Computer-aided Control System Research Articles

Assessment of basic control strategies through dynamic simulations: A CO2-based chiller under extreme off-design conditions

Modelling and simulation tools offer peerless possibilities to dominate the increasing complexity of industrial applications, accelerating innovation cycles by quickly exploring and exploiting new efficient, reliable, and green possible solutions. In this paper, a dynamic model of a chiller system is developed through a mixed causal and acausal modelling approach. The chiller system uses carbon dioxide as a refrigerant and satisfies the cooling needs of high energy-demanding buildings. The model is validated against experimental data under various operating conditions and can be used to investigate the performances of different control logics under a wide partialization spectrum ranging from around 15% to 100% of the design cooling power of the system. Three simple control strategies, combining rule-based control and PID control, are presented and compared through both steady load simulations and daily characterizations. Simulation results point out opportunities that arise from the integration of the presented model in Computer-aided Control System Design (CACSD) software tools.

Intelligent Measurement and Analysis of Sewage Treatment Parameters based on Fuzzy Neural Algorithm with ARM9 Core CPU.

After entering the new century, the state continues to increase the construction of urban sewage treatment projects in response to the deteriorating water pollution situation. How to collect and analyze the sewage parameter variables in the sewage treatment process to ensure the intelligent measurement and accurate operation of the parameters in the treatment application is an urgent problem to be solved. This paper is mainly based on the computer-aided control system built by the ARM9 core embedded chip, and the feasibility and effectiveness of fuzzy neural network algorithms are discussed to improve the intelligent processing of sewage treatment parameters. After analyzing the principle and implementation flow of fuzzy control and neural network, starting from the characteristics of data collected by ARM9 core chip, the hybrid algorithm model is optimized and improved to further improve the convergence speed and accuracy of the algorithm. The simulation experiment proves that the optimized fuzzy neural control algorithm can effectively identify the dissolved oxygen, nitrate nitrogen, and other parameter data in the sewage treatment, and the recognition accuracy is very close to the true precision. Based on biosensors, the ARM9 core chip control system established by a recursive fuzzy neural network can greatly improve the tracking and control ability of parameters such as dissolved oxygen concentration and nitrate nitrogen concentration in microbial degradation. This has a good development prospect in wastewater treatment control applications. The experimental results show that the recursive fuzzy neural network algorithm proposed in this paper can dynamically track and control the nitrate concentration and dissolved oxygen concentration and ensure that the control is within the accuracy range. The accuracy of recognition is very close to the real accuracy.

Real-time energy-efficient operation of a dedicated mechanical subcooling based transcritical CO2 heat pump water heater via multi-input single-output extreme seeking control

In the field of transcritical CO2 systems applied research, dedicated mechanical subcooling (DMS) is one of the most recently investigated and promising solutions, especially for space heating. However, this kind of system brings with it an intrinsic complexity, and to pursue effective and efficient operation, it requires suitable control and optimization strategies. The paper considers a combined transcritical CO2 and R134a -based DMS system and depicts the benefits of using a Multi-Input-Single-Output (MIMO) Extremum Seeking Control (ESC) approach. The real-time optimization strategy was obtained through a Computer-Aided Control System Design (CACSD) tool, exploiting an ad hoc Dymola model of the DMS system that has been validated and tested by using experimental data. The performance of the proposed approach has been compared with standard solutions relying on physical correlations. The MISO-ESC strategy always performed better in terms of system Coefficient of Performance (COP), under both fixed and variable ambient temperature conditions. Finally, the influence of the different refrigerants in the combined DMS system was analyzed from both heating capacity and performance points of view.

