Development of a Distributed Mathematical Model and Control System for Reducing Pollution Risk in Mineral Water Aquifer Systems

The article is devoted to the problem of the growing need of the mineral water fields’ exploitation process automation. The implementation of control systems and mathematical modeling methods can significantly reduce the fields’ structural integrity violation and pollution of aquifers risks. This research is especially relevant for the fields with difficult conditions of mineral waters occurrence, since the insufficient accuracy of determining the fields’ operating mode parameters can lead to a severe incident. The article describes a distributed mathematical model developed from the geo-filtration equation. Based on this model, a new method for assessing the mutual influence of the fields, the production of which is carried out from one aquifer, is presented. For a more detailed study of the operating mode parameters influence on the object a physical model of the reservoir was developed. The using of Arduino sensors and the developed software allows us to construct a 3D graph of the input action and its response at the different points of the object as temperature distribution. The simulation results make it possible to use the proposed model for the automatic control system synthesis.

Using the features of the photoelastic effect to measure the parameters of optoelectronic devices

The features of the photoelastic effect are discussed and it is shown that they can be used to measure the parameters of a laser and a photodetector, which are the main units of any optoelectronic product. A brief review of the known methods for measuring the parameters of a laser and a photodetector is carried out, and some limitations in their application are noted. The possibility of using the features of the photoelastic effect for measuring the parameters of the inertia of the photodetector is theoretically substantiated. A formula for calculating the response at the output of an acousto-optic processor to a rectangular input action is derived and used to separately estimate the time of crossing the optical beam by an elastic wave packet and the inertia of the photodetector. It has also been proven that by choosing a short input action, the features of the photoelastic effect can be used to determine the configuration of the cross section of the laser beam and the law of the distribution of the power flux density in it. The results of theoretical studies have been tested by numerical calculations and confirmed by experimental measurements.

Formation of Orthogonal Components of Input Currents in Microprocessor Protections of Electrical Equipment

The methods used in the microprocessor protection of electrical equipment for forming orthogonal components of input currents ensure their reliable isolation after changing the mode followed by one or more periods of the fundamental frequency. This is due to the inertia of the functional elements, in particular, digital frequency filters, as well as the saturation of the steel magnetic cores of current transformers. To increase the speed of the selection of orthogonal components of the input currents, it is proposed to form them as equivalent ones in terms of the cosine and sine components obtained using digital Fourier filters by multiplying by the resulting coefficient. The method that has been developed for determining the specified coefficient provides compensation for the delay caused by the inertia of digital filters, as well as the saturation of the steel of magnetic cores of current transformers. The proposed method of forming orthogonal components is highly effective in the modes of strong saturation of the magnetic core with a complex input action in the presence of an aperiodic component with a large damping time constant. The evaluation of the efficiency of the proposed method was performed using a complex digital model implemented in the dynamic modeling environment MatLab-Simulink. As a result of the performed studies, it was found that in the absence of saturation of the magnetic core of current transformers, as well as in the presence of a small and medium degree of saturation, the proposed method for forming equivalent orthogonal components of input currents has dynamic properties close to the ones of those that had been previously proposed. With a strong saturation of the magnetic core of current transformers, the speed of obtaining reliable values of these components is increased by 1.5–2 times.

THE METHOD OF FINDING ADEQUATE MATHEMATICAL MODELS DESCRIBING THE CHARACTERISTICS OF RADIO ENGINEERING DEVICES

The method of finding adequate mathematical models of radio engineering devices in an analytical form is proposed. RES, as a rule, is a very complex technical object that includes a large number of components with diverse connections between them, the hierarchy of construction of which can be represented in the form of a kind of pyramid. In this regard, there is a simulation of radio-electronic devices, which can be carried out at all levels of the "pyramid". Modeling at its lower levels, including semiconductor devices, links, cascades, etc., is reduced to describing their operation using a matrix, equation, formula, graph, or table. Such a mathematical model should, on the one hand, accurately reflect the physical processes in the object under study, and on the other - be suitable for use on a PC. In some cases, the mathematical model is the result of analytical or numerical analysis of the physical model of the object, but most often-experimental studies. Processing, including statistical processing, of the available data array that characterizes the operation of the cascade or element, is carried out using a PC. The operation of an object can also be defined in the form of its response or reaction to an input action without penetrating into the essence of the physical processes occurring inside the device.

Functionality of the Acousto-Optic Delay Line Beyond the Cutoff Frequency

For processing signals in the time area an efficient tool is the acousto-optic delay line (AODL). The smoothly controlled delay of signals in a broad time interval permits to build high-performance radiolocation simulators. In the work, the design of the AODL has been considered, and the parameters, determining the limit of using its potential have been noted. The features of photoelastic interaction in AODL have been considered for the case when the duration of the input pulse is shorter than the time of crossing the optical beam by an elastic wave packet. It has been found that under these conditions the duration of the output response is determined by the time of crossing the optical beam by an elastic wave packet and does not depend on the duration of the input action. It has been shown that the AODL response to the input action in the form of a rectangular pulse is determined as the sum of three terms. In this case, the process of the entry of the elastic wave packet into the optical beam determines the first term, the second one – by the process of propagation of the elastic wave packet in the optical beam aperture, and the third – by the process of the exit of the elastic wave packet from the optical beam aperture. The corresponding equations have been obtained for calculating the pulse parameters at the AODL output. It has been shown that for a sufficiently short input pulse duration, the output signal parameters contain the information on the energy-geometric characteristics of the laser radiation. The results of numerical simulation have been tested experimentally on AODL layout with the direct detection. A comparative analysis of the results of theoretical and experimental studies have unambiguously has confirmed that AODL can also be used at frequencies above the cutoff frequency, both in terms of its main functional purpose and for solving a number of other engineering problems.

