Alternance method of structural-parametric synthesis of cascade automatic control systems

There are many design methods for the multiloop control system, but a method to exactly evaluate the stability margin for multiloop control systems has not been established yet. It is very important for the designers to exactly know the stability margin of the flight control system, because it directly comes to bear on flight safety. Previous research has proposed the “-1/ξ locus” analysis method for the exact evaluation of the stability margin of multiloop flight control systems. -1/ξ is an open loop transfer function of multiloop control systems that is considered as an extension of that for single-loop control systems. In this paper, the relation between the response of the closed loop and the stability margin is considered by using the -1/ξ locus. Lateral-directional flight control system was taken for instance, important points to pay attention to use the -1/ξ locus method for designing the flight control system are presented.

The problem of structural-parametric synthesis of automatic control systems (ACS) of technological objects is deter-mined by the multi-dimensionality, multi-connectedness and nonlinearity of their mathematical models. Despite the indicated properties of such objects, traditional linear systems based on PID-algorithms are still used for process control. Since the synthesis of linear systems using input-output models does not take into account the multi-dimensionality and mutual influence of state coordinates, such systems increase the influence of parametric and signal perturbations on the quality of control processes. The increasing requirements for the quality and efficiency of technological processes control made it expedient to apply the control principle by the state vector based on the use of uninertial state regulators or combined state regulators including flexible feedback on the derivative state coordinates or state coordinate integrals. The research uses methods of system analysis of technological processes as control objects, methods of automatic control theory, methods of control systems synthesis on the state regulators basis, meth-ods of computer simulation. The linearized mathematical model of liquid-phase chemical reactor in the state space has been obtained. It has been established that the investigated object has the property of free movement stability and it is fully controlled in the state space. The problem of synthesis of a single-channel concentration vector control system in a chemical reactor using state regulator has been solved. The parameters of state regulator settings have been determined using the method of modal control. The efficiency of the automatic control system on the basis of the state regulator with an integral component has been shown using the method of computer simulation of the ‘nonlinear object – linear control subsystem’ complex. It has been demonstrated that the absence of an integral component in the control algorithm structure leads to a great static error of regulation. To eliminate the static error of control and ensure the robustness of the control system, it is recommended to introduce an integral component into the structure of state controller. This ensures the efficiency of the control system both for the case of complete measurement of the state vector and for the case of measurement of the output controlled variable only.

Purpose: To select an automatic speed control system of an electric train. To estimate the speed measurement error effects on the traction drive dynamics. To justify the selection and application of the low-pass filter, particularly Butterworth filter. To determine a set of quality criteria for an electric train speed control. To solve the problem of parametric synthesis of automatic speed control system. Methods: Simulation modelling, automatic control theory, optimizations. Results: Negative influence of speed measurement errors on the formation of the traction force control signal and, consequently, on the transient process in the traction drive has been established. As a result of solving the problem of the system parametric synthesis, proportionalintegral rational parameters with mismatch prediction of control law have been determined. The dependence of the value change of the control law parameters on the Butterworth filter order has been established. It has been revealed that with increasing the filter order it is required to increase its cut-off frequency. The inclusion of the Butterworth filter in the structure of the automatic speed control system has been proved to provide smoothing of high-frequency components in the measured speed signal. Practical significance: The structure of the automatic speed control system has been developed taking into account the presence of method error of the measuring device (pulse speed sensor). The simulation results obtained have shown the filters’ efficiency in the control system.

