Parking Path Planning And Tracking Control Research Based On Front Parking

With the continuous increase in the number of cars in our country,the parking space in cities is becoming more and more scarce,and the parking environment is becoming more and more severe.Especially in big cities,safe parking has become one of the problems that plague people.In traffic accidents,traffic accidents caused by parking errors are not uncommon.As one of the important components of autonomous vehicles,the automatic parking system has always had broad application prospects in the automotive development industry,and it is also a hot spot in the current research on autonomous driving and automotive intelligent technology.There are still several obvious shortcomings in the current automatic parking system:First,the existing automatic parking systems are based on reversing,and some new electric vehicle charging ports are installed on the front of the car,and the charging cable is too short to be charged when reversing into the garage.The problem is that even if the charging cable is long enough,there is a danger of being stretched too long and there is a potential safety hazard.Therefore,the existing parking method based on reversing is not suitable for some electric vehicles;In the research and development,the steering and braking constraint ability of the vehicle and the initial dynamic pose conditions of the vehicle have not been fully considered,and there are potential problems such as curvature discontinuity in the reference path planned by the system.These potential problems may affect the actual vehicle.On the other hand,the control effect of the existing tracking controller is greatly affected by the vehicle speed,and the trajectory tracking control method needs to control the vehicle speed and the steering wheel angle at the same time.If the vehicle speed error or steering wheel angle error is large,it will directly affect the trajectory tracking effect;finally,in the existing parking system research,there is still a situation in which a single software such as MATLAB is used for simulation,which often simplifies the vehicle.,which reduces the simulation accuracy and causes many problems in the real vehicle testing process.Aiming at the problems existing in the existing parking system,this paper designs a new parking method.The main contents are as follows:（1）A new parking method based on front parking is proposed to make it more suitable for electric vehicles,and the limit position of the parking process is determined by geometric method.And combined with the possible collision obstacles in the parking process,the feasible area of the parking starting point is analyzed.（2）Design the parking path according to the motion constraints of the vehicle,the normative constraints of the starting point and the parking point of the vehicle,and the environmental obstacle constraints.The designed parking path satisfies the path curvature and the continuous change of the steering angular velocity of the car steering wheel,while avoiding the possibility of collision in the parking environment.（3）The MPC controller is used to control the vehicle to follow the reference path to improve the tracking accuracy of the parking process,and compare with the LQR and PID controllers to illustrate the advantages of the controller.（4）The combined technology combining the Car Sim vehicle model and the Simulink model is used to carry out the simulation experiment by building the vehicle model in the Car Sim model system,and building the vehicle path planning model and the vehicle tracking controller model in Simulink respectively.The co-simulation of the vehicle parking system can accurately analyze the motion state of the vehicle during the automatic parking process.The experimental results show that the planned path satisfies the nonlinear constraints of the parking process,and the adopted MPC controller can better track the planned path and the control effect is significantly higher than that of the LQR and PID controllers.