Study And Development On The Controller Of Electric Power Steering System

Electric Power Steering(EPS) system,which emerged in recent years,is a new type of vehicle steering system.It has the advantage of small volume,lighter weight,simpler structure, lower consumption,better environmental protection,which is the developing direction for automotive steering system.The system can real-time provide a suitable power according to the status of the vehicle movements and the torque on steering wheel.Therefore,it is of great importance to study and develop this kind of steering system.On basis of summary,analysis of the system and the former postgraduates,a EPS controller based on Freescale's MC9S08AW16 was developed in order to improve the reliability and performance of system.In light of the new single-chip hardware resources,the circuit was modified,including the improvements of power supply system and peripheral circuits.On the software side,except adopting more designs of fault-tolerant,the code of corresponding trouble diagnosing and processing was programmed according to the new hardware circuit.All the measures improved the security and reliability of whole system.In addition,based on the advantages of this chip and its development tool(BDM HCS08), in-circuit programming of software was actualized through using Code Warrior.This function shortened the time from problem being found to being solved,so the efficiency of controller development was improved.The control code was tested on vehicle for a long time in order to better performance.At last,based on the standards of controllability and stability test procedure for automobile,author tested the controller on vehicle and verified its performance by comparing the test results with original Japan's controller.The results showed that:the performances of our controller and Japan's controller are very close,even on one target,it performs better than Japan's one,which proved the development of EPS controller was successful.