Kinematic Scheme Research Articles

ЗАСТОСУВАННЯ МЕХАНІЗМУ ЧЕТВЕРТОГО КЛАСУ ДЛЯ ПРИВОДУ ВУШКОВИХ ГОЛОК ОСНОВОВ’ЯЗАЛЬНОЇ МАШИНИ

Development and research of functionally-adequate target mechanisms of technological machines of light industry with application of applied CAE-programs. Used the apparatus of vector algebra; analytical and numerical methods for determining the position functions of planar mechanisms containing a structural group of the fourth class of the second order, based on the vector transformation of coordinates; random search method for metric synthesis of flat mechanisms; methods of computer visualization and animation of kinematic schemes of flat mechanisms of higher classes. Mathematical models describing the position functions of the mechanism of eyelets of a warp knitting machine containing a structural group of the fourth class of the second order with rotating kinematic pairs in the form of angles of moving links, free vectors constructed on these links and radius vectors of characteristic points of the mechanism as a function of the angle of rotation of the master crank. The geometrical parameters of the flat six-link mechanism of eyelets for the warp knitting machine containing the structural group of the fourth class of the second order with rotating kinematic pairs as a result of metric synthesis of the mechanism by random search in CAE-program are determined; computer circuit modeling of the obtained mechanism is performed; graphs of visualization and animation of the kinematic scheme of the received mechanism are constructed; identification of the kinematic scheme of the obtained mechanism for compliance with the accepted structure; the received graph of function of position of an auricular needle of the mechanism of the fourth class; the functions of the position of the eye needle of the new mechanism and the mechanism of the basic knitting machine OV-7 are compared. The structure of a flat six-link mechanism, containing structural groups of the fourth class of the second order with rotating kinematic pairs, is proposed for use as a drive in a warp knitting machine on the example of the mechanism of oscillating movement of eyelets. The geometric dimensions of the moving parts of the functionally adequate mechanism of the fourth class for the drive of the eye needles of the basic knitting machine are determined. Software blocks for automated computer metric synthesis and calculation of link angles and radius vectors of characteristic points of the mechanism in the CAE program have been created. Practical Value is to use the results for the design and construction of flat mechanisms of the fourth class with rotating kinematic pairs of warp knitting machines, in which the working bodies make stops during the work process.

Development of the methods of kinematic analysis of elliptic drum of vertical-spindle cotton harvester

The paper is devoted to the development of a graphic-analytical method for studying the lever mechanism of an elliptical drum of a cotton harvester, which favorably differs from a serial drum in the completeness of cotton picking from bushes and the quality of the harvested raw cotton. The aim of the study is to define the degree of the effect of the structure and geometry of individual links of the elliptical drum mechanism on changes in kinematic parameters of the characteristic points of the mechanism links, in particular, of the spindles centers. The kinematics of the mechanism was investigated using classical methods of theoretical mechanics, the theory of mechanisms and mechanics of machines, combined with modern methods of computer graphics. The developed research method was described, its usefulness and advantages were shown. As an example, computational and graphic procedures were performed to determine the linear and angular velocities and accelerations of the characteristic points of the mechanism of an elliptical drum in its specific position. The method is clear, easy to control the results, allows one to quickly solve applied design problems, and develops an engineering intuition to evaluate the capabilities of the mechanism according to its kinematic scheme. The research results are of interest for a wide practical application of elliptical spindle drums in the construction of vertical-spindle cotton harvesters.

Simulation of boring by smoothed particle hydrodynamics method

The possibility of applying the smoothed particle hydrodynamics method for modeling of cutting processes on the example of multi-blade boring of holes is considered in this paper. Highly nonlinear LS-Dyna solver with an explicit statement of the dynamic modeling problem is used as a software package for modeling. Johnson-Cook formulation with the corresponding empirical coefficients for each material is used as the model of the workpiece material. Absolutely solid tool is used to simplify the model. The kinematic scheme of the tool rotation is implemented using the keyword INITIAL_VELOCITY_GENERATION. The simulation results obtained in the software package are presented in the form of graphs.

