Control System Design Process Research Articles

The Initial Design of Process Control System Based on EPICS for HL-2A & HL-2M

In addition to the real time plasma magnetic and kinetic control, process control is also very important for the operation of a Tokamak. Process control aims at the normal control of the plant systems including information sharing, schema of the Tokamak operation, and alarm handling. A new tokamak named “HL-2M” will be built during the next four years and many conceptual designs for the operation of the new device might be validated on HL-2A, which is currently running at SWIP Chengdu, China. For those purposes, we select the EPICS as the basis for the process control system of HL-2A. Some user interface, data management, and development tools are adopted such as control system studio (CSS), MS SQL Server, Matlab, LabVIEW, VC++, and Java. In this study, we will describe the initial design of the whole HL-2A/HL-2M process control system and its related achievements in HL-2A. c © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research

Cost Effective Biomass Combustion Process Control

Abstract The new control algorithms were implemented into control systems of boilers for woodchips combustion with aim to reach the complete combustion with minimum excess of combustion air. The main selection criterion for carbon monoxide and oxygen sensors was an achievement of required technical parameters under minimal costs for possibility of using the designed algorithms also in control systems of the small-scale boilers. So far obtained data from monitored control systems of two types of boilers for woodchips combustion confirm the right approach to design and realization of automatic biomass combustion process control system.

Advanced Control Design for Wind Turbines

AbstractIn this contribution, the concept of a general design platform for control system of wind turbines is proposed. Different models of wind turbine systems are summarized, a novel control strategy for wind turbine control is proposed as a general platform for control system design. Simulation results are presented demonstrating the success of the proposed control method based on one of the chosen models for the design platform. A benchmark model (NREL) is chosen for the platform in order to adjust the control system design. Finally, the design process of control system based on the general platform is given and explained. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Human factors evaluation in nuclear power plant control rooms using a mobile system to support collaborative observation

Nuclear industry has several regulations and guidelines for human factors engineering (HFE) that should be applied in modernization of existing ones and in construction of new power plants. Their aim is to ensure that human factors/ergonomics are applied during the design process, making the system more controllable, reliable and safe than it would be if human factors were not adequately incorporated. Time consuming and inadequate methods for data collection and analysis in complex settings are often described as a problem to apply human factors in the design of process control systems. To facilitate the use of human factors/ergonomics in the design, we developed a mobile computer system to support collaborative observation of work teams to be used in complex environments. In this paper, we argue that collaborative observation should be used in the work teams’ knowledge elicitation for human system interface design purposes, showing the advantages of the collaborative approach in comparison to other non-collaborative ones. We describe the development of a mobile support system for collaborative observation tested in the evaluation of human system interfaces of a nuclear power simulator crew when operating a digital human-system interface. The results indicated that the mobile system stimulates collaboration among observers and the organization of overall human-system interface evaluation.

AN INTEGRATED, REAL-TIME APPROACH TO PROCESS CONTROL SYSTEM DESIGN EDUCATION

Throughout the chemical and process industries, ever more emphasis is being placed upon extracting increasingly greater value from plant equipment, with substantial interest in energy efficiency and responsible environmental stewardship. Improved process control is almost unique in its ability to deliver substantial operational efficiency and environmental improvements with relatively little additional capital investment. As such, process control has become one of the most sought after skills within the chemical and process industries. Industry needs graduates that are educated in the latest and most relevant skills. Industry practitioners rely heavily on commercially available process simulation tools and hands on, time domain based control strategy development techniques, e.g. [1-2]. This paper describes an integrated, real-time approach to the education of undergraduate chemical engineering students in process control system design [3-4]. The real-time approach to process control system design education integrates introductory process control education and industrial practice. The approach focuses on the more applied and practical time domain based techniques derived from modern process simulation. The use of computers is a central theme to the approach, and their use in simulations and the software is carefully introduced. The students gain a thorough understanding of instrumentation, process design versus controllability trade offs, control loop configurations and tuning, practical techniques for the control of unit operations and basic plant-wide control. This integrated, real-time approach to the education of undergraduate chemical engineering students in process dynamics and control has been taught as a capstone subject at the University of Calgary since 1997 using active, “hands on” or resource based learning [5-6]. A small number of lectures at the beginning of the course are advocated from a learning perspective to motivate students rather than to simply transmit information. A majority of “hands on” tutorial and / or simulation sessions are recommended on case studies, workshops or projects facilitated by the instructors [7]. The approach is illustrated by examples from this capstone course.

