Active Front Steering System (AFS) combines the advantages of Steer-by-Wire system and traditional mechanical steering system, and it has been developed rapidly recently. This paper focuses on the design of Variable Steer Ratio (VSR) for AFS, which is the key of AFS development. The objective of this study is to investigate a better approach of steer ratio design for AFS. Firstly, the typical piecewise linear style steer ratio presented in most early studies is introduced and its imperfection is analyzed. Then the guideline for VSR design is derived and a smooth curve style steer ratio is designed based on sigmoid function. Finally, the two different types of steer ratio (piecewise linear and smooth curve style steer ratio) are tested with CarSim and Simulink and analyzed comparatively. The simulation show that not only the steer ratio fluctuation effected by the smooth curve style is smaller than the piecewise linear steer ratio when vehicle velocity oscillates around the demarcation speed, but also the front road wheel angle superimposed by the smooth curve style is more smooth when vehicle speed changes in a wide range.
Research on Variable Steer Ratio of Active Front Steering System with Fluctuating Velocity
Lect. Notes Electrical Eng.
2012-10-23
11 pages
Article/Chapter (Book)
Electronic Resource
English
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