Vibration reduction of a rotorcraft UAV using PZT patches

In this paper, results achieved from an experimental activity aimed to investigate the capability of a vibration suppression approach to reduce the vibration levels aboard a rotary-wing Unmanned Aerial Vehicle, UAV, are presented. The developed approach belongs to the so called "passive" methods and uses the electromechanical characteristics of piezoelectric patches to transform the mechanical energy into electrical energy. This energy transformation is made possible by the use of a suitable electrical impedance shunted to the piezoelectric patches. The electrical parameters of such an impedance are chosen so that the resulting electromechanical system, formed by the piezoelectric patches bonded to the host structure and the structure itself, is characterized by a maximum value of the mechanical dissipation factor at a given natural frequency of the whole system. The key point of the developed approach is its intrinsic fail-safe nature and the limited increase of weight due to the installation of the required on-board hardware. In order to validate the proposed approach, a preliminary flight test campaign is carried out. Data recorded aboard the rotary-wing Unmanned Aerial vehicle in hovering flight condition demonstrated the effectiveness of the PZT patches, validating thus the proposed approach.