In an effort to continuously improving business productivity, companies are adopting new practices towards a continuous optimization of the total enterprise in the areas of business processes, supply chain and plant l...
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In an effort to continuously improving business productivity, companies are adopting new practices towards a continuous optimization of the total enterprise in the areas of business processes, supply chain and plant life cycle. This trend is supported with the enabling technology for integrated enterprise systems, such as Enterprise Resource Planning (ERP) and Supply Chain Management (SCM) systems. With an ERP system, various types of information can be accessed in one system which allows us to do work flow reengineering more effectively. The accessibility of information from the lower layer (process automation/control) system such as process data to the upper layer (enterprise) system such as business data is critical for establishing an effective SCM system. This system plays a critical role for linking the enterprise and the controlsystems in optimizing the enterprise performance. In a chemical industry, the range of feasible operation regions that is set for the SCM system to find the best operation policy will indirectly depend on the ability of the process controlsystem to perform in the range of operation regions. One of the requirements for an efficient production network is the ability to adopt changes in production operations with greater flexibility. This requirement will put a challenge on the process control technology. Meeting this requirement will allow for greater feasible operation regions set in the SCM study. Here, we discuss the potential impacts of a new trend in enterprise wide SCM practices on process controlsystem in a chemical plant operation.
A supervisory control of a multipurpose batch plant supervises that the plant is operated according to the schedule of production orders set by the scheduling module. The supervisory control depends on the plant topol...
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A supervisory control of a multipurpose batch plant supervises that the plant is operated according to the schedule of production orders set by the scheduling module. The supervisory control depends on the plant topology, which is not defined a priori but generated while scheduling the production orders. This requires that the supervisory controlsystem be able to generate the control structure after the generation of plant topologies. In the first part of this work we present a framework to represent the supervisory control of an order driven multipurpose batch plant. The framework is based on a strategy that uses Petri nets to describe and analyze the supervisory control of a process. This strategy permits the automation of the modeling of the supervisory control. Based on this framework we developed a supervisory control support system (SCSS) of an order driven multipurpose batch plant. In the second part of this work we present a description of an object oriented analysis and design of this SCSS.
For high performance position or torque control, or for many of the different possible approaches to torque ripple and acoustic noise reduction in a switched reluctance motor (SRM), position feedback is essential. How...
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For high performance position or torque control, or for many of the different possible approaches to torque ripple and acoustic noise reduction in a switched reluctance motor (SRM), position feedback is essential. However, optical position encoders add to the complexity and cost of SRMs, compromising some of their main advantages. This paper describes a novel method of sensorless position detection requiring no special converter or sensor circuitry, and which does not rely on accurate prior knowledge of the magnetic characteristics of the motor. The approach described is novel in two respects. Firstly, it does not rely on accurate prior knowledge of phase winding inductance but merely makes the assumption that it varies substantially as sin(Nrθ), where Nr is the number of rotor poles and θ is rotor angle. Secondly, the approach learns from previous good estimates of position and, once it has done so, makes use of this knowledge where performance of the basic estimation algorithm degrades (principally at low speeds of rotation). The technique has been investigated in simulation and a hardware implementation is under development.
Holonic Manufacturing systems (HMS) has during the last period presented itself as an advantageous theoretical foundation for the problems that arise in controlling agile manufacturing systems. Previous research, at t...
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Holonic Manufacturing systems (HMS) has during the last period presented itself as an advantageous theoretical foundation for the problems that arise in controlling agile manufacturing systems. Previous research, at the Department, has demonstrated how modern shop floor controlsystems can be developed based on standard architectures for cell-control supported by engineering concepts and enabling technologies. In continuation to this research new concepts and theories for shop floor control are investigated. Ongoing research on HMS has resulted in development of the Holonic Multicell controlsystem (HoMuCS) architecture and methodology for implementing a HMS. This paper specifically reviews the development of a Robot Holon based on an open controller in the context of the HoMuCS architecture. The paper will describe the results and research work that was involved in developing a robot holon for a physical robot. The robot holon was implemented on a existing robot at the department which was upgraded by removing its native controlsystem and replacing it with a new PC-based open controller. The development of the robot holon builds on the notion that a robot holon will be able to perform both processing tasks and material handling tasks. Based on that an attempt to draw up a robot-architecture in the HoMuCS that can easily be reconfigured for these types of tasks. The research results gave a further specification of the HoMuCS architecture by extending it with the special robot holon type.
In order to increase their competitiveness, companies optimize their manufacturing processes by adapting structures to the requirements of technology and market. On the other hand, they try to fulfil specific requirem...
