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Continuous I/O robust control of SISO time-varying systems

AUTOMATICA 1997年第4期33卷 533-550页

作者： Qu, ZH Kamen, EW Dorsey, JF GEORGIA INST TECHNOL SCH ELECT ENGNATLANTAGA 30332

In this paper output tracking problem of time-varying systems is investigated. A system under consideration contains time-varying parameters which may change very fast and may be subjected to high-order nonlinear disturbances. A robust controller requiring only input-output measurement is proposed. The control guarantees at least stability of uniform ultimate boundedness which can be made arbitrarily close to asymptotic stability through choosing a design constant. The resulting control is continuous, uniformly bounded, and designed by a recursive mapping procedure. The only information of unknown systems required by the robust control approach are the bounding function on the magnitude of nonlinear disturbances and the bounds on the parameters and their derivatives;which represent the distinct feature of the proposed result. That is, time-varying parameters are not restricted to be either slow time-varying or of known structure. (C) 1997 Elsevier Science Ltd.

关键词： continuous control output feedback robust control robust stability time-varying systems SISO nonlinear systems model reference control uncertain dynamic systems nonlinear control

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Approximate feedback linearization of discrete-time non-linear systems using virtual input direct design

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SYSTEMS & control LETTERS 1997年第2期32卷 63-74页

作者： Guardabassi, GO Savaresi, SM Politecnico di Milano Dipartimento di Elettronica e Informazione Piazza Leonardo da Vinci 32 20133 Milano Italy

The design of feedback-linearization and poles-placement controllers: for discrete-time non-linear plants, using Input/Output/State measurements only, is typically addressed via indirect design. In this paper we propose the use of a new technique, based on a Virtual Input Direct Design (VID2) approach. The main feature of such a technique is to reduce the control design problem into a standard non-linear mapping approximation problem, without calling for the preliminary construction of an appropriate model of the plant. As compared with the existing methods, the new one requires less computational effort, while taking full advantage of the non-linear approximation software tools already available. In this paper, the new method is described, a simple theoretical analysis is given, and some numerical examples are presented. (C) 1997 Elsevier Science B.V.

关键词： direct control model reference control non-linear systems feedback linearization identification

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Output tracking control of uncertain nonlinear second-order systems

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AUTOMATICA 1997年第12期33卷 2203-2212页

作者： Bartolini, G Ferrara, A Usai, E Univ Cagliari Dipartimento Ingn Elettr & Elettron I-09123 Cagliari Italy Univ Genoa Dipartimento Informat Sistemist & Telemat I-16145 Genoa Italy

The solution of a tracking problem for a second-order nonlinear system with uncertain dynamics and incomplete state measurement is obtained by means of a procedure directly inspired by the solution of the classical minimum-time optimal control problem. Two different types of uncertainty are considered in the paper: in the first case a constant bound on the uncertain dynamics is assumed to be known;in the second case, the bound is a function of both the measurable and the unmeasurable state variable of the system. In both cases, the possibility of applying the proposed control algorithms is proved to be determined by a proper choice of the control signal features. The resulting system is characterized by a suitable feedback switching logic and the convergence of the system trajectory to the desired one (or to a delta-vicinity of this latter) is proved also in the uncertain case. (C) 1997 Elsevier Science Ltd. All rights reserved.

关键词： model reference control sliding mode control uncertain dynamic systems

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An indirect model reference adaptive controller based on the multirate sampling of the plant output

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INTERNATIONAL JOURNAL OF ADAPTIVE control AND SIGNAL PROCESSING 1996年第6期10卷 673-705页

作者： Arvanitis, KG National Technical University of Athens Division of Computer Science Department of Electrical and Computer Engineering Zographou 157 73 Athens Greece

