Development and performance evaluation of an electromagnetic transducer with a tuned variable inerter

This paper proposes a novel vibration energy harvesting device employing a tuned variable inerter. The inerter is a device that can produce an amplified inertial mass effect by ball screw or rack and pinion mechanisms. Originally, the inerter was developed for suspensions in automobiles, and various kinds of inerter technologies have been widely studied not only in structural control but also in energy harvesting so far. As an example of such devices, the tuned inertial mass electromagnetic transducer has been proposed, and its effectiveness as an energy harvesting device has been shown already. However, at the same time, previous studies suggested that further performance improvement is possible if the inerter is variable according to changes in disturbance conditions. Thus, in this research, a prototype which can change the value of the inerter is designed, and a system to change the inerter based on the dominant frequency detected online by the fast Fourier transform of the measured data is developed. Then, it is shown through experimental studies that the proposed device can improve the energy harvesting performance compared to the existing tuned inertial mass electromagnetic transducer for disturbances with varying dominant frequencies.