Control System Design Process Research Articles

Design of Multivariable PID Control Using Iterative Linear Programming and Decoupling

The design of multivariable process control systems is specially complicated when there are strong interactions between the different control loops, and even more with multiple time delays. This paper proposes an iterative design method of centralized proportional-integral-derivative (PID) controllers for stable linear systems. The methodology is based on the linear parameterization of equivalent loop transfer functions (ELTFs) for centralized control. These functions capture the dynamics of the other loops and, from a prior design, allow solving the design problem at each iteration with linear programming that shapes the Nyquist plot of the ELTFs in the frequency domain, which also avoids the need for approximations. Two optimizations are proposed: (I) maximizing integral gains by fulfilling linear robustness margins in each ELTF and (II) maximizing linear robustness margins by fulfilling minimum bandwidths in each loop. In both optimizations, static decoupling and decoupling at a frequency close to the bandwidth of each loop are included as constraints, which improves the decoupling performance and the procedure convergence. The effectiveness of the method is verified in three simulation examples (square and non-square) and a lab experimental process. The proposed designs achieve a similar or better response when compared to that achieved by other authors.

Development MPC for the Grinding Process in SAG Mills Using DEM Investigations on Liner Wear.

The rapidly developing mining industry poses the urgent problem of increasing the energy efficiency of the operation of basic equipment, such as semi-autogenous grinding (SAG) mills. For this purpose, a large number of studies have been carried out on the establishment of optimal operating parameters of the mill, the development of the design of lifters, the rational selection of their materials, etc. However, the dependence of operating parameters on the properties of the ore, the design of the linings and the wear of lifters has not been sufficiently studied. This work analyzes the process of grinding rock in SAG mill and the wear of lifters. The discrete element method (DEM) was used to simulate the grinding of apatite-nepheline ore in a mill using different types of linings and determining the process parameters. It was found that the liners operating in cascade mode were subjected to impact-abrasive wear, while the liners with the cascade mode of operation were subjected predominantly to abrasive wear. At the same time, the results showed an average 40-50% reduction in linear wear. On the basis of modelling results, the service life of lifters was calculated. It is concluded that the Archard model makes it possible to reproduce with sufficient accuracy the wear processes occurring in the mills, taking into account the physical and mechanical properties of the specified materials. The control system design for the grinding process for SAG mills with the use of modern variable frequency drives (VFD) was developed. With the use of the proposed approach, the model predictive control (MPC) was developed to provide recommendations for controlling the optimum speed of the mill drum rotation.

Continuum Modeling and Boundary Control of a Satellite with a Large Space Truss Structure

Due to its advantages of easy deployment and high stiffness-to-mass ratio, the utilization of truss structures for constructing large satellites presents an appealing solution for modern space missions, including Earth observation and astronomy. However, the dimensions of the traditional finite element model for a satellite with a large space truss structure become exceedingly large as the structure’s size increases. The control system design process based on the finite element model is complex and time-consuming. This paper employs the continuum modeling method to represent the truss structure as a continuous entity. The bending vibrations of the truss structure are encapsulated by a simplified partial differential equation (PDE), as opposed to the more intricate traditional finite element model. Simultaneously, the satellite’s attitude motion is characterized by an ordinary differential equation (ODE). Building upon this coupled PDE-ODE model, a boundary control law that only requires sensors/actuators at the boundary is formulated to effectively mitigate structural vibrations and regulate the satellite’s attitude. The exponential stability of this closed-loop system is scrutinized using Lyapunov’s direct method. The simulation results affirm that the continuum modeling method is indeed well-suited for satellites endowed with substantial truss structures, and the proposed boundary law proves to be highly effective in both attitude tracking and vibration suppression.

Model-based control system design to manage process parameters in mammalian cell culture for biopharmaceutical manufacturing.