Mathematical model of a milking machine manipulator based on stepper motors

The automation of agriculture increases labour productivity and contributes to an increase in the output of agricultural products, an increase in their quality. These processes are closely related to the application of industrial production technology in agriculture, the improvement of planning and management. Also, the improvement of product quality and the growth of labour productivity are associated with the development of automated control systems that contribute to the autonomous operation of entire agricultural complexes. This paper deals with the development of a mathematical model of a milking installation based on stepper motors. The authors of the work recreated the operation of the milking installation, taking into account the operation of the kinematic scheme of the robot and the dynamics of the stepping motors, positioning of its working body near the tops of the teats of the udder of the animal, which are automatically recognized using image analysis from the 3D TOF camera. The uniqueness of this model lies in the fact that various stages of the operation of an autonomous milking installation are concentrated in one software product. This technology makes it possible to study the effect of each stage separately on the static positioning error of the manipulator working body. The model has been tested, an acceptable accuracy of the results of the model operation is achieved. This model can be recommended for use for engineering calculations and the development of control algorithms for the movement of the working body of the manipulator.

Method for Optimizing the Kinematic Scheme of Stretch-Forming Parts from Sheet Blanks

The modeling of the stretch-forming process a sheet on a punch is considered. A numerical method has been developed for solving the optimal control problems of the stretch-forming process sheet blanks. The values of the residual displacements are considered as an optimization criterion. The algorithms implemented in CAE allow calculating the optimal parameters for the operation of the CNC stretch-forming press. The simulation results are compared with full-scale experiments on the shaping of sheet parts on a stretch-forming press T-600.

Kinematics of the seedling plant with vertical distributor and buckets

In this paper are presented some theoretical and experimental research on the kinematics of planting seedlings of vertical disc type and buckets, the variant of planting directly in the cultivated soil, the kinematics that must ensure the correlation between the working speed of the planting equipment and the speed periphery of the bucket, so that the seedling is planted in an upright position. After a brief presentation of the research carried out worldwide in the field, the kinematic scheme of the planting apparatus and the condition that must be fulfilled by the construction and operation of the apparatus for the correct planting of the seedling are presented. The relations for the projections of the studied point, called the tracer (root of the seedling) and of the afferent angular velocity, are written in a system of xOy coordinates. Using the real values of a studied planting machine, the real and corrected trajectories of the studied tracer point were drawn, using the MatLab program. Following the research, the related conclusions and recommendations for improvement were formulated.

Algorithm for designing of speed change control devices through a gear differential with a closed-loop hydraulic system

The algorithm of practical application of researches results of speed changes management devices with a gear differential and the stopper of rotational movement in the form of the closed-loop hydraulic system has been described. An example is a single-stage single-row gear differential, when the driving link is a sun gear, driven is a ring gear, and the control link is a carrier. For such a device, the order of execution of in design steps has been described. The described execution procedure of speed change devices designing will be valid for all kinematic schemes of single- and multistage gear differentials with stoppers of rotational movement in the form of the closed-loop hydraulic systems with control through carriers.

Study of suspension systems for experimental tanks of the USSR in the second half of the 20th century

Modern pneumohydraulic suspension systems for high-speed tracked vehicles have fairly typical versions of kinematic schemes, implying the installation of an elastic-damping element directly on the suspension housing (inside or outside). This solution is structurally relatively simple, and it is understood that it allows to reduce the values of unsprung masses. Other options, with placement of elastic and damping elements inside the guide elements (balancers), did not “take root” due to the greater structural complexity of both elastic or damping element and the suspension guide element. In addition to the structural complexity of implementation, such a solution increases the values of unsprung masses and, most importantly, complicates the organization of the cooling system. The protruding elements of the chassis are clogged with soil, snow (mud) when driving, which acts as a heat insulator. Nevertheless, with modern technological capabilities, these difficulties can be overcome to a certain extent, in whole or in part. However, despite the above disadvantages, this solution also has important advantages: the suspension does not take up space in the reserved volume, but is completely inside the tracked bypass, which allows using the housing volume more efficiently, and, in addition, providing the most successful bottom design for protection from mine detonation (in the case of a heavy tank “Object 279”, this also made it possible to significantly increase the cross-country ability). This article provides an overview of Soviet prototypes of heavy and rocket tanks, which suspension system was implemented in the guide element. The article also presents a method for determining the power and kinematic transfer functions for these suspension options, analyzes the design implementations and shows that the characteristics of the elastic elements of experimental vehicles meet modern requirements for the suspensions of high-speed tracked vehicles.

