Design Of Steering Angle Tracking Controller For Steering-by-wire System

Intelligent vehic le can greatly improve the safety and comfort of the vehicle, is the technical development direction of future vehicle. As a new concept of electronic control steering system, the steering-by- wire(SBW) system can obviously improve the active safety of intelligent vehicle. SBW system has the features of variable ratio and steering sensitive which meet the requirements of the active steering. The steering angle tracking system is an important part of steeringby-wire system. Its performance determines the whole system performance directly. This paper studies the angle tracking system, aims to suppress the disturbance and improve angle tracking performance of the steering angle tracking system.The control structure of the steering angle tracking system is determined after analyzing the SBW system structure and common control strategy. Then the permanent magnet synchronous motor(PMSM) is chosen as the steering actuator, and the modle of PMSM and steering dynamic model of the mechanis m is established. The unknown parameters of the model is identified based on experimental data. Considering to the disturbance torque of the system ma inly consists of aligining torque and reactive torque caused by uneven road, the composition and the characteristics of aligning torque is analyzed. Due to there is no accurate model to describe the reactive torque caused by uneven road, it is analyzed with the help of ve DYN A software and the results show that it has low frequency characteristic.In order to compensate for the disturbance, the two-dimension MAP of aligning torque is constructed based on magic formula tire model, and it is verified in ve DYN A. Then the control law of using MAP to feed- forward compensation to suppress the disturbance is proposed. And then the H ? cotroller is designed. Finally, the controller is verified in high precision vehicle dynamics simulation software under various conditions.For verifing the performance of the designed control law in the actual system, the hardware in the loop experiment platform is built combined with the automobile chassis control simulation system. Finally, the control law designed above is verified in a variety of conditions in this exp erimental platform, and the results show that the steering angle tracking system has achieved the desired steering angle tracking function and has a good tracking performance.