On using the rotor acceleration mode to increase the accuracy of a two-stage gyrocompass

The article considers a two-stage gyrocompass with a rigid torsion suspension of the moving part. The principle of its action is based on balancing the elastic moment of the torsion bars with the gyroscopic moment. When this condition is met, the azimuth of the steady-state position of the rotor axis is calculated from the known kinetic moment , latitude and angular rigidity of the torsion bars, and the measured angle of rotation of the moving part of the gyroscope relative to its initial position. The “aging of the material” of the torsion bars, the effect of temperature on them, etc., leads to an uncontrolled change in the angular stiffness of the torsion bars, which, in turn, leads to an error in determining the position of the meridian. A method is proposed for determining the position of the meridian under conditions when the angular stiffness of the torsion is unknown. The method involves observing the motion of the gyroscope in a mode where the kinetic momentum changes linearly (the rotor accelerates). This movement is associated with the movement of the mathematical model of a two-stage gyrocompass in the same mode in the form of a differential equation of motion or in the form of its solution. As a result of minimizing the discrepancy between the real movement of the gyrocompass and the movement of its mathematical model, the “best estimate” of the parameter characterizing the position of the meridian and the “best estimate” of the angular stiffness of the torsion bars in this dimension are found. The results of modeling the corresponding information processing algorithms are considered. The advantages of the proposed method compared with traditional methods are indicated .

PARAMETRIC AMPLIFICATION OF THE SIGNALS IN THE ELECTROSTATIC GRAVIINERTIAL SENSOR

The challenges of designing simple, reliable, and high sensitivity graviinertial sensors are investigated. The sensor comprises a proof mass (PM) and is fixed with the housing by the elastic torsion suspension. PM makes small rotations under the action of gravitational forces or inertial forces.The distinctive features of the sensor are that the differential electrostatic system provides simultaneous reading of the desired signal and a control the torsional rigidity of suspension. In addition, the PM's rotational angular velocity transforms in the alternating current flowing through the capacitors. The presence of аlternating current (AC) voltage sources allows to get the parametric amplification of AC and significantly to improve the sensitivity of the sensor. In the simplest case, the sensor does not contain any feedback circuits.As an example, calculations of the micromechanical linear accelerations confirm that the periodic modulation of the coefficient of elastic stiffness of the suspension can significantly increase the sensitivity in the low frequency range, even in the absence of parametric resonance.Conditions for suppressions of background current participating in the output signal from a parametric pumping due to the asymmetry of the differential circuits are set. The frequency characteristics calculations of the sensor were carried out. It is expected, that the proposed sensor design ensures minimum noise level, which can be achievable in the graviinertial sensors. This design and the constructed theory can serve as a basis for creating a wide range of graviinertial devices operating on a movable base, for example, linear and angular accelerometer, gravity gradiometer, gravimeters, and inclinometers, which can be realized in the hybrid and in the micromechanical versions.

ABOUT DETERMINING THE POSITION OF THE GEOGRAPHIC MERIDIAN THREE-STAGE PENDULUM GYROCOMPASS DURING ACCELERATION OF ITS ROTOR

The article considers three-stage pendulum gyrocompass ground with torsion suspension unmanaged sensor, equipped with high-precision digital angle sensor azimuthal position sensor and information processing unit. During processing of information isused an indirect method to get facts about initial deviations of dynamical systems.In the process of improving the instrument have revealed that a further increasing of accuracy due to the necessity to consider the following factors. During the measurement around the vertical axis of the sensor operates permanent uncontrolled moment due to operational reasons are different from measurement to measurement. Specified point shifts the center of oscillation of the azimuthal sensor, which is in accordance with the procedure identified azimuth northerly direction on a constant value. For self-compensation of this error have been proposed several methods based on measurements with different but fixed parameters of the device. However, these measures have extended more than twice the measurement process.In this article there is proposing to define the position of the geographic meridian based on the analysis of the azimuthal motion sensor gyro during acceleration of its rotor. The proposal can bring dual gain in reducing measurement time: at first, the rotor becomes "staff " rather than ballast gyro operation mode, as it was before; secondly, there is no need for special measures to combat harmful vertical moments, as the shift of the equilibrium caused by the action of the latter, is variable in time, which allows to determine the magnitude of harmful moment during a single measurement.