High Speed, In-Flight Structural Health Monitoring System for Medium Altitude Long Endurance Unmanned Air Vehicle

Abstract : This work presents the design, qualification and flight service evaluation of an embedded Fiber Bragg Gratings (FBG) based, Health and Usage Monitoring System (HUMS) for the Israeli Air Force Medium Altitude Long Endurance (MALE) Unmanned Aerial Vehicle (UAV). A total of 54 FBG sensors were embedded on the wing and tail booms, enabling accurate tracking of both the vibrations signature and the actual loading conditions of these components. Reliable flight data, obtained during flight tests and normal UAV operational missions were recorded and analyzed both in the frequency and time domains so that normal structural behavior could be identified and tracked. Based on the data obtained, it is now possible to track the loads enveloped during each flight, construct the landing impact vibration signatures and loading spectrum for the booms and wing. The sensing system has already gained over 1000 flight hours, including more than 300 logging hours. It is the purpose of this system to early detect and identify dangerous changes in the normal structural behavior of an individual UAV, prompting the required corrective action, thereby, paving the way to condition-based maintenance.