Vol 23, No 1 (2022)

Trends in the development of the spacecraft (SC) industry present increasingly complex tasks for mechatronic systems. Due to the complexity of the assembly processes of large-sized transformable structures and solar panels, the current methods of opening structures are becoming less reliable and relevant. The development of orbital stations in addition leads to a whole range of new tasks. Using mechatronic manipulators is one of the promising approaches. However, the functionality of their application is severely limited by the algorithms for moving the executive body and manipulating objects, predetermined during development. In this regard, there is a need to develop new approaches to finding and determining the shape of the target object, for further calculation of the algorithm for its interaction with the mechatronic manipulator gripper.

The article presents a method for reconstructing the three-dimensional shape of objects, based on using a machine vision system. A stereo camera is used to obtain the scene's spatial characteristics. Based on the data obtained, the scene is divided into several independent geometric surfaces, followed by staged processing by neural network algorithms. The required parameters of the target objects are extracted at each stage of the algorithm. YolactEdge is used as a neural network architecture, which performs semantic segmentation and classification of objects. A separate task can be the correlation of the spatial characteristics of the target objects and the replacement three-dimensional model. To ensure this correlation, the neural network architecture was supplemented with a keypoint detection branch which provides a prediction of the positions of the reference points of objects that uniquely determine the spatial characteristics of the target object.

As a result, the system obtained is able to provide the construction of a three-dimensional map of the turning radius area in real time. In addition, based on the received telemetric information, it is possible to calculate the trajectory of the manipulator's executive body and its interaction with objects.

The paper proposes applying clustering methods to determine the most appropriate number of fuzzy terms to design a genetic fuzzy system. The fuzzy logic system in this study is used to solve data classification problems and is automatically generated by a genetic algorithm. In this study we used a genetic algorithm with encoding of terms and classes into a binary string, while each individual encoded a rule base. It is necessary to set the number of fuzzy terms parameter to build a rule base, since it significantly affects the quality of the generated classifiers. To determine the best method of data clustering, the most well-known algorithms were compared: DBSCAN, k-means and the mean shift algorithm. To evaluate the efficiency of the selected number of fuzzy terms, computational experiments were performed on several data sets. Based on the results, it was determined that the mean shift algorithm selects such a number of terms that allows building more accurate classifiers in comparison to the other two methods involved in testing. A comparison was also made with alternative classification methods such as k nearest neighbors, support vector machine and neural networks, as a result of which the proposed method showed comparable classification quality. The developed approach to automating the determination of the number of terms makes it possible to exclude manual selection of granulation for various data, reducing the cost of creating an effective fuzzy system for solving classification problems.

The force measuring device is a part of the bench force measurement system required for direct measurement of the rocket engine thrust during the test. One of the common types of force-measuring device calibration systems is a lever-type calibration device. The simplicity of the kinematic scheme is one of the main advantages of its use as a calibration system. Along with this, the disadvantages of this scheme are concentrated in the supporting elements of the lever system, since it is the wear of the supports that leads to the accumulation of a systematic error of the entire system with a proportional deterioration in the accuracy of the force measurement process. The aim of the work was to analyze the features of prismatic supports used as part of a lever-based calibration device of a force-measuring device, as well as to simulate the stress-strain state of a model of a real prismatic support used in an existing force-measuring system. The work considers the closest theoretical information associated with calculating the stress distribution in the wedge and half-plane in accordance with the plane problem of the theory of elasticity. The selection of the mechanical properties of materials was carried out depending on the specified hardness indicators, as well as the modeling of the contact problem in a given prismatic support, depending on the angle of inclination of the prism in relation to the pad, using the static analysis of the Solidworks Simulation software package. The calculation results are given, conclusions are drawn on the work done.

Transformable structures represent a special class of large space systems. They are delivered into orbit in a tightly packed state. When the required parameters of the orbit are reached, their opening or transformation is carried out. The shape of the transformed structure is rigidly fixed upon completion of the transformation process. At the same time, shock loads occur on its constituent elements. The complication of design schemes and the increase in the dimensions of modern transformable space systems due to the increase in their operational functionality leads to the necessity of improving their mass characteristics. To date, many variants of transformable structures of space antennas have been developed abroad and in our country, the ratio of the mass of mirrors to their areas has decreased to 0.5.–1.5 kg/m². Further improvement of transformable space structures is possible with the use of materials with the shape memory effect to create actuators that ensure controlled shock-free opening of these structures from the transport state to the working position Experimental and theoretical studies of the actuator model made of titanium nickelide material have confirmed the fundamental possibility of its use for the deployment of promising transformable space structures. During the tests, the main characteristics of the actuator model were determined, namely: the actuation force, the working stroke and the actuation time.

