Studies Of Modeling And Simulation For Electric Power Steering System Based On MATLAB/Simulink

Electric Power Steering system (EPS) is a product of the higher requirements of the vehicle steering performance.EPS system meets the demand of energy saving,environmental protection,safety,comfort,high efficiency and low cost, is the domestic developed hot of steering system,has broad application prospects.This paper briefly introduces that the development and classification of the steering system and the research status of EPS system control strategy; establishes dynamic model of mechanical steering system and the reduction mechanism and electrical model of the booster motor on the basis of the analysis of EPS system structure and working principle; analyzes the dynamics of vehicle operation,establishes the tire dynamics model and three freedom vehicle dynamics model which considers the body roll;combines the model of system,establishes the overall system simulation model,in order to analyzes the steering performance.Designes linear and curved assist characteristic curve based on the analysis of the impact of handling and stability on the steering performance;proposes the basic assist control and aligning control taking into account the system requirements for the handling stability and driving road feel,in order to obtain good steering characteristics;establishes traditional PID controller,Fuzzy-PID controller,LQG optimal controller of assist control mode and traditional PID controller of aligning control mode; studies the simulation of the system and controller by using MATLAB/Simulink software,the results show that LQG optimal control strategy is better than Fuzzy-PID control strategy, the traditional PID control has the worst effect;for the aligning control mode, in the role of controller,the steering wheel can quickly back to the middle position and does not appear the phenomenon of return insufficient or return overshoot.Finally, tests the the steering performance by use of the EPS system performance test bench of the laboratory, compares the test results with the simulation results, verify that whether the control strategy is reasonable, and the simulation model is correct or not.The results showed that:the control strategies designed in this paper is reasonable and practicable, the simulation models established in this paper is correctly.