Force analysis of the two-satellite planetary mechanism with elliptical gears

Abstract Non-circular gears can be used in modern machines and mechanisms for the implementation of various types of motion and have high strength and compactness compared to linkage mechanisms. This article presents the force analysis of non-circular gear on the example of the planetary mechanism with elliptical gears, providing the rotationally reciprocating motion of the impeller of the stirred tank. Based on the calculation schemes of the links, kinetostatic balance equations for each link of the mechanism are compiled and solved. Reaction forces in kinematic pairs and balancing moment on the input shaft of the mechanism are found. The results can be used in the synthesis and analysis of various machines with the proposed kinematic scheme of the mechanism.

Адаптивна система керування комбінованим пропульсивним комплексом з нечітким регулятором

The article is devoted to solving the problem of increasing the efficiency of control processes for ship combined propulsion complexes through the introduction of a differentiated drive-generator unit and adaptive control methods using fuzzy logic. The purpose of this study is to develop a fuzzy inference model, which can be the basis for building an adaptive control system for a ship's combined propulsion complex under the influence of disturbing environmental factors. The paper analyzes the structure of the ship propulsion system. On the basis of the analysis of the kinematic scheme, methods of stabilizing the rotational speed of the main synchronous generator shaft and the voltage frequency of the alternating three-phase current at the output of the differential synchronous drive-generator unit when changing the rotational speed of the main engine shaft are determined. Taking into account the non-stationary nature of the loads and the limited information about the disturbing effects and the state of the object, the expediency of using a fuzzy controller for building an adaptive control system for the ship's combined propulsion complex has been substantiated. The structure of a fuzzy controller has been developed, the terms of input and output linguistic variables have been determined, the functions of accessories have been selected, a rule base has been formed, which takes into account the above restrictions on determining the control action - the task of providing the desired power on the propeller. The introduction of the proposed adaptive control systems based on the fuzzy inference model allows to reduce the influence of disturbing factors on the operation of the propulsion system and stabilize the voltage parameters of the on-board network

Анализ технологической схемы и процесса взаимодействия фрезы и дорожного покрытия при фрезеровании

The choice of the most rational directions of scientific and technological progress is impossible in our time without careful study and scientifically-based analysis of the sources of information. The purpose of the work is to study the perspective designs of road cutters, providing an increase in productivity and accuracy of operations performed for milling the track of the road surface and its bulges on the basis of patent research. The patent search was carried out in two directions: review of existing processes and kinematic schemes of milling of complex profile surfaces, including pre-surface coatings; review of existing processes of milling of complex profile surfaces on the basis of coordinate closure of the milling cutter-tool-coating system. This review is based on the search for available scientific and technical information, including regulatory and technical documentation, scientific articles, current patents for inventions and utility models, information on advanced manufacturing technologies. The analysis of inventions is carried out, their principle of action is considered. Both positive and negative effects of innovations are revealed. The main perspective directions of modernization of the design of expensive cutters are defined, their classification is presented. The paper presents inventions that are not only designed to increase the productivity of production, rapid tool replacement, but also to improve the accuracy of milling the gauge of the road. The results of the work can be used in the selection of ways to improve the working bodies of road cutters.

