Wyniki wyszukiwania - BazTech

1

Solution of a mixed sensitivity problem with optimized weights and time performance index for a robust servo velocity and position controller

Sarjaš A., Chowdhury A.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 5

205-208

EN

Robustness of servo control systems in terms of uncertainties and disturbances is still an open issue in feedback control. The concept of an uncertain LTI system is essential for robust control. Model uncertainty arises when system parameters are not precisely known, or can vary over a given range. The article presents a robust velocity and position controller for a servo system with a DC-motor. The aim of the work is to synthesize a feedback control structure with a controller in the direct branch, with which the robustness and stability performance will be ensured. For the design procedure a mixed-sensitivity approach with an additional time performance index is used. The time performance index introduces a subsequent criterion in the mixed sensitivity approach to ensure accurate dynamic performance of the feedback loop. For simplification of the controller structure the evolution optimization will be employed. The control strategy has been tested on real system with use of TI-DSP microcontroller.

PL

W artykule opisano metodę sterowania pozycją i prędkością w zamkniętej pętli dla serwomechanizmu z silnikiem DC. Dla zapewnienia niezawodności i stabilności algorytmu zastosowano optymalizację typu mixed-sensitivity z dodatkowym wskaźnikiem skuteczności w czasie. W celu uproszczenia struktury sterowania zastosowana zostanie także optymalizacja ewolucyjna. Przeprowadzono badania eksperymentalne.

2

Supervisory predictive control and on-line set-point optimization

Tatjewski P.

International Journal of Applied Mathematics and Computer Science

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2010

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Vol. 20, no 3

483-495

EN

The subject of this paper is to discuss selected effective known and novel structures for advanced process control and optimization. The role and techniques of model-based predictive control (MPC) in a supervisory (advanced) control layer are first shortly discussed. The emphasis is put on algorithm efficiency for nonlinear processes and on treating uncertainty in process models, with two solutions presented: the structure of nonlinear prediction and successive linearizations for nonlinear control, and a novel algorithm based on fast model selection to cope with process uncertainty. Issues of cooperation between MPC algorithms and on-line steady-state set-point optimization are next discussed, including integrated approaches. Finally, a recently developed two-purpose supervisory predictive set-point optimizer is discussed, designed to perform simultaneously two goals: economic optimization and constraints handling for the underlying unconstrained direct controllers.

3

Sterowanie odporne układem łożysk magnetycznych w maszynach wirnikowych

Gosiewski Z., Mystkowski A.

Zeszyty Naukowe Politechniki Białostockiej. Budowa i Eksploatacja Maszyn

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2006

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Z. 13

25-39

PL

W artykule przedstawiono sterowanie odporne H[nieskończoność] i H2 ruchem wirnika łożyskowanego magnetycznie. Sterowanie odporne jest badane analitycznie. Dla po-trzeb sterowania określono model nominalny i model niepewności obiektu. Właściwości układu zamkniętego z regulatorem proporcjonalno-całkująco-różniczkującym (PID) porównano z właściwościami układu z regulatorem odpornym H[nieskończoność] /H2. W układzie zamodelowano niepewność obiektu sterowania jako multiplikatywną. Właściwości układu z regulatorami H i H2 zależą od właściwie dobranych funkcji wagowych. Wpływ zakłóceń, szumów oraz kształt i ograniczenia nałożone na sygnały można kształtować przez funkcje wagowe. Badania nad układem zamkniętym zaprezentowano w formie wykresów.

EN

The paper deals with H[infinite] and H2 optimal control of rigid rotor movement, which is supported by magnetic bearings. The robust control of magnetic bearings is investigated analytically. The nominal model of active magnetic suspension of rotor and uncertainty model is derived. The standard PID control and robust control are compared and performance of nominal feedback configuration with weights is presented. We propose a robust control with multi-objective controller to achieve good robust stability when the model of plant is uncertain. The behaviour of multiplicative uncertainty of magnetic suspension system is showed. The H2 performance and H[infinite] performance depend on a proper selection of weighting functions. The weight functions: We, Wu, Wd are connected with error, control and noise signals, respectively. The simulations of closed-loop system are presented.

