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Mekhatronika, Avtomatizatsiya, Upravlenie

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Vol 16, No 7 (2015)
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METHODS OF THE THEORY OF AUTOMATIC CONTROL

435-443 490
Abstract
The article Presents development of the classical control systems with a high gain. In the classical formulation (M. V. Meyerov) these systems found no Proper development. The basis of the proposed approach is the method of Lyapunov functions. As a result of a synthesis "a robust equivalent control" was obtained. A possibility of a limitless increase of the controller gain without violation of the stability of the system makes it possible to suppress the general components of an uncertain model to an arbitrarily small value. This ensures a high precision of the reference trajectory tracking and speed for a wide class of nonlinearities and uncertainties. In the limit the system is described by the equation of the hyperplane for an arbitrary initial state. K¥-robust system is applied to a nonlinear multidimensional coupled systems with an interval uncertainty. The author managed to solve the problem of autonomy of the direct channels without the use of the cross-channel compensators, which is of important practical significance. The disadvantages of the proposed methodology are absence of the analytical formula for determination of the gain coefficient of the controller, gain of the highfrequency noise having immediate access to the controller, as well as the use of the output derivative for formation of PD controller. Moreover, not every object can achieve a high gain. The theoretical results were proved by solving of the model problems on MATLAB/Simulink.
443-448 455
Abstract
For multi-connected process of scintillation of the single crystal growth, a synthesis of modal controller was carried out. Modal control is defined as the control, which solves the problem of selection of the dynamic system's eigenspace. The spectrum selection for the multi-connected systems results in an unpleasant problem of manipulation of a big number of eigenvalues, which significantly complicates the process of studying their influence on the behavior of a dynamic system. The main problem of a practical modal synthesis consists in an excessive number of the parameters affecting the systems with different properties. The synthesis was carried out on the basis of the modal dominance measures, which reduce the choice of many eigenvalues to selection of one or more parameters describing the spectrum compression. Modal dominance measures give a formal assessment of the eigenvalues' mobility and allow us to control quantitatively the spectrum change trends during the synthesis. It was demonstrated that an analytical solution to the problem was possible both with a single and iterative shifting of the eigenvalues, one after another, when it was possible to estimate the modal dominance measure of each eigenvalue and the rate of the modal controller feedback gain matrix with a single spectrum change. The parameters of the transition process in a closed system of the single crystal growth control show that the synthesized system meets the requirements for a quality control. It is known that in the production conditions the growth process is exposed to the transient conditions of the thermal perturbations, which may result in inhomogeneous distribution of the activator within the length of the crystal. This process impairs the single crystal's quality. A closed system with a synthesized regulator has a quick dominant eigenvalue in the channel of the single crystal diameter control, which allows the closed system to respond to such a perturbation and reduce its impact on the crystal's quality. The synthesis emphasizes the main idea that adaptation of the eigenspace in the dynamic systems is justified. It should only be carried out with the involvement of the analysis at the first stage of the synthesis procedure.