To enhance the robustness and flexibility of biopharmaceutical manufacturing, a paradigm shift toward methods of continuous processing, such as perfusion, and fundamental technologies for high-throughput process development are being actively investigated. The continuous upstream process must establish an advanced control strategy to ensure a "State of Control" before operation. Specifically, feedforward and feedback control must address the complex fluctuations that occur during the culture process and maintain critical process parameters in appropriate states. However, control system design for industry-standard mammalian cell culture processes is still often performed in a laborious trial-and-error manner. This paper provides a novel control approach in which controller specifications to obtain desired control characteristics can be determined systematically by combining a culture model with control theory. In the proposed scheme, control conditions, such as PID parameters, can be specified mechanistically based on process understanding and control requirements without qualitative decision making or specific preliminary experiments. The effectiveness of the model-based control algorithm was verified by control simulations assuming perfusion Chinese hamster ovary culture. As a tool to assist in the development of control strategies, this study will reduce the high operational workload that is a serious problem in continuous culture and facilitate the digitalization of bioprocesses.

The cascade backstepping controller design for supercavitating vehicle based on RBFNN observer

Aiming at the model uncertainty in design process of longitudinal motion control system of supercavitating vehicle, a backstepping controller is designed by combining with Radial Basis Function neural network (RBFNN). Considering that the environment of the supercavitating vehicle is complex during its traversal, it is not possible to measure all states directly. The calculation of planing force with nonlinear characteristics is related to vertical velocity, therefore, the accuracy of vertical velocity has impact on the value of planing force directly. A state observer is designed to estimate vertical velocity. In this paper, based on the backstepping method, the uncertain part of matrix coefficient in cascade control model of supercavitating vehicle is approximated by RBFNN. The output of the observer approximates the state variables, then, a depth tracking control law of the vehicle is obtained according to the observed values and the weight of neural network is calculated by Lyapunov function. Finally, it is proved that the control law can ensure the uniform ultimate boundedness of the closed-loop system.

Decentralized Adaptive Quantized Dynamic Surface Control for a Class of Flexible Hypersonic Flight Vehicles with Input Quantization

A control strategy for a certain class of hypersonic flight aircraft dynamic models with unknown parameters is proposed in this article. The strategy is adaptive dynamic surface input quantization control. To address the issues in conventional inversion control, a first-order low-pass filter and an adaptive parameter minimum learning law are introduced in the control system design process. This method has the following features: (1) it solves the problem of repeated differentiation of the virtual control law in the conventional back-stepping method, greatly simplifying the control law structure; (2) by using the norm of the neural network weight vector as the adaptive adjustment parameter instead of updating each element online, the number of adaptive adjustment parameters is significantly reduced, improving the execution efficiency of the controller; (3) the introduced hysteresis quantizer overcomes the disadvantage of the quantization accuracy deterioration when the input value is too low in the logarithm quantizer, improving the accuracy of the quantizer. Stability analysis has shown that all signals in the closed-loop system are semi-globally uniformly bounded, and simulation results have verified the effectiveness of the proposed adaptive quantized control scheme.

Integrated Flight Control System Characterization Approach for Civil High-Speed Vehicles in Conceptual Design

Recent studies have revealed that control surface deflection can cause a reduction in the aerodynamic efficiency of a hypersonic aircraft of up to 30%. In fact, the characterization of the Flight Control System is essential for the estimation of the consistent aerodynamic characteristics of the vehicle in different phases, considering the contribution of control surfaces to stability and trim. In terms of the sizing process, traditional methodologies have been demonstrated to be no longer applicable to estimations of the actuation power required for the control surfaces of a high-speed aircraft, due to their peculiar working conditions and to the characteristics of the flow to which they are exposed. In turn, numerical simulation approaches based on computational fluid dynamics or panel methods may require considerable time resources, which do not fit with the needs of the quick and reliable estimates that are typical of the early design phases. Therefore, this paper is aimed at describing a methodology to show how to anticipate the Flight Control System design for high-speed vehicles at the conceptual design stage, properly considering the interactions at vehicle level and predicting the behavior of the system throughout an entire mission. It is also a core part of the work to provide designers with an example of how neglecting the effect of trim drag can be detrimental to a reliable estimation of overall aircraft performance. The analysis, mainly focused on the longitudinal plane of the vehicle, is presented step-by-step on a specific case study, namely the STRATOFLY MR3 vehicle, a Mach 8 waverider concept for civil antipodal flights. The application of the methodology, conceived as an initial step towards an iterative Flight Control System design process, also shows that the most power-demanding phases are take-off, low supersonic acceleration, and approach, where peaks of over 130 kW are reached, while an average of 20 kW is sufficient to support deflections in a hypersonic cruise.

