Ce travail de these porte sur l’etude et la realisation de micro-capteurs dedies a la mesure de vitesse angulaire par des principes bases sur des echanges thermiques. Deux types de gyrometres ont ete developpes dont la principale difference est liee au principe qui permet la mise en mouvement du gaz : convection forcee pour l’un et expansion thermique pour l’autre. Le principe est base sur la modification par la force de Coriolis des echanges thermiques dans un fluide chauffe localement lorsque le dispositif est soumis a une vitesse de rotation. L’utilisation d’un fluide comme masse sismique est en rupture avec les concepts de gyrometres dits traditionnels. Cet avantage a pour consequence la possibilite d’une utilisation dans des conditions environnementales severes telles que de fortes accelerations (> 10 000 g) et de fortes vibrations. Les objectifs de ce travail consistent a etudier, a developper et a caracteriser ces deux types de gyrometres. Pour cela, des etudes numeriques ont ete menees afin de mieux apprehender les phenomenes physiques et thermiques mis en jeu dans la cavite. On a pu aussi etudier l’effet des parametres thermo-physiques du fluide, des differentes dimensions geometriques et de la vitesse d’ecoulement du gaz sur la sensibilite et l’etendue de mesure. Par ailleurs, des prototypes des deux types de gyrometres ont ete realises puis caracterises. Les resultats sont tres encourageants et les principes valides, mais leur confrontation avec ceux de la simulation montre que des ameliorations sont a apporter sur le modele numerique.

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Étude et réalisation de gyromètres à détection thermique

The research conducted in this work, was aimed at finding conditions that suppress the influence of the magnetic field on zero drift in Zeeman four-frequency and quasi-four-frequency laser gyroscopes. We determined the optimal areas within the gain contour in the active medium. During operation in those areas the maximum suppression of the influence of the magnetic field on the drift of the gyroscope is provided. A gyroscope control system that switches gyroscope to the regime of minimum magnetic sensitivity has been created. We obtained weakening of the effect of the magnetic field on zero drift by more than three orders of magnitude.

Creation of Conditions for the Maximum Suppression of Magnetic Field Influence on Zero Drift in Four-Frequency and Quasi-Four-Frequency Zeeman Laser Gyroscopes

This paper presents the results of our work on a four-frequency Zeeman laser gyroscope with a non-planar cavity in the form of a regular tetrahedron with a cavity length of 28 cm. A new physical principle for stabilizing the cavity length based on measuring the beat signal of orthogonal polarization modes is presented. An analysis of various other meth-ods for stabilizing the cavity length and ensuring the lasing frequency stability is made. A method for improving the sub-traction of the influence of external magnetic fields due to the optimal choice of the perimeter control system operation point is shown. We also analyzed the factors influencing the possibility of further improvement of measurement accuracy in the created four-frequency laser gyroscope.

Four-Frequency Zeeman Laser Gyroscope with Nonplanar Symmetric Resonator and Its Perimeter Control System

The paper considers the effect of coupling of counterpropagating waves caused by scattering of radiation in two- and four-frequency Zeeman laser gyroscopes on their characteristics. Methods for measuring the magnitude of coupling of counterpropagating waves via determination of parameters of the amplitude modulation of counterpropagating waves and via reconstruction of the beat signal phase are presented. The obtained values of the coupling magnitude were used to minimize it by 2–7 times by the geometry adjustment of the gyroscope cavity. Measurements of the zero drift and other parameters of two-frequency and four-frequency laser gyroscopes at different coupling magnitudes of counterpropagating waves have been carried out.

Coupling of Counterpropagating Waves in Two-and Four-Frequency Zeeman Laser Gyroscopes with a Nonplanar Cavity

In our work we estimate the maximum achievable accuracy of a four-frequency Zeeman ring laser gyroscope (ZLG) with a nonplanar symmetric cavity with a perimeter of 28 cm. Measurements of the noise component of a four-frequency ZLG signal are presented and a compared with a two-frequency ZLG. The influence of the magnetic field on the errors of the four-frequency ZLG is estimated. A method of compensating the influence of external magnetic fields is presented, as well as the corresponding system for regulating the perimeter and other parameters of the gyroscope. The efficiency of using additional output signals of the four-frequency ZLG, obtained from the interference of waves with the same direction of the cavity propagation, is considered. Additionally, the analysis of the factors prohibiting the achievement of the maximum possible measurement accuracy in the four-frequency ZLG is carried out, the most promising directions of modernization of the four-frequency ZLG are proposed.

New Four-Frequency Zeeman Laser Gyroscope with a Nonplanar Symmetric Cavity, its Parameters and Operation

The magnetic-induced drift is an important error to limit the precision of four frequency differential ring laser gyro (DILAG) in navigation application. Different from the traditional magnetic shielding technology, this paper introduces a new method to decrease the magnetic sensitivity1 of DILAG, simply by adjusting the frequency stabilization mode. Firstly, the physics principle of the method is illustrated. Then, the concrete steps for implementing are given in detail, including the hardware structure and the software flow. Finally, repeatable experiments are carried out and the results verify the validity of the method, which may be helpful to researchers.

Study on the magnetic sensitivity of four frequency differential ring laser gyro

The detection and control system is an important part of ring laser gyro (RLG) to process the signals by electronics To overcome shortcomings of the traditional analog circuits, this paper puts forward a set of digital detection and control system Based on the DSP TMS320F2812 and the necessary analog interface including acquisition circuits and driving circuits for the specific physics parameters of RLG, the hardware structure is built up Adopting the fuzzy PID algorithm and wrong state detection service, the software flow is given in detail Experiments are carried out to test the performance of the system The results show the precision of power voltage, power current, light intensity and gyro drift can reach 21 × 10−4, 15 × 10−6, 25 × 10−5 and 45 × 10−3 respectively, indicating that the digital system has better performance than analog circuits, which will do a lot of good to RLG application

Yuan Bao-lun

Papers

Study on the magnetic sensitivity of four frequency differential ring laser gyro

Digital detection and control system for ring laser gyro