Research On Force Feedback Control Strategy Of Steer-by-wire

Steering by Wire represents the future trend of power steering technology. Compared with the traditional mechanical power steering system, the steering by wire system offers a wide range of benefits, such as better stability and security of steer, comfortable of steering feel, compact structure, and enviroNMental protection. Steering by Wire system has been used to replace traditional mechanical power steering system in vehicle. The current application is only in concept cars and experimental bench. Therefore, the study of steering by wire system is of great significance. This paper studies the modeling and control algorithm for torque feedback in steering by wire system,and how to make out the road feel.Firstly, the structure and working principle of torque feedback in steering by wire system are introduced. Then analysises each of the key components from species to range, determine the type, then the test bench is completed. The steering shaft and road-feeling motor are modeled. Laplace transform of the model,make out the control problem of the whole system. Inner current loop and outer torque loop are designed. By analyzing the characteristics of open-loop system, the parameters of PI controller are confirmed.Secondly, the source and kinds of road-feeling are analyzed. According to the needs of research, vehicle model and tire aligning moment model are established, then derive the model of steering resistance torque. And compare the model of steering resistance torque to the vehicle dynamics analysis software, the results show that the modle is right. Factors affecting the steering wheel torque are analysised, especially the steering resistance torque characteristics. On the basis of the five indicators of Road-feeling Evaluation, the parameters of road-feeling planning function are confirmed. Finally, by the simulation and compared with the experience of road-feeling, the rationality of road-feeling planning function is confirmed.Finally, simulation and test, to validate road-feeling planning function and torque feedback control arithmetic. The output of road-feeling planning function is useed for input of feedback controller, simulation results show that they are all right. Then, hardware circuit for hard rapid control prototype is designed. The abundant hardware I/O of dSPACE and powerful software with Matlab/Simulink are used for the experimental bench of steering by wire torque feedback system to confirm the control arithmetic.