Comparison of Linear Flexible Aircraft Model Structures on Large Flexible Tiltrotor Aircraft

Structural modes for large aircraft occur at low frequencies and must be accounted for in the flight dynamics modeling and control system design process. An analysis is performed on various linear representations of flexible aircraft with an application to the lateral/directional flexible dynamic response of the notional Large Civil Tiltrotor (LCTR2) in hover. The goal of the work is to compare the treatment of the coupling between the rigid-body and structural states within various model structures and to develop conversions between the various model forms. The analysis shows that mean-axis and other simplified analytical representations of flexible aircraft, originally developed for fixed-wing aircraft, are also able to correctly capture the dynamic response of a tiltrotor. First, a linear model is obtained from a multibody simulation using numerical perturbation methods. This is compared with a mean-axis model, where structural dynamics are appended onto rigid-body dynamics, as would be obtained if the rigid-body aircraft response were the starting point in an analytical development of the structural coupling. Comparisons are also given with a model that would be obtained from system identification using flight-test data. Key stability and control derivatives are compared to highlight similarities and differences between the various models. The results from the analysis show the multibody model treats the structural coupling in a significantly different way than an analytical model buildup. For example, the structural coupling to roll rate response varies up to two orders of magnitude between the models, yet the overall response is identical. This work shows analysis of the structural/rigid-body coupling developed for analytical models is also valid for models developed from a multibody analysis. Lastly, structural flexibility will be shown to alter the characteristics of the lateral hovering cubic of the LCTR2 by increasing damping of an unstable oscillatory mode.

Design and Implementation of Intelligent Home Control System Based on Deep Learning in the Internet of Things Environment

The popularization of the Internet of Things has made our daily life more and more convenient. By using the Internet of Things, we can create an intelligent home control system that makes our rooms safer, more comfortable, and can meet our growing demand for items. This article discusses how to use the Internet of Things to improve the efficiency of smart homes, and focuses on how to use wireless sensor networks, embedded systems, and various technologies such as network communication, audio and video to achieve these goals. This can enable these intelligent home control systems to provide efficient services. This article also introduces how to use Internet of Things technology in the design process of home control systems to better handle wiring and other related issues. We will also explore the differences between traditional and smart homes. The results showed that four buyers rated the smart home system, with an average score of 4 before use indicating a lower score, and an average score of 9 after use indicating a higher score.

Determination of optimization criteria for a special­purpose infocommunication network management system

As of today, taking into account the realities of the war in the country and the prospects for the development of the special-purpose information communication network management system, it is possible to assert the presence of a stable trend of growth in the volume and improvement of the quality of telecommunication services provided. This leads to an increase in the quantity and quality of control information, which, in turn, leads to a disproportionate growth of the special purpose information communication network management system itself. The described trend determines the need to optimize the management system as part of a special purpose information and communication system. To solve this problem, it is necessary to define the optimization criteria for the management system of a special purpose information communication network. The characteristic features of the special purpose information communication network management system given in the article allow it to be considered a "big system". For such a "big system" the question of its optimization becomes urgent. Optimization can be considered both the optimization of the control system design process itself and the optimization of the operation of the control system. The determined directions of optimization are dependent on each other. The designed special purpose information communication network management system will have quality indicators that depend on the quality of development, resources and time spent, that is, on the optimality of the design process. On the other hand, the resources and time spent on the design of the control system will significantly depend on the expected quality parameters of the system. There are several ways to combine the partial criteria of the control system to obtain an integral generalized criterion, which will make it possible to implement a global synthesis of the control system taking into account all the selected partial criteria of the system. Thus, the paper presents a method of multi-criteria optimization of the management system of a special purpose information communication network. The external parameters of the special purpose information communication network management system, which are critical in modern conditions, are described: the amount of information, delay, survivability, functional flexibility, reliability and cost. The need to combine conflicting criteria such as the amount of control information, reliability, survivability, functional flexibility, latency, and cost is emphasized. The advantage of using multi-criteria optimization of the special-purpose information communication network management system compared to single-criteria optimization is shown.

