Study On Path Tracking Control Of Electro Hydraulic Coupling Steering Systemfor Commercial Vehicles

With the continuous advancement of technology,driverless cars have become the focus of research by major auto manufacturers.Driverless cars have many advantages,they can free people's hands,reduce traffic accidents and improve the stability of the car.Path tracking control is one of the main research contents of driverless cars.The purpose is to let the car travel according to the specified path,while ensuring the comfort,stability and safety of the car.It is the underlying control system in the driverless car architecture,and its performance directly affects the execution capability of unmanned vehicles.Compared with passenger cars,commercial vehicles are the first to achieve unmanned vehicles.Because it can travel under relatively simple conditions,it is necessary to design a commercial vehicle path tracking controller.This paper uses a sliding mode control algorithm to design a path tracking controller for a commercial vehicle electro-hydraulic coupled steering system.The main research contents of the thesis are:In order to study the commercial vehicle electro-hydraulic coupling steering system,a typical commercial vehicle vehicle parameters were selected and a three-degree-of-freedom simulation model was established.Based on sliding mode control,the commercial vehicle lateral controller is designed to establish a double-shift line and a serpentine line road model.The front wheel angle is the vehicle lateral input,the centroid side decoy,the yaw rate,the sprung mass roll angle,and the sprung mass side.The inclination speed,the unsprung mass roll angle,the lateral displacement and the yaw angle were used as the vehicle state output,and the path tracking simulation experiment was carried out.The simulation results show that the path tracking effect is ideal regardless of whether the road curve is a serpentine line or a double shift line,which verifies that the sliding mode controller has good robustness.The angle follower algorithm is used to analyze the angle and torque signals of the steering wheel Hella sensor,and the analyzed steering wheel angle and steering hand torque are input into TruckSim for testing.Compared with several control modes of permanent magnet synchronous motor,the vector control method is adopted to control the permanent magnet synchronous motor.The control algorithm such as PID is used to realize the bottom-loop torque control and the closed-loop control of the motor.Finally,the dSPACE real-time simulation system is used to verify the control effect of the permanent magnet synchronous motor.In order to verify the simulation results,a test bench for the electro-hydraulic coupling steering system of commercial vehicles was built.Then debug the built test bench to solve the problems of system lag,interference and so on.The servo motor was used to load the system.The joint simulation was carried out on the test bench using TruckSim and LabVIEW software.It was verified that the actual resistance torque of the built test bench can well follow the expected resistance torque.Finally,the hardware-in-the-loop(HIL)test of path tracking is carried out.The experimental results show that the designed sliding mode path tracking controller can follow the expected path very well.The feasibility of the control algorithm is verified.