The features of tracking estimators of ground target coordinates and motion parameters in onboard optical location systems are considered. The structure of the developed tracking estimator using onboard optical location system data is described. Some simulation results are provided.
The paper studies the possibility to use MEMS-based integrated INS/GNSS systems in the automatic control systems of precision airdrop systems (PAS ACS). Experiments have been conducted to find a navigation solution during the parachute descent. The PAS ACS prototype with remote control and guidance based on the data of a MEMS-based integrated INS/GNSS system has been developed. Flight tests of the designed prototype have been carried out.
Abstract—The paper considers the problem of optimal control of an electric propulsion spacecraft maneuvering between the spatial halo orbits around the L2 libration point in the Earth−Moon system. The proposed methodology finds the initial approximations for calculating the transfer trajectories within the framework of restricted three-body problem and improves the computational efficiency of calculations. A low-thrust transfer between the halo orbits is calculated to confirm the validity of this computational procedure.
Abstract—The paper addresses a hemispherical resonator gyroscope (HRG) with flat electrodes applied in the vehicle control and navigation. In order to enhance the gyro accuracy, we formulate the problem of constructing a new mathematical model describing the nonlinearities of the electromechanical system controlling the hemispherical resonator oscillations. The mathematical model of the resonator dynamics is based on Lagrange−Maxwell differential equations. The obtained nonlinear model is studied with the asymptotic Krylov−Bogolyubov averaging method. The reference voltage on flat control electrodes is shown to arouse systematic drift and changes in the resonance frequency. The provided example demonstrates the influence of reference voltage on the gyro drift and reduction in the resonator oscillation frequency.
Under the water, the data are transmitted for ranges above dozens of meters using the acoustic modems. The acoustic modems are employed, in particular, for data transmission in positioning and navigation of both single and grouped underwater vehicles. Network communication methods are widely used for exchanging the navigation data between grouped autonomous underwater vehicles (AUVs). They are applied, for example, to keep the AUV formation geometry and/or to exchange the navigation data with the lead vessels. These methods can be combined, i.e., provide not only the exchange of mutual/relative positions between the AUVs for formation keeping, but also underwater georeferenced positioning for the group navigation in the geographical frame. A number of factors should be taken into account in the coordinated or cooperated AUV group navigation. As the number of interacting AUVs increases, their frequent addressing the acoustic medium is undesirable, because low capacity of the acoustic channel severely limits the underwater data traffic. Moreover, it is important to minimize the effect produced by the AUV acoustic system on the acoustic medium, particularly, to make the AUV less visible when its acoustic communication and positioning system is operating.
The paper studies the temperature dependency of h-parameter of the fiber-optic gyroscope (FOG) coil. It has been shown that the thermal dependency of h-parameter behaves differently in positive and negative temperature ranges. It is noted that the polarization effect can severely limit the FOG accuracy in a broad temperature range. Ways to eliminate the polarization effect are proposed.
The paper discusses the techniques developed for inspecting inertial measurement units (IMU) with nonorthogonal orientation of their sensitive axes and the results of their application. The methodology was proposed as part of the development of IMUs for a strapdown inertial navigation system (SINS) during the modernization of the Soyuz-family spacecraft transport system under the International Space Station (ISS) program for six-axis units of angular rate sensors (ARS) and accelerometers with nonorthogonal orientation of their sensitive axes. Positive results of the ground-based and flight tests carried out aboard 86 Soyuz and Progress spacecraft from 2002 to 2023 have confirmed the effectiveness of the proposed methodology.
The paper describes a procedure based on predictive simulation for comparing the recursive suboptimal algorithms developed for nonlinear filtering problems including navigation data processing problems. The algorithms are compared in terms of accuracy, consistency, and computational complexity. The provided examples explain the procedure and illustrate its application.
This work is focused on the calibration of magnetometers for the attitude control system of the SamSat-ION university nanosatellite. A calibration methodology is proposed to take into account the temperature drift of the sensors readings. Measurements are carried out in twelve static positions, with sequential cooling and heating in the temperature range from –10 to +50°С, and are used to calculate the estimates of the temperature dependences of the bias, scale factor, and nonorthogonalities of the magnetometer axes. The main results of the ground tests of the SamSat-ION onboard systems obtained in accordance with the proposed methodology are discussed. The operability of the onboard systems during and after calibration under temperature variations (rise and drop) has been confirmed. Taking into account the found parameters, affected by various temperature gradients, decreases the measurement error about twelve-fold, which makes it possible to ensure reliable operation of the attitude control and stabilization system of nanosatellites that include magnetometers.
The paper summarizes the results of the research on angular motion dynamics carried out by the team of the authors and some problems of attitude control of nanosatellites (NS). The features of CubeSat NS passive motion dynamics are described. Conditions for the possible emergence of resonance modes are studied and discussed. Recommendations are given allowing the requirements for mass-inertia characteristics and initial conditions of NS motion to be formulated at the design stage, aimed at the NS stable motion with regard to the required equilibrium position for a wide range of orbital altitudes. Algorithms for reorientation and stabilization of NS motion are proposed based on the solution of the inverse problem of dynamics and selection of optimal nominal attitude control programs. The results of this work are implemented in practice and may be useful to the developers of small spacecraft.
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