A Contemporary Design Process for Single-Phase Voltage Source Inverter Control Systems.

This paper presents an overview of contemporary voltage source inverter control system design. Design begins with the theoretical considerations that lead to the creation of the system’s differential control law. This stage does not include scaling coefficients for the output voltage, output current, and filter inductor current. Following this, the inverter is modelled in MATLAB’s Simulink environment with an appropriate load and control system. If the resultant simulation provides satisfactory results, a hybrid system consisting of MATLAB’s Simulink and dSpace libraries with the MicroLabBox device is used to interface the simulation with an experimental hardware model in real-time. This allows the hardware plant and measuring traces to be validated. ControlDesk is used to scale the relevant coefficients. During the final stage of the design process, a microprocessor is programmed to control the inverter according to the dSpace simulation results. This requires new scaling values. Throughout every stage of the design process, too high a value of the modulation index disables the reduction of output voltage distortions. This paper details the entire design process for both single-input and multi-input control systems, explaining the scaling process and the required software. Such a modern design process ensures the shortest time between conceptualization and the final product.

Stabilization Control of Underactuated Spring-Coupled Three-Link Horizontal Manipulator Based on Energy Absorption Idea

A spring-coupled three-link horizontal manipulator (STHM) is an underactuated mechanical system that possesses two control inputs and three degrees of freedom (DOF). This paper discusses the stabilization control problem for this multi-DOF underactuated system. By using an energy-absorbing idea, we design two types of virtual friction controllers: PsD controller and PD controller. Additionally, the stability of the control system is analyzed based on Lyapunov theory and LaSalle’s invariance principle. The design of the stabilizing controller in this paper makes good use of the physical characteristics of the STHM system. The design process of the whole control system is simple. Numerical examples demonstrate the validity and superiority of our developed control strategy.

An innovative approach for the design of cryogenic electrical and process control systems at CERN: the cryogenic Continuous Integration project

Designing, building, commissioning, operating and maintaining multiple complex cryogenics process control systems involves many challenges. For several years, CERN has developed various solutions to help with the whole lifecycle of a cryogenic process control system. This has allowed the production of quality and highly reliable cryogenic control and electrical systems. This paper will present the use of these innovative and automated tools and their evolution; focusing in the first part on continuous integration practices applied to the production of Programmable Logic Controller (PLC) software. The second part will develop the practical applications for software upgrades implemented for the cryogenics processes of non-LHC detectors and test facilities at CERN. Finally, a detailed description of the approach to a standardized generation of electrical drawing for cryogenic systems will be presented along with concrete solutions already successfully implemented in operation.

실시간 PQ-RRT* 알고리즘을 이용한 유도 시스템 개발과 궤적 추종 제어기의 통합 설계 연구

Herein, the integrated design process of guidance and control systems required for the design of autonomous flight systems for aircraft is discussed. The system can generate a trajectory using real-time path planning, re-plan the path, and accurately track the created trajectory. The real-time path planning is implemented using a rapidly-exploring random tree-based algorithm. Furthermore, the problems with the real-time rapidly-exploring random tree-based algorithm and possible solutions are discussed accordingly. The control system is implemented by incremental backstepping control, which ensures trajectory tracking performance across the entire flight envelope. To verify the series of processes, simulations are run using the high-fidelity Bo-105 model. The effectiveness of the real-time PQ-RRT* and path optimization algorithm proposed in this work is verified by the simulation results.

