Research On Decoupling Control Of Longitudinal And Lateral Dynamics System For Electric Vehicle

Electric vehicle(EV)is impacting the traditional fuel vehicle market with its excellent characteristics of zero pollution and low noise.Highly integrated system injects strong power into the steady and rapid development of EV.Highly integrated motion control system has become an inevitable trend in the development of modern automobiles,but at the same time,due to integrated control,the interaction between various motion subsystems of vehicles is becoming more and more important.Especially in the current environment of pursuing safer and more intelligent transportation system,excellent handling stability and comfortable ride comfort of vehicles become an important part of the development of electric vehicles.Therefore,precise and efficient control of vehicle movement in all directions to avoid the interference between different forms of motion has become the focus on the current development of electric vehicle dynamics.Based on the dynamic coupling analysis of the electric vehicle system,this paper studies the decoupling control of the longitudinal and lateral motion system of the electric vehicle,aiming at the coupling problem between the longitudinal and lateral motion subsystems in the process of vehicle motion.Firstly,an electric vehicle model is established based on ADAMS-Car.Stepped steering,braking and steering braking are set up respectively.The displacement and velocity curves of the vehicle model along the longitudinal,lateral and vertical directions under three different working conditions are simulated and analyzed.The mutual coupling effect of the motion in each direction during the driving process of the electric vehicle is verified,and the dynamic coupling mechanism of the electric vehicle is further analyzed.Secondly,the vehicle motion is analyzed,and the 14-DOF dynamic model of electric vehicle including the longitudinal,lateral and yaw motion of the vehicle,the vertical,roll and pitch motion of suspension mass,the vertical motion of non-suspension mass and the rotation motion of four wheels is established.A reasonable tire model is established according to the tire related research theory.The longitudinal force,lateral force and return moment of automobile tire under a single working condition are analyzed and verified.A four-wheel random road input model is established by MATLAB/Simulink.According to the differential equation of vehicle dynamics,the whole vehicle model is built,and the validity of the model is verified by simulation under different working conditions.Finally,the state space equation of the dynamic system for the vehicle model is established,combined with BP neural network and inverse system theory,the reversibility of the vehicle dynamics system model is verified,and the BP neural network model is established.The BP neural network is used to approximate the inverse system of the vehicle dynamics model.Then the inverse system of the neural network is connected in series to form a pseudo-linear system before the original vehicle model.The closed-loop controller is composed of the PID controller and the inverse system of the neural network.The performance of different vehicle motion modes before and after decoupling is validated by setting different working conditions.The simulation results show that the closed-loop decoupling control based on neural network inverse system can effectively reduce the coupling effect of each motion system,and It can effectively improve vehicle ride comfort and handling stability.