José Araújo | Instituto Federal de Educação, Ciência e Tecnologia da Bahia (original) (raw)

Books by José Araújo

Linear descriptor systems compose an important class of systems, in which dynamic and algebraic e... more Linear descriptor systems compose an important class of systems, in which dynamic and algebraic equations can build a unique model. Some examples can be found in electrical circuits, robotic systems, economics, among others. The control theory regarding descriptor systems is in general constructed by extending existing results for standard systems. On the other hand, constrained control systems have gained crescent attention, given that physical constraints on system variables as, for instance, input saturation, are present in several real world applications. This work presents new results regarding control and state estimation in descriptor systems subject to such constraints, by using the set invariance approach, a methodology already well developed in applications to standard systems. By means of the concept of invariant polyhedra, state and output feedback control and state estimation are studied from the analysis and design points of view. The results concerning controlled and conditioned invariance are pointed, that give less conservative solutions than by application of designed linear a priori control and injections laws. In the same line, a study on the problem of simultaneously regularizing a non regular descriptor system with constraints satisfaction is carried out in the context of descriptor systems, whose preliminary results, numerically obtained in specic examples, taking the hypervolume of the maximal controlled invariant polyhedron projected onto the state space as the performance index points towards a family of optimal solutions.

Setores de destaque no cenário econômico mundial (indústrias, portos,...) tem no seu cerne um elo... more Setores de destaque no cenário econômico mundial (indústrias, portos,...) tem no seu cerne um elo fundamental: acionamentos baseados em motores elétricos (AEs). A evolução dos AEs a partir do advento da eletrônica de potência, que culminou com o uso extensivo dos motores de indução, introduz contribuições científicas, tecnológicas e de inovação a mais de cinco décadas. A busca por desempenhos superiores, e ao mesmo tempo da redução do consumo de energia, conferem a este campo um caráter multidisciplinar, com um olhar no desenvolvimento sustentável. Este trabalho aborda um estudo de caso com foco nas técnicas de controle, em um sistema de servoposicionamento utilizando motor de indução trifásico, o mais robusto e barato dentre seus pares. A moderna lógica fuzzy é empregada no projeto dos controladores, e quando comparada à técnica de controle PI, que é uma das mais utilizadas, exibe resultados melhores em diversas situações.
Simulações e experimentos são feitos a fim de demonstrar as melhorias introduzidas pelo controle baseado em lógica fuzzy.

Papers by José Araújo

ijicic.org

Compartmental linear systems naturally arise when someone aims to develop dynamic models for popu... more Compartmental linear systems naturally arise when someone aims to develop dynamic models for populations, economic systems, chemical reactions, hydraulic systems, among others. General theories for this class of systems have been well developed in the last decades. This paper aims to present a simple methodology of model order reduction for asymptotically stable compartmental linear systems, by observing the fact that even for higher order systems an approximately first order-like between input and output is observed in any case that involves the driven-point function. Then, a step response error minimization is carried out with DC gain retention, since by solving a single nonlinear equation it is possible to obtain the parameters of first order approximated model. Numerical examples, both theoretical and real world models support the proposed methodology.

IEEE Transactions on Control Systems Technology, 2012

A novel descriptor observer structure is proposed in the context of discrete-time descriptor line... more A novel descriptor observer structure is proposed in the context of discrete-time descriptor linear systems. On the basis of this new structure, the characterization of conditioned-invariant polyhedral sets with the purpose of limiting the estimation error is carried out. Limitation of the estimation error can be achieved by the computation of an as small as possible conditioned-invariant polyhedron, that contains

WSEAS TRANSACTIONS on SYSTEMS archive, 2017

An alternative analytical solution to six degrees-of-freedom position and attitude estimation pro... more An alternative analytical solution to six degrees-of-freedom position and attitude estimation problem is proposed. The proposed method relies on the use of Singular Value Decomposition to the transformation matrix between the currents in the transmitter and in the receiver. The proposed method is validated using synthetic data, in which a random motion is applied to the transmitter within an environment with di erent levels of noise. Once the e cacy of the method is confirmed, the proposed algorithm is benchmarked against a well established closedform solution. The presented method was able to accurately obtain the position and orientation, with performance comparable to the benchmark.

Journal of Circuits, Systems and Computers, 2014

Phase-locked loops (PLL) is a phase and/or frequency tracking system, widely used in communicatio... more Phase-locked loops (PLL) is a phase and/or frequency tracking system, widely used in communication and control systems. The sinusoidal multiplicative type PLL still remains a recurrent model, due the fact that its derivation is originated from the maximum likelihood approach. In this note, it is showed as a generalized product, called q-product, which can be used to implement the phase detector and improve some important parameters of the PLL system, as the block linearity and pull-in characteristics. Numerical examples are presented in order to illustrate the proposal.

