Systems with non-Hermitian Hamiltonians, specially those exhibiting parity-time (PT ) symmetry, a... more Systems with non-Hermitian Hamiltonians, specially those exhibiting parity-time (PT ) symmetry, are of particular interest as they describe physical open systems with alanced loss into and gain from the environment. In this context, the study of eigenvalues location and the corresponding phase transitions as a function of the degree of non-Hermiticity is analized here using automatic control tools, particularly the Root-Locus technique. This provides insight on the behavior of these systems, allowing to generalize results for higher order ones. The proposed ideas are analyzed in detail for a class of coupled resonant circuit chains.
A low-complexity timing and frequency synchronization algorithm for Orthogonal Frequency Division... more A low-complexity timing and frequency synchronization algorithm for Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed here. The preamble design is based on complementary pairs of sequences (Golay sequences) and Constant Amplitude Zero Auto-Correlation (CAZAC) sequences. This new approach is compared to existing alternatives in terms of complexity and performance. It is shown that this novel scheme achieves competitive performance and significantly reduces computational cost, thanks to the availability of efficient correlation architectures for complementary pairs of sequences.
espanolEl presente trabajo presenta una implementacion de Control Digital Directo (DDC) multilazo... more espanolEl presente trabajo presenta una implementacion de Control Digital Directo (DDC) multilazo, a traves de una estructura distribuida de procesadores dedicados, supervisados por una unidad central que opera como maestro del sistema. Esta solucion es simple y eficaz para procesos de pequena y mediana envergadura, permitiendo expansiones sin afectar el rendimiento total, dado el alto grado de paralelismo obtenido en el procedimiento. EnglishThe present paper describes the implementation of a Direct Digital Control (DDC) multiloop controller by means of a distributed structure of dedicated processors, supervised by a master central unit. This solution is simple, and useful for small and intermediate systems. Expansions are provided without affecting the perfomance, due the high degree of paralellims used.
1998 IEEE International Joint Conference on Neural Networks Proceedings. IEEE World Congress on Computational Intelligence (Cat. No.98CH36227)
Page 1. Adaptive Control of Wind Energy Conversion Systems Using Radial Basis Networks Miguel A. ... more Page 1. Adaptive Control of Wind Energy Conversion Systems Using Radial Basis Networks Miguel A. Mayosky LEICI UNLP-CICpBA CC91(19OO) La Plata (Argentina) Gustavo IE Cancel0 LEICI-UNLP-CONICET CC91 (1900 ...
he control-oriented modelling of an actual PEM fuel cell stack is approached. The proposed proced... more he control-oriented modelling of an actual PEM fuel cell stack is approached. The proposed procedure tackles the modular modelling of an experimental complex system that combines mechanical, electrical, pneumatic and electrochemical subsystems. It provides a nonlinear ...
The feasibility of SOSM techniques to control PEM fuel cells is evaluated in this chapter. Assess... more The feasibility of SOSM techniques to control PEM fuel cells is evaluated in this chapter. Assessment is accomplished through simulations, using a benchmark model of a fuel cell system for an electric vehicle. The viability of SOSM techniques for oxygen stoichiometry ...
The main purpose is to present the actual development and experimental validation of SOSM control... more The main purpose is to present the actual development and experimental validation of SOSM controllers, previously reviewed and analysed in this book. As anticipated, the controllers are designed and implemented in the real FC-based generation workbench ...
This chapter summarises the main results presented in the book, regarding the application of Seco... more This chapter summarises the main results presented in the book, regarding the application of Second-Order Sliding-Mode algorithms for robust control of autonomous PEM fuel cells. Several improvements to the existing control schemes and many open directions of ...
This chapter provides an introduction to Variable Structure Control theory and its extension to t... more This chapter provides an introduction to Variable Structure Control theory and its extension to the so-called Sliding-Mode (SM) control. The presentation is not intended as a comprehensive survey of the state-of-the-art in the field, but to supply the basic concepts ...
A Layered Evolution (LE) paradigm based method for the generation of a neuron-controller is devel... more A Layered Evolution (LE) paradigm based method for the generation of a neuron-controller is developed and verified through simulations and experimentally. It is intended to solve scalability issues in systems with many behavioral modules. Each and every module is a genetically evolved neuro-controller specialized in performing a different task. The main goal is to reach a combination of different basic behavioral elements using different artificial neural-network paradigms concerning mobile robot navigation in an unknown environment [1][2]. The obtained controller is evaluated over different scenarios in a structured environment, ranging from a detailed simulation model to a real experiment. Finally most important implies are shown through several focuses.
