Automatic Adjustment Method of Modulation Depth in Four-state Modulation of High Precision Fiber Optic Gyroscope

Abstract

The invention discloses an automatic adjustment method of the modulation depth in high-precision optical fibre gyro four-state modulation, and belongs to the technical field of optical fibre gyros. Onthe basis of the existing two closed loops, a manner of increasing a third digital closed loop is adopted; when a step wave resets, sampling values of front and rear detectors are compared; an errorsignal when 2 pi resetting is carried out is measured; a modulation signal is adjusted through an FPGA, so that a feedback loop is formed; after working for a long time, the fact that the 2 pi resetting error is 0 still can be ensured after an environment, a light source, a circuit and the like are changed; the long-time working stability of an optical fibre gyro is improved; furthermore, the digital closed loop is simple to implement; and furthermore, the digital closed loop is not influenced with other closed loops in the optical fibre gyro.

Description

technical field [0001] The invention belongs to the technical field of fiber optic gyroscopes, and relates to an automatic adjustment method for modulation depth in four-state modulation of high-precision fiber optic gyroscopes. Background technique [0002] Gyroscope is the core component of inertial system and one of the key contents of inertial technology research. Fiber optic gyroscope is a kind of optical fiber sensor sensitive to angular rate, it is actually a ring interferometer based on Sagnac effect. Because it has the advantages of all solid state, low cost, high reliability and fast startup speed, it is widely used in the fields of aircraft, submarines, warships, missiles, satellites, etc., and has become a research hotspot of inertial devices at home and abroad in recent years. The all-digital closed-loop detection scheme of the fiber optic gyroscope is the mainstream detection scheme at this stage. The fiber optic gyroscope adopting this type has the characteri...

AI Technical Summary

Problems solved by technology

[0003] In fiber optic gyroscopes, the Sagnac phase difference Δφ caused by rotation s It is proportional to the angular velocity, and the output response of the detector is the cosine function of the phase difference, which leads to two problems in the optical fiber gyroscope's detection of light intensity relative to the phase difference: nonlinearity and periodicity

[0018] However, with the increase of working time and environmental changes, as well as the aging of light sources, devices and circuits themselves, such as changes in temperature, vibration, and spectral average wavelength in actual applications, this will make the -Δφ b The phase difference at which the light intensity is equal is no longer Δφ n It is another new phase difference, which will cause the 2π voltage to be inaccurate when the ladder wave is reset.

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