Purpose of reseach is to develop a methodology for studying the wear of drill pipe threads during repeated making up and holding under load.
Methods. For the research, stand “IRS-1” was used. This stand is a device for creating a torque of up to 80 kNm and transferring it to a made-up pipe. It is equipped with a make-up torque sensor and a control system that performs make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up thread pair. The test procedure for IRS-1 stand consists of the following sequence of actions: before starting the tests, the threaded protectors are removed; the threads on the nipple and sleeve are cleaned of the preservative grease and traces of corrosion by dry wiping and subsequent degreasing; the thread on the nipple is measured according to the measurement chart using a gauge. The gauge is made on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. The gap between the gauge and the thread is measured using a set of probes from 0.01 to 0.09 mm in increments of 0.01 mm, over 0.1 mm to 0.45 mm in increments of 0.05 mm, over 0.5 mm to 1 mm in increments of 0.1 mm.
Results. A new tribotechnical stand of IRS-1 model was designed and created, which allows implementing various techniques for studying the wear of drill pipe threads during repeated making-up and holding under load. An important feature of the designed stand is a make-up torque sensor and a control system that perform make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up threaded pair. The maximum torque generated by the stand is 80 kNm. A particular technique was developed. The technique includes the requirements of the API 7G-2 standard and has shown its effectiveness in the study of thread wear of steel drill pipes. To implement the technique, a special gauge was developed on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. Within this technique, a measurement chart with two selected measurement areas was developed. An algorithm for making up a pipe at a uniform speed was created. The algorithm includes three stages. There was developed an algorithm of measurements using reference marks, providing measurements at four points in each selected area.
Conclusion. The results obtained can be used to create resource-saving technologies for processing ingot, powder, and nanocomposite materials with different dispersion of phase and structural components that are operated under extreme conditions and states.

Purpose of research. The aim of this work is to develop an algorithm for sequential movements of a three-section crawling robot, which enables the device overcoming flights of stairs by crawling on each step or descending each step in the reverse sequence of stages. A special feature of the robot is the combination of three types of movement: snake-, worm - and caterpillar-like, which makes the device more maneuverable and expands its functionality.
Methods. To develop a mathematical model of the movement of crawling robot sections at each stage of the algorithm and description of its contact interaction with the surface, the method of dynamics of multi-mass systems is used; methods of kinematic and structural analysis of the robot mechanism are used to form constraints that restrict the movement of the sections.
Results. The article presents the results of simulation experiments of a robot crawling on a step of a flight of stairs and descending it, confirming the adequacy of the proposed movement algorithm. Positions of base points at the moments of the beginning and completion of the stages, section lengths and their turning angles in the vertical plane correspond to the values of these variables specified in the algorithm in the form of applied links and laid down conditions for the completion of stages.
Conclusion. The article describes a detailed step-by-step algorithm for robot crawling on a step of a stairs flight and descending it; it is shown that crawling and descending are opposite operations from the point of view of sequence of stages implementing. The advantage of this algorithm is the versatility of its stages for moving the robot up and downstairs. In addition, the algorithm stages are designed in such a way that the robot does not roll over.

Purpose of research. The article deals with the problem of monitoring water areas in order to control their physical and chemical conditions using a flying laboratory (FL) which includes an aircraft with attachable water intake equipment and a software and hardware system. A specific feature of the monitoring of surface waters is the unpredictable behavior of air and water, periodic absence of visual contact with the aircraft, the uncertainty of tricopter characteristics. Therefore, the purpose of this article is to study the parameters of the control system (CS) to meet the requirements for the accuracy of aircraft positioning in conditions of uncertainty of external parameters.
Methods. Theoretical mechanics and robot mechanics methods were used to solve the set tasks. Methods for mathematical modeling of dynamic systems were used to study the patterns of convertiplane movement. Adaptive control with a reference model were used to plan and control the movement of the aircraft. Results. The use of adaptive FL motion control made it possible to ensure convergence to zero of the tracking errors i.e., the difference between the output signals and the reference model. The proposed control system gives a good result with small disturbing effects. The parameters of the regulator that ensure the quality indicators of the ACS within the specified limits are determined.
Conclusion. A mathematical model was developed and mathematical modeling of the convertiplane movement under conditions of uncertainty of external influences was performed. The problem of parameter control of a convertiplane was considered when the control coefficients were available for setting. The developed algorithms in the adaptive control system made it possible to provide faster suppression of external disturbances in comparison with the traditional PID control system for the case of a linear description of the controlled object.