Abstract Parallel systems are wellknown solutions to satisfy the demand of computing capabilities... more Abstract Parallel systems are wellknown solutions to satisfy the demand of computing capabilities, but parallel computer design involves difficult hardware/software tradeoffs. Standard general purpose parallel architectures don't exist, only some particular architectures are used to solve specific problems. In such complex systems the performance measurement is important to evaluate several situations for existing architectures or for systems in designing phase. This performance is highly influenced by factors as ...
Proton Exchange Membrane (PEM) fuel cells are extensively used for mobile and portable applicatio... more Proton Exchange Membrane (PEM) fuel cells are extensively used for mobile and portable applications. This is due to their compactness, low weight, high power density, and clean, pollutant-free operation. Besides, their low temperature of operation (typically 60–80 degrees Celsius) allows fast starting times, a key feature for automotive applications, for instance. In a PEM Fuel Cell, a hydrogen-rich fuel is injected by the anode, and an oxidant (usually pure oxygen or air) is fed through the cathode. Both electrodes are separated by a solid electrolyte that allows ionic conduction and avoids electrons circulation. The output of a PEM Fuel Cell is electric energy, with water and heat as the only by-products. In this chapter, the basics of PEM fuel cells operation are reviewed, including electrochemical equations, losses, and efficiency issues. The state-of-the-art in PEM fuel cells technology is summarised, including membranes, electrodes, catalysts, line heaters, water, and heat management devices. Control-oriented models in the literature are discussed, and typical control objectives are analysed.
In this paper, estimation of the dielectric properties of layered lossy structure using openended... more In this paper, estimation of the dielectric properties of layered lossy structure using openended coaxial probes is analyzed. Theoretical and empirical exponential approximations of the relaxation process are generalized for two, three and four-layers structures. As measurements are taken in the 10 MHz to 1 GHz frequency range, a wide frequency spectrum measurement procedure is proposed, providing a fast method to approximate parameters (thickness and dielectric properties) of each layer. Application of the methodology depends on some prior knowledge of the properties of the dielectric layers (i.e. number of layers and approximate values of their thicknesses and permittivities). A linear System Identification method is proposed using time domain measurements to find the corresponding frequency responses. Although these approaches and techniques have been already considered individually, they are combined here, resulting in a novel methodology to process time domain reflectometry data that is robust and numerically well-behaved. Simulations and experimental results in phantom and a biological tissue are provided. Dielectric relaxation is assumed to follow a Debye model, but comments on other parameterizations are also summarized. Experimental frequency validation data are reliable up to 700 MHz.
Behavioural robustness at antibody and immune network level is discussed. The robustness of the i... more Behavioural robustness at antibody and immune network level is discussed. The robustness of the immune response that drives an autonomous mobile robot is examined with two computational experiments in the autonomous mobile robots trajectory generation context in unknown environments. The immune response is met based on the immune network metaphor for different low-level behaviours coordination. These behaviours are activated when a robot sense the appropriate conditions in the environment in relation to the network current state. Results are obtained over a case study in computer simulation as well as in laboratory experiments with a Khepera II microrobot. In this work, we develop a set of tests where such an immune response is externally perturbed at network or low-level behavioural modules to analyse the robust capacity of the system to unexpected perturbations. Emergence of robust behaviour and high-level immune response relates to the coupling between behavioural modules that are selectively engaged with the environment based on immune response. Experimental evidence leads discussions on a dynamical systems perspective of behavioural robustness in artificial immune systems that goes beyond the isolated immune network response.
Increasing demands on pollution reduction is driving innovation on clean energy sources. Among th... more Increasing demands on pollution reduction is driving innovation on clean energy sources. Among these, fuel cells are regarded as one of the most promising technologies, due to their high efficiency, compactness, and reliability. Fuel cells are electrochemical devices that generate electrical current from hydrogen and oxygen. In this chapter, the basic operation of a fuel-cell-based generation system is analysed, and the main technologies used at each of its subsystems are reviewed. A brief history of fuel cell development is summarised, from early experiences in the 19th century to the space shuttle and automotive applications. Closed-loop operation of fuel cell (FC) systems arises as a way to improve performance and reliability. In particular, robust control techniques based on sliding modes are proposed as suitable alternatives to provide performance under model uncertainty and external disturbances, usually present in these complex systems. Finally, the general organisation of the book is briefly outlined.
Revista Iberoamericana de Automática e Informática Industrial RIAI, 2008
Resumen: En este trabajo se hace un estudio comparativo de tres diferentes técnicas de control po... more Resumen: En este trabajo se hace un estudio comparativo de tres diferentes técnicas de control por modo deslizante de segundo orden, aplicadas al problema específico del control de respiración de una pila de combustible PEM. Los algoritmos diseñados se contrastan por simulación utilizando el modelo completo del sistema, poniendo particularénfasis en la respuesta transitoria y la robustez frente a perturbaciones. Copyright c 2008 CEA-IFAC.
