Integral MRAC with Minimal Controller Synthesis and bounded adaptive gains: The continuous-time case

Model reference adaptive controllers designed via the Minimal Control Synthesis (MCS) approach are a viable solution to control plants affected by parameter uncertainty, unmodelled dynamics, and disturbances. Despite its effectiveness to impose the required reference dynamics, an apparent drift of the adaptive gains, which can eventually lead to closed-loop instability or alter tracking performance, may occasionally be induced by external disturbances. This problem has been recently addressed for this class of adaptive algorithms in the discrete-time case and for square-integrable perturbations by using a parameter projection strategy [1]. In this paper we tackle systematically this issue for MCS continuous-time adaptive systems with integral action by enhancing the adaptive mechanism not only with a parameter projection method, but also embedding a s-modification strategy. The former is used to preserve convergence to zero of the tracking error when the disturbance is bounded and L2, while the latter guarantees global uniform ultimate boundedness under continuous L8 disturbances. In both cases, the proposed control schemes ensure boundedness of all the closed-loop signals. The strategies are numerically validated by considering systems subject to different kinds of disturbances. In addition, an electrical power circuit is used to show the applicability of the algorithms to engineering problems requiring a precise tracking of a reference profile over a long time range despite disturbances, unmodelled dynamics, and parameter uncertainty.Postprint (author's final draft

Discrete-time integral MRAC with minimal controller synthesis and parameter projection

Model reference adaptive controllers with Minimal Control Synthesis are effective control algorithms to guarantee asymptotic convergence of the tracking error to zero not only for disturbance-free uncertain linear systems, but also for highly nonlinear plants with unknown parameters, unmodeled dynamics and subject to perturbations. However, an apparent drift in adaptive gains may occasionally arise, which can eventually lead to closed-loop instability. In this paper, we address this key issue for discrete-time systems under L-2 disturbances using a parameter projection algorithm. A consistent proof of stability of all the closed-loop signals is provided, while tracking error is shown to asymptotically converge to zero. We also show the applicability of the adaptive algorithm for digitally controlled continuous-time plants. The proposed algorithm is numerically validated taking into account a discrete-time LTI system subject to parameter uncertainty, parameter variations and L-2 disturbances. Finally, as a possible engineering application of this novel adaptive strategy, the control of a highly nonlinear electromechanical actuator is considered. (C) 2015 The Franldin Institute. Published by Elsevier Ltd. All rights reserved.Postprint (author's final draft

Informe mensual d'articles publicats. Campus Baix Llobregat. Base de dades Scopus. Juny, juliol i agost 2019

Informe bibliomètric mensual Campus Baix Llobregat. Base de dades Scopus. Juny, juliol i agost 2019. EETAC i DEAB, ESAB.Postprint (published version

Library-based adaptive observation through a sparsity-promoting adaptive observer

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper proposes an adaptive observer for a class of nonlinear system with linear parametrization. The main novelty of the technique is that the regressor vector is considered to be unknown. Instead, a library of candidate non-linear functions is implemented, which transforms the original parameter vector into a new one that is characterized by being sparse. In such problem, it is shown that standard adaptive observers cannot recover the original vector due to a lack of persistence of excitation. Instead, a parameter-adaptation with an implicit l1 regularization is implemented. It is shown that this new observer can recover the parameter vector under standard assumptions of sparse signal recovery. The results are validated in a numerical simulation.This work has been partially funded by the Spanish State Research Agency through the María de Maeztu Seal of Excellence to IRI (MDM-2016-0656), by the project DOVELAR (ref. RTI2018-096001-B-C32) and by the PTI FLOWBAT 2021 project (ref. 642 201980E101).Peer ReviewedPostprint (author's final draft

Building Energy Modeling for Green Architecture and Intelligent Dashboard Applications

Buildings are responsible for 40% of the carbon emissions in the United States. Energy efficiency in this sector is key to reducing overall greenhouse gas emissions. This work studied the passive technique called the roof solar chimney for reducing the cooling load in homes architecturally. Three models of the chimney were created: a zonal building energy model, computational fluid dynamics model, and numerical analytic model. The study estimated the error introduced to the building energy model (BEM) through key assumptions, and then used a sensitivity analysis to examine the impact on the model outputs. The conclusion was that the error in the building energy model is small enough to use it for building simulation reliably. Further studies simulated the roof solar chimney in a whole building, integrated into one side of the roof. Comparisons were made between high and low efficiency constructions, and three ventilation strategies. The results showed that in four US climates, the roof solar chimney results in significant cooling load energy savings of up to 90%. After developing this new method for the small scale representation of a passive architecture technique in BEM, the study expanded the scope to address a fundamental issue in modeling - the implementation of the uncertainty from and improvement of occupant behavior. This is believed to be one of the weakest links in both accurate modeling and proper, energy efficient building operation. A calibrated model of the Mascaro Center for Sustainable Innovation’s LEED Gold, 3,400 m2 building was created. Then algorithms were developed for integration to the building’s dashboard application that show the occupant the energy savings for a variety of behaviors in real time. An approach using neural networks to act on real-time building automation system data was found to be the most accurate and efficient way to predict the current energy savings for each scenario. A stochastic study examined the impact of the representation of unpredictable occupancy patterns on model results. Combined, these studies inform modelers and researchers on frameworks for simulating holistically designed architecture and improving the interaction between models and building occupants, in residential and commercial settings

Process modelling and adaptive control of a metal milling process

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Control adaptativo por modelo de referencia con síntesis de controlador mínima en sistemas con incertidumbre y sujetos a perturbaciones

