The Simulation And Control System Design Of The Electric Power Steering System

Electric Power Steering(EPS) system is the inevitable developing direction for automobile power steering,which is much superior to hydraulic power steering system. So it becomes one of hotspot of modem steering system research.After studying and analysing the eps research status and development trend,some researches on working principle of eps.Then we designed and developed the Electronic Control Unit(ECU) and the software program of the ECU, and done the EPS bench test.Firstly mathematics model of EPS system was established.In order to obtain the model close to the actual steering system,AMESim software and Simulink software are connect to co-simulation for the system,different mode was analysised, and the efferctive control strategy was introduced. Comparing of the three control algorithm P control,PD control,and the Fuzzy-PD control,through the simulation analysis to verify the advantage of Fuzzy-PD control algorithm.Secondly analyzing the functions and considering the reliability of the electronic control unit of EPS system,the thesis studied and developed the hardware that adopted MC9S12DG128 as its microprocessor. The ECU contains the drive DC motor control circuit, various sensors signal acquisition and processing circuit. The whole process are a variable duty cycle was set through the single-chip pulse of the PWM to control the H bridge DC motor drive,and it meet the EPS control request.The hardware completely finished,in the software part the modular design method was adopted to compile the control procedure.The control procedures in the system mainly includes the main program,signal acquisition subroutine program, determine models subroutine procedures,motor assisted sub-control procedures.At last, we develop and independently built bench test device, it proves the correctness and effectiveness of the whole design of the EPS system by experiment which base on the hardware circuit and software system,and the result showed that the ECU work stable performance and achieve a good effect of the power steering.