Sba: Controle & Automação Sociedade Brasileira de Automatica, 2008

Redução de ordem de modelos monovariáveis, de sistemas lineares invariantes no tempo, contínuos, ... more Redução de ordem de modelos monovariáveis, de sistemas lineares invariantes no tempo, contínuos, descritos por uma função de transferência racional, é uma técnica amplamente difundida na simplificação de modelos, como forma de reduzir complexidade envolvida em análise e projeto. Um método simples para redução de ordem baseado na minimização da norma dos coeficientes do numerador do polinômio de erro é proposto, e diversos resultados apresentados demonstram a validade e o mérito da abordagem.

MATEC Web of Conferences, 2018

The control of vibrations for systems with second-order linear dynamics is a cornerstone for seve... more The control of vibrations for systems with second-order linear dynamics is a cornerstone for several engineering application, as structural vibration control in civil and aerospace structures. In such systems, sometimes only a few eigenvalues must be mitigated in situations as resonances, flutter, and another dangerous vibratory phenomenon. The use of active vibration control is an attractive alternative due to its flexibility and the availability of general design approaches. In the case of partial eigenvalue assignment, no spillover can be achieved, that is, only a small spectrum or eigenstructure partition is reallocated, with the remaining being unperturbed. In this paper, the no spillover property of Brauer’s spectrum perturbation theorem is applied to compute a dense influence matrix structure of actuation, reassigning then the dangerous target eigenvalues and kept the remaining of the spectrum unchanged. A Sylvester equation must be solved using only the part of the spectrum ...

International Journal of Structural Stability and Dynamics, 2019

This paper presents an approach for eigenvalue assignment in second-order linear systems with no ... more This paper presents an approach for eigenvalue assignment in second-order linear systems with no spillover property. Second-order differential equations arise from dynamical modeling of vibrating structures by finite element or lumped parameter first principles approach in several practical problems. Certain structures can face practical issues when subjected to external perturbation forces, as resonance or flutter type vibrations. The control of excessive vibrations can be attempted by techniques of active vibration control using linear feedback. To change only a few eigenvalues and eigenvectors that cause excessive vibrations, the requirement of no spillover property is a somewhat attractive issue. Furthermore, only the part of the eigenstructure whose eigenvalues must be reassigned is necessary to be known for an efficient parametrization of the feedback matrices. Brauer’s theorem, a milestone result of linear algebra, as well as some recent related results, is applied here to ac...

Journal of Low Frequency Noise, Vibration and Active Control, 2018

Based on the notions of spectrum sensitivities, proposed by us earlier, we develop a novel optimi... more Based on the notions of spectrum sensitivities, proposed by us earlier, we develop a novel optimization approach to deal with robustness in the closed-loop eigenvalues for partial quadratic eigenvalue assignment problem arising in active vibration control. A distinguished feature of this new approach is that the objective function is composed of only the system and the closed-loop feedback matrices. It does not need an explicit knowledge of the eigenvalues and eigenvectors. Furthermore, the approach is applicable to both the state-feedback and derivative feedback designs. These features make the approach viable to design an active vibration controller for practical applications to large real-life structures. A comparative study with existing algorithms and a study on the transient response of a real-life system demonstrate the effectiveness, superiority, and competitiveness of the proposed approach.

Proceedings XXII Congresso Brasileiro de Autom�tica, 2018

Neste artigo trata-se do controle de sistemas realimentados com compensacao de atraso na presenca... more Neste artigo trata-se do controle de sistemas realimentados com compensacao de atraso na presenca de atraso de transporte variavel. A compensacao da componente minima do atraso variavel permite mitigar a degradacao causada pelo tempo-morto, ao passo que a parcela variavel e tratada atraves um novo criterio de estabilidade simplificado. A compensacao de componente constante e realizada com o preditor de Artstein, o que permite aplicar a estrategia e seu respectivo criterio a sistemas instaveis em malha aberta. O criterio proposto e simples uma vez que se requer apenas a definicao da norma infinito de um sistema linear convencional. Um estudo de caso e utilizado para ilustrar os beneficios da estrategia proposta.