Intermediate heat transfer heaters are widely used for the preheating of oil and gas to reduce the viscosity of oil during its transportation through main pipelines or for heating gas before pressure reduction to prevent the formation of hydrates, which occur because of the Joule-Thomson effect. One of the main components of a heat transfer heater is a cylindrical or rectangular bath filled with plain water or water with additives, inside which a coil is placed, through which the working fluid (oil) flows. Typically, indirect heaters use plain water. The water bath is heated by flue gases passing through fire tubes. The flue gases may originate from various sources, such as the combustion of oil refining by-products, specifically gases after oil distillation. The fire tubes are structurally connected to the combustion chamber, where natural gas is burned. Thus, an intermediate heat transfer heater is a complex dynamic system in which heat is transferred to the working fluid (oil) through several intermediate stages. The created mathematical model of the dynamics of the heat transfer heater considers the sequential heat transfer processes from one element to another. Each element in the heat transfer chain is described by a nonlinear differential equation derived based on the law of energy (heat) conservation. This approach to describing the dynamics of the heat transfer heater generates a system of differential equations, which, in addition to input and output variables, also includes intermediate variables such as the temperature of the intermediate medium (water), the temperature of the coil walls, and so on. After linearizing the system of differential equations, the intermediate variables were eliminated, which made it possible to obtain a linearized mathematical model of the heater suitable for the synthesis of a multi-loop automatic control system for the indirect heater

One of the actual problems for the theory and practice of control of dynamic objects is the development of methods for research and synthesis of control systems of multidimensional objects. The paper proposes a universal approach to construct Lyapunov vector functions directly from the equation of state of control system and a new gradient-speed method of Lyapunov vector functions to study aperiodic robust stability of linear control system with m inputs and n outputs. The study of aperiodic robust stability of automatic control systems is based on the construction of Lyapunov vector functions and gradient-speed dynamic control systems. The basic statements of Lyapunov's theorem about asymptotic stability and notions of stability of dynamic systems are used. The representation of control systems as gradient systems and Lyapunov functions as potential functions of gradient systems from the catastrophe theory allow to construct the full-time derivative of Lyapunov vector functions always as a sign-negative function equal to the scalar product of the velocity vector on the gradient vector. The conditions of aperiodic robust stability are obtained as a system of inequalities on the uncertain parameters of the automatic control system, which are a condition for the existence of the Lyapunov vector-function. A numerical example of synthesis of aperiodic robustness of a multidimensional control object is given. The example shows the main stages of the developed synthesis method, the study of the system stability at different values of the coefficients k, confirming the consistency of the proposed method. Transients in the system satisfy all requirements

The algorithm of structural and parametric synthesis of automatic control systems for limitedly uncertain non-linear objects with unstable balance status and right own values in their exit matrix is proposed. The pecu-liarity of the structural synthesis algorithm is that synthesized automatic control systems use differential com-pensating connection with two components. The signal of one of them is proportional to the signal of disa-greement between the required and measured values of the state vector of the system. A signal of another com-ponent is formed by the sign-operated integral feedback on the module of the control influence. The algorithm of parametric synthesis is reduced to solving the problem at a conditional minimum of integral regulatory error when limiting the characteristic frequency multi-member module to an algorithmically linearized system.

The article discusses the creation of an algorithm and the synthesis of a two-loop automatic control system for level and density, instead of the current single-loop one. Aim. Density stabilization and stabilization of the flotation machine power supply by creating a two-circuit automatic level and density control system in order to improve the quality of the final product. Materials and methods. Since there is no net lag in the system, the controller is tuned using the parametric optimization method, namely: according to the criteria of modular (MO) or symmetric optimum (CO). The MO/CO criterion is also used to adjust the contour. All automatic control systems are obtained in the MATLAB Simulink software package. Control quality is measured by metrics such as transient time, overshoot, and system error. The first two indicators show the dynamics of the process, and the last indicator shows the accuracy of the system. Conclusion. The finished two-loop automatic control system, developed in the software package MATLAB Simulink, according to the analysis of the obtained process parameters, provides stabilization of the density and level in the agitation tank for flotation.

