Novel Piezoelectric Energy Harvesting Devices for Unmanned Aerial Vehicles

The development of small aircraft including unmanned aerial vehicles (UAVs) and micro air vehicles (MAVs) has gained tremendous interest in the research community. One particular area of interest involves creating innovative techniques to increase the flight time or endurance of UAVs and MAVs. Energy harvesting technology presents a potential solution for the improvement of flight times by converting ambient energy into electrical energy that can be used to power the aircraft. Adding the necessary components to perform energy harvesting can, however, add a significant amount of mass to the aircraft, which often have small payload capacities. The additional mass can hinder the performance of the aircraft and, in fact, result in a decreased overall endurance. A novel concept is presented in this paper involving the combination of piezoelectric devices and new thin-film battery technology to form multifunctional self-charging, loadbearing energy harvesting devices for use in UAV systems. The proposed self-charging structures contain both power generation and energy storage capabilities in a multilayered, composite platform consisting of active piezoceramic layers for scavenging energy, thinfilm battery layers for storing scavenged energy, and a central metallic substrate layer. The compact nature of the devices allows easier integration into UAV systems and their flexibility provides the ability to carry load as structural members. A potential application of the selfcharging structures is use in the wing spars of UAVs or as the entire wing of an MAV. This paper addresses several aspects of the development and experimental evaluation of the proposed self-charging structures. Details of the design and fabrication of the selfcharging structures and appropriate energy harvesting circuitry are given. Results of experimental testing to evaluate the energy harvesting performance of the devices under harmonic loading are also presented.