In various branches of mechanical engineering, faucets, valves, gate valves and other shut-off devices are manufactured and used. Their main purpose is to regulate the flow rate and direction of flows of liquid and gas media. Features of such products in the aerospace and petrochemical engineering are special strict requirements due to the specificity of their operation. These include, for example, high pressure, resistance to aggressive, fire-and explosive environments, leaks of which are unacceptable according to safety rules and environmental legislation. The design of such products, as a rule, assumes high requirements for accuracy and roughness, especially at the interface of parts, high strength in case of impact pulse effects of the fluids in them. To ensure the above characteristics, finishing abrasive treatment is most commonly used, which can result in the effect of impregnation of the surfaces of products, which will negatively affect the useful life and performance indicators of the mating surfaces. At the same time, it is obvious that mechanical finishing without any use of abrasives is extremely difficult and time-consuming. The authors of the article suggest elimination of the negative effect of impregnation by means of mixed machining techniques with the application of electromagnetic fields.
Purpose. The purpose of the work is to develop a technology for non-abrasive finishing of machine parts by developing a model that allows selection or calculation of the production modes of gapless mating parts of locking devices applied in various industries.
Methods. The method of the research is the use of the scientific basis of mixed machining techniques, the theory of mass transfer in electrical machining, the fundamental foundations of mechanical engineering technology, modern methods for studying characteristics at the final stages of machining, modern measuring tools, special technological equipment, as well as computer technologies.
Results. As a result of the research, new technique and devices were developed. This made it possible to implement a non-abrasive finishing operation of the mating surfaces of parts made of metal materials, the processing of which by mechanical methods is difficult.
Conclusion. As a result of the conducted research, it became possible to obtain high-quality high-resource gapless locking products and to reduce labor intensity of the finishing operation up to 5 times and preparation for the production up to 2 times.

Purpose of research. Development of a mathematical model of an exoskeleton equipped with a hybrid linear gravity compensator (HLGC), dynamic analysis on the example of a typical exoskeleton application scenario (in the process of lifting a load), obtaining time patterns of changes in system parameters, including electric drive torques allowing assessment of power plan power consumption and energy efficiency. The article deals with the challenging issue of improving the efficiency of the exoskeletal suit by means of HLGC. The use of a hybrid approach makes it possible to increase the efficiency of assisting the exoskeletal suit when performing various technological operations, for example, when lifting a load, when tilting and holding.
Methods. When developing a mathematical model, an original approach was used to form the motion trajectory of the exoskeleton sectors during operation, based on the use of seventh-order polynomials. The paper uses a mathematical model represented by a system of second-order differential equations that connects the moments acting on the operator and the exoskeleton, the angular accelerations of the operator's back and the exoskeleton.
Results. During numerical simulation, time diagrams of changes in system parameters, angles of rotation of exoskeleton hinges, moments that occur in a hybrid LGC, as well as graphs of current consumption of engines when performing lift and tilt with a load are obtained.
Conclusion. In the course of the research, a kinematic model of an exoskeleton suit equipped with a GLGC was developed, second-order differential equations describing the dynamic behavior of the electromechanical system were written, and numerical simulation was performed to estimate the forces and energy consumption in the exoskeleton hinges and the drive of the hybrid linear gravity compensator.

