IN-FLIGHT STRUCTURAL TEST OF A HOVERBIKE USING FIBER OPTIC SENSORS

Abstract

A hoverbike is a vehicle that can fly and hover. Demand for using hoverbikes in various missions, including transport, surveillance, reconnaissance, and infiltration is increasing. While various attempts have been made to develop hoverbikes, there is still a lack of experimental verification on whether the frame structure of a hoverbike can provide sufficient structural strength to withstand extreme loads that may occur during flight without causing damage. Therefore, in this paper, we aim to experimentally investigate the structural characteristics of the hoverbike frame. KAIST is developing a hoverbike that can load up to 100 kg. As part of the development process, structural tests were conducted on the hoverbike. Fiber Bragg Grating (FBG) sensors were utilized for the structural testing. The FBG sensor is capable of multiplexing, in which several sensors can be placed on one optical fiber and is not affected by electromagnetic interference (EMI). Structural strength tests were conducted on the carbon pipes that were used for the manufacturing of hoverbike frames. A down-scaled hoverbike was manufactured. When thrust was generated in the prop connected to the main motor, the dynamic characteristics of the frame was measured. FBG sensor was attached to the frame, and frequency analysis was performed by FFT on the frame strain data measured when thrust was applied. A flight test was performed assuming a rapid maneuvering situation. The maximum bending load generated during rapid maneuvering was calculated using frame strain data. The hoverbike frame was modeled with finite elements, and the internal load analysis was performed by assuming the flight load as a static load. Analysis were compared with flight test, and the validity of the finite element model for internal load analysis was confirmed.