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In order to increase their competitiveness, companies optimize their manufacturing processes by adapting structures to the requirements of technology and market. On the other hand, they try to fulfil specific requirements by extreme customer orientation and manufacturing on demand. This leads to new organizational structures and manufacturing systems. Appropriate organization forms, such as the fractal company, are distinguished by high flexibility, rapid adaptability and exploitation of human potentials. However, these manufacturing companies also require appropriate PPC-systems (Production Planning and controlsystem) or, rather, new methods of PPC. In addition to high planning reliability, these systems have to ensure high flexibility, distributed processes of planning and decision-making, general orientation towards common goals, and an information flow that conforms to the requirements. The most important elements of such a PPC-system are long-range analysis of the production structure, medium- and long-range planning for the entire production area, short- and medium-range coordination among production fractals and short-range shop-control inside the fractals. At the Fraunhofer Institute for Manufacturing Engineering and Automation, simulation-based systems are being developed to support the planning and control of such organization forms within production. The user is put into the position of planning job orders reliably and optimizing production, concerning cost and schedule reliability, by making use of the advantages of decentralized structures.
In this paper we propose a method to eliminate the imbalance vibrations in magnetic bearing systems using discrete-time gain-scheduled Q-parameterization controllers. Imbalance in rotating machines generates variable ...
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In this paper we propose a method to eliminate the imbalance vibrations in magnetic bearing systems using discrete-time gain-scheduled Q-parameterization controllers. Imbalance in rotating machines generates variable frequencies sinusoidal disturbance forces that cause the vibrations. Since the frequency of vibrations equals the rotational speed, the free parameter Q of the Q-parameterization controllers is scheduled as a function of the rotational speed to achieve rejection of the imbalance sinusoidal disturbance forces at all operating speeds. First we present a mathematical model for the magnetic bearing in state space from which includes the effect of imbalance. Second, we explain the discrete-time Q-parameterization controller design for the magnetic bearing to achieve robust stability and rejection of the variable frequencies sinusoidal disturbance forces. The free parameter Q is assumed to be a second order proper stable transfer function whose denominator parameters are fixed and the numerator parameters are scheduled as second order polynomial functions of the rotational speed such that rejection of the imbalance sinusoidal disturbance is achieved. Finally several simulation results are presented. The results showed that elimination of the imbalance vibrations are achieved at all operating speeds, moreover robust stability is also achieved.
This paper presents how MaTX is used to aid the education of classical and modern control theory in a lecture, called the system engineering practice, for students at the Department of computers and system Engineering...
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This paper presents how MaTX is used to aid the education of classical and modern control theory in a lecture, called the system engineering practice, for students at the Department of computers and system Engineering, College of Science and Engineering, Tokyo Denki University, Japan.
Rational matrices are extensively used in the analysis, synthesis and design of controlsystems. The main purpose of this work is to present useful symbolic computational tools for the study of the structure of ration...
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Rational matrices are extensively used in the analysis, synthesis and design of controlsystems. The main purpose of this work is to present useful symbolic computational tools for the study of the structure of rational matrices and furthermore for the solution of basic synthesis control problem.
Multilevel Flow Models (MFM) are graphical models of goals and functions of technical systems. MFM was invented by Morten Lind at the Technical University of Denmark and several new algorithms and implementations have...
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Multilevel Flow Models (MFM) are graphical models of goals and functions of technical systems. MFM was invented by Morten Lind at the Technical University of Denmark and several new algorithms and implementations have been contributed by the group headed by Jan Eric Larsson at Lund Institute of Technology. MFM provides a good basis for computer-based supervision and diagnosis, especially in real-time applications, were fast execution and guaranteed worst-case response times are essential. The expressive power of MFM is similar to that of rule-based expert systems, while the explicit representation of means-end knowledge and the graphical nature of the models make the knowledge engineering effort less and the execution efficiency higher than that of standard expert systems. The paper gives an overview of existing MFM algorithms, and different MFM projects which have been performed or are currently in progress.
A theoretical approach and applied techniques for designing analogues engineering devices and systems with due account of random variations in system parameters and reliability specifications are considered. For solvi...
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A theoretical approach and applied techniques for designing analogues engineering devices and systems with due account of random variations in system parameters and reliability specifications are considered. For solving this problem a so-called operational/parametric approach is used. This approach is based on the computer-aided simulation of system capability and availability, parameter deviations and techniques of optimal parametric synthesis in terms of reliability criteria. Special attention is paid to algorithms that reduce the labor content of parameter optimization problems. For seeking a numerical solution of the parametric design problem a computer-aided reliability-oriented designsystem is proposed.
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