A novel method for determining and improving the quality of a quadrupolar fiber gyro coil under temperature variations

Abstract

We introduce a parameter called pointing error thermal sensitivity (PETS) for quantitatively determining the quality of a quadrupolar (QAD) fiber coil under radial temperature variations. We show both analytically and experimentally that the pointing error of a fiber gyro incorporating the fiber coil is linearly proportional to the final radial thermal gradient on the coil, with PETS as the proportional constant. We further show that PETS is linearly proportional to another parameter called effective asymmetric length of the coil. By thermally inducing different radial thermal gradients on the fiber coil and measuring the corresponding pointing errors in a gyroscopic measurement setup, we can confidently determine the PETS of the fiber coil and its associated effective asymmetric length caused by imperfections in coil winding. Consequently, we are able to precisely trim the coil to achieve best thermal performance.

A Thermal Performance Analysis and Comparison of Fiber Coils with the D-CYL Winding and QAD Winding Methods

“…The principal configuration of IFOG consists of six parts: light source, optical coupler, Y-branch, electro-optical phase modulator, photoelectric detector and fiber coil. It is well know that the stability performance of an IFOG is greatly worsened under the influence of time-varying temperature gradients, especially asymmetric temperature excitation, therefore the key problem in developing highly-accurate IFOGs is the compensation of thermally induced drifts errors [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Considering the characteristics of IFOGs, we concluded that thermally induced drift errors are mainly caused by the following five factors: unstable wavelength of the light source, the temperature drift of integrated optical devices (Y waveguide) [ 2 ], unstable performance of electronics, unstable performance of PN dark current and thermal noise of the photoelectric detector, and thermally induced changes of the refractive index of the fiber coil.…”

“…The fourth method is to improve the winding quality of the fiber coil. For example, quadrupolar (QAD) [ 12 ], random [ 13 ], octupolar [ 14 ], cross [ 15 , 16 ], crossover-free [ 17 ] and double-cylinder (D-CYL) [ 18 ] winding methods have all been investigated to reduce thermally induced nonreciprocal drift errors. Some time ago, the thermal performance of the cross winding method and the D-CYL were briefly compared, but only by a simulation method [ 19 ].…”

Self-calibration method based on navigation in high-precision inertial navigation system with fiber optic gyro

“…The positions and rotational movements that the turn table affords differ from the actual operating condition of INS; hence, the values of error parameters calibrated by the method above are not accurate enough for system requiremenst. Especially for FOG INS, a gyro's performance is more susceptible to environmental conditions, such as temperature, 13,14 magnetic field, 15 and vibration. 16 Therefore, for the sake of high-precision, conventional multiposition and rotation method is treated as a basic calibration in the proposed INS, and a precise calibration considering the sensors' actual operating condition is required.…”

Distributed transverse stress measurement along an optic fiber using polarimetric OFDR

“…Distributed stress sensing is another area of active research with many important applications [1][2][3][4], one of which is to measure the stresses along the fiber in a fiber gyro coil, the most critical component whose quality directly affects the accuracy of the gyro [5,6]. One of the most common coil defects is the stress induced during the coil winding process.…”