Lithium-ion batteries (LIB) are widely used as energy accumulators in the electrical power systems (EPS) of spacecraft. The article considers the automated bench SIA 12/24 for electrical tests and diagnostics of the resource characteristics of lithium-ion cells (LIC), on the basis of which the EPS LIB of spacecraft is developed and manufactured. LIC resource tests are the most time-consuming and lengthy, they are carried out in ground conditions for several months with repeated cycling of charge/discharge and cell temperatures until the conditions for completion of the tests are reached with periodic monitoring, measurement and registration of LIC parameters. The use of the automated bench, which makes it possible to carry out resource testing of LIC based on dynamic stress testing (DST), makes it possible to shorten the resource testing of LIC and thereby significantly accelerate the design and development of EPS LIB of spacecraft. The structure, the description of the component parts and the technical characteristics of the bench SIA 12/24 allowing to perform electrical tests simultaneously of twelve LIC are given. The principle of operation and technical characteristics of the original charging-discharge device with a load converter (CDD-LC) forming the basis of the bench are considered. The proposed original CDD-LC and load converter (LC) topologies with two-stage power conversion and stabilized bridge transformer converter (BTC) input voltage make it possible to automate the process of lithium-ion cells electric testing by automatically reproducing functionally necessary test modes and by ensuring energy saving in cells charging-discharge modes.

For a two-stage power conversion CDD-LC, it is shown that the use of  BTC input voltage stabilization gives the following benefits:

– extension of the LIC attribute control ranges: current, voltage, power;

– low dependency of static error of stabilization of LIC attributes and transition quality indicators on the type of LC load.

The design of a spacecraft at the initial stages is carried out in the presence of uncertainties in terms of parameters and conditions. Determination of design parameters is carried out step by step: determination of nominal values of design parameters, normalization of resource reserves (mass, volume, energy consumption) according to design parameters to parry uncertainties, designing a spacecraft for marginal resources.

The operation of a spacecraft with an electrical load switched on includes several stages: launching into the target orbit, putting into regular operation, regular operation for the intended purpose, decommissioning from the intended use in case of emergencies. The power supply system is designed to provide uninterrupted autonomous power supply to the onboard equipment in all modes and at all stages during the period of active existence of the spacecraft, taking into account the presence of shadow sections of the orbit from the Earth and the Moon.

In this article, methodological principles for designing a spacecraft for the maximum power supply of the payload in the presence of uncertainties in parameters and conditions are developed. Mathematical models for calculating the parameters of the energy balance of the spacecraft have been developed for various options for realizing the power of the session load, depending on the level of illumination of the orbit and the period of operation of the spacecraft. The effectiveness of using the methodological principles of designing a spacecraft for the maximum power supply of the payload, depending on the level of illumination of the orbit and the period of operation of the spacecraft, has been evaluated. A technique has been developed for rationing reserves by spacecraft energy resources to parry uncertainties in terms of parameters and conditions, as well as the principles of its application when designing a spacecraft for maximum payload power supply.

Bismuth stagnnates Bi₂Sn_2–хFe_хO₇, х = 0,1; 0,2 which reveal the properties of multiferroics, are investigated. The mechanism of interaction between dielectric and electronic subsystems is studied, based on measurements of electrical resistance at alternating current, impedance, capacitance and dielectric loss tangent in the temperature range 100–600 K at frequencies 10²–10⁶ Hz. From a comparison of the dielectric permittivity and the reactive component of impedance, the paramagnetic contribution of electrons to the dynamic magnetic susceptibility was established. Impedance jumps on temperature  were detected as a result of changes in structural characteristics. The temperature dependences of the permittivity are described in the Debye model. An activation character of the relaxation time and two relaxation channels were found. The activation energy of electrons in the migratory polarization is calculated.