Design and Optimization of a Neuro-Fuzzy System for the Control of an Electromechanical Plant

One characteristic of neuro-fuzzy systems is the possibility of incorporating preliminary information in their structure as well as being able to establish an initial configuration to carry out the training. In this regard, the strategy to establish the configuration of the fuzzy system is a relevant aspect. This document displays the design and implementation of a neuro-fuzzy controller based on Boolean relations to regulate the angular position in an electromechanical plant, composed by a motor coupled to inertia with friction (a widely studied plant that serves to show the control system design process). The structure of fuzzy systems based on Boolean relations considers the operation of sensors and actuators present in the control system. In this way, the initial configuration of fuzzy controller can be determined. In order to perform the optimization of the neuro-fuzzy controller, the continuous plant model is converted to discrete time to be included in the closed-loop controller training equations. For the design process, first the optimization of a Proportional Integral (PI) linear controller is carried out. Thus, linear controller parameters are employed to establish the structure and initial configuration of the neuro-fuzzy controller. The optimization process also includes weighting factors for error and control action in such a way that allows having different system responses. Considering the structure of the control system, the optimization algorithm (training algorithm) employed is dynamic back propagation. The results via simulations show that optimization is achieved in the linear and neuro-fuzzy controllers using different weighting values for the error signal and control action. It is also observed that the proposed control strategy allows disturbance rejection.

Інформаційна технологія проектування системи автоматичної стабілізації потоку хлібної маси на вході до молотарки зернозбирального комбайну

The article presents a new methodology for creating information technology for the design of a combined system for stabilizing the flow of bread mass at the entrance to the combine thresher. The characteristic features of such a methodology are outlined. This allows the design of process control systems on the combine, taking into account external influences that are stochastic in nature. The stages of creation of information technology for the synthesis of the optimal combined stabilization system with feedback on the deviation of the bread weight from the average value and correction for changes in yield are substantiated. The article substantiates the composition and determines the content of operations of the new information technology of designing a combined system of stabilization of the flow of bread mass at the entrance to the thresher of the combine. The new technology has several distinctive features. First, its introduction allows to obtain differential equations of the combine harvester, which take into account the dynamic properties and design features of hydraulic transmissions operating in the mode of constant load change. Secondly, it allows you to design process control systems on the combine, designed for external influences that are stochastic in nature. Third, the new technology allows the synthesis of optimal combined stabilization systems under the conditions of two multidimensional independent sources of disturbance at the input and output of the stabilization object.

СПЕЦИАЛИЗИРОВАННЫЕ ЛАБОРАТОРНЫЕ СТЕНДЫ КАК МОДЕЛИ НЕФТЕХИМИЧЕСКОГО ПРЕДПРИЯТИЯ ДЛЯ ПРАКТИКООРИЕНТИРОВАННОЙ ПОДГОТОВКИ СПЕЦИАЛИСТОВ

The article provides arguments in favor of the introduction of modern information technologies in the organization of production, in particular, in the field of training specialists in higher educational institutions based on modern laboratories, in which laboratory facilities are "digital twins" of real enterprises. Specialized laboratories that act as digital twins of real production facilities are ready-made solutions for conducting a laboratory workshop in the training of specialists in the field of industrial automation. They include laboratory stands, specialized software, additional devices for research activities. That is, the equipment of laboratories is often focused on specific tasks. Direct demonstration of the work of real automation tools increases the interest of students in obtaining new relevant knowledge, leads to an increase in students' competence in the field of design, installation and maintenance of modern automatic process control systems. The description of laboratory complexes is given, with a description of their functionality. The APCS laboratory, opened at KNRTU together with Yokogawa in 2011, includes: a classroom with instrumentation; training class of control computing systems; a classroom with installations simulating heat metering units for liquid and gaseous products; training class for computer simulation systems of chemical-technological processes; research laboratory. The equipment of the laboratory allows for the training of specialists with a focus on a specific industrial enterprise and a well-defined technological process, advanced training for workers in the oil and gas processing industry, and retraining of specialists servicing heat transfer metering systems. The availability of powerful software makes it possible to carry out work on optimizing technological processes in terms of energy saving and reducing production costs. When training specialists, specialized laboratories as digital twins of technological processes can provide indispensable basic knowledge for further successful work in real conditions. The significance of the APCS laboratory lies in the training of practice-oriented specialists with a high level of professional knowledge. These laboratory complex can be further upgraded for specific production tasks.

