Abstract
Smart structure technologies have gained increasing interest on the market during the last years. The demand for active systems refers predominantly to active vibration control, especially vibration reduction. The challenge in this area is to realize availability of "extremely" stiff, light and well damped structures which fully and deeply integrate new adaptronic devices with electromechanical, electronic devices, measuring systems, sensors and actuators. A major factor that limits the performance of dynamic-positioning machines is their propensity to vibrations, which will impose limitations on size of the working space, settling time and/or positioning accuracy. The objective of this research is to develop an Active 3DOF Stiffness Element (A3DSE) that can be installed at appropriate locations of a machine, which could dynamically compensate for the vibrations of the mechanical structure, by actuating in three degrees of freedom: one axial and two bending. The design idea is based on the incorporation of three piezoelectric displacement actuators, each equipped with a collocated, piezoelectric force sensor, in an axisymmetrical configuration within a mechanical holding structure, using suitable mechanical and electronic interfaces. Firstly, the mechanical design requirements and the design procedure for each of its components are discussed. Secondly, the active vibration control strategy, which will be used, is presented. Finally, the discussion is illustrated by means of experimental active damping results that have been obtained, which shows that The A3DSE element, equipped with appropriate control, is an effect device for a variety of active disturbance-rejection and active vibration damping applications.