Research On The Auto Electric Power Steering System Design And Control

At present,the EPS system in China is still in the growth period,its core technology most monopoly by foreign industry,few domestic enterprises with independent intellectual property rights.Therefore,urgent need of the EPS system design and development.This topic in the EPS system on the basis of basic principle and mathematical model,design a auto electric power steering system,using fuzzy control method,obtain comprehensive performance of the optimal control strategy of the auto electric power steering system,and based on the Matlab/Simulink,automobile EPS system model is established to simplify,to establish the simulation model and simulation analysis.First of all,briefly analysis the composition of EPS system,including the power of the motor,electronic control unit,sensors,speed reducer and the electromagnetic clutch,power transmission work organization and mechanical steering gear,etc.EPS are classified,including steering power type,rack power type and gear dynamical type,Expounds the working principle of EPS system,analyzed the linear model,folding lines,curves,three kinds of dynamical characteristics curve,and established the mathematical model of EPS system,including the steering system model,auto two degree of freedom model and the mathematical model.Second,the selection of power motor of EPS system design,including the selection of machine type,the choice of motor rated torque,the motor rated power and rated speed choice,the choice of the motor rated voltage etc.Expounds the type selection design of reduction drive mechanism,analyzes the two kinds of reduction drive mechanism,and established a differential gear train retarding mechanism of 3 d entity model,and completes the torque sensor,speed sensor,clutch,and the design of the electronic control unit(ECU),EPS system for assembly design.Third,in view of the design of a certain automobile EPS system,establish the control strategy.The brief analysis of the current of electric power steering power curve.Compensation current algorithm is proposed,including EPS system calculation of compensation current and compensation current logic.Key based on the fuzzy control algorithm,completed the design of fuzzy controller,and establishes the membership function of fuzzy control,the EPS system to complete the design of fuzzy rules,and expounds the system output of the fuzzy method.Finally,based on Matlab/Simulink software,the automobile EPS system model is simplified,the simulation model is established,including the steering wheel and steering shaft parts,rack and the steering shaft parts,motor,motor PID control module,and the overall simulation model of EPS system in the case of adding power curve and compensation current are simulated.Got the compensation current approximate linear relationship.In the case of tire pressure 230 kpa motor output rated current 17 A compensating current is 3.5 A,the compensation current is more than 10% of the original control current,on the vehicle driving performance has improved greatly.