Performance Analysis of Different Refrigerants in Automobile Air Conditioning Equipment Using Variable Capacity Compressor

In this study, the experimental performance of the use of R1234yf refrigerant al-ternative to R134a refrigerant in an automobile air conditioning system with var-iable capacity compressor was investigated. The automobile air conditioner con-sists of a variable capacity compressor, evaporator, condenser, liquid tank and expansion element. The experimental air conditioner is equipped with computer-aided control systems to obtain the desired experimental conditions and data col-lection systems for measuring and collecting experimental data. Tests were per-formed at different compressor speeds and different condenser and evaporator inlet air flow temperatures. Energy analysis was applied to the obtained experi-mental data and the results were presented in comparative graphs. In the results, it was seen that while the cooling effect coefficient and evaporator outlet air flow generally decreased in both refrigerants with the increase of the compressor speed, the mass flow rate of the refrigerants, the compressor outlet temperature, the heat discharged from the condenser, the cooling capacity and the compressor power increased. In cases where the evaporatör inlet airflow temperature is low, it has been observed that the change in the data is very small with the increase of the compressor speed with the effect of the capacity control system

Dynamic modal control of unmanned vehicle movement in open pit mining

The purpose of this study is to present a number of aspects in the modern concept of computer-aided dynamic modal control of unmanned quarry vehicles in open pit mining. In particular, the software and hardware module that is a part of the “Smart Quarry” global structure deals with the conditions of matching a form of specific current trajectories (their deviation to the left or right of the nominal axial trajectory) to information “trajectory” chirp signals. The study employs the methods of wavelet transforms to convert one-dimensional signals that generate unmanned vehicle current trajectories into the time-frequency distributions of Cohen’s class. The formation of unmanned vehicle current trajectories under their deviation to the left / right from the nominal axial trajectory on straight and curved routes is considered schematically. It is noted that the tracking of unmanned current trajectories on quarry routes is carried out taking into account the nature of trajectory signals. The difference between the introduced dynamic modal control of the unmanned vehicle and the static one is formulated. Some fragments displaying 1D-signals in a wavelet medium are introduced into the autonomous and external control subsystems. The computer-aided control system uses such elements of the wavelet transforms technique as Gabor wavelet functions, the wavelet matching pursuit algorithm, and Cohen’s class time-frequency distributions. The research results in formulating the criteria for forming the unmanned vehicle current trajectories by the control system in the form of its reactions to sporadic disturbances caused by the occurrence of static or dynamic obstacles on a route. The algorithm of dynamic modal control of current trajectories has been developed. The concept of forward and reverse transient processes of signals of unmanned vehicle trajectory deviation has been introduced. The estimation procedure of modal controller parameters has been described. The algorithm has been developed for modal controller matrix recalculation, which has the form of the chain of sequentially implemented matrix procedures. It should be noted in conclusion that a computer-aided system for modal control of current trajectory deviation has been developed on the basis of the performed research. It enables to implement the functions of controlling the dynamics of technological and safe movement of unmanned vehicles along the quarry routes in a conflict environment of open pit mining.

СИСТЕМА АВТОМАТИЗИРОВАННОГО ПРОЕКТИРОВАНИЯ И ПРОТОТИПИРОВАНИЯ УЧАСТКОВ СИНТЕЗА УГЛЕРОДНЫХ НАНОКЛАСТЕРНЫХ СТРУКТУР

The article focuses on using the integrated multi-component computer-aided design and control systems, which changes the product life cycle processes in the high-tech complex chemical and technological systems. In the integrated design of production facilities, special attention is paid to safety, productivity, reliability, ergonomics of the production line and the material and technical environment. The most effective in project management are flexible life cycle models that connect diverse specialists in a single information environment. The relevance of the task of developing and implementing problem-oriented heterogeneous computer-aided design and digital prototyping systems is justified. There is described a method for improving the efficiency of designing production facilities while minimizing the time required preparing a design solution, and the risks of design errors caused by the communication dissonance of diverse specialists. The architecture of the computer-aided design and digital prototyping system with a description of its basic components is presented. The creation of a digital model of the design object is described on the example of the reactor site and the material and technical base of the process of synthesis of carbon nanocluster structures that are in high demand in various industries. The conducted tests and the introduction of the resulting applied software solution into the educational process proved its efficiency in solving problems of integrated computer-aided design and digital modeling not only of objects of the carbon nanoindustry, but also for other industries with a similar material and technical base.