Underactuated Motion Planning and Control for Jumping With Wheeled-Bipedal Robots

This letter studies jumping for wheeled-bipedal robots, a motion that takes full advantage of the benefits from the hybrid wheeled and legged design features. A comprehensive hierarchical scheme for motion planning and control of jumping with wheeled-bipedal robots is developed. Underactuation of the wheeled-bipedal dynamics is the main difficulty to be addressed, especially in the planning problem. To tackle this issue, a novel wheeled-spring-loaded inverted pendulum (W-SLIP) model is proposed to characterize the essential dynamics of wheeled-bipedal robots during jumping. Relying on a differential-flatness-like property of the W-SLIP model, a tractable quadratic programming based solution is devised for planning jumping motions for wheeled-bipedal robots. Combined with a kinematic planning scheme accounting for the flight phase motion, a complete planning scheme for the W-SLIP model is developed. To enable accurate tracking of the planned trajectories, a linear quadratic regulator based wheel controller and a task-space whole-body controller for the other joints are blended through disturbance observers. The overall planning and control scheme is validated using V-REP simulations of a prototype wheeled-bipedal robot.

The Method of Formation the Reference Speed of Movement of the Working Tool of Multilink Manipulator

The solution of task of increasing the productivity of robotic systems containing multilink manipulators is presented in this paper. Their actuators have power limitations. To solve this task, a method has been developed for automatic formation of extremely high reference speeds of their working tools. This method allows to maintain a set dynamic control accuracy, taking into account interactions between all degrees of freedom of these manipulators and restrictions on input signals of their electric drives. The created method consists in calculating the maximum allowable speed of the working tool of the manipulator. The main feature of the method is conditions for selecting required data for quick calculation of all necessary control parameters. A system for forming the speed of the working tool of the manipulator with three rotational degrees of freedom was synthesized based on the proposed method. These degrees of freedom are driven by DC motors. This manipulator can move working tools along arbitrary smooth spatial trajectories formed using third-order parametric splines. The performed simulation confirmed the high efficiency of the proposed method in comparison with other known methods for forming the reference speed. This method provides significant increasing of the reference speed of the working tools due to continuous operation of at least one of the manipulator electric drives near the saturation zone of its power amplifier without entering it. At the same time, the system speed was increased without reducing dynamic accuracy. The created method can be used to generate the extremely high reference speed of the working tools of manipulators with any kinematic schemes and various numbers of degrees of freedom.

A Kinematic Kinetic Energy Backscatter Parametrization: From Implementation to Global Ocean Simulations

AbstractOcean models at eddy‐permitting resolution are generally overdissipative, damping the intensity of the mesoscale eddy field. To reduce overdissipation, we propose a simplified, kinematic energy backscatter parametrization built into the viscosity operator in conjunction with a new flow‐dependent coefficient of viscosity based on nearest neighbor velocity differences. The new scheme mitigates excessive dissipation of energy and improves global ocean simulations at eddy‐permitting resolution. We find that kinematic backscatter substantially raises simulated eddy kinetic energy, similar to an alternative, previously proposed dynamic backscatter parametrization. While dynamic backscatter is scale‐aware and energetically more consistent, its implementation is more complex. Furthermore, it turns out to be computationally more expensive, as it applies, among other things, an additional prognostic subgrid energy equation. The kinematic backscatter proposed here, by contrast, comes at no additional computational cost, following the principle of simplicity. Our primary focus is the discretization on triangular unstructured meshes with cell placement of velocities (an analog of B‐grids), as employed by the Finite‐volumE Sea ice‐Ocean Model (FESOM2). The kinematic backscatter scheme with the new viscosity coefficient is implemented in FESOM2 and tested in the simplified geometry of a zonally reentrant channel as well as in a global ocean simulation on a 1/4° mesh. This first version of the new kinematic backscatter needs to be tuned to the specific resolution regime of the simulation. However, the tuning relies on a single parameter, emphasizing the overall practicality of the approach.

A framework for set-based kinematic control of multi-robot systems

In this paper, a novel control framework for coordinated motion for kinematically redundant multi-robot systems is developed. The framework embeds both tasks expressed as equality constraints and set-based tasks, i.e., tasks expressed via inequality constraints, in a task-priority kinematic control scheme. The effectiveness of the approach is experimentally demonstrated on two different multi-arm systems. The first system, aimed at operating in household tasks, is composed by two arms mounted on a mobile holonomic base, the second system is mounted on an aerial vehicle and is conceived to perform inspection and maintenance tasks.