ROBOTIC SYSTEMS

449-455 652
Abstract
The article is devoted to the process of adaptation of the control system of a mobile robot for its movement along a line. To this end, the article proposes a fuzzy logic and structural model for robot control, combining two methods of adaptation. The first method consists in variation of the parameters of the triangular membership functions and structure of the fuzzy rules, which are used to describe the input and output variables of a fuzzy robot control system. In order to improve the reliability of the solutions proposed in the structure of the fuzzy inference, hard and soft arithmetic operations are used. Evaluation of the system is based on calculation of a standard deviation (RMSE - root mean square error). The best solution for the fuzzy system is the option, in which the RMSE is minimal. The second method envisages a change in the structure of the control code of a mobile robot. The results of the experimental studies presented in the article show that without the use of the methods of the structural and parametric adaptation the accuracy of the soft fuzzy model is 2,7 times higher than the accuracy of a rigid fuzzy model, which has a dead zone, reducing its stability. However, a combination of the above methods makes the accuracy of the rigid model higher than that of the soft model. At that, a deadband is ruled out and computational complexity is reduced. In order to explain the proposed methods of adaptation the article presents the results of the experimental studies evaluating the movement of a mobile robot along a line on an oval track.
456-463 712
Abstract
This paper presents a new method of solving the inverse kinematics problem of manipulators with the help of the biquaternion theory of kinematics control. Application of the method reduces solving of Cauchy problem for differential kinematic equations of a manipulator motion. Vectors of the angular and linear velocities contained in these equations are considered as controls. They are formed according to the feedback principal as certain functions of generalized coordinates. As the result of solving of Cauchy problem for any given initial values of the generalized coordinates from their operational range the generalized coordinates will finally take the values corresponding to the desired position of the end effector, so the inverse kinematics problem will be solved. In this paper an algorithm for solving the inverse kinematics of Stanford robot arm is introduced. Control laws used in the algorithm are valid for any manipulator. A numerical solution of the inverse kinematics problem of Stanford robot arm has been found. It proves efficiency of application of the biquaternion theory of kinematics control for solving of the inverse kinematics problem of manipulators. Given examples of the numerical solution demonstrate dependency between the solution results (obtained values of the phase coordinates, solution time) and the input parameters, such as initial pose (position and orientation) of the end effector of a manipulator, accuracy of the solution and dual feedback gain. Graphs of the changes of the generalized coordinates, the main and moment parts of the biquaternion of the end effector error pose, the main and moment parts of the control and tensor were built.
464-470 482
Abstract
Simultaneous detection of multiple stationary and moving obstacles in the near field of the mobile robots is a challenging task, since a robot has to detect a maximal possible number of obstacles, and ensure its movement without collisions. In this paper, the authors propose modified algorithms for detection of objects. Detectable objects are divided into two types: familiar objects (stationary obstacles, for example, a table, a chair, a computer, etc.), and unknown objects (moveable objects - people). The authors present specific recognition algorithms for each object type: the nearest neighbor search algorithm modified for the use with FLANN library and search trees (KNN) used for detection of the stationary obstacles; the built-in algorithms (Microsoft Kinect development kit-SDK) are intended for recognition of such movable objects as persons. The efficiency of the search algorithm of the nearest neighbors for detection of stationary objects is shown. This algorithm is implemented in FLANN library, which contains main algorithms for extraction of the handles of images and creation of indexes. The effectiveness of finding objects is increased due to application of SURF algorithm. Use of FLANN Library together with SURF algorithm satisfies the requirements for detection of objects in real time. The experimental results prove the effectiveness of the proposed approach in a vision system of a mobile robotic platform.
470-475 547
Abstract
The purpose of this article is to present an example of an industrial manipulator, a possibility of successful application of power shell elements such as a pneumatic muscle as an actuator. The power shell elements have such advantages as low weight, high power density, high speed, no backlash and dry friction in the moving parts. These advantages make the power shell elements a promising actuator for various robotic systems, including manipulation. A manipulator's design calculation and its kinematic scheme make it suitable to work in the assembly lines and implement the function of sort or rejection of products. To meet these requirements, the calculation is based on the manipulator's working efficiency of 60-90 cycles per minute and capacity of up to 2 kg. These initial data present an important problem of reduction the inertia of the boom geometry. This problem is solved due to certain power actuators of the shell elements and use of the passive degrees of freedom. The article presents a possible kinematic scheme for such a manipulator, its external appearance and approximate weight and size parameters of its units. In the article the manipulator's characteristics are proved by the static and dynamic calculations. The static analysis took into consideration the current weight loads from the parts of the manipulator in its various configurations. The dynamic analysis of the selected parts of the trajectory of the manipulator is based on the most optimal mode in terms of the emerging dynamic loads and the calculations are done with their account. In order to prove a possibility of application of the force elements as actuators of the manipulator, the total load is presented, which is exerted on them by the movement of the manipulator jib, and which is compared with the characteristics of the power shell elements. At the end of the article the conclusions and analysis of the results are presented.
476-483 433
Abstract
The article describes new robotic systems for specific applications in the field of the regenerative medicine. One of the important directions in the regenerative medicine is the massage physiotherapy. It is a combination of the dosed mechanical techniques in the form of friction, pressure and vibrations applied directly to the surface of a human body. Since a manual application of these actions involves high energy costs, their efficiency and productivity are rather limited. These restrictions can be removed due to the use in the physiotherapy of special robotic systems, which ensure automation of the massage procedures and manual therapy, and their availability for all the patients. The article presents the measuring units of the robotic systems, which ensure the systems' adaptive functionalities, and methods of their calculation and experimental characteristics. It also describes the schemes for a longitudinal movement of the tools intended to improve the effectiveness of the massage and the systems for a loop-massage, giving a holistic effect. A system is presented, which makes it possible to control the depth of the toning processes and relaxation of patients with the help of a biofeedback loop and an advanced system, combining the effect of a simultaneous tactile and musical influence on patients. The sound of music is converted by an electric microphone into an electric signal of a broad range. With the help of bandpass amplifiers this range is divided into three frequency bands. The intensity level of the AC input signal is formed on the output of the rectifiers, a DC voltage signal from which allows us to control the vibration intensity of the corresponding electromechanical vibrators in accordance with the content of the music. All the presented designs are patented.