The subject of study is the process of forming algorithms for controlling the angular and translational movements of a two-wheeled experimental sample (TWES). The aim is to develop approaches to the formation of control algorithms for the translational and angular movements of a non-stationary automatic control object. Tasks: to concretize the process of synthesis of a control algorithm by state according to the criterion of the minimum integral of the weighted error modulus for a linear mathematical description of an automatic control object in the state space. Form a block diagram of an automatic control system by the state. Improve the approach to the synthesis of output control algorithms for mathematical description in the frequency domain of short-period and long-period motions of TWES. Illustrate the peculiarity of the approach using a specific example of a TWES under control and disturbing influences. Develop a simulation scheme in the Simulink environment and investigate responses to external step influences. Develop an approach to the formation of control algorithms by the diagnosis of TWES as an object of automatic control. Describe the procedure and means of deep diagnostics of emergencies of TWES. Develop algorithms for restoring the operability of the automatic rational control system. Used methods are a method of state space, the method of relative functions, the method of transfer functions, the method of optimization by integral criterion, the method of synthesis by logarithmic asymptotic frequency characteristics, methods of diagnosing and restoring operability. The following Results: three approaches were formed to the formation of control algorithms of the angular and translational movements of the TWES using linear mathematical descriptions in the time and frequency domains. Conclusions. The scientific novelty lies in the formation of approaches to the combined control of angular and translational movements, considering the structural and parametric features of the mathematical descriptions of TWES.

Aiming at causing frequency traffic accidents by the drunken driving, the paper puts forward an automatic locked control system of vehicle drunken driving as a smart solution to prevent the phenomenon. And designs a automatic locked control system based on PIC16F877A. The system hardware modules and software system are elaborated in detailed. At last through the experiment, it verifies that the automatic control system has reached requirement.

Automatic control system is the representative of social comprehensive technological innovation, which has the characteristics of digitalization, programming and flexibility, and provides more reliable technical support for the performance of mechanical production. Based on this, this paper takes the food packaging machine system as an example to optimize the existing automatic food packaging machinery control system, give full play to the advantages of automation ability, and promote the improvement of social productivity.

The issues of analytical synthesis of automatic control systems with a finite transient time of control in relation to a class of linear stationary systems are discussed. The control object is represented by a continuous vector-matrix model of arbitrary order, control unit is represented by a not-recursive discrete model in the form of the finite State Space regulator. The method of algebraic synthesis of finite and quasi-finite control, including optimal synthesis stages of free and forced system motion, is presented. An example of the synthesis of an electromechanical servo control system is considered. The results of the synthesis and simulation are given, confirming the effectiveness of the proposed approaches.

The advanced technology of the Internet and extensive agricultural transformation and upgrading have made the overall agricultural industry chain and modern agriculture better. In view of the high cost and suffering of traditional agricultural planting management, the Internet of Things (I O T) is applied to agriculture to realize real-time detection and intelligent management of crop growth conditions, remote control, and change the traditional agricultural equipment planting mode. The purpose of this article is to design and research the I O T automatic control (A C) system for smart agriculture. This article first introduces the core technology of the I O T through an overview of the basic theories of the I O T. Combined with the current status of agricultural automation in my country, the existing problems and deficiencies are analyzed. On this basis, use the core technology of the I O T to supplement and improve it. This article systematically expounds the overall scheme design, module function design and A C algorithm realization of the I O T brake control system. And use field investigation method, comparative analysis method and other research forms to carry out research on the theme of this article. Experimental research shows that the sampling data of the greenhouse is selected as the sample, the appropriate initial membership function is selected, and the fuzzy control rules obtained through the training of the fuzzy neural network algorithm are relatively correct. The output result of the automatic temperature control system is mostly consistent with the actual data on site. Overall, the temperature A C system designed in this subject can meet the A C requirements of agriculture.

