Research On Fuzzy Controller Of Electric Power Steering

In the modern automobile industry, the sign of level of automobile industry is not only the improvement of the mechanical structure, automobile electronic degree is seen as another important symbol, which Electric Power Steering(EPS, Electric Power Steering) system replacing traditional hydraulic power steering system, is a important application in the field of automotive electronic power steering, its prospect of market is wide.According to reports by China Association of Automobile Manufacturers, sales of electric power steering increased from 620000 to 6 million from 2007 to 2012 in our country, market share is expanding, but it has some disadvantages, only 9% of local production market, the rest are occupied by foreign capital or joint venture, thus to develope with independent intellectual property rights of electric power steering(EPS) system is important for development of EPS industry in our country.The project is basic research project from Science and Technology Agency of Sichuan province, takes EPS of the steering column type as the research object, takes LPC922 FN single-chip microcomputer as control core and permanent magnet dc motor as power device, to designe the EPS controller with high reliability and low cost. First of all, the work principle of EPS system and characteristics of the power function curve are analyzed, the fuzzy control algorithm is applied to the EPS aiming at the limitations of the traditional PID control, established the membership functions of input and output parameters and the corresponding control rules; and combining with the dynamic equation of EPS system, simulation system model is established under the environment of MATLAB/SIMULINK; in the hardware part, to determine the scheme of realization of the main circuit and complete the design of each function module,in the software part, writing overall process of system and the various software modules; finally completed joint debugging of the system software and hardware, a large number of test experiment was carried out, including the functionality and performance experiments, basically completed the design index, achieved the design of EPS by as the steering wheel input torque and the speed and steering shaft rotation angle as input signal,and as motor power current as the output signal.This paper is to apply fuzzy control to the design of automotive power steering gear, under the precondition of safety, effectively completes power-assisted steering, steering resistance or correction function, effectively improves the portable drive during a low-speed and the driving stability during a high speed to sedate driving experience, basicly meets the expected design goal, has great guiding significance for practical engineering.