Abstract
In recent years, harvesting energy from broadband or low-frequency vibrations via piezoelectric effect has been realized due to worldwide research efforts, however harvesting energy from sway and multidirectional vibrations still present some challenges. To address this interesting issue, this paper reports a design and experimental verification of a beam-roller piezoelectric energy harvester that can scavenge energy from both sway and bi-directional vibrations. The beam-roller harvester is composed of a piezoelectric cantilever beam, a roller, and a frame. The beam and the roller are sensitive to two orthogonal directions of vibrations. The roller is also designed to sense the sway of the frame that acts as the guide rail of the roller. The energy captured by the roller is transferred to the beam via magnetic coupling, and the latter conducts the piezoelectric conversion. The frequency up-conversion is also achieved through this configuration which converts the low-frequency sway and vibration to the higher-frequency vibration of the beam. A lumped parameter model is used to predict the voltage output of the beam and simulate the excitation exerted to the beam by the roller. Experimental studies are performed as well to validate the theoretical predictions and examine the effects of different sway parameters on the performance of the beam-roller harvester. The obtained results indicate that employing a roller to actuate the piezoelectric cantilever beam to function is a feasible way to harvest energy from both the sway and the bi-directional vibrations. (C) 2015 Elsevier Ltd. All rights reserved.