The use of sampled-data multirate-output controllers for model reference adaptive control of possibly non-stably invertible linear systems with unknown parameters is investigated. Multirate-output controllers contain a multirate sampling mechanism with different sampling period at each system output. Such a control allows us to assign an arbitrary discrete-time transfer function matrix for the sampled closed-loop system and does not make assumptions on the plant other than controllability, observability and the knowledge of two sets of structural indices, namely the controllability and the observability indices. An indirect adaptive control scheme based on these sampled-data controllers is proposed which estimates the unknown plant parameters (and consequently the controller parameters) on-line from sequential data of the inputs and the outputs of the plant, which are recursively updated within the time limit imposed by a fundamental sampling period T-0. Using the proposed adaptive algorithm, the model reference adaptive control problem is reduced to the determination of a fictitious static state feedback controller owing to the merits of multirate-output controllers. Known indirect model reference adaptive control techniques usually resort to the direct computation of dynamic controllers. The controller determination reduces to the simple problem of solving a linear algebraic system of equations, whereas in known indirect model reference adaptive control techniques, matrix polynomial Diophantine equations usually need to be solved. Moreover, persistent excitation of the continuous-time plant is provided without making any special richness assumption on the reference signals.

关键词： adaptive control model reference control sampled-data systems multirate digital controllers indirect adaptive schemes

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Adaptive controller performance used for RAM velocity control during filling phase

Adaptive controller performance used for RAM velocity contro...

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54th Annual Technical Conference of the Society-of-Plastics-Engineers - Plastics: Racing into the Future (ANTEC 96)

作者： Zhang, CY Leonard, J Speight, RG Moldflow Pty Ltd Victoria

Injection molding is an extremely complex: time variant, non-linear process which places extremely high demands on screw injection velocity control algorithms. This batch molding process has the capability to produce high added value products and represents the major polymer processing sector, with a diverse range of molded products. Adaptive velocity control forms an integral part of the Intelligent Process control (IPC) programme at Moldflow, where the requirement is for a self-tuning high performance velocity controller that can accommodate changing process dynamics, regardless of screw wear and tool geometry, the polymeric material being processed and the technology of the injection molding machine (IMM). This paper briefly describes the methodology of a universal adaptive controller for the control of ram velocity during the primary injection (filling) phase. Results of the controller performance are presented for both simple linear injection profiles and more complex stepped injection profiles. The response of the adaptive controller to ramp inputs will be reported in future publications. The controller performance has been verified, in terms of flexibility on several different IMM's, ranging from 100 to 550 tonnes. Performance was investigated and assessed in terms of coefficient variation derived from continuously monitored injection molding cycles.

关键词： adaptive control model reference control self tuning control algorithms in-line process measurements

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Shortest-Prediction Horizon Nonlinear model Predictive control 1

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IFAC Proceedings Volumes 1996年第1期29卷 5817-5822页

作者： Masoud Soroush Masoud Nikravesh Dept of Chemical Engineering Drexel University Philadelphia PA 19104 USA Earth Sci Division Lawrence Berkeley National Lab. Berkeley GA 94720 USA

This article presents a continuous-time formulation of model predictive control. This formulation allows (i) to establish the connections between model predictive control and input-output linearizing control methods and (ii) to address the problems of constraint handling and windup in input-output linearizing control methods. model predictive control laws with the shortest possible prediction horizon are derived for constrained nonlinear processes with deadtime. They have explicit analytical form, and thus their implementation does not require on-line optimization. Furthermore, in the absence of constraints, they are input-output linearizing.

关键词： nonlinear control model predictive control differential geometric methods input-output linearization model-based control model reference control

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ROBUST model-reference control OF LINEAR MIMO TIME-VARYING SYSTEMS

CONTROL-THEORY AND ADVANCED TECHNOLOGY

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control-THEORY AND ADVANCED TECHNOLOGY 1993年第2期9卷 405-439页

作者： HUANG, PY CHEN, BS NATL TSING HUA UNIV DEPT ELECT ENGNHSINCHU 30043TAIWAN

The model reference control problem is studied for the linear MIMO time-varying systems which encounter unmodeled dynamics and external disturbances. It is desired that the controlled time-varying feedback system will track the output of the prespecified linear time-invariant reference model. Based on the two-degree-of-freedom frozen-time controller structure, by employing the internal model principle on the feedback-loop controller and the proposed frozen-time optimal model matching design via H-2 optimization on the feedforward controller, it is shown that if the time-varying plant and the time-varying nominal model are asymptotically slowly varying, then the exact reference model tracking requirement, which has zero steady reference model tracking errors, will be achieved under the situations of unmodeled dynamics, external disturbances and time-varying effects of the system. The associated robustness on the mismodeling errors, which depends only on the frozen-time computations, is characterized. Optimal robustness based on l1 optimization is also discussed. Some simulations present good performances of the robust model reference control of linear MIMO time-varying systems by the proposed controller designs.