One way of providing irrigation water to improve irrigation efficiency is the use of solar power-based automatic control systems. This technological innovation was designed by utilizing digital technology, microcontroller and sensor network. This automatic control system operates based on the value of soil moisture as the lower set point value and the upper set point value to set the pump on/off. The aims of this research are to develop a solar-powered automatic control system with reference to the control of soil moisture for set on/off the pump and can keep the soil moisture from the water capacity. The stages of the research are hardware design of solar-powered control systems, design of automatic control system software, design of sprinkler irrigation networks, testing and data analysis. The results showed that the total power to operate an automatic sprinkler irrigation system of 67.0 Watt and can reduce battery consumption of 234.7 Watt. The use of a 30 Wp solar panel unit is able to meet the power needed for the automatic control system during the experiment. Key words: automatic control system, microcontroller, solar power, sprinkler irrigation

This paper considers the state and prospects for studies of the central problem of the theory and practice of automatic control—the problem of controller synthesis for systems with nonlinear plants. A crucial factor in the performance of controllers for nonlinear plants is the use of deep feedback for derivatives of the output variable, which provides localization of disturbances in fast subprocesses (against the background of the main processes) and allows the generation of the required dynamic properties

The non-weighing lysimeter system in the Minqin desert areas was firstly used in the 1970 s, and mainly performed the orientation research on the water consumption by the transpiration of several desert plants and the evaporation on the surface of sand, which aimed to provide the theoretical guide for the selection of afforestation density and the utilization of sand and water in Chinese sand areas. At present the system has been running for 30 years, most of the lysimeters showed the jam and leakage phenomenon, and the observation was by conventional artificial means. All the factors seriously affected the accuracy of the data monitoring. However, on the basis of the non-weighing lysimeter system structure and its testing principle, the evapotranspiration area could be extended, the capacity of testing soil column could be increased, more real natural environment conditions could be simulated and the limitations of weighing lysimeter could be overcome, in sum, the lysimeter's application field and adaptability were extended. Owing to the problems of low automation, and lack of scalability and reliability, the non-weighed lysimeter monitoring and control system in the Minqin desert areas has been retrofitted to improve its performance based on structure characteristics. The non-weighed lysimeter proving ground of 720 m2was designed in Minqin sand areas, where 30 individual lysimeters (120 cm×120 cm) of desert plant were upgraded and 12 small groups of desert plant lysimeters (400 cm×400 cm) were expanded and built, at the same time, the lysimeter groups in different types could be used to carry out the test of water supply for plant under the constant water level of 190, 290 and 390 cm. The lysimeter proving ground upgraded and expanding-built could realize synchronous observation for evapotranspiration test from the desert plant individual scale to small group scale, and the experiment platform was provided for studying water consumption of desert plants transpiration in different scale and its coupling relationship. The distributed monitoring scheme was adopted in the new automatic monitoring system, in which the superior industrial computer was set up as the center with multiple lower machine monitoring points, such as lysimeter constant water level control and water-supplying measurement system, drainage measurement system, atmospheric precipitation monitoring system, soil moisture monitoring system, environment temperature measurement and control system, SMS cat alarm system, data remote transmission and monitoring system, and UPS over-voltage protection system, and the RS485 bus, ISM wireless communication and TCP/IP network structure were used in the system. The automatic control of the lysimeter water level, water supply and drainage, the automatic monitoring of water metering, and the soil water content were designed, and the atmospheric rainfall and the temperature indoor were monitored in real time in the new system; the system also had the functions of real-time data collection and processing, information communication and data entering, historical data storage, data report printing and remote transmission download, and the power supply system was protected against over-voltage to enhance the reliability of system operation and the stability of data acquisition. Additionally, the internet-based remote monitoring and control system was used, and the users could process the abnormal situation. According to the monitoring data analysis by the regression method, we could know that the errors of data regression analysis were ± 2.2% for the pressure sensor, ± 2.0% for the drop counter and ± 12.5% for the moisture sensors. The research extended the scale for locating observation of the desert plant and implemented the automatic monitoring for evapotranspiration of the desert plant. © 2015, Chinese Society of Agricultural Engineering. All right reserved.