Hybrid systems theory as a growing field in control theory provides some contributions for traditional control problems. control of switched linear systems as a member of these categories has well-known solutions like...
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(纸本)9788995003848
Hybrid systems theory as a growing field in control theory provides some contributions for traditional control problems. control of switched linear systems as a member of these categories has well-known solutions like multiple model control. multiple model controllers provide a global control action by interpolating the individually-designed controllers. Since the hybrid systems methods are usually more complicated than the conventional control schemes, it is of great importance to explain these potential superiorities. The goal of this paper is to explain potential benefits which could be achieved by using hybrid control methods. Predictive control -as a powerful strategy to deal with complicated dynamics- is selected as the design basis for hybrid controller and for a multiple model controller. An illustrative test bench problem is introduced to compare the behavior of two controllers. It has been shown that the hybrid controller provides more intelligent and systematic design procedure for control of switched linear systems and is superior to multiple model controller in the sense of speed of response, optimality and domain of attraction.
A hybrid approach to model predictive control of a polymer grade transition problem is developed The controller is posed as a mixed integer programming problem in which the discrete elements of the algorithm include b...
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A hybrid approach to model predictive control of a polymer grade transition problem is developed The controller is posed as a mixed integer programming problem in which the discrete elements of the algorithm include both linear switching models used to approximate the nonlinear process and operating heuristics that are incorporated as propositional logic inequalities. The algorithm is tested in simulation on a polypropylene loop reactor system. Feed rates of monomer, hydrogen, and catalyst are manipulated to regulate slurry density, melt flow rate, and production rate, for various grades. Robust performance is demonstrated for grade transitional control. (C) 2004 American Institute of Chemical Engineers.
An approach for converting continuous densities into discrete ones with a pre-assigned set of support points is developed. The algorithm performs this conversion in a most skeptical, least-informative way, by finding ...
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An approach for converting continuous densities into discrete ones with a pre-assigned set of support points is developed. The algorithm performs this conversion in a most skeptical, least-informative way, by finding the discrete distribution with the maximum entropy that satisfies a set of moment constraints derived from the stated continuous distribution, such as means and variances. Individualized drug therapies based on multiple model control rely on the availability of discrete distributions to generate the underlying model set. The methods developed herein are especially compatible with individualized drug therapies based on multiple model control that rely on the availability of discrete densities to generate the model set. (C) 2001 Elsevier Science Ltd. All rights reserved.
We consider the problem of determining an appropriate model set on which to design a set of controllers for a multiplemodel switching adaptive control scheme. We show that, given mild assumptions on the uncertainty s...
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We consider the problem of determining an appropriate model set on which to design a set of controllers for a multiplemodel switching adaptive control scheme. We show that, given mild assumptions on the uncertainty set of linear time-invariant plant models, it is possible to determine a finite set of controllers such that for each plant in the uncertainty set, satisfactory performance will be obtained for some controller in the finite set. We also demonstrate how such a controller set may be found. The analysis exploits the Vinnicombe metric and the fact that the set of approximately band- and time-limited transfer functions is approximately finite-dimensional. Copyright (C) 2000 John Wiley & Sons, Ltd.
Most chemical processes are nonlinear in nature and large setpoint changes or load disturbances make such processes more challenging for control. Recently a simple transition control structure was introduced so that t...
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Most chemical processes are nonlinear in nature and large setpoint changes or load disturbances make such processes more challenging for control. Recently a simple transition control structure was introduced so that the tradeoff between nominal performance and robust stability of the model with large uncertainties is converted into the development of several models with small uncertainties in such a way that the former problem can be solved satisfactorily. In this work, a modification to that transition control structure is proposed to address nonlinear systems. The performance of this transition control structure is demonstrated on a nonlinear pH neutralization process. The simulation results show that the proposed structure has good properties not only for setpoint changes but also for disturbance rejection.
Recently a newly introduced concept called “cyclic switching” was was shown provide a viable solution to the long standing certainty equivalence stabilizability problem which arises in the design of estimator-based ...
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Recently a newly introduced concept called “cyclic switching” was was shown provide a viable solution to the long standing certainty equivalence stabilizability problem which arises in the design of estimator-based parameter adaptive controls because of the existence of points in parameter space where the estimated model upon which certainty equivalence control is based, looses stabilizability (Pait and Morse, 1994). Still more recently a simple, ‘high-level’ controller called a ‘supervisor’ was proposed for the purpose of coordinating the switching into feedback with a siso process, of a sequence of linear positioning or set-point controllers from a family of candidate controllers, so as to cause the output of the process to approach and track a constant reference input (Morse, n.d.). The purpose of this paper is to demonstrate that cyclic switching and supervisory control are compatible concepts.
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