关键词： model reference control TIME-VARYING SYSTEMS ROBUSTNESS INTERNAL model PRINCIPLE H-2 OPTIMIZATION

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AN EXTENSION OF NEWTON-TYPE ALGORITHMS FOR NONLINEAR PROCESS-control

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AUTOMATICA 1995年第2期31卷 281-286页

作者： DEOLIVEIRA, NMC BIEGLER, LT CARNEGIE MELLON UNIV DEPT CHEM ENGNPITTSBURGHPA 15213

This study extends the multistep, Newton-type formulation [Li and Biegler (1989) Chem. Eng. Res. Des., 67, 562-577] for nonlinear constrained process control. The computation of the control law is based on an augmented performance index, which improves the performance of the method over the original formulation. A number of modifications are also introduced in the computational algorithm to extend the range of problems, eliminate steady-state offsets, and extend the output predictive horizon to infinity. We show that the global stability properties of the original Newton controller are preserved by the present modifications. Moreover in the absence of active constraints, the method behaves as an extension of the linear quadratic regulator for, exhibiting therefore excellent stability properties for a large range of tuning parameters. The capabilities of the method are illustrated by application to various process examples.

关键词： PROCESS control CHEMICAL INDUSTRY model reference control NONLINEAR control SYSTEMS NONLINEAR PROGRAMMING QUADRATIC PROGRAMMING

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model-reference ADAPTIVE-control FOR PLANTS WITH UNKNOWN RELATIVE DEGREE

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IEEE TRANSACTIONS ON AUTOMATIC control 1993年第6期38卷 976-982页

作者： TAO, G IOANNOU, PA UNIV SO CALIF DEPT ELECT ENGN SYSTLOS ANGELESCA 90089

One of the basic assumptions in stable model reference adaptive control (MRAC) that the relative degree n* of the modeled part of the plant is known exactly and matches that of the reference model is relaxed by the development of a new MRAC scheme which requires only an upper bound n(u)* for n*. This is done at the expense of updating additional parameters and projecting some of the estimated parameters onto appropriate convex sets in the parameter space These convex sets can be developed without using any a priori knowledge about the plant parameters. Furthermore, when a lower bound n(l)* in addition to an upper bound for n* is known, the number of the estimated parameters can be reduced considerably. The new MRAC scheme guarantees signal boundedness and zero residual tracking error. In addition, it is robust with respect to plant uncertainties provided a modified adaptive law is used to update the controller parameters.

关键词： Plant control ANALYSIS modelS unmodeled dynamics Denominator adaptive control model reference adaptive control Feedback loop Numerator FEEDFORWARD model reference control

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model-reference ADAPTIVE-control OF A CIRCULATORY model FOR COMBINED NITROPRUSSIDE-DOPAMINE THERAPY

MODEL-REFERENCE ADAPTIVE-CONTROL OF A CIRCULATORY MODEL FOR ...

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4TH IFAC Symposium on Adaptive Systems in control and Signal Processing 1992

作者： WESTVOLD, S KAUFMAN, H ROY, RJ RENSSELAER POLYTECH INST DEPT ELECT COMP & SYST ENGNTROYNY 12180

ISBN: (纸本)0080417175

A direct model reference adaptive control (MRAC) algorithm is used to compute the infusion of two drugs in order to control blood pressure and cardiac output in a realistic physiological nonlinear multiple-input multiple-output representation. Consideration is given to the effects of digitization, unequal output sampling rates, and to a modification to alleviate the nonsatisfaction of a positive real condition.

关键词： ADAPTIVE control DRUG INFUSION model reference control BIOMEDICAL MEDICAL SYSTEMS

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