Research On Vehicle Stability Control Of Integrated Electronic Control Brake System

At present,the automobile industry is facing the reform of intelligent and electric.The traditional vacuum brake booster can not meet the demands of functions about advanced driving assistance system(ADAS).At the same time,the government agencies and automobile manufacturers are vigorously promoting the electric vehicles,which requires that the brake system does not rely on vacuum supply,and has the functions of braking energy recovery and active braking.Under this background,the electronic control brake system shows a good development prospect.With the continuous development of electronic control brake system,the integrated electronic control brake system-the 1-Box brak system,has attracted wide attention.It relies on high-performance motor as the power source to complete the braking servo assist.More importantly,after integrating the functions of braking servo assist,wheel cylinder pressure regulation and braking pressure decoupling,it can complete the functions of active braking,composite braking,anti-lock braking and vehicle stability control,which better meets the requirements of intelligent vehicles for the brake system.Based on the school-enterprise cooperation projects ’ Research on Control Algorithm of Intelligent Driving Braking ’ and ’ Development of Integrated Braking Control Algorithm ’,this paper studies the integrated electronic control brak system and vehicle stability control,the paper consists of the following parts:(1)Architecture analysis and modeling of integrated electronic control brake system.In view of the mainstream architecture schemes of electronic control brake system in China and abroad,three typical architecture schemes of electronic control brake system are analyzed,and the main components,working principle and key components of the brake system are analyzed in detail.Then combined with the advantages and disadvantages of each brake system architecture scheme such as the speed of pressure building-up,reliability and the existing resources of the research group,the architecture scheme of the integrated electronic control brake system to be studied in this paper is determined.Then,the dynamic models of permanent magnet synchronous motor(PMSM),deceleration transmission mechanism and hydraulic system in the braking system are established,and the data are collected on the experimental platform to complete the model comparison and verification.(2)Research on control strategy of integrated electronic control brake system.Firstly,in the active pressure control strategy of integrated electronic control brake system,the servo three closed-loop control strategy including current loop,speed loop and position loop is designed to complete the closed-loop control of motor servo position.Then,the servo three closed-loop control is applied as the inner loop,and the pressure loop control is applied as the outer loop.The pressure loop adopts the feedforward compensation + PID feedback control structure.Then,the electrical and hydraulic characteristics of the linear solenoid valve in the hydraulic control unit of the brake system are analyzed.The appropriate fundamental frequency is determined through a series of experiments,and the calibration of the pressurization and decompression of the inlet and outlet valves is completed through multiple sets of experiments.Finally,the wheel cylinder pressure control strategy of integrated electronic control brake system is designed,including single wheel pressure regulation mode and multi wheel pressure regulation mode.The differential braking control of wheel cylinder pressure is realized,which lays a foundation for responding to the brake pressure requirements of each wheel cylinder in vehicle lateral stability control.(3)Research on vehicle lateral stability control strategy.Firstly,the ’ magic formula ’ tire model and the 2-DOF vehicle reference model are established.Through the vehicle lateral stability analysis,the yaw rate and the sideslip angle are selected as the control variables for the vehicle yaw control.Then,considering the delay characteristics of the vehicle actual yaw rate response and the variation of vehicle stability factor,the ideal value of the yaw rate is corrected.The vehicle lateral stability controller designed in this paper adopts hierarchical control strategy,including decision layer,calculation layer and distribution layer.The decision layer firstly calculates the ideal value of the control variable,and then utilizes the phase plane method of sideslip angle – sideslip angular velocity(-?)and the limit deviation value of yaw angular velocity at different speeds as the stability criterion to determine whether the vehicle is in lateral instability.In the calculation layer,two parameters self-tuning fuzzy PID controllers are designed to separately calculate the additional yaw moment,and the expected additional yaw moment is output by joint weighted control.In the distribution layer,the steering characteristics of the vehicle are judged by combining the positive and negative values of the steering wheel angle,the steering wheel angular velocity and the expected additional yaw moment.Then,through the single-wheel differential braking,the brake pressure is distributed to the corresponding brake wheel cylinder,and the additional yaw moment is applied to the vehicle to correct the understeer or oversteer.(4)Simulation test and hardware-in-the-loop experimental verification based on integrated electronic control brake system.Firstly,a joint simulation environment is built by Matlab / Simulink and Car Sim RT,and a variety of test scenarios and working conditions are set to prove the effectiveness of the lateral stability hierarchical control strategy.Then,based on the tool chain of d SPACE rapid control prototype,a hardware-in-the-loop(HIL)experimental platform is built.The hardwares mainly include hydraulic brake system of passenger car,integrated electronic control brake system,real-time controller Micro Auto Box,real-time simulator SCALEXIO,etc.The softwares mainly include Matlab / Simulink,Control Desk,Configuration Desk,etc.The steering wheel step input,double lane change(DLC)and sine with dwell(SWD)test coditions are set in the hardware-in-the-loop experiments.The experimental results show that the hierarchical control strategy of vehicle lateral stability and the cylinder pressure control algorithm of the integrated electronic brake control system have good control effect.