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IEEE National Conference on Aerospace and Electronics (NAECON)

作者： D.L. Pogoda P.S. Maybeck Advanced Flight Control Unit of the Aircraft Control Systems Department General Electric Company Limited Department of Electrical and Computer Engineering Air Force Institute of Technology OH USA

A multiple model adaptive controller that provides for reconfiguration in response to sensor and/or actuator failures is developed for an approach and landing profile for the short take-off and landing (STOL) F-15 aircraft. Each elemental controller within the multiple model controller is based on a command generator tracker/proportional plus integral/Kalman filter design, with residual monitoring used as the mechanism to select the appropriate controller. The elemental controllers are each based on an assumed system status: no failures or a single failed surface or sensor. controller selection is evaluated for controller mixing based on all algorithm-computed probabilities of each elemental controller being the 'correct' controller to use. The entire multiple model controller is evaluated against a truth model with a selected failure, and then repeating the process for all failure modes of interest.< >

关键词： Pi control Proportional control Programmable control Adaptive control Actuators Aircraft Aerospace control Condition monitoring control systems Sensor systems

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H∞ identification of stable LSI systems: a scheme with direct application to controller design

H∞ identification of stable LSI systems: a scheme with dire...

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American control Conference (ACC)

作者： A. J. Helmicki C. A. Jacobson C. N. Nett Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA Department of Electrical and Computer Engineering Northeastern University Boston MA USA Control Systems Laboratory GE Corporate Research and Development Center Schenectady NY USA

In this paper several techniques are given for the identification of stable LSI discrete time systems from input-output data. Explicit H ∞ norm error bounds are given and convergence in the noise free and the uniformly bounded deterministic noise case are established. The assumptions made on the unknown system are minimal and are limited throughout the paper to a lower bound on the decay rate of the unknown system and an upper bound on the gain of the unknown system. Given this information an experiment and a construction are specified: the experiment involves obtaining a specified number of frequency measurements of the unknown systems at a set of specified frequencies; the construction uses this experimental data to generate an identified model with prescribed H ∞ norm error tolerance to the unknown system. The resulting model identification process is highly efficient from a computational point of view.

关键词： Large scale integration control systems control system synthesis Robust control Research and development Jacobian matrices Error correction Convergence Frequency Taylor series

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Practical Considerations in the Use of Distributed Parameter systems in Modeling: A control Point of View

Practical Considerations in the Use of Distributed Parameter...

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American control Conference (ACC)

作者： A. J. Helmicki C. A. Jacobson C. N. Nett Department of Electrical Computer and Systems Engineering Raneselaer Poytechiic Institute Troy NY USA Department of Electrical and Computer Engineering Northeastern University Boston MA USA Control Systems Laboratory GE Corporate Research and Development Center Schenectady NY USA

This paper is a condensed version of recent work [17] wherein several fundamental practical concerns pertaining to the use of linear, time-invariant, distributed parameter systems as models of physical processes are investigated. In particular, it is argued here that certain common distributed parameter systems exhibit properties which make them unsuitable for use as plant models in the design of feedback compensation. Classes of distributed parameter systems exhibiting these properties are defined and are said to be ill-posed for use in feedback compensator design. The structure of these classes is investigated within an extremely general mathematical framework which imposes no a priori restrictions on the class of distributed parameter systems under consideration. Within this framework necessary and sufficient conditions are given which completely characterise the classes of ill-posed models and establish their equivalence. These conditions are concretely illustrated by way of applications to several well-known flexible structure models. Surprisingly, several of these models are determined to be ill-posed for use in feedback compensator design.

关键词： Distributed parameter systems Feedback control systems Integral equations Distributed computing control system synthesis Jacobian matrices Flexible structures Frequency Linearity

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Nonlinear controller Design for Flight control systems *

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IFAC Proceedings Volumes 1989年第3期22卷 385-390页

作者： J. Hauser S. Sastry G. Meyer Department of Electrical Engineering and Computer Sciences University of California Berkeley CA 94720 USA Flight Control Systems NASA Ames Research Center Moffett Field CA 94305 USA

There has been a great deal of excitement recently over the development of a theory for explicitly linearizing the input-output response of a nonlinear system using state feedback. One shortcoming of this theory is the inability to deal with non-minimum phase nonlinear systems. Highly maneuverable jet aircraft, such as the V/STOL Harrier, belong to an important class of a slightly non-minimum phase nonlinear systems. The non-minimum phase character of these aircraft is clue in part to a slight coupling between rolling moments and lateral accelerations. In this paper, we show that, while straightforward application of the linearization theory to a non-minimum phase system results in a system with a linear input-output response but unstable internal dynamics, designing a feedback control based on a minimum phase approximation to the true system results in a system with desirable properties such as bounded tracking and asymptotic stability.

