Multi Modal Vibration Absorber based on Hybrid Electromagnetic Shunt Damper

Abstract

Electromagnetic transducers have been widely employed as vibration absorbers in numerous control applications. Their purpose lies in dissipating the unwanted vibrations that may arise in any resonant structure, using those electromagnetic transducers as the actuators of the control strategies. Such strategies can be active, using an integration of the actuator with a sensor and control unit, or passive, employing electrical networks to the actuator that respond to the movement of the structure. Although the active techniques usually outperform the passive control systems in terms of the closed-loop damping and robustness to resonance uncertainty, they require external power for the operation. This project proposes a hybrid control system capable of dissipating multiple resonant modes by combining a passive shunt circuit and the use of an external current source. The optimization of the passive components used in the hybrid system is based on the method of maximum damping, consisting of minimizing the settling time of the response subjected to the action of an external disturbance. The control law proposed for the active current source ensures the stability of the system by using the absolute velocity of the first mass of the structure as a feedback to the designed controller. The employment of hybrid control systems enhances the robustness and control performance of passive systems while reduces considerably the power consumption of purely active systems and provides a fail-safe behavior. The efficacy of this strategy has been experimentally validated through the vibrational control of a flexible cantilever beam.