The importance of compatible sub-grid scale and spatial discretization models on the simulation of large-scale pool fire

Using discretization technique is one of the challenges associated with numerical modeling. In the Large Eddy Simulation (LES) method, this issue becomes more critical because it affects the sub-grid scale (SGS) model and creates errors. Using an LES method, we investigated the numerical errors and compatibility of different discretization methods with SGS in pool fire modeling. First-order, central, and second-order upwind and linear upwind stabilized transport (LUST) schemes were examined in Smagorinsky (S_SGS) and k-equation (K_SGS) sub-grid scales. First-order upwind and second-order upwind methods estimated the velocity field, temperature, and perturbation with a significant error, so that in the plume area, there was 90% error with the first-order upwind and 50% error with the second-order upwind concerning the results of the mean square horizontal velocity perturbation. With an error of 20%, the LUST method had a better agreement with the experimental results. Besides, SGS did not have a significant effect on the results of this method. However, the second-order upwind method was more consistent with the S_SGS model. To improve the results of upwind methods, Quadratic Upstream Interpolation for Convective Kinematics and Monotonic Upwind Scheme for Conservation Laws discretization methods are recommended.

Simulation of upsetting process using kinematic schemes of metal flow

The problems of simulation the on the basis of kinematic schemes of metal flow, which is observed in the processes of forging and stamping workpieces with flat areas, are considered. Presented traditional kinematic schemes of metal flow: normal and radial. To solve these problems, a modernized program complex EQUI was developed, which is used for computer simulation of metal flow in the workpiece plane. It is shown that for any parameters of upsetting process is a real «intermediate» kinematic scheme of metal flow, which consists of areas of the flow normal to the contour and areas of radial flow. The results of a virtual experiment were obtained using the program complex DEFORM, which has proven well in solving plastic forming problems. For computer simulation of the spatial diagram of contact stresses and the dividing line of metal flow is selected known software COMPAS. The horizontal projection of the solid model allows you to get an image of the dividing line of metal flow. Comparison of results, obtained in the COMPAS and EQUI, shows good agreement.

Mathematical support of walking robots-tetrapods movement algorithms

This work presents a mathematical model that describes the movement of robots with four limbs (tetrapods). The relevance of the publication is justified by the popularity and increased demand for robotic devices used in production and everyday life. The main advantage of these machines is the ability to move over rough terrain, so are often used to perform transport and loading operations. The authors considered the most common movement scheme, taking into account the features of the kinematic scheme of this type devices. Tasks of transforming the coordinates of legs contact points of the supporting surface are formulated and solved to form tasks for controlling servo drives. The resulting mathematical expressions are universal for the considered robots and allow their statically stable movement in all directions and turning through a given angle. The obtained results can be used in development of algorithms of control programs for different microprocessor systems, in design of kinematics of these devices, in selection of optimal electromechanical equipment, as well as in creation of similar mathematical models for other types of walking robots. The materials of the article can be useful for engineers and scientists in the field of robotics and automation.

Development a general-service weighting batcher with automatic control

A general-service weighting batcher with automatic control, which is related to the field of packaging equipment and is intended for weighing and dosing of food or non-food bulk production, has been developed. The existing constructions have been studied and patent search of analogues has been carried out. The kinematic scheme of the mechanism has been drawn out on the basis of analysis of study subject analogues. The construction of the dosing unit, block diagram and operation algorithm of automatic control system of the batcher have been developed. Modeling and research of the device construction have been carried out. Choice of optimal dimensions of the device has been grounded mathematically.

Blagonravov Continuously Variable Transmission: computational model of load distribution over elements of control system

The paper presents a kinematic scheme of a differential planetary control gear designed to change the vibration amplitude of the intermediate links of the Blagonravov mechanical continuously variable transmission on the move and under load. A computational model of load distribution over the elements of the planetary gear is developed. The influence of the internal gear ratio and vibration amplitude on the load distribution is estimated. The established dependencies are recommended to be applied when choosing the drive motor power of the transmission control system.