Matching Research And Evaluation Analysis Of Electric Power Steering System Characteristic On A Vehicle

Electric Power Steering System(EPS) provides power-assisted steering by directly using assisted motor, and controls the assistance by using ECU. It has obvious advantages of saving energy, protecting environment and keeping safe, it also finds a good balance between the sense of steering and road. Around the world, the electrification of vehicle steering system is an irreversible trend, which has been widely used in major automotive companies. However, the application of EPS not always brings vehicle steering system into good performance. Thus, how to match and evaluate EPS has become a hot topic in the world of automotive technology development.This paper based on a development of a certain kind of automobile. From a perspective of vehicle steering performance, matching technology and evaluation technology of EPS were studied. The main research content includes the following aspects:This paper briefly described the structure, working principle and recent research of the EPS, and pointed out the outstanding advantages and disadvantages between different structural forms of EPS.The study of matching techniques among key components of EPS and vehicle steering performance is conducted. Depending on the performance requirements of the booster motor, mechanical steering gear selection, and analyzed to verify experimentally the impact caused by its steering performance.EPS assistance characteristics and vehicle steering performance matching is studied. The basic principles of curve matching for assist characteristic is put forward, evaluation and analysis of three different forms of assist characteristic curve is analyzed. This paper includes the simulation analysis of the power characteristic curve of dynamical gain coefficient characteristic value influence on steering portability and road sense. Combined with matching test coefficient of the actual vehicle, the speed sensor coefficient is gained by fitting characteristic curve of assist steering, and the full-speed assist characteristic curve is also obtained.Combined with practical experience in project development, subjective evaluation system for EPS is proposed according to practical experience Driver’s task, test readiness, road conditions and environmental conditions are demanded. From the five aspects for 50 meters driving feelings, steering performance of parking, low speed driving, straight driving, turning driving, and interfering turning driving. Evaluation and assessment criteria are shown in detail and examples of project development is given.The objective evaluation system for EPS is summarized, and the test methods and evaluation of steering agility, turning back positive, turning centers flu assessment are also discussed. Finally, the analysis and evaluation of some vehicle is conducted combined with development project.