Study On The Path Tracking Of Driverless Cars Based On Preset Rolling Time Domain LQR

Pilotless automobile can emancipate human hands,reduce the frequency of traffic accidents,and ensure people’s safety,so pilotless automobile is a direction for the future development of the car,which has a profound impact on the automobile industry and even the transportation industry.At the same time,with the breakthrough and continuous development of artificial intelligence,sensor detection and other core technologies,pilotless automobile will be more intelligent,and it can also realize the industrialization of unmanned vehicles.Therefore,unmanned vehicle has gradually become a hot spot in the world of automotive research.Path tracking control is one of the key technologies of pilotless driving,its main purpose is to track the expected path and ensure the safety,stability and comfort of the running vehicle.It belongs to the upper control of the automobile control system,and the design of the lower layer control is to control the steering angle of the steering wheel by the motor.The upper control and the lower control directly affect the intelligent behavior of unmanned vehicle.Therefore,it is of great significance to study the path tracking control of the unmanned vehicle.The main research work of this paper is as follows:In order to obtain the steering system parameters(rotational inertia J,damping coefficient B,and stiffness coefficient K),the common methods of system identification are first studied in detail,and then the commonly used identification methods are compared in terms of identification accuracy,anti-interference ability,and convergence.Finally,the recursive least square method with forgetting factor was used to identify the parameters of the steering system and a visual interface was written using MATLAB/GUIDE software.The control of steering wheel is studied.Under the condition that the steering system parameters can not be accurately obtained,the steering angle of the steering wheel is controlled by traditional PID,and the control effect can not meet the industrial requirements.In this paper,a robust-backstepping-slidin-mode controller is built by using the parameters of the identified steering system.The experimental results show that the controller has good robustness and the precision of control achieves the desired goal.The path tracking control is studied.Based on the multi point preview driver modeland linear two order optimal control(LQR),the steering control strategy is derived by the rolling time domain(Receding Horizon)method.The simulation results show that the algorithm is ideal for tracking accuracy and stability with the use of two common working conditions of double line and snake line.In order to verify the result of the simulation,the closed loop control system is built by combining the path tracking control with the motor control.The HIL experiment of path tracking is designed by using d SPACE/Micro Auto Box hardware.The experimental results show that the path tracking control algorithm has good anti-interference energy,and the tracking accuracy and stability are also achieved Expected effect.