Modeling Of Electric Power Steering System And Simulation Of Steering Characteristics

Electric power steering system has the best power steering method and extensive application prospect, therefore, it has become the hotspot of automotive steering technology at present. A lot of countries, especially the developed countries, have gained brilliant achievements in the related fields. As the classical active safety control technology, EPS has the vital significance to the improvement driving safety, control stability and the steering portability. Nowadays, the development of EPS has been paid attention by more and more people. Rack and pinion type electric power steering system is the object in the thesis. Study the control method based on the optimum steering characteristics, and analyze the control effect of the two algorithms to the EPS in the different working conditions.To improve the dynamic performance of electric power steering system, this thesis uses ADAMS/Car to establish a multi-body dynamic model and the linear power characteristic curve which applies to this multi-body dynamic model. Then analyze the mathematical model of the electric power steering system of the components and establish a steering system simulation model based on MATLAB/Simulink; Finally, contrast the electric power steering system control strategy which includes the upper and lower layers:the upper controlling strategy determines the target current by using the method of basic power control and compensation control;The lower strategy tracks and controls the target current by using the fuzzy PID control strategy and pulse width modulator (PWM),as well as adjust the error between the target current and motor current to make the motor output the idealpower booster torque. Simulation results show that:(1) The car with the electric power steering system has a good operational stability compared with the car without electric power steering system;(2) Contrast the four typical simulation of the double lane change, fish hook, impulse steer and cornering with steer release in low speed, it can draw a conclusion that the vehicle model with assistant characteristic designed in the thesis has a better steering portability and steering road feeling for drivers as well as Improves the car’s dynamic steering effect and the positive capacity for cornering with steer release in low speed. (3) Contrast the PID and fuzzy PID control algorithm, the comparative analysis shows that the two control algorithms can achieve good steering control effects, but the control parameters of fuzzy PID has a better adjustment and correction capability currently. Therefore, in relation to the PID control, fuzzy PID control has a better adaptability and robustness.