ACTUATORS OF MECHATRONIC SYSTEMS AND TECHNOLOGIES

484-490 599
Abstract
The main trend in designing of automobiles and mobile robots is a widespread use of mechatronic modules and systems. But there are many questions concerning the mechatronics-based approach. We see a constant integration of the theory and practice of an automobile and a mobile robot. Thus, research in these areas can be carried out simultaneously. The aim of the research is development of a designing approach of the mechatronics-based locomotion module for the automobiles and mobile robots. Mechatronics-based locomotion module is intended to control: (i) turning of the wheels of the axle, (ii) pressure in the chambers of the hydraulic cylinders of the axle suspensions and (in) vertical displacement of the left and right wheels of the axle. The task of the research is development of a complex mathematical model, which includes development of control algorithms for the all-wheel steering system and the regulated wheel springing system, choice of the control system components and of electro-hydraulic servo drive of wheels turning. On the basis of the mathematical model the authors studied all the components of the mechatronics-based locomotion module. All the obtained results of physical modeling were done with the use of a mechatronics-based locomotion module test bench. The article describes the study of electro-hydraulic servo drive with a centralized hydraulic system.
491-496 394
Abstract
A method was developed for construction of mathematical models, which describe the geometry of the industrial robots and multi-axis machine tools. This method takes into account the primary deviations in size, shape and location. Primary deviations occur during manufacture of the industrial robots and multi-axis machine tools. Such deviations can be measured. For this purpose modern metrology methods may be used. A method was developed for correction of the integrated deviations in the industrial robots and multi-axis machine tools. The method allows us to offset the effect of the primary geometric deviations. The method ensures a coincidence of the trajectories of real industrial robots and multi-axis machine tools and their ideal models. The task is reduced to solving of a system of nonlinear equations. For this purpose modern numerical methods may be applied. These methods can improve the accuracy control of the industrial robots and multi-axis machine tools. Determination of the primary deviations is presented on the example of a five-axis machine tool. On the basis of a kinematic scheme of a machine tool, the following deviations were revealed. Deviation of the angular position of the spindle machine tool during its movement. Deviation from the straightness of motion along the specified axes. Deviation of the lengths of the links of the movement mechanism of the spindle. Deviations from the parallelism and perpendicularity to the axes of the turntable. Radial run out of the turntable. Axial runout of the turntable. Deviations in positioning by the linear and angular coordinates. Deviations from the parallelism and perpendicularity to the frame guides. References are made to the works of the other researchers.

INTELLIGENT TECHNOLOGIES IN AUTOMATED CONTROL SYSTEMS

497-504 480
Abstract
Problem statement: Modern supply chains are presented by large-size models. Supply network scheduling requires considerable computing resources and a lot of time. The traditional centralized supply chain management systems cannot handle the increasing complexity of the scheduling tasks in the conditions of fast-changing market situation, fluctuations in supply and demand, various disruptions and unpredictable events. The paper describes a new approach to management of the supply networks based on multi-agent technologies and ontologies. Methods: A method of a virtual "round table" is suggested for support of decision-making during supply chain scheduling. Besides, a method of adaptive dynamic supply chain scheduling depending on the events is proposed, which is based on multi-agent technology using ontology. Results: A virtual "round table" concept was developed, as well as regulations for coordination of decisions at all the stages of product supplies, and involving all the interested participants in this process. Advantages of the suggested approach are illustrated by an example of multi-criteria decision-making under condition of company department common values. Main components of the client-server architecture for the multi-agent system of the network supply management were singled out. The decision to use ontology for description of the concept knowledge necessary for the chain supply management was substantiated. The developed models and scheduling methods ensure an adaptive dynamic supply scheduling in a real-time mode in accordance with the individual orders and demand forecast for any time-period and with any details. Practical value: application of the multi-agent system for the network supply management is most efficient in the situations, when it is necessary to adapt a schedule to small, but important deviations of the input data instead of processing a new set of data. The conducted research and modeling demonstrate that a transfer to a real-time scheduling and management will make it possible to increase the companies' profits due to a quicker adaptation to the changing conditions.


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ISSN 1684-6427 (Print)
ISSN 2619-1253 (Online)