Acionamento vetorial por controlador fuzzy modo deslizante de motor de indução

Este trabalho estuda a técnica de acionamento vetorial aplicado ao motor de indução trifásico (MIT), utilizando como estratégia de controle a combinação de controle fuzzy com controladores chaveados do tipo modo deslizante, em uma configuração aqui denominada de Controlador Fuzzy Modo Deslizante (FSMC – Do inglês: Fuzzy Sliding Mode Control). Um modelo dinâmico do MIT é desenvolvido em variáveis ‘d-q’ o que conduziu a um modelo eletromecânico em espaço de estados que exibe fortes não linearidades. A este modelo são aplicadas as condições de controle vetorial que permitem desacoplar o torque e o fluxo no MIT, de maneira que o seu comportamento dinâmico se assemelha àquele verificado em uma máquina de corrente contínua. Nesta condição, são implementados controladores do tipo proporcional e integral (PI) às malhas de controle de corrente e velocidade do motor, e são realizadas simulações computacionais para o rastreamento de velocidade e perturbação de carga, o que levam a resultados satisfatórios do ponto de vista dinâmico. Visando investigar o desempenho das estratégias não lineares nesta abordagem é apresentado o estudo da técnica de controle a estrutura chaveada do tipo modo deslizante. Um controlador modo deslizante convencional é implementado, onde se verifica que, a despeito do excelente desempenho dinâmico a ocorrência do fenômeno do “chettering” inviabiliza a aplicação desta estratégia em testes reais. Assim, é proposta a estratégia de controle FSMC, buscando associar o bom resultado dinâmico obtido com o controlador modo deslizante e a supressão do fenômeno do chettering, o que se atinge pela definição de uma camada de chaveamento do tipo Fuzzy. O controlador FSMC proposto é submetido aos mesmos testes computacionais que o controlador PI, conduzindo a resultados superiores a este último no transitório da resposta dinâmica, porém com a presença de erro em regime permanente. Para atacar este problema é implementada uma combinação Fuzzy das estratégias FSMC com a ação de controle PI, onde o primeiro busca atuar em regiões afastadas da superfície de chaveamento e o segundo busca introduzir o efeito da ação integral próximo à superfície. Os resultados obtidos mostram a viabilidade da estratégia em acionamento de velocidade variável que exigem elevado desempenho dinâmico.

Proposta de metodologia de auxílio à decisão utilizando conjuntos Fuzzy para repotenciação de PCHs

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Lógica Fuzzy aplicada ao controle de um sistema híbrido de geração de energia elétrica: eólica, fotovoltaica e biogás

Pós-graduação em Engenharia Mecânica - FEG

Redes neurais artificiais artmap-fuzzy aplicadas ao estudo de agitação marítima e ondas de lagos

Pós-graduação em Engenharia Elétrica - FEIS

Classificador Fisherface Fuzzy para o reconhecimento de faces

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A New Approach to Reducing Search Space and Increasing Efficiency in Simulation Optimization Problems via the Fuzzy-DEA-BCC

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reconstruction of the Environmental Quality Fuzzy Index

In the world stage, the environmental condition has been a big public policies issue. A clear understanding of the parameters that determine the state of the environment is essential for estimation of the quality of life of the population, not least since ecosystems are highly complex. Consequently, definition of public policies demands the use of evaluation tools that can combine and quantify information in a clear way. The use of indicators and indices that are able to translate the complexity of environmental conditions in cities into simpler terms has been increasingly effective in decision-making, since they assist in general evaluation of the situation in question, identification of priority actions and anticipation of future trends. In an attempt to evaluate the environmental conditions of the Brazilian city, Sorocaba, an Environmental Quality Fuzzy Index (IFQAmb) was proposed. In this work this methodology is improved. After reviewing the IFQAmb methodology, a number of changes in the index are proposed. Additional variables are suggested, derived from a State Environment Department program whose objective is to grant municipalities the title of Municipio Verde e Azul (Green and Blue City). In addition, a new rule base is being drafted to enable consideration of all possibilities, since in the existing version the use of specific criteria eliminates a significant number of rules. The changes seek to define with clarity and precision the conceptual aspects and structure of the IFQAmb, so that it can provide an even more effective evaluation of environmental performance, guiding future actions in order to improve the living conditions of the population of Sorocaba.

