Multifunctional wings with flexible batteries and solar cells for robotic birds

Abstract

Inspired by nature, Flapping Wing Aerial Vehicles (FWAVs), also known as "robotic birds" use flexible compliant wings that deform while flapping for aerodynamic force generation to achieve flight, just like real birds. However, unlike real birds, these vehicles require an artificial power source, like a battery, which limits flight time depending on how much the FWAV can carry (i.e., the payload) and the energy density of the power source. Previously, we have integrated flexible solar cells into a novel FWAV we developed called "Robo Raven" that has programmable wings capable of flapping independently. With the solar cells, energy is harvested during flight to extend the flight time of the FWAV. Recently, we have begun investigating the use of flexible batteries in the wings. By replacing wing mass with material capable of storing energy, it is possible to further increase the flight time and energy storage potential of the platform. However, we are assessing the effects of replacing the regular wing materials with battery materials on the generation of lift and thrust forces. In this paper, different wing designs were designed, built, and tested and flown with the Robo Raven platform. The aerodynamic forces generated by each wing design were measured using a test stand with a six degree of freedom load cell inside of a wind tunnel to simulate flight conditions. A mass-based multifunctional performance analysis is developed to assess the tradeoffs and benefits of using battery materials in the wings for the platform’s time-of-flight.