This paper proposes a design method for vibration isolaton control of a structure with a semiactive damper. We formulated the liner parameter varying system taking acount of constraints, valve stroke of a semi-active damper and the damping cofficient restriction, using nonlinear functions. The gain-scheduled control based on the linear matrix inequalities is obtained so that the closed-loop system is stable and has good performance. By simulations it is verified that the semi-active damper system designed is useful for non-stationary random inputs such as earthquakes.