Journal of Sound and Vibration, 2016

We propose an optimization approach to the solution of the partial quadratic eigenvalue assignmen... more We propose an optimization approach to the solution of the partial quadratic eigenvalue assignment problem (PQEVAP) for active vibration control design with robustness (RPQEVAP). The proposed cost function is based on the concept of sensitivities over the sum and the product of the closed-loop eigenvalues, introduced recently in our paper. Explicit gradient formula for the solutions using state feedback and derivative feedback are derived as functions of a free parameter. These formulas are then used to build algorithms to solve RPQEVAP in a numerically efficient way, with no need to compute new eigenvectors, for both state feedback and state-derivative feedback designs. Numerical experiments are carried out in order to demonstrate the effectiveness of the algorithms and to compare the proposed method with other methods in the literature, thus showing its effectiveness.

ijicic.org

This paper addresses the problem of excitation control for damping the electromechanical oscillat... more This paper addresses the problem of excitation control for damping the electromechanical oscillation modes (EOM) in power systems with decentralized stabilizers (PSS) of reduced order to ensure robust stability and good performance of a power system under disturbances and uncertainties. Good stabilizer coordination is achieved by simultaneously designing all PSS. A frequency domain H ∞ mixed sensitivity optimization approach is proposed. The proposed technique is not affected by the pole-zero cancellation problem associated with the conventional mixed sensitivity techniques.

Proceedings of the 4th WSEAS …, 2008

Haya Shida, Subscribe (Full Service), Register (Limited Service, Free), Login. Search: The ACM Di... more Haya Shida, Subscribe (Full Service), Register (Limited Service, Free), Login. Search: The ACM Digital Library The Guide. ...

Sba: Controle & Automação Sociedade Brasileira de Automatica, 2009

A realimentação da derivada de estados tem recebido grande atenção em tempos recentes, por ser um... more A realimentação da derivada de estados tem recebido grande atenção em tempos recentes, por ser uma alternativa à realimentação de estados e ser capaz de, exceto nos casos em que há pelo menos um pólo na origem, prover a conhecida alocação de pólos de um sistema linear invariante no tempo, que é uma das principais aplicações da realimentação de estados. Com base em procedimentos já consolidados para alocação de pólos por realimentação de estados utilizando a solução da equação de Lyapunov, são apresentados procedimentos análogos para realimentação da derivada de estados, e então apresentadas proposições análogas às aplicadas para realimentação de estados. Exemplos são então apresentados, comprovando a validade de tais procedimentos.

Applied Sciences, 2021

This paper proposes a method for active vibration control to a two-link flexible robot arm in the... more This paper proposes a method for active vibration control to a two-link flexible robot arm in the presence of time delay, by means of robust pole placement. The issue is of practical and theoretical interest as time delay in vibration control can cause instability if not properly taken into account in the controller design. The controller design is performed through the receptance method to exactly assign a pair of pole and to achieve a given stability margin for ensuring robustness to uncertainty. The desired stability margin is achieved by solving an optimization problem based on the Nyquist stability criterion. The method is applied on a laboratory testbed that mimic a typical flexible robotic system employed for pick-and-place applications. The linearization assumption about an equilibrium configuration leads to the identification of the local receptances, holding for infinitesimal displacements about it, and hence applying the proposed control design technique. Nonlinear terms,...

Anais do 14º Simpósio Brasileiro de Automação Inteligente, 2019

A solução de problemas de controle para sistemas de segunda ordem com atraso constitui um dos des... more A solução de problemas de controle para sistemas de segunda ordem com atraso constitui um dos desafios da engenharia. Fenômenos como vibrações mecânicas, ressonância e oscilações, podem ser descritos matematicamente por equações diferenciais de segunda ordem, nomeando estes sistemas como sistemas de segunda ordem. Este trabalho tem como objetivo principal projetar controladores para sistemas de segunda ordem com atraso, utilizando a abordagem por resposta em frequência, dispensando a necessidade de aproximações para o atraso, garantindo soluções estáveis sem necessidade de análise à posteriori. Definindo matematicamente o problema de controle como um problema de otimização, é feita uma busca pelos ganhos do controlador com a utilização de um algoritmo genético, tendo como parâmetro de projeto garantir que a curva de Nyquist do sistema permaneça a uma distância suficiente da região de instabilidade. Essa metodologia visa garantir que os ganhos calculados resultem em sistemas robustos para que mesmo sujeitos a alterações de parâmetros, a estabilidade seja garantida. Os resultados obtidos de simulações ao final do trabalho se mostraram satisfatórios dentro das especificações desejadas.

ICIC Express Letters, 2008

Decoupling or noninteracting control (NIC) on MIMO linear time-invariant systems is a result of g... more Decoupling or noninteracting control (NIC) on MIMO linear time-invariant systems is a result of great importance on systems and control. Algebraic and geometric techniques are very interesting in presenting the solvability conditions for a perfect decoupling problem, but quite complex in nature. On this paper, a very simple approach for quasi-noninteracting (quasi-NIC) control for MIMO square systems is presented. Static state feedback, output feedback and the forward gains are determined by an unconstrained minimization problem where the cost function is based on the distance between the matrix of polynomial norms of numerators and the identity matrix. The proper choice of initial guess for numerical minimization algorithm yields stable closed-loop poles simultaneously with minimal interacting. The merit of the proposed approach is also shown from its application to examples found in literature.