Vibration levels on operator’s workplace and vibration protection characteristics of seat suspensions

This article analyzes the nature and parameters of the main operational disturbances, which ener-gy is directly or indirectly transferred to the operator's workplace of tractor with a caterpillar or wheeled propeller when performing various technological operations, based on experimental re-search data. The main operating frequency range of these operational disturbances is considered. The contribution of each frequency component to the overall level of vibration at the operator's workplace is assessed. The example of implementation the results of field measurements of real op-erational disturbances and vibration characteristics on a K-744R1 (st.) wheeled tractor, which oper-ated in a unit with a PG-3-5 plane cutter in the mode of plowing stubble at a constant speed of movement was used. The comparative study of vibration-protective properties of various designs of seat suspension was carried out. The technique of field measurements, including specialized equip-ment of the ZETLAB and Assistant companies, the mode, the sensor installation scheme and other conditions are described. Using the numerical Runge-Kutta method and mathematical modeling tools in the Simulink MatLab software environment, the operation of the serial suspension of the K-744R1 (st.) tractor seat, air suspension of the Sibeco seat with a scissor guiding mechanism and the innovative air suspension of the seat (based on Sibeco) with controlled extraction of vibration ener-gy and its subsequent recuperation was simulated. There were obtained the calculated oscillograms and spectra of vertical accelerations on a seat cushion, sprung with each of the considered suspen-sions under the input action of measured real operational disturbances. The results of the analysis of the research results are summed up.

The rationale for the loading modes of diesel engines for the diagnosis at unsteady load

To increase the reliability of diagnosing tractor engines, a dynamic loading mode is proposed under bench conditions. The loading modes are substantiated from the point of view of diagnostics of the input action and the most informative mode of engine operation.

On the motion/stiffness decoupling property of articulated soft robots with application to model-free torque iterative learning control

This article tackles the problem of controlling articulated soft robots (ASRs), i.e., robots with either fixed or variable elasticity lumped at the joints. Classic control schemes rely on high-authority feedback actions, which have the drawback of altering the desired robot softness. The problem of accurate control of ASRs, without altering their inherent stiffness, is particularly challenging because of their complex and hard-to-model nonlinear dynamics. Leveraging a learned anticipatory action, iterative learning control (ILC) strategies do not suffer from these issues. Recently, ILC was adopted to perform position control of ASRs. However, the limitation of position-based ILC in controlling variable stiffness robots is that whenever the robot stiffness profile is changed, a different input action has to be learned. Our first contribution is to identify a wide class of ASRs, whose motion and stiffness adjusting dynamics can be proved to be decoupled. This class is described by two properties that we define: strong elastic coupling, relative to motors and links of the system and their connections; and homogeneity, relative to the characteristics of the motors. Furthermore, we design a torque-based ILC scheme that, starting from a rough estimation of the system parameters, refines the torque needed for the joint positions tracking. The resulting control scheme requires minimum knowledge of the system. Experiments on variable stiffness robots prove that the method effectively generalizes the iterative procedure with respect to the desired stiffness profile and allows good tracking performance. Finally, potential restrictions of the method, e.g., caused by friction phenomena, are discussed.

Optimization of Analog-Discrete Conversions of the Input Action in the Subsystem of the Receiving Channel of the Information-Measuring System

Perpose of research is to develop a technique for developing system and local models of targeted processes of functioning of the subsystem of the receiving channel of an information-measuring system. These models should make it possible to substantiate the possibility of optimizing the processes of interaction of the components of the analog-discrete conversion of the input action of a random nature.Methods. The technique for obtaining measurement information in the information-measuring system involves the use of algorithms that minimize information loss at each stage of conversion of the input action. A possible approach is the use of rational and optimal solutions when selecting and substantiating functional support of the input action ),,( St  in order to obtain current measurement information while minimizing residual uncertainty.Results. To solve this problem, it is necessary to build a system model for the totality of the basic functions that determine the implementation of the targeted process of analog-discrete conversion ) ,,( S t  ; to substantiate the way these functions are implemented, the criteria for their interaction; to determine the optimization technique and (or) rational construction of local targeted processes; to prepare guidelines and rules for structural constructions of the subsystem of the information-measuring system, the input actions of which have priori unknown characteristics. The paper proposes an approach to the functional organization of analog-discrete conversions of the input action of a random nature in the receiving channel subsystem of an information-measuring system, which allows improving the quality of the receiving channel of the information-measuring system and the operation of its components by optimizing the interrelated targeted processes for detecting pulse signals and measuring their parameters against the background of noise with a priori unknown characteristics.Conclusion. The application of procedures for temporary selection of signals controlled by the detection channel allows increasing the speed and accuracy of determining their parameters, increasing the noise immunity of the receiving channel subsystem of the information-measuring system, reducing the probability of skipping weak signals as well as increasing the accuracy of measuring the temporal parameters of pulse signals.