Modeling And Simulation Of Electric Power Steering System And Electronic Control Unit Study

Electric Power Steering System (EPS) is an automotive electronics and intelligentproducts, and it is the technical breakthrough on the automobile steering technology,EPS has many advantages over the past steering system. Electric Power SteeringSystem has high efficiency, good in road feel, environmentally-friendly andenergy-saving, convenient installation, and successfully applied in some models, ithas broad market prospects.This paper fully shows the characteristic that combination of automobileengineering, automatic control theory and mechatronics, from the modelingsimulation and ECU, EPS was studied deeply in this paper.First of all, the characteristics, basic structure and working principle of EPSsystem were elaborated in this paper, and have made the detailed analysis andselection about key parts of EPS. Then taking EPS as research objective, hasestablished the steering system dynamics model, DC motor model, as well as twodegrees of freedom vehicle dynamics model. On the basis of that, analysis of assistcharacteristics and control strategy were made, and the motor’s target current on thebasis of fuzzy control was worked out, it got the assist characteristic curves atdifferent torque input of steering wheel and velocity, which showed that fuzzy controlstrategy, can meet the requirements of EPS system. In the target current trackingstrategy, PID controller and fuzzy-PI compound controller, while the steering returncontrol strategy and damping control strategy were discussed. The simulation resultsshow that, the actual motor current can track target current well, with high responsespeed, the current control method was effective and feasible. Moreover, the vehicleyaw velocity effect of EPS system was discussed with the use of vehicle simulationplatform.At last, Electric Control Unit function was given full consideration, According tothe characteristics of ECU’s input signal and output signal, the hardware circuit wasdesigned. At the same time, this paper introduced the driving circuit of direct-currentmotor and relay, input signal processing circuit and switching circuit in details. Alsoin the base of safe, the fault processing circuit was designed.