A Method for Improving Light Intensity Stability of a Total Reflection Prism Laser Gyro Based on Series Correction and Feedforward Compensation

Abstract

The instability of scale factor and null shift are closely related to the change of the light intensity of a total reflection prism laser gyro (TRPLG). To improve the light intensity stability, the light intensity stabilization principle of TRPLG was analyzed, and a mathematical model of light intensity stabilization system was established. Aiming at the problem that original system has a long adjustment time, a series correction method of adding a proportional integral differential (PID) link in the forward channel was adopted. According to the third-order optimal design, the original I-type third-order overdamped system was optimized to the new II-type third-order underdamped system, which ultimately improved the system's dynamic and steady-state performance. Feedforward compensation was used to introduce the light intensity disturbance during the longitudinal mode hopping into the closed-loop system, which realized the full compensation of the light intensity error and improved the light intensity characteristics during the longitudinal mode hopping. Combined with the above two methods, experimental results showed that the new system with feedforward compensation improved the light intensity stability by 32% at constant temperature and by 40% at variable temperature, with the TRPLG's bias stability improved by more than 16% at constant temperature and by 22% at variable temperature.

Computer simulation of the Zeeman laser gyros resonator length control system behavior

“…Even though the TEC of these materials is at a level about 10 -7 1/°С, no real material with the lowest TEC can provide passive path length stabilization with accuracy required for LG, especially while working in a wide temperature range from minus 55°С to 75°С. That is why lots of effort are invested by researchers into the development and optimization of the active resonator length control system (RLCS) often using simulation [7,14,15,20,[28][29][30].…”

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Laser strapdown inertial navigation system has become the mainstream of the medium and high precision inertial navigation systems, and its core component is a laser gyro (LG) [20,23].The LG have the advantages of high precision, large dynamic range, fast starting, super stable scale factor, strong environmental adaptability, high reliability and long working life [1,13,18].Apart from Russia, only four countriesthe United States, France, China and Israelhave been able to master the complex knowledge-intensive technology of laser gyros production [13,23,24].Even though the new types of gyros appeared, but the LGs still keep the highest market share and are largely used in navigation and guidance systems. As it is seen in Fig.

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“…Laser strapdown inertial navigation system has become the mainstream of the medium and high precision inertial navigation systems, and its core component is a laser gyro (LG) [20,23].…”

“…In such gyros particularly of multi-frequency (four-mode) version, the influence of noise is eliminated, and the linearity of the scale factor is high, so that they are especially suitable for the applications with requirements on low noise and large dynamic mechanical environment [1,2,13,17,22,23]. Of Western firms, only Northrop Grumman (after acquired Litton) [20,23] realized an approach with a magneto-optic biasing, but its disadvantage is the introduction of a magneto-optic element (Faraday cell) inside the resonator, which complicates the design and creates a thermosensitive, scattering-added, optically inhomogeneous zone in the path of the laser beam. Some papers were published on development of fourmode LG [4] and LG with nonplanar resonator in China [12].…”

Zero-bias error compensation method of laser gyro based on neural network

“…However, the domestic research on laser gyroscope is still in the stage of continuous exploration and learning, and there is still a large gap between the scientific research ability and the road of realising the localisation of laser gyroscope. The problems faced by the laser gyroscope at this stage are mainly reflected in the high cost caused by factors such as weight, volume and production technology (Hao et al, 2021;Tao et al, 2020;Aviev and Enin, 2018). At present, the commonly used error modelling methods of laser gyro include time series method, wavelet network, neural network and so on.…”