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Proceedings Paper

Fiber optic strain monitor for an uninhabited aerial vehicle
Author(s): Thomas Owens; Philip Pesavento; Robert Ice; Steven Knudsen; Mary Ann Harrison
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Paper Abstract

The Institute for Scientific Research (ISR) and the Naval Research Laboratory (NRL) will build and operate portable real-time fiber Bragg grating interrogator systems for monitoring strain in ISR's Multi-Modal Sensor (MMS) uninhabited aerial vehicle (UAV). ISR's UAV is constructed of fiberglass composites with aluminum stiffeners. The cargo bay and on-board electronics are intended to accommodate a variety of compact sensors. Because of the small size of the UAV, weight and volume are restricted, necessitating considerable redesign of laboratory interrogators to meet UAV constraints. NRL will be supplying a multiplexed interrogator for monitoring structural response rates in the UAV up to about 2 kHz, while ISR will develop an optical frequency domain reflectometer (OFDR) for measuring lower frequency response of large numbers of gratings below about 100 Hz. The OFDR system will test a special differencing technique to separate strain induced signals from environmentally induced signals. A National Instruments CompactRIO system with a 3 million gate FPGA and a 200 MHz Pentium processor is being used for real-time data acquisition and onboard signal analysis. The CompactRIO system weighs about 1.6 kg, measures 18cm x 9cm x 9cm, consumes less than 5 W of power, and withstands over 50g of shock. Lithium polymer batteries will be used to power the system for flight times up to about one hour in the present configuration. While the near-term objective of this project is to overcome the challenges of applying fiber-optic strain monitors to aerial vehicles, the longer-term objective is to develop a system for detecting damage in aerial vehicles using chaotic attractor based methods. One of the key issues in damage detection by this means revolves around the ability to use the chaotic excitation of the airframe from random aerodynamic vortices to detect the onset of composite degradation. There is evidence that attractor based methods applied to these ambient chaotic vibrations will provide a very sensitive indication of damage.

Paper Details

Date Published: 20 March 2006
PDF: 11 pages
Proc. SPIE 6176, Nondestructive Evaluation and Health Monitoring of Aerospace Materials, Composites, and Civil Infrastructure V, 61761G (20 March 2006); doi: 10.1117/12.658778
Show Author Affiliations
Thomas Owens, The Institute for Scientific Research (United States)
Philip Pesavento, The Institute for Scientific Research (United States)
Robert Ice, The Institute for Scientific Research (United States)
Steven Knudsen, The Institute for Scientific Research (United States)
Mary Ann Harrison, The Institute for Scientific Research (United States)


Published in SPIE Proceedings Vol. 6176:
Nondestructive Evaluation and Health Monitoring of Aerospace Materials, Composites, and Civil Infrastructure V
Aftab A. Mufti; Andrew L. Gyekenyesi; Peter J. Shull, Editor(s)

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