A Comparative Analysis of Machine Learning Algorithms in Design Process of Adaptive Traffic Signal Control System

In recent decades machine learning technology has proved its efficiency in most sectors by making human life easier. With this popularity and efficiency, it is applied to design traffic signal control systems to mitigate traffic congestion and distribute waiting delays. Hence, many researchers around the world are working to address this issue. As a part of the solution, this article presents a comparative analysis of various machine learning models to come up with a suitable model for an isolated intersection. In this context, eight machine learning models including Linear Regression, Ridge, Lasso, Support Vector Regression, k-Nearest Neighbour, Decision Tree, Random Forest, and Gradient Boosting Regression Tree are selected. Shivakumara Swamiji Circle (SSC), one of the intersections in Tumakuru, Karnataka, India is selected as a case study area. Essential data is collected from SSC through videography. The selected models are developed to predict green time based on traffic classification and volume in Passenger Car Units (PCU) for each phase on the PyCharm platform. The models are evaluated based on various performance metrics. Results revealed that all the selected models predict green splits with 91% accuracy using traffic classification as input, whereas, models showed 85% accuracy with PCU as input. And also, Gradient Boosting Regression Tree is the best suitable model for the selected intersection, whereas, Decision Tree is not referred model for this application.

Short Time Correlation Analysis of Melt Pool Behavior in Laser Metal Deposition Using Coaxial Optical Monitoring

The development and improvement of monitoring and process control systems is one of the important ways of advancing laser metal deposition (LMD). The control of hydrodynamic, heat and mass transfer processes in LMD is extremely important, since these processes directly affect the crystallization of the melt and, accordingly, the microstructural properties and the overall quality of the synthesized part. In this article, the data of coaxial video monitoring of the LMD process were used to assess the features of melt dynamics. The obtained images were used to calculate the time dependences of the characteristics of the melt pool (MP) (temperature, width, length and area), which were further processed using the short-time correlation (STC) method. This approach made it possible to reveal local features of the joint behavior of the MP characteristics, and to analyze the nature of the melt dynamics. It was found that the behavior of the melt in the LMD is characterized by the presence of many time periods (patterns), during which it retains a certain ordered character. The features of behavior that are important from the point of view of process control systems design are noted. The approach used for the analysis of melt dynamics based on STC distributions of MP characteristics, as well as the method for determining the moments of pattern termination through the calculation of the correlation power, can be used in processing the results of online LMD diagnostics, as well as in process control systems.

Advanced Controller Development Based on eFMI with Applications to Automotive Vertical Dynamics Control

High-level modeling languages facilitate system modeling and the development of control systems. This is mainly achieved by the automated handling of differential algebraic equations which describe the dynamics of the modeled systems across different physical domains. A wide selection of model libraries provides additional support to the modeling process. Nevertheless, deployment on embedded targets poses a challenge and usually requires manual modification and reimplementation of the control system. The novel proposed eFMI Standard (Functional Mock-up Interface for embedded systems) introduces a workflow and an automated toolchain to simplify the deployment of model-based control systems on embedded targets. This contribution describes the application and verification of the eFMI workflow using a vertical dynamics control problem with an automotive application as an example. The workflow is exemplified by a control system design process which is supported by the a-causal, multi-physical, high-level modeling language Modelica. In this process, the eFMI toolchain is applied to a model-based controller for semi-active dampers and demonstrated using an eFMI-based nonlinear prediction model within a nonlinear Kalman filter. The generated code was successfully tested in different validation steps on the dedicated embedded system. Additionally, tests with a low-volume production electronic control unit (ECU) in a series-produced car demonstrated the correct execution of the controller code under real-world conditions. The novelty of our approach is that it automatically derives an embedded software solution from a high-level multi-physical model with standardized eFMI methodology and tooling. We present one of the first full application scenarios (covering all aspects ranging from multi-physical modeling up to embedded target deployment) of the new eFMI tooling.