Unified CACSD Toolbox for Hybrid Simulation and Robust Controller Synthesis with Applications in DC-to-DC Power Converter Control

The current article presents the design, implementation, validation, and use of a Computer-Aided Control System Design (CACSD) toolbox for nonlinear and hybrid system uncertainty modeling, simulation, and control using μ synthesis. Remarkable features include generalization of classical system interconnection operations to nonlinear and hybrid systems, automatic computation of equilibrium points for nonlinear systems, and optimization of least conservative uncertainty bounds, with direct applicability for μ synthesis. A unified approach is presented for the step-down (buck), step-up (boost), and single-ended primary-inductor (SEPIC) converters to showcase the use and flexibility of the toolbox. Robust controllers were computed by minimization of the H∞ norm of the augmented performance systems, encompassing a wide range of uncertainty types, and have been designed using the well-known mixed-sensitivity closed loop shaping μ synthesis method.

К ВОПРОСУ ОБ АВТОМАТИЗАЦИИ ПРОЦЕССА ОСВЕЩЕНИЯ ОБСТАНОВКИ В АСУ ВМФ

Current development of Armed Forces of the Russian Federation is determined by advancing information technologies. The role of information support in the Navy is constantly growing and is crucial in military decision-making. The article deals with the conceptual approach to the integrated automation of situation awareness in the Navy’s computer-aided control system in order to enhance forces/troops management by providing the force command and military authority officers/ operators with analytical data obtained through acquisition and processing of situation information. For automation upgrade and effective management, the mathematical models of data processing represented by linear differential firstdegree equations are given. These models describe the kinetics of various generated information resources and show analytical solutions of the volume of output information resources versus the volume of initial data and conversion rate.

Towards Industrialization of FOPID Controllers: A Survey on Milestones of Fractional-Order Control and Pathways for Future Developments

The interest in fractional-order (FO) control can be traced back to the late nineteenth century. The growing tendency towards using fractional-order proportional-integral-derivative (FOPID) control has been fueled mainly by the fact that these controllers have additional “tuning knobs” that allow coherent adjustment of the dynamics of control systems. For instance, in certain cases, the capacity for additional frequency response shaping gives rise to the generation of control laws that lead to superior performance of control loops. These fractional-order control laws may allow fulfilling intricate control performance requirements that are otherwise not in the span of conventional integer-order control systems. However, there are underpinning points that are rarely addressed in the literature: (1) What are the particular advantages (in concrete figures) of FOPID controllers versus conventional, integer-order (IO) PID controllers in light of the complexities arising in the implementation of the former? (2) For real-time implementation of FOPID controllers, approximations are used that are indeed equivalent to high-order linear controllers. What, then, is the benefit of using FOPID controllers? Finally, (3) What advantages are to be had from having a near-ideal fractional-order behavior in control practice? In the present paper, we attempt to address these issues by reviewing a large portion of relevant publications in the fast-growing FO control literature, outline the milestones and drawbacks, and present future perspectives for industrialization of fractional-order control. Furthermore, we comment on FOPID controller tuning methods from the perspective of seeking globally optimal tuning parameter sets and how this approach can benefit designers of industrial FOPID control. We also review some CACSD (computer-aided control system design) software toolboxes used for the design and implementation of FOPID controllers. Finally, we draw conclusions and formulate suggestions for future research.

Remote Control of a Robotic Unit: A Case Study for Control Engineering Formation

Hands-on experimentation has widely demonstrated its efficacy in engineering training, especially in control formation, since experimentation using computer-aided control system design (CACSD) tools is essential for future engineers. In this context, this article describes a case study for Control Engineering formation, based on a new lab practice for the linear and angular velocity control for a commercial P3-DX robot platform, to teach industrial control. This lab proposal includes all the stages involved in the design of a real control system, from plant identification from an open-loop test to real experimentation of the designed control system. The lab practices proposed have a twofold objective: First, it is an interdisciplinary approach that allows students to put into practice the skills from other subjects in the curriculum, facilitating the integration of knowledge. In addition, it allows increasing the motivation of the students by working with a complex and realistic plant. The proposal has been evaluated through the grades of the students, as well as the perception of both students and instructors, and the results obtained allow to confirm the benefits of the proposal.

