Research On Performance Testing For Automobile Electric Power Assisted Steering Controller

Abstract：Automobile electric power steering system (EPS) assembly has became adeveloping direction of power steering technology for vehicles, beacause ofcharacteristic of energy-saving, environmental protection, simple structure, safetyand good assisted steering performance. Quality problem is being concentrated stageby stage against the background of industrialization of automobile electric powerassisted steering in the domestic automobile industry. However, the controller as thecore component of EPS assembly has faced the embarrassment of lacking systematictest method and special test equipment. The research of this project is aimed atsolving a problem that quantitative evaluation of controller performance and creatingconditions for the matching of controller and assisted motor.Firstly, EPS assembly test method was studied in this paper, then a simulationmodel for controller test of closed-loop system in view of AMESim andMatlab/Simulink was established based on EPS controller functions and its relationcharacteristic requirements with assisted motor. In particular load conditions, thestatic and dynamic performance testing methods for controller on three differentstandard excitation signal involves step, sine and triangle signal inputs were studied.With joint simulation and result analysis, EPS controller dynamic performance testmethod and quality evalution index were proposed. This result of research offered areliable theory for design of special equipment for EPS controller performance test.Secondly, special EPS controller semi-physical simulation test device was builtunder the condition of standard torque signal input and standard assisted motor load,which constituted a dynamic mechanical equilibrium system depend on assistedmotor, torque sensor and servo motors. Assisted motor is drived by EPS controller,also servo motor as a loading of assisted motor and steering torsion bar is drived byservo drive. The interface circuit of the semi-physical simulation test device wasdesigned to generate standard signal and realize the analog signal input for EPScontroller, at the same time, it was designed to detect current signal and torque signalfrom output terminal of assisted motor in the course of the test, and it can communicate with PC, which can realize data transmission and preserves.Finally, using the semi-physical simulation test device constructed, multiperformance test for EPS controller including assisted current characteristics, outputcurrent response speed, output current lag characteristic and so on were verified andanalysized after data was collected respectively. It proved the feasibility of the testmethod. Then, future study plan and outlooks were mentioned according to someexisting problems in this paper.