Purpose of research. Errors and inaccuracies in the preparation of deliverables based on the results of engineering surveys which are an integral and important part of the design and estimate documentation, can lead to irreversible consequences and significantly reduce the life of buildings and structures. The main difficulty in investigating soil physical and mechanical properties at a construction site is to determine the depth of excavation. This is due to the fact that an increase in the calculated depth leads to the increase in the cost of work, and its decrease leads to the risk of inaccuracies and errors in the design of foundations of buildings and structures. In accordance with the current regulatory documents, the excavation depth during soil investigation should be 1-2 meters below the boundary of the compressible strata. The condition on the basis of which the specified boundary is determined is provided. The development of a technique that allows determining the depth of the compressible strata at the stage of engineering surveying with adequate accuracy is an important task from a practical standpoint.
Methods. Determining natural stress Ϭ_zg,0 as the product of foundation depth d and the specific gravity of the soil above the base ɣ′_ІІ,  , taking into account the fact that the average pressure tends to the value of the estimated resistance of the soil, it is shown that physical-mechanical structure of the base soil exerts the main influence on the parameters of the compressible strata, and correspondingly, to the excavation depth value. In this case, the stresses transferred by the foundation of a building or structure have an indirect effect.
Results. The maximum values of the depth of excavation for engineering and geological surveying for tight coarse sand, medium density and fineness sand, and fine sand and sandy loam are determined.
Conclusion. It is concluded that the given technique allows determining the depth of excavation during engineering and geological surveying with an adequate accuracy.

Purpose of research. Study of the influence of pine wood shelf life on endurance under compression along the grains, as well as grounds for results obtained. Wood is anisotropic, depending on the grains, the mechanical and physical properties of the material differ greatly.
Methods Wood is anisatropic, the change in its endurance depends not only on conditions, shelf life, moisture, but also on the direction of the grains in the timber. However, the relevance of using this material still remains unchanged. The tests were carried out on a press of the UM-5 type. After carrying out the compression test, moisture tests were performed and the test results of the specimens were reported at 12% moisture. Untested samples were stored from 1981 to 2019 in the laboratory of the Department of Industrial and Civil Engineering at South-West University. In 2019, the stored samples were prepared for testing and tested.
Results. To obtain substantiated data on the influence of wood shelf life on endurance, an experiment was carried out with the bars that had undergone a 39-year wait in the laboratory of the Department of Industrial and Civil Engineering. From among the samples, 16 samples were selected, which were tested for short-term compression load along the grains. For these samples diagrams “Load-displacement” were recorded on the press UM-5. The experiment showed two types of sample destruction which led to the corresponding conclusion.
Conclusion. The strength characteristics revealed as a result of experiments from core and sapwood of pine on samples 20x20x30 in 1981 and in 2020 significantly differed from normal ones, this was influenced by a relatively small number of samples.

Purpose of research. To obtain a two-parameter model characterizing the aerodynamic and heat exchange processes occurring in a vortex heat exchanger, giving a better agreement between the calculated and experimental values of the heat transfer coefficient taking into account the curvature of the swirling gas flow in a vortex heat exchanger, in which a controlled gas pressure drop is used as a source of thermal energy. This technical solution will make it possible to abandon the installation of autonomous sources of thermal energy, which will reduce the cost of gas as a fuel in the heating system of the industrial premises of the gas distribution point (GDP), as well as provide more comfortable working conditions for the hydraulic fracturing pressure regulator.
Methods. Comprehensive analysis of thermal and hydraulic characteristics in a vortex heat exchanger is based on well-known theoretical positions and equations of motion of a swirling gas flow and heat exchange laws.
Results. It is obtained a dependence that characterizes the intensification of heat transfer based on the influence of the axial and rotational speed, as well as the path of motion of the swirling gas flow. This dependence is obtained on the basis of a comprehensive analysis of the aerodynamic and heat exchange characteristics of a vortex heat exchanger, in which a controlled gas pressure drop is used as a source of thermal energy.
Conclusion. The obtained two-parameter model gives the best agreement of the calculated values of the heat transfer coefficient with the values obtained experimentally, which were used in the thermal engineering calculation of the design parameters of the vortex heat exchanger.

