Abstract
In this paper an approach to vibration suppression is presented that does not use any form of viscous damper. That is, the force generated by the actuator has no velocity dependence. We give three different hardware configurations for an actuator that behaves effectively as a spring with an adjustable unstressed length. By adjusting this unstressed length on-line from feedback, it is possible to obtain fast settling times and superior shock isolation characteristics. At the instants when energy in the actuator is maximized, we discard this energy as heat in the working fluid by opening a low power solenoid valve for a short time interval. This sets the unstressed length of the actuator, or effective spring, to be zero. The total energy in the vibrating structure is therefore decreased at these instants of unstressed length adjustment. Analytical results and simulations are given that demonstrate the performance of our approach.
