Electromechanical pendulum for vibration control and energy harvesting

This paper presents the design of an experimental electromechanical device for vibration control and energy harvesting. Traditionally, when the broadband resonant response due to a selected mode of a lightly damped structure needs to be controlled a vibration absorber is used. The resonance frequency of the absorber can be chosen to minimise the response of the structure under control. Optimising the damping ratio to achieve this aim also dissipates the most power in the damper, but care must be taken not to exceed the maximum throw of the device at high excitation levels. The absorber may also be mistuned by changes in operation condition and thus underperform. It is thus important to be able to design tuneable vibration absorbers, able to adapt their resonance frequency and their damping ratio depending on the operation condition. In this paper an electromechanical device consisting of a pendulum connected to an electrical motor is proposed. It is shown that by shunting the terminal of the device with an appropriate electrical circuit it is possible to control both its resonance frequency and its damping ratio. The power dissipated in the resistive part of the shunt circuit could also be harvested and used to implement the tuning mechanism, or for other purposes.