Reduction of Thermal Strain Induced Rate Error for Navigation Grade Fiber Optic Gyroscope

Abstract

In this paper, we present the latest efforts of developing a navigation grade fiber optic gyroscope coil in Turkey. One of the main precision limits for a fiber optic gyroscope coil is its sensitivity to thermally induced rate error. We used an advanced thermal modeling of a fiber optic gyroscope coil in order to obtain the strain fields along the coil and calculate the rate error. An intermediate validation step which compares the strain field calculations with the optical time domain reflectometer (OTDR) measurements of a laboratory fiber optic gyroscope setup is presented. In literature, there are several works indicating the relation between strain and rate error and trying to reduce the total strain as a whole [1], [2]. The strain analysis is separated into axial and radial gradients along the fiber coil. A new fiber coil structure using titanium as the spool material is designed and two fiber coils are produced. Fiber coils are tested under a temperature profile ranging from-40 °C to +60 °C. Simulation and experimental results are consistent. Proposed coil design is promising with 8-fold reduction in rate error.

Experimental Analysis and Multiscale Modeling of the Dynamics of a Fiber-Optic Coil

“…The errors due to temperature effects in a FOG sensor are able to be analytically modeled, and these errors can be compensated from the sensor output by employing proper algorithms [16][17][18][19][20]. The utilization of the finite element (FE) method is an alternative approach to the analytical modeling of disturbance effects due to temperature variations on FOG coils [21][22][23][24][25].…”

“…In the finite element analysis (FEA) of FOG coil conducted here, a meaningful section of the coil, including a single fiber with a fiber core, cladding, glue, and sections of neighboring cables, is modeled in an appropriate symmetry boundary condition to represent the global behavior of the coil material. This section is called the representative volume element (RVE) and a homogenization procedure is followed where the coil material properties are obtained from the RVE [20,22,23,25,36,37]. FOG coil is composed of a fiber-optic cable in a staggered formation glued to each other by adhesives in an orderly fashion.…”