关键词： Aerospace control nonlinear control systems linearization techniques nonlinear non-minimum phase systems

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The GE MEAD computer-aided control engineering environment

The GE MEAD computer-aided control engineering environment

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IEEE International Symposium on computer Aided control System Design (CACSD)

作者： J.H. Taylor D.K. Frederick C.M. Rimvall H.A. Sutherland Control Systems Laboratories GE Corporate Research and Development Center Schenectady NY USA Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

The GE multidisciplinary expert-aided analysis and design (MEAD) project, which involves the integration of several computer-aided control engineering (CACE) packages under a supervisor which coordinates the execution of these packages with a database manager, an expert system, and an advanced user interface, is discussed. The principal components are, in functional terms: a supervisor, which integrates the underlying CACE packages and coordinates all activity within the GE MEAD computer program (GMCP); an expert system shell and rule bases for expert aiding of specific procedures to relieve the user from unnecessary low-level detail; a database manager for tracking system models that evolve over time along with associated results; and a user interface that facilitates access to the CACE package capabilities by permitting the user to work in several modalities, i.e. menu/forms style, using GE MEAD commands, the core packages' native commands, or the GE MEAD macro facility. The operation of the GMCP, including the user interface, expert system, and database manager, is illustrated by examples.< >

关键词： control engineering computing control engineering Packaging User interfaces Expert systems computer interfaces control systems Data engineering Design engineering engineering management

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Identifying modeling errors in mine electrical power flow input

Identifying modeling errors in mine electrical power flow in...

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： D.J. Tylavsky L. Gopalakrishnan Department of Electrical & Computer Engineering Arizona State University Tempe AZ USA Systems Control Technology Inc. Palo Alto CA USA

Calculation of voltages in a mine electrical distribution system using a power-flow program may fail to yield meaningful results if the iterative power-flow procedure fails to converge. A modified power-flow technique that converges for most of the mine electrical power-flow input data, even though the same input data do not yield a convergent solution with a traditional Newton power-flow algorithm, is presented. When no operable solution to the power-flow problem exists, the results tend to indicate the location of the modeling error that is responsible for nonconvergence. An extensive case study using data for a mine electrical power system is presented to demonstrate the robustness and error identification properties of the power-flow algorithm.< >

关键词： Load flow Power system modeling Power engineering and energy Data engineering computer errors Voltage Power system analysis computing systems engineering and theory Distributed computing Power engineering computing

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An arm-powered racing bicycle

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Assistive Technology 1989年第3期1卷 71-74页

作者： Cooper, Rory A. Institute of Environmental Stress Laboratory and the Control Systems Laboratory Department of Electrical and Computer Engineering University of California Santa Barbara CA United States

A new arm-powered racing bicycle is described. The features and performance of this bicycle are delineated, and the relative advantages over tricycles are outlined. © Taylor & Francis Group, LLC.

关键词： Racing bicycle Recreational equipment Sports

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Workload redistribution for fault-tolerance in a hard real-time distributed computing system

Workload redistribution for fault-tolerance in a hard real-t...

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International Symposium on Fault-Tolerant Computing (FTCS)

作者： S. Balaji L. Jenkins L.M. Patnaik P.S. Goel Control Systems Division ISRO Satellite Centre Bangalore India Department of Electrical Engineering Indian Institute of Science Bangalore India Department of Computer Science & Automation Indian Institute of Science Bangalore India