IFIP Advances in Information and Communication Technology, 2010

This paper addresses the problem of constructing controlled invariant polyhedral sets for linear ... more This paper addresses the problem of constructing controlled invariant polyhedral sets for linear discrete-time descriptor systems subject to state and control constraints and persistent disturbances. Regardless the large number of contributions on set invariance for linear systems in the standard form, there are few works dealing with set invariance properties in the case of descriptor systems. Here, assuming regularity and causality of the descriptor system, the state equations are written in such way that standard algorithms can be directly applied. Moreover, state and control constraints can be enforced through a piecewise linear delayed state feedback. A numerical example is presented to illustrate these ideas.

WSEAS Transactions on Systems, 2017

An alternative analytical solution to six degrees-of-freedom position and attitude estimation pro... more An alternative analytical solution to six degrees-of-freedom position and attitude estimation problem is proposed. The proposed method relies on the use of Singular Value Decomposition to the transformation matrix between the currents in the transmitter and in the receiver. The proposed method is validated using synthetic data, in which a random motion is applied to the transmitter within an environment with different levels of noise. Once the efficacy of the method is confirmed, the proposed algorithm is benchmarked against a well established closed-form solution. The presented method was able to accurately obtain the position and orientation, with performance comparable to the benchmark.

ijicic.org

IEEE Transactions on Control Systems Technology, 2012

WSEAS TRANSACTIONS on SYSTEMS archive, 2017

Journal of Circuits, Systems and Computers, 2014

Sba: Controle & Automação Sociedade Brasileira de Automatica, 2008

MATEC Web of Conferences, 2018

International Journal of Structural Stability and Dynamics, 2019

Journal of Low Frequency Noise, Vibration and Active Control, 2018

Proceedings XXII Congresso Brasileiro de Autom�tica, 2018

Journal of Sound and Vibration, 2016

ijicic.org

Proceedings of the 4th WSEAS …, 2008

Sba: Controle & Automação Sociedade Brasileira de Automatica, 2009

Applied Sciences, 2021

Anais do 14º Simpósio Brasileiro de Automação Inteligente, 2019

ICIC Express Letters, 2008

IFIP Advances in Information and Communication Technology, 2010

WSEAS Transactions on Systems, 2017

An alternative analytical solution to six degrees-of-freedom position and attitude estimation pro... more An alternative analytical solution to six degrees-of-freedom position and attitude estimation problem is proposed. The proposed method relies on the use of Singular Value Decomposition to the transformation matrix between the currents in the transmitter and in the receiver. The proposed method is validated using synthetic data, in which a random motion is applied to the transmitter within an environment with different levels of noise. Once the efficacy of the method is confirmed, the proposed algorithm is benchmarked against a well established closed-form solution. The presented method was able to accurately obtain the position and orientation, with performance comparable to the benchmark.

This paper aims to present the use of Neural Networks (NN) to approximate the input-output map ma... more This paper aims to present the use of Neural Networks (NN) to approximate the input-output map manifold for online output injection laws in the context of observers with error limitation. The set invariance approach is applied for computation of as small as possible conditioned invariant sets that confine the estimation error of a full-order observer. Online output injection laws are attractive due to its ability to cope with the peak phenomenon, but the runtime of its computation may turn its use unfeasible in systems with fast dynamics. The input-output map of such injection law is then approximated via NN training. Structures with NNs present processing times as fast as the adequate technology is employed for their implementation, for instance, FPGAs. Two examples, one of which the classical well-known magnetic levitation ball system, are presented to illustrate the merit of the approach. Resumo— Neste artigo, o uso de Redes Neurais Artificiais para a aproximação do mapa da varie...

In this work an analysis is made of the use of the wind with the objective generate energy electr... more In this work an analysis is made of the use of the wind with the objective generate energy electrical, as much of wind-electrical direct form, as of indirect form through hydroelectric with pumping. It is known that a hydroelectric power station, that uses the pumping, has the advantage to have a more consistent power storage and with greater potential, since uses dam of the water instead of storage batteries. Furthermore, the work defines the processes of wind-hydroelectric conversion and makes a comparison of the advantage of energy among them, from the wind form to the electrical form, and, comments the peculiarities of the electrical, isolated electrical and mechanical pumping, presented through the demand graphs. Finally, it concludes that the pumping losses can be compensated by the difference between the power costs of the different hours, and that the type of to be adopted technology depends on the local scene in each case.