Controllability analysis for the liquid-phase catalytic oxidation of toluene to benzoic acid

The liquid-phase catalytic oxidation of toluene is the main industrial commercial process for producing benzoic acid. It is a strongly exothermic and highly nonlinear process that exhibits poor controllability characteristics with input/output multiplicity and non-minimum phase behavior. Focusing on inherent safety, this study explores the open and closed-loop controllability of this process. The framework contains two parts. First, an approach for analyzing the stability of zero dynamics of the system is used to investigate the phase behavior of the process and is selected as an open-loop indicator for controllability. Second, based on the model predictive controller, closed-loop dynamic simulation, including set-point tracking and disturbances rejection, is performed to illustrate the dynamic performance in various sub-regions with different controllability characteristics. The results of the dynamic simulation confirm everything predicted by the open-loop controllability analysis. The outcomes are expected to guide realistic industrial operation and process control system design. An attempt is made with the help of this liquid-phase oxidation process to show how to clarify and deal with the causes of the complex phenomena that arise in the operation and control of the chemical processes.

슬립을 고려한 트랜스퍼 크레인의 주행제어에 관한 연구

Abstract: The most important thing in the container terminal is to handle the cargo effectively in the limited time. To achieve this object, many strategies have been introduced and applied to. If we consider the technical trends and environment of the automated container terminal, it is necessary that the systems for cargo handling are equipped with more intelligent control technologies. To cope with this tendency, from the middle of the 1990's, the automated RMGC (Rail-Mounted Gantry Crane) and RTGC (Rubber-Tired Gantry Crane) have been developed and widely used to handle containers in the yards. Recently, in these cranes, the many equipments like CCD cameras and sensors are mounted to cope with the automated terminal environment. If we want to obtain more efficient handling performance, the modelling, tracking control, anti-sway system design, skew motion suppressing and complicated motion control problems must be considered in the control system design and application process. Considering these problems, in this paper, the system modelling with the tire slip and a tracking control approach are proposed. Especially, we design the tracking control system based on the 2DOF servosystem design approach to cope with undesirable disturbance input. The experiment results show the desirable performance and usefulness of the designed control system. Keywords: rail-mounted gantry crane, rubber-tired gantry crane, automated container terminal, 2DOF servosystem, observer, tracking control

Dynamic Sensitivity to Atmospheric Turbulence of Unmanned Air Vehicles with Varying Configuration

DOI: 10.2514/1.46860 Air vehicle flight in turbulence is generally treated as an anomalous part of the flying environment. Aircraft geometries and flight-control systems are often designed and tested for calm atmospheric conditions, where both steady winds and gusts are minor. As a result, the flight performance of small aircraft deteriorates in the presence of atmospheric turbulence, where gust disturbances can be large relative to the flying speeds. A better approach is needed in the aircraft and control system design process that specifically accounts for the effects of turbulence and providesameansofmitigatingdisturbancestoimprovethemissioneffectivenessofmicrounmannedairvehiclesand small unmanned air vehicles. The current research considers untethered flight tests of a small unmanned air vehicle in a large wind engineering tunnel that can be configured to replicate turbulence levels expected from urban and suburban environments. Systematic changes to the configuration of the fixed-wing aircraft are made to evaluate the roleofmetrics,suchasc.g.,mass,momentofinertia,wingspan,andwingloadingtoturbulencesensitivity.Estimates of the force and moment disturbances indicate that some parameters, such as moment of inertia, have simple and expectedinfluencesontheresponsetoturbulence. Conversely,wingareaandmasshaveconflictingeffectsduetothe compounded influences on the aircraft response. The sensitivity of the various aircraft configurations to turbulence are presented as control equivalent turbulence disturbances, which equate forces and moments acting on the airframe to control deflections. This method normalizes the aircraft responses with respect to the ability to suppress disturbances with actuated controls.

Plantwide Control System Design and Performance Evaluation for Ammonia Synthesis Process

The emphasis on process economics in modern chemical plants has led to the increased use of material recycle and energy integration that significantly alter process dynamics and add complexity. As a result, many plantwide control (PWC) methodologies have emerged. However, there are very few comparative studies to evaluate the effectiveness of alternate methodologies. In this study, a PWC structure for the ammonia synthesis process is developed using the integrated framework of simulation and heuristics [Konda et al. Ind. Eng. Chem. Res. 2005, 44, 8300−8313], which is then compared with that developed by Araújo and Skogestad [Araújo and Skogestad, Comput. Chem. Eng. 2008, 32, 2920−2932] using the self-optimizing control procedure. The different control structures are evaluated in a comprehensive manner including assessment of the dynamic performance and steady-state profit.

