Basic Control Structures Research Articles

Сравнение линейных алгоритмов управления положением для прямых сервоприводов

Direct servo drives are used in industrial installations that place high demands for the motion dynamic and precision characteristics. Proper control system design is the key factor in achieving the required servo drive accuracy and dynamic performance characteristics. Two basic linear control structures for controlling a precision servo drive’s position are considered: the structure with a PID position controller and the structure with a P position controller and a nested speed loop with a PI controller. The structures were analyzed with taking into account the possibility of supplementing them with filters, observers, and predictors. The results of simulation and experiment carried out on the basis of a rotary precision servo drive have shown that the control structures are able to ensure commensurable motion accuracy provided that that the system parameters are known exactly. To this end, equations for recalculating the tunings from one structure to another are derived for analog and digital systems. With variable system parameters, the structure with a PID position controller ensures high tracking accuracy and requires the minimal computation effort, a circumstance that makes its use preferable in high-precision servo drive control systems. It is shown that commensurable performance characteristics in a subordinated control system can be achieved by using a Smith predictor.

Optimization and control of a reactive and extractive distillation process for the synthesis of isopropyl acetate

A conventional reactive distillation column will not be able to produce high purity isopropyl acetate (IPAc) due to the existence of a minimum boiling azeotrope in the system. In this work, a novel reactive and extractive distillation (RED) process was proposed and used for the synthesis of IPAc. Results showed that the purity of IPAc reached 99.5%. Then, the RED flowsheet was optimized with minimum total annual cost (TAC), and a number of key variables were determined with the assistance of program written in Visual Basic 6.0 (VB). After that, two control structures of the RED process were developed: a basic control structure with temperature/proportional cascade control and an improved control structure with composition/temperature cascade control. The integral of squared error (ISE) was introduced to evaluate the performance of control systems, it revealed that the improved control structure had better controllability.

Energy-saving columns: Design and control of a Kaibel and a multi-sidestream column for separating hydrocarbon mixture

Due to the conventional sequence has a disadvantage of high energy consumption, this paper proposes the optimal design and control of the Kaibel and multi-sidestream column for separating five-component hydrocarbon mixture. First, three processes are simulated by steady-state simulation. The three distillation structures are designed by minimizing the total annual cost (TAC) and the results show that the multi-sidestream column is the most energy-efficient configuration, with savings of 29.5% to the conventional sequence, and 12.2% to the Kaibel dividing wall column (KDWC). Second, the suitable control of three processes are designed. The temperature controller is used in multi-sidestream column and the component controller is used in KDWC. The results show that the response time towards disturbance of the KDWC is longer and the purity of the multi-sidestream column is not up to the requirement. Finally, aiming at the problem above, the control structures of KDWC and multi-sidestream column are optimized. Temperature controller is added in the KDWC instead of the component controller. Under the control of temperature, it can return to stable in a short time. A double temperature controller is added in multi-sidestream column based on defects of basic control structure. Its product purity can attain above the designed value. Compared to the multi-sidestream column process, the control structure of KDWC can handle feed disturbance more effectively, and the purity is closer to the design value.

Inertia and Primary Frequency Provisions of PLL-Synchronized VSC HVDC When Attached to Islanded AC System

The islanded scenarios of voltage source converter (VSC) high-voltage DC (HVDC) directly supplying power to islanded loads or connecting to wind farm are becoming popular, in which some new issues are required to be further addressed. While several control strategies have been studied, to the authors’ best knowledge, few have investigated the potential capability of VSC HVDC using the typical phase-locked loop (PLL)-synchronized vector control (PLLSynVC) to address islanded operation issues. To explore the potential capability of the typical PLLSynVC in islanded system, this paper proposes a frequency regulation scheme (FRS), including inertia and primary frequency control, for the PLL-synchronized VSC HVDC based on the motion equation concept. By adding the FRS, the VSC HVDC using the PLLSynVC, similar to a synchronous generator from the view of the phase motion equation, not only can self-maintain the frequency stable in an islanded system, but also naturally avoids the transition of control operation modes without changing the basic control structure. Furthermore, based on the developed phase motion equation, the inertia characteristics of VSC HVDC with the FRS is studied, which synthetically considers the impact of different controllers and PLL, and makes VSC HVDC's manifested inertia clear. The effectiveness of FRS and inertia analysis results is verified by time-domain simulations.