Practical experiences with Python and Linux RT at the SUPSI Laboratory

This paper presents a Computer Aided Control System Design (CACSD) environment completely based on the programming language Python. Students can perform all the control design tasks (modeling, identification, controller design, simulation) in this environment, and at the end, they can automatically generate RT code for targets like a PC or a Raspberry PI with a Linux RT OS. A Python package for control purposes have been developed at the Caltech by Richard Murray, with the aim of integrating the most used functions and methods available in other commercial and non commercial software. Using this package it is possible to design different kinds of controllers for laboratory plants (PID, state-feedback, LQR, including full and reduced order observers). An additional package developed at SUPSI allows representing the full system in a graphical block diagram, similar to xCos or Simulink, and automatically generating code for RT targets. This application offers the most used blocks required for the design of a control system. New blocks can be easily integrated into this SW. This environment has been validated at the SUPSI laboratory on different electromechanical plants: the classical Inverted Pendulum, the Disks and Spring system, the Ball on Plate and the Ball on Wheel plants.

Software of GAMMA-3 system for synthesis and mathematical modelling of UAV control systems

Control system design for complex technical plants includes execution of computationally complicated procedure sets. Many of those demand repeated iterative execution. Iterations are caused by uncertainty of a control task, incompleteness of the information on control plant and conditions of its functioning. Another important reason is related to insufficiently perfect methods of the automatic control theory, because of its ongoing active development. Therefore, the task of developing the computer-aided control system design is as relevant as before. The publication is devoted to the statement of an approach to expansion of GAMMA-3 multipurpose system opportunities. An important feature of GAMMA-3 system includes opportunities for solving the tasks via both traditionally procedural and non-procedural statements. At the first stage, the proposed approach provides the expansion of classes of procedural task statements as the most formalized process. At the following stage, formalization and generalization of saved procedural knowledge in new expanded model of the subject domain takes place. The domain in question allows for non-procedural task statement. Solving non-procedural declared tasks requires using intellectual components of GAMMA-3 system. In this paper, we illustrate the first stage of the proposed approach on the example of creating GAMMA-3 software package for solving the problems on the synthesis of a control system by modeling UAV movement on defined trajectory. One of the main tasks conducted by UAV is surveying remote areas, where data acquisition by habitual ways is complicated or there is a danger to lives and health of the people.

An ontology-based approach to knowledge representation for Computer-Aided Control System Design

Different approaches have been used in order to represent and build control engineering concepts for the computer. Software applications for these fields are becoming more and more demanding each day, and new representation schemas are continuously being developed. This paper describes a study of the use of knowledge models represented in ontologies for building Computer Aided Control Systems Design (CACSD) tools. The use of this approach allows the construction of formal conceptual structures that can be stated independently of any software application and be used in many different ones. In order to show the advantages of this approach, an ontology and an application have been built for the domain of design of lead/lag controllers with the root locus method, presenting the results and benefits found.

Research of High-Level Control System for Centrifuge Engine

Complex centrifuge stands or other complex machines with an electrical motor require a complex control system. As a rule, control systems implemented as physical devices or modules are not replaceable or scalable while programmable control systems can be easily replaced or updated. This paper discusses the black-box electrical motor scheme of interaction based on computer-aided control system.

Investigation of multidimensional control systems in the state space and wavelet medium

The notions are introduced of “one-dimensional-point” and “multidimensional-point” automatic control systems. To demonstrate the joint use of approaches based on the concepts of state space and wavelet transforms, a method for optimal control in a state space medium represented in the form of time-frequency representations (maps), is considered. The computer-aided control system is formed on the basis of the similarity transformation method, which makes it possible to exclude the use of reduced state variable observers. 1D-material flow signals formed by primary transducers are converted by means of wavelet transformations into multidimensional concentrated-at-a point variables in the form of time-frequency distributions of Cohen’s class. The algorithm for synthesizing a stationary controller for feeding processes is given here. The conclusion is made that the formation of an optimal control law with time-frequency distributions available contributes to the improvement of transient processes quality in feeding subsystems and the mixing unit. Confirming the efficiency of the method presented is illustrated by an example of the current registration of material flows in the multi-feeding unit. The first section in your paper.

Multi-objective optimization based tuning tool for industrial 2doF PID controllers

A computer-aided control system design tool is presented. This tool is able to take advantage of a database of Pareto optimal PID controllers. The idea is to give to the control engineer an useful tool to close the gap between the optimization procedure and the final selection of the parameters. The input to the tool are the allowed degradation of the considered cost functions, the desired level of robustness and the information of the plant, in the form of second order plus time delay model or a set of input-output data. The tool is written as a graphical user interface in MATLAB© and freely available to anyone.

