Abstract
Two methods for parameters optimization of traditional passive suspension based on the invariant point theory are presented in this paper. Firstly, the two degree-of-freedom dynamical model for a quarter vehicle suspension is established. Then all the invariant points for the acceleration of vehicle body, suspension deformation, and tire displacement are obtained through the invariant equation associated with Laplace transform. Secondly, two optimization methods for the system parameters of passive suspension are presented, and the design objectives are to designate the invariant points as the local maximum points of the amplitude-frequency curves so as to improve the control performance of vibration isolation. At last, the control performances of the two improved passive suspension systems are compared with those of the original passive suspension, the active suspension, and the semi-active suspension by some performance indexes. The results show that the two optimization methods could greatly improve the control performance of passive suspension systems.