Applying Student Team Achievement Divisions (STAD) Model on Material of Basic Programme Branch Control Structure to Increase Activity and Student Result

Based on my experience of teaching the material of branch control structure, it is found that the condition of the students is less active causing the low activity of the students on the attitude assessment during the learning process on the material of the branch control structure i.e. 2 students 6.45% percentage of good activity and 29 students percentage 93.55% enough and less activity. Then from the low activity resulted in low student learning outcomes based on a daily re-examination of branch control material, only 8 students 26% percentage reached KKM and 23 students 74% percent did not reach KKM. The purpose of this research is to increase the activity and learning outcomes of students of class X TKJ B SMK Muhammadiyah 1 Banjarmasin after applying STAD type cooperative learning model on the material of branch control structure. The research method used is Classroom Action Research. The study was conducted two cycles with six meetings. The subjects of this study were students of class X TKJ B with a total of 31 students consisting of 23 men and 8 women. The object of this study is the activity and student learning outcomes. Data collection techniques used are test and observation techniques. Data analysis technique used is a percentage and mean. The results of this study indicate that: an increase in activity and learning outcomes of students on the basic programming learning material branch control structure after applying STAD type cooperative learning model.

Design and control of different pressure thermally coupled reactive distillation for amyl acetate synthesis

The different pressure thermally coupled reactive distillation (DPT-RD) process is an attractive heat-integrated design in chemical engineering development processes. In this study, a rigorous simulation of the DPT-RD process for amyl acetate synthesis in a neat operation mode is performed using the Aspen Plus simulator. The economic feasibility and controllability of the DPT-RD process were evaluated based on the research of steady-state optimization and dynamic control. The optimum DPT-RD process in terms of the total annual cost (TAC) is screened. The results show that 33.74% reduction in energy consumption and 7.96% savings in TAC can be achieved by the DPT-RD process compared to the conventional reactive distillation. The control strategy of the DPT-RD process was developed and the basic control structure with proportional control and the improved control structure with temperature/composition cascade control were presented. The dynamic results indicate that the improved control structure can effectively handle disturbances of ±20% in feed flow rate and of 5% in feed composition. Overall results demonstrate that the DPT-RD process is a promising approach for amyl acetate synthesis.

A hybrid modeling approach for steady-state optimal operation of vapor compression refrigeration cycles

This paper presents a steady-state hybrid modeling approach for vapor compression refrigeration cycles which is intended to achieve an optimal system operation from an energy consumption point of view. The model development is based on a static characterization of the main components of the cycle using a hybrid approach, and their integration in a new optimization block. This block allows to determine completely the system stationary state by means of a non-linear optimization procedure subjected to several constraints such as mechanical limitations, component interactions, environmental conditions and cooling load demand. The proposed method has been tested in an experimental pilot plant with good results. Model validation for each identified hybrid model is carried out from a set of experimental data of 82 stationary operating points, with prediction errors below ±10%. The model is also globally validated by comparing experimental and simulated data, with a global mean relative absolute error less than 5%. The basic control structure consists of three decentralized control loops where the controller variables are the secondary fluid temperature at the evaporator inlet, the superheat, and the condenser pressure. While the secondary temperature is assumed as an imposed requirement, the optimal set-points of the other two control loops are searched offline using the proposed refrigerant cycle model. This set-point optimality is defined according to the coefficient of performance for minimizing the total electrical power consumption of the system at steady-state. This energy saving has been confirmed experimentally. The proposed method can be easily adapted for different sets of controlled variables in case of modification of the basic control structure. Furthermore, other energy efficiency metrics can be handily adopted. Considering the tradeoff between the accuracy and computational cost of the hybrid models, the proposed procedure is expected to be used in real-time applications.

