Electrostatic Gyroscope Research Articles

THE EFFECT OF SURFACE ROUGHNESS AND ELECTROSTATIC BONDS OF RESIDUAL GASES ON THE SETTLING OF THE GYROSCOPE ROTOR

Consider the rotor of an electrostatic gyroscope (ESG) for contactless operation. The rotors of the ESG are made in the shape of a ball and placed in an electric field. The gyroscope operates contactless between the rotor and the mutual oscillation force of the electrodes. Air is sucked out of the chamber in which the rotor is located. Due to the lack of air resistance and the lack of friction force, the rotor can rotate for a long time. But the rotor, located inside the vacuum, also slows down. The reason for this is the roughness and residual deposits of the rotor surface. This is the notorious effect of the rotor of these residual gases on braking. When calculating the effect of residual gases on the rotor, it is considered as separate gases, and not as a homogeneous medium. For this reason, the viscosity of the gas can be set without consideration. The effect of the action of individual particles on the rotor is determined by the roughness of its surface. That is, the momentum by which the particles somehow hit the "peaks" or "troughs" creates a torque that acts on the rotor.

Gimballess Electrostatic Gyroscope with a Rotor without TiN Coating

Gimballess Electrostatic Gyroscope with a Rotor without TiN Coating

Electrostatic Gyroscope in Spacecraft Attitude Reference Systems

Electrostatic Gyroscope in Spacecraft Attitude Reference Systems

Strapdown electrostatic gyro with and without self-compensation

Various applications of strapdown electrostatic gyroscopes (ESG), depending on the type and purpose of the vehicle on which the gyro is installed, as well as operation conditions, impose substantially different requirements on this gyro, including accuracy of information it provides. One of traditional methods used to ensure the gyro accuracy is self-compensating rotation of the housing. The paper considers some applications of a strapdown ESG with a solid rotor and the self-compensation methods used in these applications. This gyroscope was developed 20 years ago at the CSRI Elektropribor, but the work on its improvement goes on continuously. Theoretical aspects of the ESG operation are discussed, taking into account the developed drift model, as well as their experimental validation based on the analysis of ESG operation in polar orientations.

Integrated approach to the technology of manufacturing electrostatic gyro rotors

Technological solutions based onthe integrated approach are presented, which optimize the manufacturing process and satisfy the requirements imposed on spherical rotors of electrostatic gyros. System modelingis used to study the main stages of defining the rotor functional parameters and to constructa system of models that determines the coordinated processes of diffusion welding, precision sphere lapping and rotor weight correction. The practical results of rotor manufacturing and the prospects for accuracy enhancing are provided.

Электростатический гироскоп в системах ориентации космических аппаратов

25 years ago, the CSRI Elektropribor proposed to use a gimballess electrostatic gyroscope (ESG) in spacecraft attitude reference systems. The system called BIS-EG passed the first flight tests in 2004. By 2013, 20 such systems had been manufactured for three types of spacecraft. The flight tests and regular operation of BIS-EG revealed a number of limitations inherent in them; at the same time, calibration methods were developed and tested and the ways of improving the system accuracy and reliability were identified. Гироскопия и навигация. Том 29. №3 (114), 2021 79 Электростатический гироскоп в системах ориентации космических аппаратов As a consequence, BIS-EG was upgraded for the next generation spacecraft, and it is still in operation. Its distinctive features are higher reliability, the gyroscope of greater stability, and the possibility of in-flight calibration of its drift model. The next modification of the BIS-EG, which is under development now, must meet the requirements for higher accuracy characteristics and the need to work in the unpressurized spacecraft compartment. The stages and methods for improving the gimballess ESG and BIS-EG family systems are described, as well as the results of their operation in accordance with their purposes in different types of spacecraft.

Effect of Stoichiometric Composition on the Functional Characteristics of Thin-Film Surface Structures on Gyroscope Components

The results of research into the effect of stoichiometry on the properties of titanium nitride thin-film coatings on the components of floated and electrostatic gyroscopes are presented. The article also considers the results of research into the mechanical and optical characteristics of titanium nitride thin-film structures: microhardness, resistance to wear and friction, and image contrast, which is determined by the reflection coefficients of the titanium nitride base surface and the raster pattern generated by the method of local laser oxidation. The future and technological methods of generation of functional surface structures of niobium carbide and niobium nitride in the process of development of a rotor of a cryogenic gyroscope are discussed. It is shown that the formation of a coating of required composition requires a thermodynamic assessment of possible interactions during which structural-phase modification of the material is carried out, determined by the complex of possible topochemical reactions leading to the formation of compounds, including the ones with nonstoichiometric composition.

