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Simultaneous Fault Detection Of Heat Exchangers

IFAC Proceedings Volumes 1998年第10期31卷 365-370页

作者： Gcibor Szederkényi Erik Weyer Katalin M. Hangos Dept. of Computer Science University of Veszprem H-8201 Veszprem Egyetem u. 3. Hungary Dept. of Electrical and Electronic Engineering The University of Melbourne Parkville VIC 3052 Australia Systems and Control Research Laboratory Computer and Automation Institute HAS H-1518 Budapest PO Box 63 Hungary

A grey box model-based method for fault diagnosis is proposed in this paper. The method is based on a first principle model of the process unit: a heat exchanger, and on a grey box model of the faults: the deterioration of the heat transfer surface by aging and the leaking of the outer container. The deterioration of the heat transfer surface is due to material settling, and in old heat exchangers pieces of this material can break off and cause damage in the equipment. A recursive least squares estimator with forgetting factor is used to track both the heat transfer coefficients and the cold side volume. The heat transfer coefficients are estimated both from the hot and cold side equations. The settled material breakage fault is detected via detection of abrupt positive jumps in the estimated heat transfer coefficients using a detector based on a cumulative sum (CUSUM) test. The proposed method enables simultaneous detection of the two fault types considered. Fault localization along the equipment length is also possible when temperature measurements are available along the length.

关键词： Fault detection Fault isolation Fault location Process model Grey box modelling Identification

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Fielded object networks as a framework for computer intelligence

Fielded object networks as a framework for computer intellig...

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IEEE International Symposium on Intelligent Control (ISIC)

作者： R. Goncalves F. Gomide R. Gudwin Dept. of Comput. Eng. & Ind. Autom. State Univ. of Campinas Brazil Department of Computer Engineering and Industrial Automation-DCA-Faculty of Electrical and Computer Engineering-FEEC State University of Campinas Brazil

Semiotics is becoming the focus of attention of AI researchers due to its interesting capabilities in symbolic processing and knowledge representation. We propose the fielded object network (FON), a framework aimed at integrating many scientific fields related to artificial intelligence (e.g. artificial life and distributed artificial intelligence), in order to acquire a knowledge representation tool capable of performing semiotic processing. Following this trend, this work presents the basis of FON and shows how it can be used to a hierarchical knowledge processing in intelligent systems. To show that, we implement a generalized subsistence machine proposed by Meystel (1996) using a FON approach. We also provide simulation results for an AGV application built under the proposed framework.

关键词： computer networks Intelligent networks Competitive intelligence Artificial intelligence Intelligent systems Knowledge representation Knowledge engineering Machine intelligence Marine vehicles computer industry

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Avoiding chaotic processes in current control of AC drive

Avoiding chaotic processes in current control of AC drive

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Annual IEEE Conference on Power Electronics Specialists (PESC)

作者： Z. Suto I. Nagy E. Masada Dept. of Autom. Tech. Univ. Budapest Hungary Computer and Automation Institute Hungarian Academy of Sciences (ATOMKI) Budapest Hungary Department of Automation Technical University of Budapest Budapest Hungary Department of Electrical Engineering University of Tokyo Tokyo Japan

The main objective of the paper is to highlight the strange and complex behaviour of a motor drive consisting of a three-phase induction machine fed by a voltage source inverter (VSI) and controlled by a hysteresis current controller (HCC). This system exhibits either periodic, subharmonic or chaotic trajectory movements, and shows bifurcation phenomena. The paper presents simulation results to introduce some astonishing properties, and applies two techniques in reaching them: continuous trajectory; and trajectory with discrete time steps. The first approach is theoretically significant while the second one represents the model of practical hardware implementation. Maps showing the chaotic and periodic regions are presented. After convincing maps regarding the chaotic nature of the system the influence of such important variables as the load torque or the speed command and parameters as the stator resistance and transient inductance is investigated. It could help either in stabilizing the periodic motions or inducing chaos. It can be concluded that periodic process cannot be maintained in wide range of change in system variables without additional measures.