Purpose of reseach is to analyze the practice in the application of surfaces formed by the movement of a straight line. It is known that among the second-order surfaces cones, cylinders, hyperboloids of one sheet and hyperbolic paraboloids, as well as lines represented in the polar coordinate system in the form of intricate shapes that can be represented in space by the above-mentioned surfaces, adding a third dimension, have rectilinear generators. The strength resulting from covering each point of the listed surfaces with straight lines from different families does not make the structure heavier but strengthens it and makes it light compared to monoliths without reinforcements made of other materials, in which stability is not based on Shukhov calculation formulas.
Methods Finding families of rectilinear generators for second-order surfaces calculation of which is based on the separation of equations that represent a second-order surface as a difference of squares in one part of the equation and as a product with an arbitrary parameter in the other part.
Results. Analyzing second-order surfaces, we came to the conclusion that cones, cylinders are prone to this method of Shukhov calculations; equation of the form F (x,y)=0 in space defines a cylindrical surface whose generators are parallel to axis oz. Similarly, F (x, z)=0 defines a cylindrical surface with generators parallel to axis oy and F (y;z)=0 is a cylindrical surface with generators parallel to axis ox. A hyperboloid of one sheet, hyperbolic paraboloid, i.e. 10 surfaces out of 14, make up more than 70%.
Conclusion. As a result of applying these formulas for calculating reinforced building structures, city buildings will acquire a new appearance, which will create a comfortable environment for residents, as well as lead to saving construction material resources.

Purpose of research. In modern automatic information collection systems, autonomous mobile devices are increasingly used, data from which can be obtained in conditions hazardous to human health, from geographically remote places, in difficult meteorological conditions and in round-the-clock observation mode. For the autonomous operation of such devices, it is necessary to use methods and algorithms that allow you to build a map of the area, link a mobile platform to it, determine a route to a target point, highlight obstacles along the route and correct the route taking into account detected obstacles.
Methods. The article proposes a method and an algorithm for the selection of dynamic objects from a mobile platform, based on the analysis of data obtained from a multispectral camera, which allows the selection of obstacles, such as water, plant origin, technogenic nature, etc. with reduced computational complexity. To improve the accuracy of determining the coordinates of detected objects, a laser rangefinder is used.
Results. We consider the well-known methods of multispectral images recognition and present their comparative analysis. A method and an algorithm for recognition dynamic objects from a mobile platform, from images obtained in different spectral ranges and lidar data are proposed. Experimental studies were carried out to confirm the adequacy of the mathematical substantiation of the method, to reduce the error in calculating the coordinates of the object, at a distance of up to 100 meters to the object, RMSE - 0.447%, MAPE - 0.397, to increase the performance, it took 0, 04 seconds to select the object and determine its coordinates.
Conclusion. The article analyzes modern methods for recognizing multispectral images, presents the principles on which each method is based, gives advantages and disadvantages. The authors have developed a method and an algorithm that make it possible to identify static and dynamic obstacles along the route of a mobile platform, based on a sequence of images obtained in different spectral ranges. In the course of experimental studies, the performance of the proposed solutions and compliance with the specified requirements for accuracy and reliability were confirmed.

Purpose of reseach. Studyof bifurcations in piecewise-smooth bimodal maps using a piecewise-linear continuous map as a normal form.
Methods. We propose a technique for determining the parameters of a normal form based on the linearization of a piecewise-smooth map in a neighborhood of a critical fixed point.
Results. The stability region of a fixed point is constructed numerically and analytically on the parameter plane. It is shown that this region is limited by two bifurcation curves: the lines of the classical period-doubling bifurcation and the “border collision” bifurcation. It is proposed a method for determining the parameters of a normal form as a function of the parameters of a piecewise smooth map. The analysis of "border-collision" bifurcations using piecewise-linear normal form is carried out.
Conclusion. A bifurcation analysis of a piecewise-smooth irreversible bimodal map of the class Z₁–Z₃–Z₁ modeling the dynamics of a pulse–modulated control system is carried out. It is proposed a technique for calculating the parameters of a piecewise linear continuous map used as a normal form. The main bifurcation transitions are calculated when leaving the stability region, both using the initial map and a piecewise linear normal form. The topological equivalence of these maps is numerically proved, indicating the reliability of the results of calculating the parameters of the normal form.