Stoichiometric composition of thin-film surface structures and its influence on the functional characteristics as regards gyroscopic devices

This article considers the research results of the effect of stoichiometry on the properties of titanium nitride thin-film coatings of the float and electrostatic gyroscopes. It presents the results of tests of such mechanical and optical characteristics of titanium nitride thin-film structures as microhardness, resistance to wear and friction, and image contrast determined by the reflection coefficients of a titanium nitride base surface and a raster pattern formed by local laser oxidation. When making a rotor of a cryogenic gyroscope, the prospects of use and technological methods for the formation of functional surface structures of niobium carbide and nitride are considered. It is shown that during the formation of coatings of the required composition, the most important is the thermodynamic estimation of possible interactions. These interactions allow us to accomplish the structural-phase modification of the material, which is determined by the complex of possible topochemical reactions leading to the formation of compounds, including non-stoichiometric composition.

Refinining the Drift Model of a Strapdown ESG for Orbital Spacecraft

Refinement of the electrostatic gyroscope (ESG) drift model aboard an orbital maneuverable satellite for remote sensing of the Earth’s surface is considered. Some changes of the drift model also hold for the ESG ground-based applications. The paper also analyzes the quasi-continuous correction mode of the ESG-based strapdown inertial attitude reference system (SIARS) using raw (unsmoothed) data from the star tracker and the extended Kalman filter (EKF) algorithm. A special feature of solving the problem of SIARS output data correction and the calibration problem in this mode is rejection of incorrect measurements. The algorithm for this problem solution is described. The ESG drift model is given both for the SIARS calibration mode in order to ensure an adequate prediction of ESG drifts over a long time interval and for the quasi-continuous correction mode under spacecraft maneuvering conditions. The results of data processing of the flight tests of the SIARS and the star tracker aboard one of the spacecraft are discussed.

Composition analysis of thin films formed on beryllium surfaces under pulsed laser action by the method of chemical thermodynamics

The thermodynamic approach to determine the phase-chemical composition of thin films formed on the beryllium surface under laser exposure in air and nitrogen gas environments is suggested. Laser marking in a gas environment is used to create contrast patterns on beryllium which is a base material for spherical rotors of the electrostatic gyro. According to thermodynamical calculations of isobaric-isothermal potentials (Gibbs thermodynamic potentials) and kinetic analysis of the chemical reactions, a formation of Be3N2 in nitrogen and BeO in air atmosphere during laser marking of beryllium has the highest probability. As a result, it is possible to control the conductivity of the laser-marked patterns by changing the content and partial pressures of the components of the gas environment. Simulated results agree with the experimental data provided by X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning probe microscopy (conductivity).

Investigation on correcting process of spherical rotor imbalance at thin film deposition stage

We propose a method of rotor imbalance correction for electrostatic gyroscope. The method is based on redistribution of the material on the beryllium rotor surface during deposition of the titanium nitride coating by cathodic arc physical vapor deposition (Arc-PVD) technique. The deposition process is carried out using one arc source made of BT-1-00 material, located in the horizontal plane of the vacuum chamber of "Bulat-6" installation at nitrogen pressure of 1.2ˑ10-3 Pa. Size distortion of the rotor caused by thermal expansion during heating to 300 °C, is not more than one hundredth of a micrometer because of the high dimensional stability of beryllium. The titanium nitride coating with a thickness about 1 μm is formed during 30 min deposition on the spherical surface of the rotor with a diameter of 10 mm. The imbalance correction is achieved by deposition of the coating with the center of the coating sphere displaced relative to the geometrical center of the rotor in the direction opposite to the direction of the rotor imbalance vector. The required displacement is determined by the rotor kinematics during the deposition process and is provided by the developed device with three degrees of freedom: two rotational ones – constant and cyclic around two different axes of the rotor, and reciprocating displacement of the rotor relative to the source of the sputtered material along the flow axis of this material. The developed device provides fastening of the rotor in four- needle clamp. The calculation of rotor fixation scheme in this clamp is carried out, ensuring the positioning needles outside the area of the raster pattern formed in the rotor equatorial zone during the next laser marking operation. The experimental data showed that it is possible to produce real rotors with the imbalance correction accuracy within two decimal places of a micrometer.