Introducing programming through acoustics and audio at Belmont University

A course in computer programming has been offered within the department of Audio Engineering Technology at Belmont University to provide an introduction to audio and physics students interested in learning about programming. This course is based on a foundation of acoustics and audio concepts, without requiring previous programming experience. The pedagogical approach has been to expose students to the application of programming within their discipline of interest as a motivation for further exploration. Topics in the course introduce programming concepts for specific signal processing methods. Programming concepts include: variables, operators, data types, as well as basic control structures like loops, conditional statements and functions. While learning programming concepts, students perform various signal processing methods such as: changing a signal’s amplitude, signal synthesis, stereo panning functions, mid-side processing, amplitude fades, amplitude modulation, soft/hard clipping, rectification, bit reduction, echo effects, convolution, algorithmic reverberation, expander/compressor dynamic-range processing, and various spectral filters. Course lessons for a “flipped classroom” are freely and publically available at http://www.hackaudio.com/. Since the initial offering of this course, the number of students in the audio engineering program who double-major or minor in computer science has quadrupled.

Program Complexity Finder: A Tool for Finding Program Complexity in Terms of Cognitive Weight based on Complexity Measurement Algorithm

Measurement of any piece of programming problems is a key issue for Distributing Equivalent Problems among examinees. Basic Control Structure or BCS Plays an Important role to design a program and hence measuring complexity value of any piece of programming problems. Using of Cognitive weight concept of any BCS are purely based on the thinking Capacity of Human Brain. In this Research Basic control structure has been established in such a way to reduce the limitation of existing Measures. According to these cognitive data, a new software tool based on java SE language and MySQL Database has been established by using own developed algorithm. This software is structured and developed based on the outcome of research data which is capable of determining the complexity value of several programming languages. It will facilitate the instructors distributing the programming problems among the students by maintaining equivalent level of difficulty. Thus, the automatic complexity measurement application will ensure the students to obtain programming problems with equal difficulty level for evaluation.

Linear programming predictive control with actuator saturation: Experimental robustness and performance results

Linear programming optimization is widely used in several application areas. One possible application of this optimization technique, which has not received sufficient attention, is process control. In particular, the standard structure of linear programming optimization problems allows formulating optimal predictive control schemes with the additional advantage of facilitating the handling of actuator saturation. Actuator saturation appears in many engineering applications and there are several control approaches dealing with this problem. In this article, a very simple predictive control scheme based on linear programming optimization for actuator saturation control is proposed. The main characteristics of the presented scheme are simplicity and practical robustness/performance tuning parameters. First, the simplest possible output-feedback linear programming predictive controller is proposed as a starting point. Next, through several practical observations inspired in classical control engineering, a series of modifications to the basic controller structure are proposed. These modifications aim at effectively increasing the performance and robustness of the control algorithm. The experimental results confirm that the proposed control algorithm can operate effectively under the presence of perturbations, something which is currently not widely reported in the literature for linear programming actuator saturation predictive control.

Design and control of reactive dividing-wall column for the production of methyl acetate

A reactive dividing-wall column (RDWC) is developed for the production of methyl acetate (MeAc) in this work. Both design and control of the RDWC are investigated by using commercial chemical simulator Aspen Plus and Aspen Dynamics. The optimum RDWC design in terms of total annual costs (TAC) is screened based on the proposed optimization procedure. The results show that about 7.7% savings in energy consumption, 8.3% reduction in operating cost and 15.5% decrease in capital investment can be achieved by the RDWC design compared to the corresponding two-column design. Two control structures (i.e., basic control structure and improved control structure) for the RDWC are presented. The results indicate that the improved control structure can handle disturbances in ±20% feed flow rate and −5wt% feed composition effectively.