Decentralized Control System Design for MIMO Processes with Integrators/Differentiators

This work extends the concept of relative normalized gain array (RNGA) and proposes a systematic approach to designing decentralized proportional−integral−derivative (PID) control for multi-input−multi-output (MIMO) processes containing integrators and/or differentiators. By determining the input−output-pairing using the relative gain array (RGA)−Nederlinski index (NI)−RNGA criterion, equivalent transfer functions (ETFs) for the selected input−output pairs are derived by utilizing the RGA and RNGA information, which has incorporated the information on loop interactions. Based on the ETFs, decentralized PID controllers are tuned to stabilize the MIMO system independently. The proposed approach is simple, easy to understand, and easy to implement by field engineers. Three industrial MIMO processes with different dimensions and interaction modes are employed to demonstrate the efficiency of the proposed approach.

System Identification using Orthonormal Basis Filters

Models are extensively used in the design and implementation of advanced process control systems. In model predictive control (MPC), model of the plant is used to predict the future output of the plant using the current and future optimal inputs and past outputs. Therefore, the design of MPC, essentially, includes the development of an effective plant model that can be used for predicting the future output of the plant with good accuracy (Camacho & Bordon, 2004; Rawlings, 2000). Models can be developed either from purely theoretical analysis (conservation principles, thermodynamics, etc.) or from experimental data or somewhere in between. The process of model development from experimental data is known as system identification. The identification test can be conducted either in open-loop (open-loop identification) or while the plant is under feedback control (closed-loop identification).

A broader view of the economic design of the X-bar chart in the semiconductor industry

This paper starts from a notice made in the semiconductor industry: a process control system and especially control charts provide information that can be exploited for correlation analyses during process investigations. In this industry, key and costly investigations are made for improving yield and reducing scrap. Daily, engineering teams are working at manufacturing improvements. Without process data, their work could take much more time and lead to weak improvements. Nevertheless, design of process control systems and in particular control charts lacks from taking into account this remark as there is no sound application to infer an optimal control chart depending on business parameters like yield, scrap, customer audits, etc. Meetings between several engineering teams (process control, quality, process integration, industrial engineering and production) occur frequently to find an affordable quantity of controls for each operation. The literature point of view does not provide more recommendations to take into account the reuse of data into these costly investigations. The paper investigates this issue. For this first investigation, work has been focused on the design economics of control charts for a simplified process model. The paper translates this concept into the Lorenzen and Vance's (1986) model. It simulates the design economic of a control chart taking into account this new model and infers new optimal statistical process control (SPC) set points. An analysis of this new link is made in a context of yield improvement, providing reference for knowing optimal quantity and frequency of controls.

小型精密機器のための組込み型多軸アクティブ制振・除振装置の開発(機械力学,計測,自動制御)

Recently, high-resolution measurement instruments such as probe microscopes have been used widely, since their price is getting lower, and their size is becoming smaller. Therefore, these measurement instruments have been used in various environments. However, to use these instruments effectively, it is important to isolate the environmental vibration transmitted to the instruments. For this reason, we are developing new built-in type multi-axis vibration isolation devices equipped with inertia force generators (IFG). In designing this vibration isolation device, modal analysis and "direct inertia force control (DIFC)" are used. DIFC is the newly developed design method for the vibration control systems proposed by authors. Combination of modal analysis and DIFC can make the complex control system design process simple and clear. In this paper, we show how the controller is designed, and also discuss the effectiveness of the method by experiment.

Optimizing Control of CSTR/Distillation Column Processes with One Material Recycle

Control system design for recycle processes that are composed of a continuous stirred tank reactor (CSTR) and a distillation column is discussed. It is shown that the reflux ratio control, which has been known to serve as a self-optimizing control for the process with the elementary chemistry A → B, can be also applied to processes with more-general types of chemistry that involves side reactions. Using the self-optimizing control as the basis, control systems that seek economically optimal operations are hierarchically constructed for example processes with different types of process chemistry. Particularly, for a process that exhibits tradeoff between product yield and separation cost, a linear model predictive controller design example is given with simulation results.

