Experiments in augmenting active control of a flexible structure with passive damping

Abstract

Control ling the motion of large flexible structures through purely active measures can become cumbersome in terms of hardware and computation time requirements. Moreover, for any practical implementation, the need to limit the order of the system model and controller may lead to problems associated with spill over and modeling uncertainty. In many cases it is possible to augment active controllers using passive vibration control measures thereby relaxing the burden of active control. In this paper we discuss the results of an experimental investigation of using this highly practical scheme. The experimental system under consideration is a flexible arm that rotates in the horizontal plane when driven at its pinned end by a DC torque motor. Passive dampening is s provided by a constrained viscoelastic layer damping treatment. Experiments were performed to demonstrate the stabilizing effect of the damping treatment on a system using modal feedback and one using only colocated control. A root locus analysis of the colocated system substantiates the experimental results.