A Light-Weight Rapid Control Prototyping System Based on Open Source Hardware

In this paper, we propose a light-weight rapid control prototyping (RCP) system based on off-the-shelf open source hardware to achieve high performance computing, cost effectiveness, portability, and easy accessiblity. The proposed RCP system consists of a PC-based computer-aided control system design (CACSD) tool for computing control action and tiny palm-sized open source hardware for input and output (I/O) operation and data transfer through a built-in high-speed USB interface. The popular-priced and portable open source hardware is used as a bridge between CACSD tools and real plants to deliver the control and sensor data at the sampling time points. Ten I/O function blocks written in C code are developed based on the CACSD tool employed for the proposed light-weight RCP system in order to handle I/O operation in a simple way. In addition, we suggest two practical strategies, a batch transfer strategy and a variable sampling period method, to increase the sampling rate of the control system. It is shown through experiment that the proposed light-weight RCP system works well up to a sampling rate of 2 kHz without adopting expensive hardware and C code generators. It is expected that the proposed RCP system will be considered as affordable and readily available to schools for mass education.

An Experience of CACSD for Networked Control Systems: From Mechatronic Platform Identification to Control Implementation

Continual advances in information and communication technologies (ICT) are revolutionizing virtual education and bringing new tools on the market that provide virtual solutions to a range of problems. Nevertheless, nonvirtual experimentation using computer-aided control system design tools is still fundamental for future engineers. This paper describes a control course laboratory element, which is designed to teach electronic control engineering, in which students use a networked control system to steer and drive an electric car prototype. Multidisciplinary in nature, this laboratory allows students to take advantage of their previous academic training, as they model the plant from an open-loop test and contrast the simulated behavior with experimental results obtained on the prototype. A goal in this work was that students, across multiple engineering disciplines, should be able to integrate the knowledge acquired throughout their degree studies. An evaluation of students' grades, and their perception of the course, was conducted; this confirmed the educational benefits of the approach.

Machine tool syntheses in virtual machining

It is beneficial to realize the cutting forces generated in the early stages of the design and process planning. This paper describes the concept of machine tool/process modelling for virtual machining purposes. It is based on the dynamic model of a machine and the cutting process. The model can be used in virtual manufacturing systems (VMS) where computer models that depict the manufacturing process are integrated to form an overall model to portray the real machining system. Modelling can be considered as a very important step in design, performance evaluation, model based monitoring/diagnostics, adaptive control and in design sensitive studies. Computer aided engineering (CAE) systems provide engineers with many design and analysis tools, by combining solid modelling programs with analytical tools, such as finite element codes and dynamic simulation programs, for a specific task. However a model for virtual machining should encompass a total solution. As an example, a CNC machining centre is modelled herein by the integration of Computer Aided Control System Design (CACSD), Computer Aided Multi–Body Dynamic and Finite Element Modelling tools for Machine Tool/Process Modelling (MPM). The derived model includes a regenerative force, cutting process as the interacting phenomena between the spindle and feed axes where dynamic deflection of the elastic parts are included.

Theoretical and Experimental Analysis of Electromagnetic Variable Valve Timing Control Systems for Improvement of Spark Ignition Engine Performance

The objective of this paper is to meet the requirements of higher torque values at all engine speeds. This can be achieved by varying the valve timing automatically using a new variable valve timing system (VVT), which gives continuously variable valve actuation at all engine speeds. A model engine is designed using dimensional analysis methods and then implemented to verify the proposed control system. Moreover, microcontroller and computeraided control systems are constructed and used to modify the variable valve timing control in the laboratory. In this paper, a mathematical model of variable valve timing is developed to obtain the best volumetric efficiency with optimum valve timing at different engine speeds. From this model, the look-up table is created at all ranges of the engine speed. A single cylinder engine is used to estimate engine performance characteristics for conventional camshaft. In addition, a model engine is designed and constructed to apply the Variable Valve Timing control system. The investigations show that the system is flexible throughout the entire range of operation speeds and is able to alter valve timing concerning both valve opening and closing. The ability of valve opening and closing can be realized with rates higher than these of the conventional timing mechanisms.