Active Vibration Suppression by Moving Force Actuators

The use of fixed force actuators in the active control of vibration of distributed parameter systems gives acceptable performance only if the modal content of the unwanted motion to be suppressed aligns well with the modes retained for the controller synthesis [4]. In this paper we present a novel concept for the active control of distributed parameter systems. It is based on the idea of dynamically varying the location of actuators. For illustrating the main features of this concept, we consider a simply supported, thin, long, flexible beam controlled by a single moving actuator as the focus of the study. The strategy of dynamically varying the actuator location is used primarily, to shift the relative dominance of the contributions of each mode to the total energy content of the unwanted motion. The idea is to localize the vibration modes and confine it to a region close to the actuator. This phenomenon is referred to as normal mode localization and was first predicted by Anderson [1] in the field of solid state physics. Our preliminary results indicate that all odd numbered modes or even numbered modes can be totally eliminated by moving the actuator at a constant velocity along the span of the beam. We are currently working on a strategy for total elimination of vibration. An experimental set up for demonstrating the feasibility of the above concept is currently being built and we expect to have experimental data by the end of the year.