidance and is an important auto accessory in active safety technology of vehicles.The ESC of domestic passenger car assembly is mainly provided by foreign companies,so it is of great significance for the research of ESC technology and the development of product.The research is completed on the basis of the school enterprise cooperation project.The project is based on passenger cars,taking the automobile dynamics and modern control theory as the means.The main work is the estimation of state parameters,stratified control strategy,pressure estimation and pressure control of wheel-cylinder in ESC system Research.The main contents of this paper are as follows:The first part is the estimation of the vehicle driving state parameters and the simulation verification of the algorithm.This paper analyzes the research trends of vehicle state parameter estimation in recent years,establishes two vehicle models based on linear tire model and nonlinear tire model,and uses IMM-SRCKF algorithm to estimate the side slip angle and other state parameters.SRCKF is responsible for calculating the estimated value of the state parameters of two vehicle models.The IMM algorithm is responsible for adjusting the weight of the two filters.The estimation method of the adhesion coefficient of the pavement and the correction method of the output data of the lateral acceleration sensor are described in this paper.Simulink and Carsim software are combined to verify the algorithm under multiple road condition experiments.The simulation results show that the algorithm can not only accurately estimate the side-slip angle and tire force on bank road,but also adjust the weight of the filter model based on road condition,so that we can get the parameters accurately under various conditions.The second part is the research and verification of the ESC control strategy of the passenger car.In this paper,the research progress of stratified direct yaw moment control algorithm and its application in engine torque regulation algorithm is analyzed.A coordinated control method based on b-b(5)plane method is researched and designed,which enables direct yaw moment algorithm and engine torque regulation to achieve coordinated control in maintaining vehicle stability.The direct yaw moment is a sliding mode control algorithm,in which the target value is calculated based on the linear two degree of freedom vehicle model.The distribution method of yaw moment and the calculation process of wheel cylinder target braking pressure are described.The engine torque regulation is obtained by fuzzy algorithm.The input value of fuzzy algorithm is composed of vehicle state parameter and steering wheel angle of driver input.The output value of engine torque regulation is sent to EMS through CAN bus,so as to achieve engine torque adjustment.The algorithm is verified by the combination of Simulink and Carsim software.The algorithm is verified by sine dwell test and steering wheel amplification test.The three cases are simulated,simulation results show that DYC and ETC control strategy can effectively ensure vehicle driving stability and improve vehicle's maneuverability under extreme conditions.The fourth part is the research of HCU modeling and wheel cylinder pressure estimation and control algorithm.The research progress of wheel cylinder pressure estimation and pressure control is analyzed in this paper.The mathematical model of each component of HCU is studied,and the hydraulic model of HCU is established by using the hydraulic simulation software AMESim.An estimation method of wheel cylinder pressure based on P-V characteristics of brake wheel cylinder is designed.The pressure control part of the wheel cylinder is designed based on the sliding mode control algorithm and the control method of the oil outlet valve based on the decompression and pressure maintaining.The active pressurization control part mainly studies the motor control and the study of the active boost pressure through the conversion valve.In the active pressurization control part,the research of motor control and the research of converter valve control are mainly done.The pressure estimation and pressure control of wheel cylinder and active supercharging are verified by Simulink and AMESim software.The fifth part is the hardware in the loop simulation platform experiment and the real car verification.The structural frame of the hardware in the loop simulation platform is designed.Because the brake pressure of the wheel cylinder target calculated by the ESC control algorithm depends on the realization of the HCU,the underlying drive circuit board is designed.The bottom drive circuit board includes solenoid valve drive circuit,plunger hydraulic pump drive circuit,CAN bus circuit,main cylinder pressure sensor power supply and AD acquisition circuit.In the bench test,pressure control,pressure estimation and ESC control strategy is verified;and finally the experimental vehicle modified by sinusoidal hysteresis and double lane change conditions to verify the algorithm.