S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Mechanical Aerospace Engineering (기계항공공학부) Others_기계항공공학부
Flexure Analysis of Inertial Navigation Systems
- Kim, Kwangjin; Park, Chan Gook; Park, Jai-Yong
- Issue Date
- ICCAS 2004, August 25-27, The Shangri-La Hotel, Bangkok, Thailand
- Ring Laser Gyroscopes used as navigational sensors inherently experience a lock-in region, where very low rotational
rates are not measurable. Most RLG manufacturers use a mechanical dither motor that applies a small oscillatory rotational motion
larger than this region to resolve this problem. Any input acceleration that bends this dithering axis causes flexure error, which is a
noncommutative error that can not be compensated by simply using integrated gyro sensor output. This paper introduces
noncommutative error equations that define attitude errors caused by flexure errors. In this paper, flexure error is classified as
sensor level error if the sensing axis coincides with the dithering axis and as system level error if the two axes do not coincide. The
relationship between gyro output and the rotation vector is introduced and is used to define the coordinate transformation matrix
and angular motion. Equations are derived for both sensor level and system level flexure error analysis. These equations show that
RLG based INS attitude error caused by flexure is directly proportional to time, amount of input acceleration and the dynamic
frequency of the vehicle.
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