A Class of Semi-Active Suspension Schemes for Vehicle Vibration Control

As a compromise between passive and active suspensions, a semi-active (SA) suspension scheme is suggested and demonstrated for both 1- and 4-degree-of-freedom (DOF) vehicle models. Because only limited number of vehicle aspects can be studied using a 1-DOF model, a more comprehensive 4-DOF model is suggested, based on an optimal active suspension strategy. For this purpose, a fully active fail safe suspension is developed for the 4-DOF model using the optimal regulator theory. Rood mean square (r.m.s.) bounce and pitch absolute acceleration transmissibility plots of the sprung mass and plots of maximum suspension and tire deflections are presented for SA suspensions, and compared with passive and active schemes.