ISSN 0021-3454 (print version)
ISSN 2500-0381 (online version)
Summaries of the issue


FEATURES OF DESTRUCTION OF MATERIAL SURFACE, STRENGTHENED BY PARTICLES Yury A. Fadin, Perevislov Sergey N., Danilovich Dmitry P., Markov Mikhail A.
The process of wear of ceramic composites with polycrystalline matrix of silicon carbide with dry friction in tool steel is considered. Fragile particles of various sizes are used as fillers of the composite matrix. Wear as a process of multiple surface destruction occurs in the field of mechanical stresses created by the interaction of roughnesses of contacting bodies, each roughness plays the role of an indenter, as in the case of "Hertz contact". Variation of the load makes it possible to regulate both the depth of the layer of the maximum tangential stresses and the numerical value of the stresses. The wear resistance of composites hardened by particles of 1—1000 μm in size is shown to depend on the ratio of the depth of the layer of maximal tangential stresses and the size of the hardening particles.
An approach to optimization of operational parameters of solid-state laser by means of maximization f compensation of thermo-optical distortions in the laser active element is discussed. Compensation of thermo-optical distortions is understood as compensation for the displacement of the laser optical axis, as well as elimination of the nonuniform distribution of the optical path length along the beam crosssection. As a cause of such phenomena, the presence of a temperature gradient in the active element of the laser is considered. The known methods for compensating the thermo-optical distortions are analyzed, a classification of the method according to the types of compensated distortions is proposed.
The problem of determining the running-in time of the friction unit shaft – liner of plane bearing is considered depending on the vibration acceleration index of the low, medium, and high frequencies in the tri-band spectrum obtained with the SM-21 vibrometer. On the base of results of experiments carried out with the use of a friction machine, a relationship between the running-in time of the friction unit and the vibro-acoustic component is established. A method is proposed for predicting the running-in period of a cylindrical friction pair not only by controlling the vibroacoustic component, but also by the amount of wear.
Processes occurring on the surfaces of materials during interaction between metal and non-metal parts of orthoses, prostheses and exoskeletons are considered. These biomechatronic devices are noted to require careful selection of materials for their design and manufacturing with the account for both mechanical properties of the materials and their tribological characteristics. Samples of duralumin — fluoropolymer and stainless steel 100CrMn6 — fluoropolymer friction pairs are chosen for the research; the plane-on-plane contact scheme without any lubricants is applied. Results of experiments carried out with the use of the universal friction machine MTU-1 are described. Dependencies of friction torque, friction coefficient, and the temperature in the contact area on the runtime are obtained on the base of the experimental data. Estimation of the wear of contacting samples is presented. Analysis of the results are reported to justify the choice of suitable materials for design of orthoses, prostheses and exoskeletons.


The methods for calculating the accuracy of the involute cylindrical gear train (the dead course of the transmission) are considered. Expressions from standards GOST 21098-82 and GOST 1643-81 are analyzed, formulas for calculating the dead run of the gear transmission by the maximum method (in which all parameters take the maximum values) are derived. A formula is given for transferring the magnitude of the dead travel of the transmission from micrometers to angular minutes. Calculation of the dead run of the gear transmission by a probabilistic method (the Monte Carlo method) is performed. An algorithm for calculating the dead path is presented.
Mathematical simulation method accounting for continuous changes in the teeth shape is used for investigation of regularities of gears wear. Parameters of all investigated pairs of gears and conditions of their joint application are given. Conditions and limitations on possible application of the obtained results are analyzed, basic relations used for calculating the linkage parameters are presented. The data of modelling are used to draw graphs of the distribution of wear during the initial period of contact and make several conclusions about the wear nature. The change in the line of engagement of the wheel and gear during the running-in of the gearing elements is demostrated. The conditions of occurrence and development of the position error are analyzed. The cause of the growth of the cyclic error and the consequence of uneven wear are determined. The graphs of redistribution of wear in the areas of double-pair gearing during wear are presented, conclusions are drawn about its nature, as well as the tooth profiles and the engagement line. The cause of stabilization of a cyclic error is determined and the schedule of its changes is given. A graph is given of the variation of the dead stroke during the meshing of the gears. Conclusions about the nature and regularities of wear of spur gears are formulated.
The dynamics of free and forced rotation of a rigid body around the central but not the principal axis of inertia Oz, supported by a bearing and thrust bearing, is modeled mechanically under the conditions of hydrodynamic and dry friction. It is shown that The inertial pairs and pairs of dry friction arising in the plane of the axis are shown to depend not only on the centrifugal moments of inertia and the angular velocity, but also on the acceleration. The revealed dependence leads to dynamic equations with an irrational right-hand side in the general case, and with a discontinuous one in the particular case. The equations for simplest types of the motion are integrated analytically and numerically.
APPROXIMATE GEAR TRANSMISSION WITH A PIECE-LINEAR CONTACT Timofeev Boris P., Ponomarenko Maxim Yu., Kovalevich Alexander V.
The possibilities of gears with the use of the simplest surfaces - the plane, the cylinder and their various combinations — as working surfaces of the teeth are analyzed. It is shown that with such simple outlines of the teeth it is possible to obtain a high-quality transmission. The resulting values of position and gear ratio errors are minimal and in the case of multi-row transmissions can be negligible. Calculations of the kinematic parameters of the proposed engagement options are made. The prospects of using gears with the simplest outlines of teeth are associated with the absence of the need for complex processing equipment and the possibility of manufacturing and repairing in the field.