Fuzzy Index for Public Supply Water Quality

Human population growth and increased industrial activity in recent decades have contributed to a range of environmental problems, including the contamination of groundwater and surface water. In order to help in the management of these resources, water quality indices are used as tools to summarize multiple parameters and express them in the form of a single number. The ability to provide both an integrated assessment of changes in environmental variables, as well as performance tracking, has resulted in such indices being increasingly employed in surface water monitoring programs. The aim of this study was to develop an Index for Public Supply Water Quality (IPS) using a fuzzy inference methodology. Linguistic systems generally provide satisfactory tools for qualitative purposes, enabling the inclusion of descriptive variables with reduced loss of individual information. Validation of the technique was achieved by analysis of measurement data obtained for the Sorocaba River, provided by CETESB. The new procedure proved more rigorous, compared to classical IPS. It could be readily applied in the evaluation of other water bodies, or be adjusted to incorporate additional parameters also considered important for the assessment of water quality.

Control of Limit Cycle Oscillation in a Three Degrees of Freedom Airfoil Section Using Fuzzy Takagi-Sugeno Modeling

This work presents a strategy to control nonlinear responses of aeroelastic systems with control surface freeplay. The proposed methodology is developed for the three degrees of freedom typical section airfoil considering aerodynamic forces from Theodorsen's theory. The mathematical model is written in the state space representation using rational function approximation to write the aerodynamic forces in time domain. The control system is designed using the fuzzy Takagi-Sugeno modeling to compute a feedback control gain. It useds Lyapunov's stability function and linear matrix inequalities (LMIs) to solve a convex optimization problem. Time simulations with different initial conditions are performed using a modified Runge-Kutta algorithm to compare the system with and without control forces. It is shown that this approach can compute linear control gain able to stabilize aeroelastic systems with discontinuous nonlinearities.

Robust Switched Control Design for Nonlinear Systems Using Fuzzy Models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicação de lógica fuzzy na elaboração de planta de valores genéricos

Pós-graduação em Ciências Cartográficas - FCT

Estimating the average length of hospitalization due to pneumonia: a fuzzy approach

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimating outcomes in newborn infants using fuzzy logic

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A Lógica Fuzzy Aplicada à Recuperação de Informação

The information retrieval process involves subjective, imprecise and vague concepts, such as "information need", "relevance", and the very concept of "information". The main information retrieval models treat these concepts accurately, represented by a single numerical value. The fuzzy logic, while operating with the uncertainty of natural phenomena in a systematic and rigorous manner, represents a promising alternative to solve some problems related to information retrieval. This paper presents the fuzzy logic and some examples of its use in information retrieval systems (IRS).

A Fuzzy Goal Programming model for solving aggregate production-planning problems under uncertainty: A case study in a Brazilian sugar mill

This paper proposes a Fuzzy Goal Programming model (FGP) for a real aggregate production-planning problem. To do so, an application was made in a Brazilian Sugar and Ethanol Milling Company. The FGP Model depicts the comprehensive production process of sugar, ethanol, molasses and derivatives, and considers the uncertainties involved in ethanol and sugar production. Decision-makings, related to the agricultural and logistics phases, were considered on a weekly-basis planning horizon to include the whole harvesting season and the periods between harvests. The research has provided interesting results about decisions in the agricultural stages of cutting, loading and transportation to sugarcane suppliers and, especially, in milling decisions, whose choice of production process includes storage and logistics distribution. (C)2014 Elsevier B.V. All rights reserved.