ABSTRACT
The invariant points of the quarter vehicle 2-DOF model shape many properties that concerned in vehicle suspension design. According to their traits, the invariant points are sorted into three categories in this paper. Then, the invariant points of semi-active suspension are proposed, which were not ever mentioned in the past. An equivalent linear approximate model is derived from the transformation of the sky-hook semi-active suspension model, which is utilized to analyze the invariant points of semi-active suspension. Finally, the effects of invariant points on suspension design and control are discussed.