The algorithms for optimizing the manipulator trajectories with an excessive number of degrees of freedom are investigated. The goal of optimization is to improve the energy efficiency of traffic. Trajectories are parameterized by spline functions passing through given points, and the search for optimal parameters is performed with the use of the gradient descent method with step division, which allows finding the global extremum. The chosen objective function simultaneously accounts for the influence of the electrical components of the system and ensures minimization of deviations from a given trajectory in the Cartesian space. The results of simulation modeling in the MatLab environment are presented for the example of optimizing the trajectories of the mobile manipulator Kuka youBot.
The action principle of a power-efficient actuator for transforming an applied force into translational movement is considered. An elastic element (which has the functioning principle based on the phenomenon of loss of stability) is used as an operating element of the device. An analysis of analogues of the proposed mechanism is presented. An actuator design is proposed, and the main components of the mechanism are described. Calculations of the mechanical properties are carried out. Conditions for the applicability of a working unit of the device (an elastic element) are formulated. It is supposed that the obtained results can be used in design of machines and mechanisms, in robotics area as a new type of power-efficient actuators, and in the process of bionic systems modeling.
DESIGNING A TEST BENCH FOR A WAVING WING MECHANISM CONTROL Moya Jose Luis Zarate, Meshkov Alexey V., Lukin Alexander Е.
The development of an adaptive system for analyzing the properties of flight dynamics in a system with a waving wing helps to study the system characteristics and makes it possible to use various control methods to improve its efficiency. A test bench is developed for study of a mechanism with a waving wing. Results of investigations based on a mathematical model of the lever are presented. Description of the test bench and information on the construction elements are presented. The Simulink model used for control over the test bench in real time is discussed. The designed test bench is reported to allow for testing of various control systems.
Filament winding is a common method of manufacturing cylindrical composite products. It is the process of placing threads or tapes in strict geometric order on the surface. The winding material is usually carbon fiber or glass fiber coated by a synthetic resin. The mandrel is removed when the resin hardens and then the final product is formed. Linear speed of winding material and thread tension (tape) are maintained at a given level by special devices in the process of winding up, so no less it is impossible to stabilize the winding tension of the surface layer and to ensure the same winding mode and the same winding density for all reproduced products. Final products have differentiations in radius of winding along generator line of the cylindrical body and surface layer of the finished product has tuberosity. To address this shortcoming, a control system of the composite winding density is proposed. The system is anticipated to ensure stability of the composite product’s geometric parameters and its density.
Approaches to development of software component for module of lengthy objects shooting for sawn timber scanner are described. The use of known image recording algorithms is shown to simplify the scanner designing. The proposed algorithm of the software component operation is a computational graph; and the computational operations performed during processing of the survey frame are listed. An algorithm for separating the object from the background is presented. An algorithm of full search for the comparison of control points between frames and the RANSAC algorithm, which is used to construct the transformation model, is chosen. The implementation scheme of the RANSAC algorithm is compared with the PROSAC algorithm.


The problem of manual control of a wheelchair with an electric motor is considered when there is an error in the control task coming from the joystick. A joint control algorithm is developed to prevent collisions with obstacles during movement in a complex dynamic environment. Identification of obstacles is carried out with the help of optical range finders installed along the perimeter of the control object in question. Results of experimental approbation of the developed algorithm with the use of the Robotino mobile robotics platform (FestoDidactic) are presented.
DEVELOPMENT OF A REHABILITATION DEVICE FOR THE ELBOW JOINT Krivosheev Sergey V., Sokolov Sergey K., Olejnik Roman V., Stanislav S. Reznikov
Results of the work on creating a robotic orthosis for the elbow joint are presented. A design of the device is proposed, a three-dimensional model is created. Several changes made in the functional, were dictated by analysis of competitive solutions. The development process is described, the main calculations and the main functional features of the developed devices are discussed. A brief conclusion includes prospects of a further development of the project.
The possibility of automation of the processes of medical diagnostics and quantitative evaluation of anatomical structures by segmentation of magnetic resonance (MR) images is considered. The values of intensity of MR signals from various tissues of the knee joint are analyzed, weak dependence of contrast of signals on external factors is revealed. The algorithm for the segmentation of cartilage and bone structures based on the calculated contrast of tissues is implemented, including threshold processing, morphological analysis, and the delineation of borders by the Canny method. The results are approved by tomograms of different weights (sequences of rapid spin echo, gradient-echo), and can be used for cartilage mapping and 3D joint modeling.