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Optical Engineering

New technique for reducing the angle random walk at the output of fiber optic gyroscopes during alignment processes of inertial navigation systems
Author(s): Aboelmagd Noureldin; Dave Irvine-Halliday; Herb Tabler; Martin P. Mintchev
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Paper Abstract

Angle random walk (ARW) is the noise component at the output of a fiber optic gyroscope (FOG) and it affects the FOG short-term accuracy. Practical applications of FOGs inside an inertial navigation system necessitate monitoring the Earth's rotation rate component along the FOG sensitive axis to determine the initial attitude of the moving object. The ARW increases the measurement uncertainty, thus affecting the overall accuracy. We introduce a new filtering approach that significantly reduces the ARW at the FOG output to a level that can ensure an accurate measurement of the Earth rotation rate. The filtering approach employs the forward linear prediction (FLP) technique to design a tap delay line filter and a new criterion, based on controlling the step size parameter, is introduced to ensure the fastest possible convergence of the adaptive algorithm, while keeping the minimal possible mean square error. The proposed FLP filter of 300 tap weights is capable of reducing the ARW from 4.66 to 0.0694 deg/h(?Hz)-1. Although it introduces longer delay at the FOG output, a 600-tap weight FLP filter reduces the ARW to 0.015deg/h(?Hz)-1. The presence of the FLP filter at the FOG output significantly improves the estimation accuracy while monitoring the Earth rotation and it can successfully replace all other conventional filtering techniques.

Paper Details

Date Published: 1 October 2001
PDF: 10 pages
Opt. Eng. 40(10) doi: 10.1117/1.1404117
Published in: Optical Engineering Volume 40, Issue 10
Show Author Affiliations
Aboelmagd Noureldin, University of Calgary (Canada)
Dave Irvine-Halliday, Univ. of Calgary (Canada)
Herb Tabler, International Downhole Equip (Canada)
Martin P. Mintchev, Univ. of Calgary (Canada)

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