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computer-aided control engineering Environments: Architecture, User Interface, Data-base Management, and Expert Aiding

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IFAC Proceedings Volumes 1990年第8期23卷 337-348页

作者： J.H. Taylor D.K. Frederick C.M. Rimvall H.A. Sutherland Control systems Laboratory GE Corporate Research and Development P.O. Box 8 Schenfctady NY 12301 USA Dept. of Electrical Computer andd Systems Engineering Rensselaer Polytechnic Institute Troy NY 12180 USA

Modern CAD environments for control systems engineering have begun to support substantial functionality beyond modeling, numerical analysis, and simulation. Three major areas that have emerged in the last five years are advanced user interfaces, data-base management, and expert-systems support ("expert aiding"), In addition, there has been a steady thrust to integrate more completely the various functionalities and software that comprise computer-aided control engineering (CACE). These trends have produced CACE environments which have relatively modest improvements in numerical quality but a vastly different "feel" in terms of integration, support, and "user friendliness. The basic considerations and requirements for a CACE user interface (UI), data-base manager (DBM), and expert aicling are discussed in detail. In many cases, these will be illustrated by examples based on various CACE software suites including the new GE MEAD CACE environment; the basic thrust will be to define needs and show how these can be met. The GE MEAD Project involves the integration of powerful CACE packages under a supervisor which coordinates the execution of these packages with a modern UI, a CACE-oriented DBM, and an expert system. The user interface is designed to facilitate access to the CACE package capabilities by users with widely different levels of familiarity with the environment. The data-base manager keeps track of system models that evolve over time and associates each analysis or design result with the correct model instance. The expert system supplies the machinery for expert aiding complicated or heuristic procedures to free the user from low-level detail and tedium. This system thus exemplifies the trends mentioned above

关键词： computer-aided system design computer interfaces for CAD control engineering applications of computers data-base management systems expert systems software tools

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Simultaneous H2/H∞ optimal control with state feedback

Simultaneous H2/H∞ optimal control with state feedback

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American control Conference (ACC)

作者： Mario A. Rotea Pramod P. Khargonekar Center for Control Sciences and Dynamical Systems University of Minnesota Minneapolis MN USA Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

In this paper we consider a mixed H 2 /H ∞ -optimal control problem. It is assumed that the plant as well as the feedback controller are finite-dimensional and linear time-invariant, and that the plants state is available for feedback. More specifically, among all the state-feedback controllers that minimize the H 2 -norm of a closed loop transfer matrix, we give necessary and sufficient conditions for the existence of a controller that also satisfies a prescribed H ∞ -norm bound on some other closed loop transfer matrix. When these conditions are satisfied, the solution to the above problem is also a global solution to the constrained optimization problem of minimizing an H 2 -norm performance measure subject to an H ∞ -norm constraint. We also give state-space formulae for computing the solutions. An example is given in which all solutions to the constrained optimization problem are necessarily dynamic, i.e, there is no static gain solution even though plant state is available for feedback. A conclusion of this work is that a priori assumptions on the structure of the solutions to mixed H 2 /H ∞ problems could turn out to be conserative.

关键词： Optimal control Hydrogen State feedback Sufficient conditions Performance evaluation Gain measurement Tellurium Performance gain Ice Robustness

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Trends in shop floor control: modularity, hierarchy, and decentralization

Trends in shop floor control: modularity, hierarchy, and dec...

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IEEE International Symposium on Intelligent control (ISIC)

作者： T.L. Johnson A.D. Baker Control Systems Laboratory GE Corporate Research and Development Center Schenectady NY USA Department Electrical & Computer Engineering Rensselaer Polytechnic Institute Troy NY USA

Computational architectures for shop floor control in automated job shops and midvolume manufacturing facilities are evolving into three identifiable forms, which are contrasted here. The first architecture, termed the modular approach, is based on earlier monolithic MRP/order-release systems and is typified by recent CIM (computer-integrated manufacturing) product offerings such as GEs CIMPLICITY. The second architecture is a hierarchical architecture, such as NIST's AMRF (National Institute of Standards and Technology's Automated Manufacturing Research Facility) system. The third architecture is a contract net architecture which is fully decentralized and may be a candidate for future CIM systems. These architectural forms may be distinguished on the basis of the partitioning principles which predominate in their design.< >

关键词： computer integrated manufacturing Hardware Power capacitors Local area networks Subcontracting Debugging Workstations Programmable control Cost function Software packages

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TRANSPUTER control OF A FLEXIBLE ROBOT LINK

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MICROPROCESSORS AND MICROsystems 1989年第3期13卷 227-232页

作者： STAVENUITER, ACJ TERREEHORST, G BAKKERS, AWP Control Systems and Computer Engineering Laboratory Department of Electrical Engineering University of Twente PO Box 217 7500 AE Enschede The Netherlands

The applicability of transputers in control systems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transputers. It is found that a control system with transputers offers a great improvement compared with conventional digital control systems. Transputers can solve the common problem in control practice, i.e. having very sophisticted controllers but not being able to implement them because they need too much computing time. However, transputers are not an optimal solution for more sophisticated control systems because of shortcomings in the scheduling mechanism.

关键词： control systems robots transputers

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Racing wheelchair crown compensation

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Journal of Rehabilitation Research and Development 1989年第1期26卷 25-32页

作者： Cooper, R.A. Control Systems Lab Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 United States

This paper is concerned with the directional stability of racing wheelchairs on crown roads. Three types of crown compensators are described and evaluated: the push-pull, the push-push, and the pull-pull. It was found that the push-push and the push-pull types of compensators have the most desirable characteristics, and were, in general, safer than the pull-pull type. In addition, the equations necessary to specify the minimum spring force required to compensate for the downhill turning moment, were derived and compared to the actual preset forces for the various compensators presently in use. It was found that the force required to maintain directional stability was less than that to deflect the crown compensator. This was due to the preference of athletes for additional stiffness needed for disturbance rejection, and to help compensate for any asymmetry in their stroke kinematics.

关键词： Biomedical Equipment

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Racing wheelchair rear wheel alignment

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Journal of Rehabilitation Research and Development 1989年第1期26卷 47-50页

作者： Cooper, R.A. Control Systems Lab Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 United States

This technical note describes a time-saving device for aligning the rear wheels of a racing wheelchair. The newly-developed analog alignment device is compared to the now standard discrete alignment device. The analog alignment device is found to reduce the time needed to align the rear wheels by nearly 75 percent, while increasing the accuracy of the alignment. The device does not noticeably alter the performance of the racing wheelchair and, if installed properly, the device is sufficiently resistant to fatigue.

关键词： Biomedical Equipment

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Optimum Algebraic Design of Continuous-Time Regulators with Polyhedral Constraints

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IFAC Proceedings Volumes 1989年第6期22卷 291-294页

作者： M. Vassilaki G. Bitsoris AMBER S.A.Computer Systems POB3500 Athens.Greece Control Systems Laboratory.Electrical Engineering Department University of patras 26500 Patras Greere

In this paper, the Linear Constrained Regulation Problem for continuous-time systems will be studied and a design algorithm for a linear constrained feedback controller will be developed. Both state and control vectors are assumed to be subjected to linear constraints The approach presented, is based on the notion of positive invariance of polyhedral sets. Existence conditions for a control law that transfers asymptotically to the origin all initial states in a polyhedral subset of the state space is formulated. Then, a solution to the LCRP is derived solving a non-linear optimization problem

关键词： Linear systems stability positively invariant sets optimisation

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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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