In a hard real-time distributed computing system (HRTDCS), all the tasks are required to meet their associated deadlines; a task not meeting its deadline leads to a catastrophic failure of the system. The authors consider an HRTDCS that executes both periodic and aperiodic tasks associated with timing, precedence, and resource constraints. The fault-tolerance capability in such a system is achieved through the use of time redundancy. The problem of workload redistribution for fault tolerance in an HRTDCS is studied. A graph model to represent the system workload is developed. Three performance measures for the analysis of an HRTDCS are defined. A nonpreemptive scheduling algorithm is proposed to distribute the workload of the operational nodes of the HRTDCS in the presence of both hardware and task failures. This task allocation strategy is applied to a practical system, namely, the HRTDCS onboard a spacecraft. The performance measures obtained for a typical system workload indicate that the algorithm is quite suitable for an HRTDCS with regard to uniform workload distribution.< >

关键词： Fault tolerance Real time systems Distributed computing Timing Fault tolerant systems Redundancy Performance analysis Scheduling algorithm Hardware Space vehicles

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CLEER - AN AI-SYSTEM DEVELOPED TO ASSIST EQUIPMENT ARRANGEMENTS ON WARSHIPS

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NAVAL ENGINEERS JOURNAL 1989年第3期101卷 127-137页

作者： ZHOU, HH SILVERMAN, BG SIMKOL, J Dr. H. Harry Zhou:is a research professor at the Institute for Artificial Intelligence of The George Washington University. Dr. Zhou received his master's degree and Ph.D. in computer science from Vanderbilt University in 1984 and 1987 respectively. He did his dissertation in the fields of artificial intelligence analogical reasoning and machine learning. His research interests include: classifier systems genetic algorithms learning by analogy inductive learning adaptive expert systems automated knowledge acquisition and adaption. He is also interested in data base design programming languages mental modeling and software engineering. Dr. Barry G. Silverman:is director of the Institute for Artificial Intelligence and a professor at the Engineering Administration Department of The George Washington University. He is also president of IntelliTek Inc. an AI consulting firm. Dr. Silverman received the B.S.E. M.S.E. and Ph.D. degrees from the University of Pennsylvania. He has been a principal developer of four generic AI products as well as eight AI applications. Since 1979 he has written over 100 papers and reports on these AI efforts. Joel Simkol:is a research scientist currently engaged in designing expert system architectures to support electronic warfare vulnerability analyses threat assessments shipboard topside antenna arrangements and C3countermeasures employment. Mr. Simkol's work in applying expert systems technology to electromagnetic interference and to spectrum management has generated increased interest and participation from all branches of government agencies.

This paper describes a modularized AI system being built to help improve electromagnetic compatibility (EMC) among shipboard topside equipment and their associated systems. CLEER is intended to act as an easy to use integrator of existing expert knowledge and pre-existing data bases and large scale analytical models. Due to these interfaces; to the need for portability of the software; and to artificial intelligence related design requirements (such as the need for spatial reasoning, expert data base management, model base management, track-based reasoning, and analogical (similar ship) reasoning) it was realized that traditional expert system shells would be inappropriate, although relatively off-the-shelf AI technology could be incorporated. In the same vein, the rapid prototyping approach to expert system design and knowledge engineering was not pursued in favor of a rigorous systems engineering methodology. The critical design decisions affecting CLEER's development are summarized in this paper along with lessons learned to date all in terms of “how,” “why,” and “when” specific features are being developed.

关键词： Artificial Intelligence

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ON THE ROBUSTNESS OF LOW-ORDER SCHUR POLYNOMIALS

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IEEE TRANSACTIONS ON CIRCUITS AND systems 1988年第5期35卷 570-577页

作者： KRAUS, FJ ANDERSON, BDO JURY, EI MANSOUR, M Institute of Automatic Control ETH Zurich Zurich Switzerland Department of Systems Engineering Australian National University Canberra ACT Australia Department of Electrical and Computer Engineering University of Miami Coral Gables FL USA

Robust Schur stability conditions are obtained for polynomials of orders two to five. For n=2 and 3, the conditions obtained are related to stability of the corner points, while for n=4 and 5, the conditions are related to stability of corner and possible supplementary points. The number of points increases substantially as the polynomial order increases. The obtained results are of importance in the robust design of control systems. The difficulty in extending the approach to higher-order polynomials is discussed. Special cases for such extensions are mentioned. Further applications of the results obtained may be of use in the stability study of two-dimensional systems. Some examples for the application of the stability conditions are given and, in particular, the two counterexamples presented in the literature are discussed.

关键词： low-order Multidimensional systems control systems higher-order Polynomial Steady state stability study corners Point of inflexion Robustness

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