Study On Modeling And Simulation Of Electric Power Steering System

With the development of automobile technology, the improvement of road traffic and the improvement of people'demand for driving performance, the modern vehicle has been put forward new and higher requirements for handling stability, comfort and safety. As the operation link between people and the car, the performance of steering system is directly related to the driver's driving comfort and safety. As a new generation of steering system, electric power steering has become a hot spot of research and production because of its unique advantages.In this paper, on the basis of two degree of freedom vehicle model, considering the influence of roll on the vehicle handling and stability, based on vehicle dynamics, the electric power steering system performance is simulated and analyzed with sliding mode control theory, it has a positive role to accelerate automobile electric power steering system industry of our country. The main research work of this paper is as follows:(1)Establish the model of EPSFirstly the EPS system part is divided into modules, and then the EPS system steering resistance moment of the formation mechanism is analyzed. Finally, the analyed and to established the mathematical model of each subsystem of the EPS model,eg motor model, vehicle model, tire model, motor model.(2)Analysis on control strategy of electric power steering systemFirstly, according to the requirement of EPS system function, the paper analyzed the framework of EPS control strategy, namely EPS control strategy can be divided into four categories, namely, basic power assistant, back to center, damping and compensation control strategy. Then, the operating condition identification module is analyzed. At last, the detailed engineering and control logic analysis of each control strategy is given.(3)Control theory analysis and simulation model buildingFirstly, the parameter tuning of PID controller is carried out by using the PID control method. Secondly, in order to improve the ability of adaptive and anti disturbance of the system. sliding mode variable structure controller is designed Finally, the complete EPS simulation model including the mechanical system and the controller model is built by using matlab/simulink simulation software.(4)The results of the simulation and analysis of EPS systemFirst the assist characteristic of EPS is verified based on model built, secondedly, a comparative analysis on target current and measure tracking performance of the torque between the PID control and sliding mode control is carried out, finally, the steering system was evaluated by transient response of the system and the simulation of steering portability, back to center performance at low speed and high speed.