Measuring Complexity, Development Time and Understandability of a Program: A Cognitive Approach

One of the central problems in software engineering is the inherent complexity. Since software is the result of human creative activity and cognitive informatics plays an important role in understanding its fundamental characteristics. This paper models one of the fundamental characteristics of software complexity by examining the cognitive weights of basic software control structures. Cognitive weights are the degree of the difficulty or relative time and effort required for comprehending a given piece of software, which satisfy the definition of complexity. Based on this approach a new concept of New Weighted Method Complexity (NWMC) of software is developed. Twenty programs are distributed among 5 PG students and development time is noted of all of them and mean is considered as the actual time needed time to develop the programs and Understandability (UA) is also measured of all the programs means how much time needed to understand the code. This paper considers Jingqiu Shao et al Cognitive Functional Size (CFS) of software for study. In order to validate the new complexity metrics we have calculated the correlation between proposed metric and CFS with respect to actual development time and performed analysis of NWMC with CFS with Mean Relative Error (MRE) and Standard Deviation (Std.). Finally, the authors found that the accuracy to estimate the development time with proposed measure is far better than CFS.

Compensation of droop control using common load condition in DC microgrids to improve voltage regulation and load sharing

Abstract DC microgrid is one feasible and effective solution to integrate renewable energy resources, as well as to supply reliable electricity. The control objective of DC microgrids is to obtain system stability, low voltage regulation and equal load sharing in per unit. The droop control is an effectively method adopted to implement the control of microgrids with multiple distributed energy units. However in the application of low-voltage DC microgrids, the nominal reference mismatch and unequal cable resistances require a trade-off to be made between voltage regulation and load sharing. In this paper, a unified compensation framework is proposed using the common load condition in local controller, to compensate the voltage drop and load sharing errors. The voltage deviation is compensated with a P controller while the load sharing is compensated through a PI controller. An additional low bandwidth communication is introduced to share the output current information, and the average output current in per unit is generated to represent the common load condition. The performance of the proposed method is analyzed and compared with basic droop control and hierarchical structure method. The large signal stability is analyzed to define the margin of compensation coefficients. Simulations and experiments are carried out to verify the performance of the proposed method.

Design and control of distillation processes for methanol–chloroform separation

The binary mixture of methanol–chloroform exhibits a minimum-boiling azeotrope with ∼34mol% methanol at 327K under atmospheric pressure. In this paper, design and control of alternative distillation processes for separation of methanol–chloroform azeotropic mixture are explored. The steady-state and dynamic simulations are carried out with Aspen Plus and Aspen Dynamics. The comparison in terms of steady-state design is done between homogeneous extractive distillation and pressure-swing distillation processes. The pressure-swing distillation process is found significantly more economical than the homogeneous extractive distillation process. Based on results, a heat-integrated pressure-swing distillation process is considered, and found economically feasible. Thus, the dynamic comparison is done between pressure-swing distillation systems with and without heat integration. The pressure-swing distillation process without heat integration can be controlled using a basic control structure, while the heat-integrated pressure-swing distillation system requires a pressure-compensated temperature control structure. Results show that dynamic controllabilities of both processes are quite similar.

Design and Control of Extractive Dividing-Wall Column for Separating Ethyl Acetate–Isopropyl Alcohol Mixture

An extractive dividing-wall column (EDWC) is simulated as a three-column system in this work. The design and control of the EDWC to separate ethyl acetate and isopropyl alcohol using ethylene glycol as the entrainer is studied in Aspen Plus and Aspen Dynamics. The optimum EDWC design with minimal total annual cost is screened first; then sensitivity analysis is conducted to investigate whether the entrainer flow rate and vapor split ratio can be used as control variables to hold the purity specifications; finally, three control structures for the EDWC are established, and the dynamic results of these control structures are compared. It is found that two improved control structures achieve satisfactory performance with much smaller deviation and shorter settling time by comparison to the basic control structure. Dynamic results also revealed that it is useful to adjust the entrainer flow rate or vapor split ratio to hold the purity specifications.