关键词： Chaos Current control Voltage control Motor drives Induction machines Inverters Hysteresis Bifurcation Hardware Torque

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Fuzzy rule base interpolation based on semantic revision

Fuzzy rule base interpolation based on semantic revision

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IEEE International Conference on Systems, Man and Cybernetics

作者： P. Baranyi S. Mizik L.T. Koczy T.D. Gedeon I. Nagy Dept. of Autom. Tech. Univ. Budapest Hungary Department Automation Technical University of Budapest Budapest Hungary Department Information Engineering School of Computer Science and Engineering University of New South Wales Sydney Australia

Sometimes it is not possible to have a full dense rule base as there are gaps in the information. Furthermore, it is often necessary to deal with a sparse rule base to reduce the size and the inference/control time. In such sparse rule bases classic algorithms such as the CRI of Zadeh (1973) and the Mamdani method do not function for observations hitting gaps between rules. A linear fuzzy rule interpolation technique (KH-interpolation) has been introduced that is suitable for dealing with sparse bases. However, this method often results in conclusions which are not directly interpretable. In this paper an interpolation technique is proposed that is based on the interpolation of the semantics and interrelation of rules. This method guarantees the direct interpretability of the conclusion.

关键词： Interpolation Fuzzy sets Nonlinear control systems Telematics Telecommunication computing automation Australia Size control Inference algorithms Computational complexity

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Grey Box Fault Detection in Heat Exchanger Networks

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IFAC Proceedings Volumes 1997年第18期30卷 191-196页

作者： E. Weyer K.M. Hangos Dept. of Chemical Engineering University of Queensland Brisbane QLD 4072 Australia Systems and Control Research Laboratory Computer and Automation Institute HAS H-1518 Budapest PO Box 63 Hungary

A grey box model-based method for fault diagnosis is proposed in this paper which is based on a first principle model of the process unit: a heat exchanger, and on a grey box model of the fault: the deterioration of the heat transfer surface by aging. Under normal operating conditions the heat transfer coefficient is constant or slowly decreasing due to a layer of settled material building up on the heat transfer surface, and we propose to use a recursive least squares estimator with forgetting factor to track the heat transfer coefficients during these stages. In old heat exchangers, big chunks of the settled material can break away from the surface causing the heat transfer coefficients to rise sharply. This fault is detected via detection of abrupt positive jump in the estimated heat transfer coefficients using a Hinkley detector

关键词： Fault diagnosis grey box modelling fault modelling identification

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Neural networks based sensorial signal fusion: an application to material identification

Neural networks based sensorial signal fusion: an applicatio...

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International Conference on Digital Signal Processing (DSP)

作者： S.G. Tzaiestas Y. Anthopoulos Dept. of Electr. & Comput. Eng. Nat. Tech. Univ. of Athens Greece Intelligent Robotics and Automation Laboratory Department of Electrical and Computer Engineering National and Technical University of Athens Athens Greece

Data acquisition and learning capabilities are necessary for an intelligent system operating in unstructured, dynamically changing environments. For this purpose, a method for the effective use of multiple sensors must be developed. This paper shows how multisensor fusion can be accomplished by neural networks. It first summarizes the conventional fusion techniques and consequently describes the use of neural networks for sensor fusion as well as their advantages. Finally, an application is presented where a neural network is used to fuse the signals of several sensors, of different type, for material identification purposes.

关键词： Neural networks Signal processing Sensor fusion Intelligent sensors Sensor phenomena and characterization Sensor systems Intelligent systems Intelligent robots Costs Recursive estimation

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The HIMAC Project: Hierarchical Management and Control in Manufacturing Systems

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IFAC Proceedings Volumes 1997年第1期30卷 309-314页

作者： E. Canuto M. Christodoulou c. Chu F. Donati V. Gaganis B. janusz J.M. Proth W. Reithofer M. Vallauri Dipartimento di Automatica e Informatica. Politecnico di Torino. Corso Duca degli Abruzzi 24 1-10129 Torino. Italy Dept. of Electrical & Computer Engineering. Laboratory of Automation Technical University of Crete. GR-73100 Chania (Crete). Greece INRIA Lorraine Technopôle Metz 2000. Rue Marconi 4. F-57070 Metz. France Institute for Real-time Computer Systems and Robotics. University of Karlsruhe Kaiserstrasse 12 D-76128 Karlsruhe. Germany

The paper presents the major features of the ESPRIT Basic Research HIMAC, proposed to the EC after a thorough investigation of the state of the art of manufacturing systems control. HIMAC has followed a new approach, by developing a specific mathematIcs, the Manufactunng Algebra (MA), for modelling and controlling the production processes of discrete manufacturing systems. As a key feature, the MA models can be bottom-up aggregated starting from the very detailed levels used in simulation, thus making poSSIble a coherent model hierarchy at the base of the design and realization of Hierarchical control strategies and architectures. The formulation of the original mathematical approach and its validation criteria are outlined in the paper. For a deeper understanding, the mterested reader can take advantage of the list of references given at the end.

