Active Damper Using Electrorheological Suspension and Its Application to Vibration Isolation Control.

The concepts and the damping characteristics of an active damper using electrorheological (ER) fluids containing numerous dielectric particles have been proposed, and applications to vibration isolation control have been investigated numerically, based on the analytical model of the ER damper involving the approximate function of pressure drops across an ER valve obtained experimentally. The ER damper was found to be analogous to the hybrid damper having a viscous damper with constant damping and an electrically variable friction damper. Therefore, the ER damper under constant input voltage behaves like a coulomb friction damper, and the active damper can be constructed, by electrically varying the friction like forces proportional to the piston speed, to be a linear viscous damper with electrically variable damping coefficient. Three methodologies of vibration isolation control using the ER active damper were applied to a single-degree-of-freedom excited vibration system consisting of a mass, a spring, and the ER damper. Among these control methodologies, the nonlinear feedback control of the square root of the absolute velocity of the mass was found to be most effective to reduce the vibration transmissibility of the system, and to enable control of transmissibility approaching that which can be achieved with a full active vibration isolation system using an actuator.