Accurate closed-loop control scheme for fiber-optic gyroscope transit time

Abstract

The invention relates to an accurate closed-loop control scheme for fiber-optic gyroscope transit time. The accurate closed-loop control scheme comprises on-line real-time locking of fiber-optic gyroscope transit time parameters, two-stage feedback closed-loop control and four modulation waveform combination schemes given according to different design requirements. The main working process of themethod comprises the steps that high-frequency cosine wave modulation is applied to a phase modulator, spectral analysis is conducted on detector output, online real-time monitoring of the transit time is achieved through a digital phase locking scheme, real-time accumulation and rounding filtering processing are conducted on data, and the data are output to the next stage; a preliminary adjustment result is given through frequency division of control circuits such as an FPGA or a DSP, output of the adjustable crystal oscillator is controlled according to a further difference value, and feedback control with the precision superior to the ppm magnitude is achieved. The scheme is a third key parameter closed-loop control scheme after the fiber-optic gyroscope realizes rate closed-loop and phase modulation coefficient closed-loop, and has very important significance for stabilizing the scale factor and the zero offset parameter and improving the engineering performance of the fiber-opticgyroscope.

Description

technical field [0001] The invention belongs to the technical field of fiber optic gyroscopes, and in particular relates to a precise closed-loop control scheme of the transit time of fiber optic gyroscopes. [0002] technical background [0003] The fiber optic gyroscope is an all-solid-state gyroscope instrument based on the theory of relativity and quantum optics, which has extremely high reliability and design flexibility. The part of the fiber optic gyroscope that is sensitive to the rotational speed is called the fiber optic interferometer (including the splitter / combiner and the fiber optic ring), which is the sensing core of the fiber optic gyroscope. The time length of optical pulse propagation in the fiber optic interferometer is defined as the transit time of the fiber optic gyroscope, which is the basis for signal modulation and demodulation and closed-loop control of the fiber optic gyroscope, and is a key parameter in the design of the fiber optic gyroscope. ...

AI Technical Summary

Problems solved by technology

In the fiber optic gyroscope, the modulation of the rotational speed signal and the closed-loop control of the rotational speed are directly corresponding to the parameters of the transit time. The deviation caused by the change of the transit time directly leads to the degradation of the output noise, zero bias and scale factor of the gyroscope, which affects both The instantaneous accuracy affects the long-term drift index

[0005] At present, the scheme of measuring the transit time of the fiber optic gyroscope is mainly based on various square wave or sawtooth wave modulations related to the transit time. The scheme is limited by factors such as low calculation frequency, unsatisfactory modulation waveform, and signal sampling configuration. The measurement accuracy not tall

Some studies have used a multi-octave cosine wave modulation scheme to measure the transit time, which theoretically improves the measurement accuracy, but it is only in the initial stage of frequency sweep change and response point fitting, and cannot be used for online real-time monitoring

In addition, the current circuit frequency division module that realizes the closed-loop adjustment of the transit time has a large discreteness, and the error reaches several ppm. It is difficult to realize the online precise adjustment of the transit time of the fiber optic gyroscope.

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