Applied Technology in the Grid Workflow Quality of Service Calculation and Estimation

For the grid workflow system include a large of candidate services, the activity scheduling in workflow’s ex-ecution base on quality of service (QoS) constraints can pro-vide optimal service for users. This paper established the QoS’s parameter system with applied technology of grid workflow, and introduced the each parameter’s calculation model of activity’s QoS, the grid work-flow’s QoS estimation method based on the basic flow control structures defined by the abstract grid workflow language (AGWL). The experimental results show that the calculation method in this paper can estimate stably QoS parameter values of grid workflow combining with the multi candidate services, and, can provide a reasonable basis for process scheduling based on QoS constraints.

Integrated control system for the beam commissioning of the PEFP 100-MeV proton accelerator

The Proton Engineering Frontier Project (PEFP) has developed an integrated control system for beam commissioning of its 100-MeV proton linear accelerator. The final goal of the PEFP control system for beam commissioning is to develop a network of attached and distributed control systems. The PEFP control system was designed into the basic control structure of three groups including the central control system, the local control system, and the console system. The central control system is responsible for the timing synchronization and interlock. The local control system is responsible for the distributed control system for several linac components, such as the vacuum, power supply, data acquisition, RF, and so on. The console system is responsible for the user interface as a control system client. In order to implement the control system, we have adopted an Experimental Physics and Industrial Control System (EPICS) software framework as the standard development tool. The EPICS is based on a distributed architecture that provides several solutions, such as independent programming tools on several hardware and operating-system platforms. The Input Output Controllers (IOCs) of the PEFP control system have been tested with a wide variety of hardware solutions from a personal computer to embedded devices. In this paper, we will present the details of the integrated control system for beam commissioning of the PEFP 100-MeV proton linac.

Control structure and scheduling of a hybrid assembly system

This paper describes a hybrid control structure, working scenarios and logic of working cycles during the assembly of an unlimited sequence of assembly orders in a bionic assembly system (BAS). Focus is given on the realization of the communication between subsystems, different modes of the assembly process and scheduling strategies and basic tasks of mobile robots during assembly. BAS is a new concept in advanced assembling systems, which combines two basic control structures and principles: a centralized control system, based on the hierarchy, and a self-organizing control system, based on the heterarchy.

Physical Constraints on Biological Integral Control Design for Homeostasis and Sensory Adaptation

Synthetic biology includes an effort to use design-based approaches to create novel controllers, biological systems aimed at regulating the output of other biological processes. The design of such controllers can be guided by results from control theory, including the strategy of integral feedback control, which is central to regulation, sensory adaptation, and long-term robustness. Realization of integral control in a synthetic network is an attractive prospect, but the nature of biochemical networks can make the implementation of even basic control structures challenging. Here we present a study of the general challenges and important constraints that will arise in efforts to engineer biological integral feedback controllers or to analyze existing natural systems. Constraints arise from the need to identify target output values that the combined process-plus-controller system can reach, and to ensure that the controller implements a good approximation of integral feedback control. These constraints depend on mild assumptions about the shape of input-output relationships in the biological components, and thus will apply to a variety of biochemical systems. We summarize our results as a set of variable constraints intended to provide guidance for the design or analysis of a working biological integral feedback controller.

Design and Control of Extractive Dividing-Wall Column for Separating Methylal–Methanol Mixture

The design and control of extractive dividing-wall columns (EDWCs) have not yet been investigated, whereas those of dividing-wall columns (DWCs) and conventional extractive distillation columns (CEDCs) have been studied by many researchers. The control of EDWCs is more difficult than that of CEDCs and somewhat different from that of DWCs because of differences in the inner structure and interactions among control loops in EDWCs. In this work, the design and control of an EDWC for methylal/methanol separation are investigated using commercial chemical simulators (Aspen Plus and Aspen Dynamics). The optimum EDWC design based on the total annual cost (TAC) is screened first; then, the interaction between design and control is observed; and finally, two control structures for the EDWC are presented. The first proposed basic control structure featuring four composition controllers and an adjustable vapor split ratio αV can handle all disturbances well with small offsets in product purities, except for a 20% de...