An experimental study of a vehicle suspension system equipped with passive and on-off type semi-active dampers is presented. For this purpose, a suspension test rig driven by computer-controlled hydraulic exciter to generate several type of road profile is implemented. The test rig is modeled as a nonlinear two degree-of-freedom system representing heave and pitch motions of the sprung mass and translatory motion of each unsprung mass. Sprung mass accelerations are measured in the steady state and it has been verified that the vibration isolation performance of the on-off damper is superior to that of a conventional passive damper. A comparision of simulation and experimental results reveals that good correlations are found between them.