Construction of a geographically oriented horizon trihedron in gyroscopic orientation systems intended to aid navigation dead reckoning part 1. Gyroscopic orientation with a correctable pendulum. Implementation in a free gyroscope

The paper considers the construction of a geographically oriented horizon trihedron intended to determine a carrier position by navigation dead reckoning. In most cases, gyroscopic orientation with a correctable pendulum (GOCP), the method proposed by the author, is more suited for this purpose than the inertial method. The gist of the new method is that the error in computed coordinates caused by the construction of the horizon plane with the use of accelerometer readings disturbed by the carrier inertial accelerations can be inertialessly corrected due to external velocity aiding. A scheme is proposed for the implementation of high-precision dead reckoning with three accelerometers and a gimballess electrostatic gyro, which is both an example of practical implementation and a prototype of a class of single-gyro orientation systems intended to aid navigation dead reckoning.

Об эффективности модуляционного вращения корпуса бескарданного электростатического гироскопа в полярной ориентации

Об эффективности модуляционного вращения корпуса бескарданного электростатического гироскопа в полярной ориентации

Strapdown inertial navigation system of pendulum type

We consider two implementations of an isotropic oscillator to be used in the construction of a strapdown inertial system of new type [1]. The first implementation is a contact-free suspension of an electrically conductive ball used in electrostatic gyros, and the second implementation is a 3D combination of elastic constraints holding a mass point.

Analysis of functional relation equations in the electrostatic gyroscope (ESG)

Analysis of functional relation equations in the electrostatic gyroscope (ESG)

Rotor motion in a strapdown electrostatic gyro onboard an orbiting spacecraft

The article presents the motion equations for ESG rotors with spin axes being in-plane and orthogonal to the orbital plane during the start. Motion equations are solved analytically using the deterministic drift model of a strapdown ESG, and effects of various physical factors on the motion parameters are investigated. The obtained solutions correlate well with flight test data.

Integrated attitude reference and navigation system for orbital spacecraft

The paper considers an integrated attitude reference and navigation system for an orbital spacecraft. The system comprises a strapdown inertial attitude reference system based on electrostatic gyros (ESGs) and fiber-optic gyros (FOGs). Algorithms for joint processing of ESG and FOG data which use a Kalman filter and the corresponding criteria are described. Results of computer simulation of the system algorithms with MATLAB using ESG and FOG real test data are given.

Improving the attitude determination accuracy for an earth remote sensing spacecraft

This paper considers the problem of improving the accuracy of spacecraft attitude determination through refining the drift model coefficients of strapdown electrostatic gyros and defining the misalignments between the gyro and the star sensor axes. The results of the office studies of the data of electrostatic gyros are presented.

Refining the drift model of a gimballess inertial attitude control system based on electrostatic gyros: Methods of calibration on a ground-based test bench and on board an orbiting space vehicle

The calibration mode of a gimballess inertial attitude control system (GIACS) based on electrostatic gyros (ESGs) is considered upon activation of the system on board an orbiting space vehicle, with implementation of the algorithm for solving problems of angular position correction and refined drift model coefficient (DMC) calibration of electrostatic gyros, based on data from a space vehicle astrosighting device (ASD). The ESG-based GIACS was tested on a ground test bench. The results from solving the problem by processing the test data are presented.

A planar vibratory gyroscope using electromagnetic force

A planar vibratory gyroscope using electromagnetic force is proposed and tested. Such a gyroscope has the advantages of simple fabrication and large output characteristics compared with an electrostatic gyroscope. The fabricated gyroscope comprises a gyroscopic element with two gimbals, driving and sensing coils. The driving coils, which are under the outer gimbal, vibrate the gyroscopic element. Vibration of the inner gimbal due to an applied angular rate is detected by sensing coils underneath it. Maximum output is obtained when the output gimbal is driven at a resonance frequency of the inner gimbal. Measured sensitivities are from 4.2 to 26 mV (° s −1) −1. Sensitivities are measured at several exciting voltages and several values of the air gap of the sensing parts.