Systems with non-Hermitian Hamiltonians, specially those exhibiting parity-time (PT ) symmetry, a... more Systems with non-Hermitian Hamiltonians, specially those exhibiting parity-time (PT ) symmetry, are of particular interest as they describe physical open systems with alanced loss into and gain from the environment. In this context, the study of eigenvalues location and the corresponding phase transitions as a function of the degree of non-Hermiticity is analized here using automatic control tools, particularly the Root-Locus technique. This provides insight on the behavior of these systems, allowing to generalize results for higher order ones. The proposed ideas are analyzed in detail for a class of coupled resonant circuit chains.
A low-complexity timing and frequency synchronization algorithm for Orthogonal Frequency Division... more A low-complexity timing and frequency synchronization algorithm for Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed here. The preamble design is based on complementary pairs of sequences (Golay sequences) and Constant Amplitude Zero Auto-Correlation (CAZAC) sequences. This new approach is compared to existing alternatives in terms of complexity and performance. It is shown that this novel scheme achieves competitive performance and significantly reduces computational cost, thanks to the availability of efficient correlation architectures for complementary pairs of sequences.
espanolEl presente trabajo presenta una implementacion de Control Digital Directo (DDC) multilazo... more espanolEl presente trabajo presenta una implementacion de Control Digital Directo (DDC) multilazo, a traves de una estructura distribuida de procesadores dedicados, supervisados por una unidad central que opera como maestro del sistema. Esta solucion es simple y eficaz para procesos de pequena y mediana envergadura, permitiendo expansiones sin afectar el rendimiento total, dado el alto grado de paralelismo obtenido en el procedimiento. EnglishThe present paper describes the implementation of a Direct Digital Control (DDC) multiloop controller by means of a distributed structure of dedicated processors, supervised by a master central unit. This solution is simple, and useful for small and intermediate systems. Expansions are provided without affecting the perfomance, due the high degree of paralellims used.
1998 IEEE International Joint Conference on Neural Networks Proceedings. IEEE World Congress on Computational Intelligence (Cat. No.98CH36227)
Page 1. Adaptive Control of Wind Energy Conversion Systems Using Radial Basis Networks Miguel A. ... more Page 1. Adaptive Control of Wind Energy Conversion Systems Using Radial Basis Networks Miguel A. Mayosky LEICI UNLP-CICpBA CC91(19OO) La Plata (Argentina) Gustavo IE Cancel0 LEICI-UNLP-CONICET CC91 (1900 ...
he control-oriented modelling of an actual PEM fuel cell stack is approached. The proposed proced... more he control-oriented modelling of an actual PEM fuel cell stack is approached. The proposed procedure tackles the modular modelling of an experimental complex system that combines mechanical, electrical, pneumatic and electrochemical subsystems. It provides a nonlinear ...
The feasibility of SOSM techniques to control PEM fuel cells is evaluated in this chapter. Assess... more The feasibility of SOSM techniques to control PEM fuel cells is evaluated in this chapter. Assessment is accomplished through simulations, using a benchmark model of a fuel cell system for an electric vehicle. The viability of SOSM techniques for oxygen stoichiometry ...
The main purpose is to present the actual development and experimental validation of SOSM control... more The main purpose is to present the actual development and experimental validation of SOSM controllers, previously reviewed and analysed in this book. As anticipated, the controllers are designed and implemented in the real FC-based generation workbench ...
This chapter summarises the main results presented in the book, regarding the application of Seco... more This chapter summarises the main results presented in the book, regarding the application of Second-Order Sliding-Mode algorithms for robust control of autonomous PEM fuel cells. Several improvements to the existing control schemes and many open directions of ...
This chapter provides an introduction to Variable Structure Control theory and its extension to t... more This chapter provides an introduction to Variable Structure Control theory and its extension to the so-called Sliding-Mode (SM) control. The presentation is not intended as a comprehensive survey of the state-of-the-art in the field, but to supply the basic concepts ...
A Layered Evolution (LE) paradigm based method for the generation of a neuron-controller is devel... more A Layered Evolution (LE) paradigm based method for the generation of a neuron-controller is developed and verified through simulations and experimentally. It is intended to solve scalability issues in systems with many behavioral modules. Each and every module is a genetically evolved neuro-controller specialized in performing a different task. The main goal is to reach a combination of different basic behavioral elements using different artificial neural-network paradigms concerning mobile robot navigation in an unknown environment [1][2]. The obtained controller is evaluated over different scenarios in a structured environment, ranging from a detailed simulation model to a real experiment. Finally most important implies are shown through several focuses.
