Research On Vehicle Stability Enhancement Using Active Aerodynamic Control System

To improve the stability of vehicles under high-speed working conditions is a main technical problem in the field of vehicle safety.The existing safety auxiliary control of high-speed vehicles mainly includes braking,suspension and steering.However,each method has some limitations.Although studies have considered the integration of multiple control methods,they are mainly based on the integrated control of the active steering,active/semi-active suspension,and traditional differential braking.This subject focuses on the main problems and urgent application needs in traffic safety,and selects high-speed vehicles as the research object.The effects of active aerodynamic system on vehicle dynamics and stability control are studied from two aspects:active aerodynamics and integrated control of vehicle dynamics.Firstly,the MIRA international standard model of stepped back was established by UG software.On the basis of this model,the 3D digital model of actuators of active aerodynamic system was added.Based on the theory of computational fluid dynamics,the flow characteristics of vehicle flow field are combined.The ANSYS/ICEM software was used to mesh and optimize the grid.In the ANSYS/Fluent software,the Realizable model was used to simulate the turbulence of the flow field.The setup of the solver and the simulation algorithm were analyzed and selected.Secondly,in order to improve the high-speed stability of the vehicle,a new control method for vehicle stability control was presented,which was applied additional yaw moment to intervene the state of the vehicle by means of active aerodynamic control and differential braking control.The aerodynamic force and aerodynamic moment of the vehicle are controlled by controlling the angle of attack of two active airfoils independently.The control architecture for the stability system is hierarchical.In the upper layer,the desired yaw rate was calculated with the consideration of vehicle dynamics and tyre adhesive limit.In the middle layer,a Fuzzy controller was designed to determine the additional yaw moment in real time.In the lower layer,a new control stratage was proposed to coordinate active aerodynamic control and differential braking control,and stability control was carried out by tracking desired yaw response.The proposed method was evaluated via Carsim/Simulink.The results show that the proposed method can make the vehicle yaw response track the desired value,and can effectively reduce the tyre work load.Finally,The hardware in loop simulation platform was established,and the hardware in loop test was carried out on the active aerodynamic vehicle stability control method in this paper.The real-time simulation model was established by using Carsim/LabviewRT,and the data acquisition system was established.The experimental results show that the wheel cylinder pressure of the vehicle was lower than that of the vehicle under differential braking control,which reduces the working load of the braking system and avoids the tire saturation when the vehicle is running at high speed.