关键词： Manufacturing systems Production control Hierarchical control

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Characterization of Singular Controls for Nonholonomic Path Planning

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IFAC Proceedings Volumes 1996年第1期29卷 2460-2465页

作者： Dan O. Popa John T. Wen Center for Advanced Technology in Automation Robotics and Manufacturing Dept. of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY 12180

A class of Iterative algorithms have been proposed in recent years for the nonholonomic motion planning problem. The convergence of these algorithms predicates on the control signal in each iteration be "nonsingular". At the present, the singularity structure is only identified for the unicycle and front-wheel-drive car kinematic models. In this paper, we extend the consideration to all systems reducible to one-chain form, which include unicycle, car, as well as any N-trailer system. In particular, we show that a control is singular if and only if the first control variable is identically zero. We also identified all singular controls for the ball rolling on a plate problem. which is not reducible to the one-chain form.

关键词： Nonholonomic motion planning Nonholonomic Systems Path Planning Gradient algorithms Singular Controls

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H/sub /spl infin// vibration control of active suspension for automotive application

H/sub /spl infin// vibration control of active suspension fo...

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SICE Annual Conference

作者： A. Kanbolat Y. Okuyama F. Takemori L. Gianone S. Horvat J. Bokor Department of Information and Knowledge Engineering Facult of Engineering Tottori University Japan Tottori Daigaku Tottori JP Dept. of Inf. & Knowledge Eng. Tottori Univ. Japan Systems and Control Laboratory Computer and Automation Research Institute Hungarian Academy of Sciences Hungary Department of Transpoi-talion Engineering Technical University of Budapest Hungary

This paper deals with simultaneous control of acceleration transmission, wheel load fluctuation, suspension deflection and sprung mass displacement. The control theory is based on the robust H/sub /spl infin// control theory with the consideration of the modeling errors lumped into an unstructured uncertainty acting on the unperturbed plant. The design method is new and powerful for electronic car suspension's control systems, as it presents a new approach to the designers for the computation of a controller maintaining robust stability while guaranteeing the performance in a wide frequency range, even in the case of the controller is applied to the actual plant. Additionally, the paper emphasizes that the assumptions in the modeling step may lead to unrealistic control designs and, as an example, the effect of the rigidity assumption on the behavior of the open loop system is discussed.

关键词： Control systems Control theory Open loop systems Displacement control Weight control Acceleration Wheels Fluctuations Robust control Power system modeling

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Application of the Hopfield network in robust estimation of parametric membership sets for linear models

Application of the Hopfield network in robust estimation of ...

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IEEE International Conference on Systems, Man and Cybernetics

作者： I.N. da Silva L.V.R. de Arruda W.C. do Amaral Department of Computer Engineering and Industrial Automation UNICAMP Sao Paulo Brazil CPGEI CEFET-PR Curitiba Brazil Universidade Estadual de Campinas Campinas SP BR Dept. of Comput. Eng. & Ind. Autom. Univ. Estadual de Campinas Sao Paulo Brazil

High computation rates can be achieved using artificial neural networks. Optimization problems can be solved by neural networks with feedback connections by employing a massive number of simple processing elements with high degree of connectivity between these elements. In this paper, an application of Hopfield neural networks in robust parametric estimation with unknown-but-bounded disturbance is presented. The internal parameters of the Hopfield neural network are obtained using the valid-subspace technique. These parameters are explicitly computed to assure the network convergence. A comparative analysis with other robust estimation methods is carried out by a simulation example.

关键词： Intelligent networks Robustness computer networks Vectors Noise measurement Artificial neural networks Hopfield neural networks Parameter estimation Least squares approximation Uncertainty

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