Abstract Parallel systems are wellknown solutions to satisfy the demand of computing capabilities... more Abstract Parallel systems are wellknown solutions to satisfy the demand of computing capabilities, but parallel computer design involves difficult hardware/software tradeoffs. Standard general purpose parallel architectures don't exist, only some particular architectures are used to solve specific problems. In such complex systems the performance measurement is important to evaluate several situations for existing architectures or for systems in designing phase. This performance is highly influenced by factors as ...
Proton Exchange Membrane (PEM) fuel cells are extensively used for mobile and portable applicatio... more Proton Exchange Membrane (PEM) fuel cells are extensively used for mobile and portable applications. This is due to their compactness, low weight, high power density, and clean, pollutant-free operation. Besides, their low temperature of operation (typically 60–80 degrees Celsius) allows fast starting times, a key feature for automotive applications, for instance. In a PEM Fuel Cell, a hydrogen-rich fuel is injected by the anode, and an oxidant (usually pure oxygen or air) is fed through the cathode. Both electrodes are separated by a solid electrolyte that allows ionic conduction and avoids electrons circulation. The output of a PEM Fuel Cell is electric energy, with water and heat as the only by-products. In this chapter, the basics of PEM fuel cells operation are reviewed, including electrochemical equations, losses, and efficiency issues. The state-of-the-art in PEM fuel cells technology is summarised, including membranes, electrodes, catalysts, line heaters, water, and heat management devices. Control-oriented models in the literature are discussed, and typical control objectives are analysed.
In this paper, estimation of the dielectric properties of layered lossy structure using openended... more In this paper, estimation of the dielectric properties of layered lossy structure using openended coaxial probes is analyzed. Theoretical and empirical exponential approximations of the relaxation process are generalized for two, three and four-layers structures. As measurements are taken in the 10 MHz to 1 GHz frequency range, a wide frequency spectrum measurement procedure is proposed, providing a fast method to approximate parameters (thickness and dielectric properties) of each layer. Application of the methodology depends on some prior knowledge of the properties of the dielectric layers (i.e. number of layers and approximate values of their thicknesses and permittivities). A linear System Identification method is proposed using time domain measurements to find the corresponding frequency responses. Although these approaches and techniques have been already considered individually, they are combined here, resulting in a novel methodology to process time domain reflectometry data that is robust and numerically well-behaved. Simulations and experimental results in phantom and a biological tissue are provided. Dielectric relaxation is assumed to follow a Debye model, but comments on other parameterizations are also summarized. Experimental frequency validation data are reliable up to 700 MHz.
Behavioural robustness at antibody and immune network level is discussed. The robustness of the i... more Behavioural robustness at antibody and immune network level is discussed. The robustness of the immune response that drives an autonomous mobile robot is examined with two computational experiments in the autonomous mobile robots trajectory generation context in unknown environments. The immune response is met based on the immune network metaphor for different low-level behaviours coordination. These behaviours are activated when a robot sense the appropriate conditions in the environment in relation to the network current state. Results are obtained over a case study in computer simulation as well as in laboratory experiments with a Khepera II microrobot. In this work, we develop a set of tests where such an immune response is externally perturbed at network or low-level behavioural modules to analyse the robust capacity of the system to unexpected perturbations. Emergence of robust behaviour and high-level immune response relates to the coupling between behavioural modules that are selectively engaged with the environment based on immune response. Experimental evidence leads discussions on a dynamical systems perspective of behavioural robustness in artificial immune systems that goes beyond the isolated immune network response.
Increasing demands on pollution reduction is driving innovation on clean energy sources. Among th... more Increasing demands on pollution reduction is driving innovation on clean energy sources. Among these, fuel cells are regarded as one of the most promising technologies, due to their high efficiency, compactness, and reliability. Fuel cells are electrochemical devices that generate electrical current from hydrogen and oxygen. In this chapter, the basic operation of a fuel-cell-based generation system is analysed, and the main technologies used at each of its subsystems are reviewed. A brief history of fuel cell development is summarised, from early experiences in the 19th century to the space shuttle and automotive applications. Closed-loop operation of fuel cell (FC) systems arises as a way to improve performance and reliability. In particular, robust control techniques based on sliding modes are proposed as suitable alternatives to provide performance under model uncertainty and external disturbances, usually present in these complex systems. Finally, the general organisation of the book is briefly outlined.
Revista Iberoamericana de Automática e Informática Industrial RIAI, 2008
Resumen: En este trabajo se hace un estudio comparativo de tres diferentes técnicas de control po... more Resumen: En este trabajo se hace un estudio comparativo de tres diferentes técnicas de control por modo deslizante de segundo orden, aplicadas al problema específico del control de respiración de una pila de combustible PEM. Los algoritmos diseñados se contrastan por simulación utilizando el modelo completo del sistema, poniendo particularénfasis en la respuesta transitoria y la robustez frente a perturbaciones. Copyright c 2008 CEA-IFAC.
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