Evaluation of ratio control schemes in a two-temperature control structure for a methyl acetate reactive distillation column

A two-temperature control structure for a methyl acetate reactive distillation (RD) column, originally proposed by [Roat, S.D., Downs, J.J., Vogel, E.F. and Doss, E.J., 1986, Integration of rigorous dynamic modeling and control system synthesis for distillation columns, in Chemical Process Control CPC III, Morari, M. and McAvoy, T.J. (eds.) (Elsevier, New York.)], is modified to incorporate ratio controllers in three different configurations between the column inputs. Closed loop results for these three configurations, namely, acetic acid feed in ratio with the methanol feed, methanol feed in ratio with the acetic acid feed and the two fresh feeds in ratio with the reboiler duty (through-put manipulator) show that the control performance for load disturbances does not improve and may deteriorate when the two fresh feeds are fed in ratio (acetic acid to methanol or methanol to acetic acid). The deterioration in performance is attributed to input multiplicity and unfavourable dynamic interaction between the control loops. Tighter product purity control is achieved for a through-put change when the two feeds are fed in ratio with the reboiler duty, the through-put manipulator. It is also shown that an alternative design that avoids input multiplicity exhibits better control performance. The results highlight the need for considering the non-linear effects in column and control system design for RD processes.

Normalized Decoupling —A New Approach for MIMO Process Control System Design

In this paper, a novel engineering oriented decoupling control system design method for two-input, two-output processes is presented. By employing the concept of integrated error, gain and phase changes of a transfer function when other loops are closed can be uniquely determined. Consequently, an equivalent transfer function matrix for a closed-loop control system can be obtained and its relations with the original process transfer function matrix are derived. On the basis of the equivalent transfer function matrix, parameters of a stable, proper, and causal ideal diagonal decoupler can then be easily determined by proper parameter assignments of the decoupled transfer function matrix elements. The method avoids the drawbacks of existing decoupling schemes, is very simple and can be easily understood, and can be implemented by field control engineers. An industrial process is employed to demonstrate its simplicity in design and effectiveness in control system performance.

비행제어시스템 설계 및 검증 절차

Relaxed static stability(RSS) concept has been applied to improve aerodynamic performance of modern version supersonic jet fighter aircraft. Therefore, flight control systems are necessary to stabilize an unstable aircraft, and provides adequate handling qualities and achieve performance enhancements. Standard FCSDVP (Flight Control System Design and Verification Process) is provided to reduce development period of the flight control system. In addition, if this process is employed in developing flight control system, it reduces the trial and error for development and verification of flight control system. This paper addresses the flight control system design and verification process for the RSS aircraft utilizing design goal based on military specifications, linear and nonlinear system design and verification based on universal software, handling quality test based on HILS(Hardware In-the-Loop Simulator) environment, and ground and flight test results to verify aircraft dynamic flight responses.

Multidisciplinary machine building

In today's world it is rare to find electromechanical devices without some kind of embedded intelligence. From production systems, remote control vehicles and automotive subsystems, like ABS, to everyday equipment like digital cameras, CD players and washing machines, most electromechanical devices rely on embedded controllers. Mechatronics is a system-level approach to the process of designing intelligent, embedded systems - devices that are not just electrical or mechanical, and are more than just control systems. It is a complete integration of electrical, mechanical and control system design process.

Virtual factory approach for implementation of holonic control in industrial applications: A case study in die-casting industry

Design and implementation of holonic manufacturing control systems for the real industrial applications require risky, careful decisions to ensure that the manufacturing system will successfully satisfy the demands of an ever-changing market. This paper suggests a virtual reality (VR)-based methodology for enhancing the design and implementation process of holonic control systems in manufacturing practice. The major focus has been given to the implementation of holonic control into the small to medium size manufacturing enterprises (SMEs). The ‘virtual holonic factory’ concept has been introduced, as a test bed for integration of a holonic control into a virtual factory, i.e. three-dimensional VR model of a factory in order to visually realize the effects of holonic control, when implemented to a real manufacturing system. A case study has been carried out in a medium size die-casting manufacturing plant. Through the virtual factory, a holonic control architecture for flow-line manufacturing system has been implemented for dynamic scheduling of machines in the medium size factory in order to achieve robustness necessary to handle the disturbances. The system performance and key attributes of the holonic control, such as re-configurability and robustness, have been tested and validated by using VR technology and analysis results have been presented.

Formal Design Process for FlexRay-Based Control Systems with Network Parameter Optimization

Formal Design Process for FlexRay-Based Control Systems with Network Parameter Optimization