A Novel Approach for an Autonomous Weighing System through Fuselage Interface Loads

摘要

According to a N.A.L report, from May 2007 (G.W.H.van Es[ 4]), each year numerous aircraft accidents occur due to weight and balance issues, major factors in weight and balance accidents/incidents being errors in load sheet, cargo shifting, incorrect loading etc. This paper presents an ESL patented novel method and system for estimating an aircraft's weight while it is on the ground. Additionally, the system enables measuring the takeoff/landing weight profile, which includes information pertaining to weight/force as a function of time, including the time of contact with the ground. This enables various conditions such as heavy landing and the like to be identified. One of the main advantages of this development, over prior methods, is that this system measures loads above the landing gear, thus avoiding bias due to the flexibility of the landing gears. It also offers high repeatability of the measured load. The measurement subsystem includes sensors configured to measure a physical property (load/strain) at several locations near and/or at the fuselage interface with the landing gears. Such a sensor can be based on several technologies such as: strain gages, optical fibers (Bragg Gratings), load cells, etc. The specific solution and sensor implemented is a tailor-made design for each aircraft, taking into account the effect of the aircraft weight and desired sensitivity due to weight change on the results being measured. As part of the work done by ESL in developing the system, that for a given (existing) Hermes 900 fleet, an average of 1 flight hour can be saved. This paper presents the design and integration of such a system on ESL's Hermes 450 UAV, based on load cells. A proof-of-concept test was performed and is presented in this paper. The main test findings show, that the maximum deviation between the standard weighing procedure and ESL's system result is 0.6% at weight and 0.9% at COG. The conceptual methodology suggested here is still under development. Nevertheless, the integration of the sensor technology into the fuselage has its own promise to develop higher levels of safety of flight, while increasing the specific range of the aircraft.