Purpose of reseach is Study of vibration stability of the impulse system of direct current electric drive in order to ensure operating modes with specified dynamic characteristics.
Methods. The stability analysis of periodic solutions of differential equations with discontinuous right-hand side is reduced to the problem of studying local stability of fixed map points.
Results. The analysis of stability is carried out depending on the supply voltage of the electric drive and the gain of the correcting link in the feedback circuit. It is revealed that the boundary of the stability region on the plane of the variable parameters has a pronounced extremum in the form of a maximum at the bifurcation point of codimension two, also called the resonance point 1: 2. On one side of this point, the stability region is bounded by the NeimarkSacker bifurcation line, and on the other, by the period-doubling bifurcation line. This means that with a change in the parameters, the radius of the stability region first increases, reaching a maximum at the resonance point 1: 2, and then decreases. This important conclusion can be used in optimization calculations.
Conclusion. The analysis of the vibration stability of the impulse system of direct current electric drive, the behavior of which is described by differential equations of the discontinuous right-hand side, is carried out. The problem of finding periodic solutions to differential equations is reduced to the problem of finding fixed points of the map. The fixed points of the map satisfy a system of nonlinear equations, which was solved numerically by the NewtonRaphson method. The stability of periodic solutions of differential equations corresponds to the stability of fixed points of the corresponding map. The studies were carried out with variation of the gain in the feedback circuit and the supply voltage. It is revealed that the loss of a fixed point occurs through the supercritical Neimark-Sacker bifurcation, when the complex-conjugate pair of multipliers leaves the unit circle when the parameters change. However, with an increase in the supply voltage, the Neimark-Saker bifurcation boundary passes into the perioddoubling bifurcation boundary at the 1: 2 resonance point.

Purpose of reseach is of the work is to develop an algorithm for calculating stable invariant manifolds of saddle periodic orbits of piecewise smooth maps.
Method is based on iterating the fundamental domain along a stable subspace of eigenvectors of the Jacobi matrix calculated at a saddle periodic fixed point.
Results. A method for calculating stable invariant manifolds of saddle periodic orbits of piecewise smooth maps is developed. The main result is formulated as a statement. The method is based on an original approach to finding the inverse function, the idea of which is to reduce the problem to a nonlinear first-order equation.
Conclusion. A numerical method is described for calculating stable invariant manifolds of piecewise smooth maps that simulate impulse automatic control systems. The method is based on iterating the fundamental domain along a stable subspace of eigenvectors of the Jacobi matrix calculated at a saddle periodic fixed point. The method is based on an original approach to finding the inverse function, which consists in reducing the problem to solving a nonlinear first-order equation. This approach eliminates the need to solve systems of nonlinear equations to determine the inverse function and overcome the accompanying computational problems. Examples of studying the global dynamics of piecewise-smooth mappings with multistable behavior are given.

Purpose of reseach. Digital signal filtering allows real-time noise reduction in electronic devices. Currently, there are many different digital filters, differing in speed, computing power, algorithms and restrictions on the conditions of use. One of these filters is the Kalman filter, but adjusting the gains of this filter is very complicated by the process of additional experiments and collection of statistical information. Therefore, in this paper, the authors consider a simplified algorithm for finding the control coefficients of a fuzzy digital filter with defuzzifier based on the area ratio method and investigate the influence of the area ratio method parameters on signal filtering, thereby achieving the goal of improving the accuracy of the fuzzy digital filter.
Methods. For the algorithm for finding the control coefficients of the digital filter, a fuzzy logic apparatus was used. The control factors are determined using a defuzzifier based on the area ratio method.
Results. In the course of experimental studies, the mean square error RMSE was calculated for a fuzzy digital filter using the area ratio method, the center of gravity method and the Kalman filter. Based on the results obtained, it was concluded that the fuzzy filter based on the area ratio RMSE method is 5.43 times less than for the Kalman filter and 2.77 times less than for the defuzzifier based on the center of gravity method. The results obtained prove the effectiveness of using a fuzzy digital filter with the area ratio method.
Conclusion: This article considers an algorithm for the operation of a fuzzy digital filter, simulates a fuzzy digital filter and a Kalman filter in the Simulink system and calculates the RMSE values for a fuzzy digital filter with the area ratio method and the center of gravity method, as well as the Kalman filter.