4

Estymacja i wizualizacja niepewności modeli powierzchniowych

Drapikowski P.

Studia z Automatyki i Informatyki

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2005

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T. 30

49--56

PL

W pracy przedstawiono metodę wyznaczania niepewności modeli powierzchniowych, będących rekonstruowanymi fragmentami ludzkiego organizmu, a zbudowanych na podstawie warstwowych obrazów uzyskanych z tomografii komputerowej lub rezonansu magnetycznego. Dokonano analizy struktury geometrycznej modeli wyznaczając cechy takie jak lokalny kąt nachylenia normalnej do powierzchni względem kierunku skanowania i lokalny promień krzywizny. Cechy te oraz odległość pomiędzy obrazami warstwowymi mają największy wpływ na dokładność rekonstruowanych modeli powierzchniowych. Wyznaczono model niepewności porównując odpowiednio dobrane wirtualne fantomy i ich rekonstrukcje przestrzenne. Następnie, estymowany model niepewności zastosowano do wyznaczenia lokalnych błędów struktury geometrycznej modeli powierzchniowych. Przedstawiono jakościową wizualizację błędów modelu geometrycznego w postaci skali odcieni szarości oraz wizualizację ilościową w postaci wstęgi, której szerokość jest proporcjonalna do niepewności modelu.

EN

An uncertainty estimation and visualization method of surface models of human body based on CT or MRI slices is presented in the paper. The analyses of geometrical structure of the models were performed to obtain geometrical features (local angle between normal to the surface and CT scanning direction, local radius of curvature). These features and slice thickness have the most important influence on uncertainty of surface models. The uncertainty model was estimated by comparison of virtual phantoms and their surface models. The qualitative uncertainty visualization is based on color range. The quantitative visualization is performed in form of ribbon which width is proportional to the local uncertainty of the surface model.

5

Variable- and Fixed-Structure Augmented Interacting Multiple-Model Algorithms for Manoeuvring Ship Tracting Based on New Ship Models

Semerdjiev E., Mihaylova L.

International Journal of Applied Mathematics and Computer Science

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2000

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Vol. 10, no 3

591-604

EN

Real-world tracking applications are related to a number of difficulties caused by the presence of different kinds of uncertainty, e.g. unknown or incompletely known system models and statistics of random processes or abrupt changes in the system modes of functioning. These problems are especially complicated in the marine navigation practice, where the commonly-used simple models of rectilinear or curvilinear target motions are not adequate for highly non-linear dynamics of the manoeuvring ship motion. A solution to these problems is to derive more suitable descriptions of real ship dynamics and to design adaptive estimation algorithms. After an analysis of basic hydrodynamic models, new ship models are derived in the paper. They are implemented in two versions of the Interacting Multiple Model (IMM) algorithm which has become very popular recently. The first one is a standard IMM version based on fixed model structures (FS's). They represent various modes of ship motion, distinguished by their rates of turns. The same rate of turn is additionally adjusted in the proposed new augmented versions of the IMM (AIMM) algorithm by using FS's and variable structures (VS's) of adaptive models estimating the current change in the system control parameters. Monte Carlo simulation experiments indicate that the VS AIMM algorithm outperforms the FS AIMM and FS IMM ones with respect to both accuracy and adaptability.

6

Robust Control of Nonlinear Time-Delay Systems

Antoniades C., Christofides P. D.

International Journal of Applied Mathematics and Computer Science

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1999

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Vol. 9, no 4

811-837

EN

This paper focuses on single-input single-output nonlinear differential difference equation (DDE) systems with uncertain variables. For such systems, a general methodology is developed for the synthesis of robust nonlinear state feedback controllers that guarantee boundedness of the states and ensure that the ultimate discrepancy between the output and the external reference input in the closed-loop system can be made arbitrarily small by an appropriate choice of controller parameters. The controllers are synthesized by using a novel combination of geometric and Lyapunov-based techniques and enforce the above properties in the closed-loop system independently of the size of the state delay. The proposed control method is successfully applied to a fluidized catalytic cracking unit with a time-varying uncertain variable and is shown to outperform a proportional integral (PI) controller, a nonlinear controller that does not account for the uncertainty, and anonlinear controller that does not account for the state delays.