Study On Tracking Characteristics And Control Strategy Of Electric Vehicles

The electrification and intelligence of automobiles have become a research hotspot in the automotive field at present.Electric vehicles will also become the mainstay of future unmanned vehicles.As one of the key technologies for unmanned driving,tracking control is the executor of upstream decision-making,which directly affects the driving performance of the car.As the power source of electric vehicles,permanent magnet synchronous motor is one of the key factors affecting the tracking effect.In this paper,aimed at the tracking control of electric vehicles,the drive control and tracking control of permanent magnet synchronous motor are studied.The main research contents of the thesis are as follows:(1)According to the driving equation of electric vehicle,the dynamic parameters of the Rainbow car independently developed by Dalian University of Technology are matched,the performance parameters of the permanent magnet synchronous motor are designed,and the vector control method is adopted for the matched permanent magnet synchronous motor.The mathematical model of permanent magnet synchronous motor is built in Simulink environment.Combined with CarSim,the vehicle environment is modeled and the dynamic performance of the motor and the speed following performance of the vehicle are simulated.(2)The influence of the design of the tracking controller and the design of the tracking control on the tracking effect during the driverless process is studied.In the input of the tracking controller,the relationship between the current state of the vehicle,the location of the vehicle and the planned trajectory is studied.The establishment of the state equation and the selection of the control strategy are analyzed in the design of the controller.A three-degree-of-freedom vehicle dynamics model and a magic formula-based tire model are established.Based on the load transfer characteristics of the tire under the dynamic condition of the vehicle,the tracking controller is established by using the model predictive control algorithm.The variation of longitudinal force and lateral force under dynamic load transfer of the tires is analyzed.(3)By building Simulink and CarSim co-simulation platform,vertical PID and horizontal MPC tracking controller are designed.Considering the kinematics and dynamics of the car,path planning and velocity planning are performed on the trajectory by fitting the polynomial curve.The urban road conditions and high-speed road conditions are analyzed.The path and speed of the trajectory are designed from the perspective of road construction and vehicle dynamic performance.The simulation analysis of the tracking and control of urban working conditions and high-speed working conditions in the joint simulation environment is carried out.(4)Based on dSPACE equipment and UWB indoor positioning module,using the positioning algorithm based on least squares method,the experimental platform of vehicle tracking control is built,and the experiment of low speed overtaking condition is carried out to verify the real-time performance and reliability of the algorithm.The experimental results show that the it has good tracking performance under low speed conditions.