In this research work, a non-linear technique called Minimum Controller Synthesis (MCS) is presented. This is a variant of the Model Reference Adaptive Control (MRAC), which has the main advantage of requiring very little information from the device to be controlled. It can be implemented in continuous or discrete time, and that guarantees that if the parameters of the plant are constant or that vary more slowly than the adaptive gains, the error between the desired characteristics and those of operation, tend to zero in steady state. This guarantees stable conditions of performance and robustness to parametric variation. The tracking speed and the rejection of disturbances are other inherent characteristics of the technique. The mathematical development of the MCS technique is presented, starting from the MRAC to obtain its basic presentation, its modeling in continuous time, and then arrive at discrete time. Then, they are evaluated mathematically and experimentally in systems to be controlled (with parametric uncertainty and/or disturbances presence) in order to propose a development alternative to current automatic control systems. For this purpose, the following two systems with uncertainty and under disturbance were evaluated: a Laboratory control system called "Roto-Magnet" and a Single-Phase Inverter based on a LCL (a device widely used today to the incorporation of electrical energy from renewable sources to electrical networks). The methodology used is to implement the adaptive algorithms and evaluate them in continuous time through the mathematical model of the Roto-Magnet plant. Then, take them at discrete time and observe their operation both in simulation and in real way in the Laboratory, taking in consideration that the Roto-Magnet has a vector of first-order states. These experiences were scaled to the LCL based Inverter, whose state vector is third order. The results of the adaptive control implemented to control the LCL-based single-phase inverter can be seen through the averaged and switched mathematical models that were developed in Matlab/Simulink. The results obtained in the two plants with the adaptive control, allow visualizing the performance of MCS, its robustness in the face of the uncertainty in the parameters, in its modeling and also in the face of periodic disturbances. These adaptive designs incorporated parametric projection to avoid the drift growth of adaptive gains and a controller based on the Principle of the Internal Model, which improves the capabilities of reference tracking and rejection of disturbances of this class. The thesis is divided into nine chapters that describe from the basic aspects to more complex aspects, and at the same time show how these have been solved, their implementations and the results obtained from the Minimum Controller Synthesis technique. The results in the mathematical field as in the real plants are compared with other techniques developed for the Roto-Magnet plant and the Inverter based on LCL. Based on this, its advantages and disadvantages are observed in order to present the advances made in the technique. Finally, the explanations have been sought to be detailed and easy to understand throughout all the chapters of the thesis, enriching this description with references to multiple scientific articles and texts, which allow better orienting and deepening the topics according to the interests and requirements of each reader.En este trabajo de investigación se presenta una técnica no lineal denominada Síntesis de Controlador Mínima MCS, una variante al Control Adaptativo por Modelo de Referencia MRAC, la cual tiene como principal ventaja la de requerir muy poca información del dispositivo a controlar, que puede ser implementada en tiempo continuo o discreto, y que garantiza que si los parámetros de la planta son constantes o que varían más lentamente que las ganancias adaptativas, el error entre las características deseadas y las de funcionamiento, tiendan a cero en estado estacionario, garantizando condiciones estables de funcionamiento y robustez ante variación paramétrica. La velocidad de seguimiento y el rechazo de perturbaciones, es otra característica inherente de la técnica. Se presentan los desarrollos matemáticos de la técnica de MCS, partiendo del Control Adaptativo por Modelo de Referencia, para obtener su presentación básica, su modelado en tiempo continuo, para luego llegar a tiempo discreto, y se evalúan de manera matemática y experimental en sistemas a ser controlados (sistemas presentan problemas de incertidumbre paramètrica y/o presencia de perturbaciones), para plantear una alternativa de desarrollo a los sistemas de control automático actuales. Con este propósito, los sistemas con incertidumbre y sujetos a perturbación a evaluarse, serán dos, por un lado, un sistema de control de Laboratorio denominado ¿Roto-Imán¿ y por otro lado un Inversor Monofásico basado en LCL (dispositivo muy usado actualmente para la incorporación de energía eléctrica proveniente de fuentes renovables a las redes eléctricas). La metodología que se sigue es la de implementar los algoritmos adaptativos y evaluarlos en tiempo continuo mediante el modelo matemático de la planta Roto-Imán, para luego llevarlos a tiempo discreto y observar su funcionamiento tanto en simulación como de forma real en el Laboratorio, teniendo en cuenta que el Roto-Imán tiene un vector de estados de primer orden. Estas experiencias serán escalas al Inversor basado LCL, cuyo vector de estados es de tercer orden. Los resultados del control adaptativo implementado para controlar el Inversor monofásico basado en LCL se verán a través de los modelos matemáticos promediados y conmutados, que fueron desarrollados para el efecto en Matlab/Simulink. Los resultados obtenidos en las dos plantas con el control adaptativo, permiten visualizar las prestaciones de MCS, su robustez frente a la incertidumbre en los parámetros, en el modelado de la misma y también frente a perturbaciones periódicas. A estos diseños adaptativos se le incorporará proyección paramétrica para evitar el crecimiento a la deriva de las ganancias adaptativas y un controlador basado en el Principio del Modelo Interno, que mejore las capacidades de seguimiento de referencias y rechazo de perturbaciones de esta clase. La tesis está dividida en nueve capítulos que van describiendo desde los aspectos básicos hasta irse adentrando en aspectos más complejos, y mostrando a la vez como estos han sido resueltos, sus implementaciones y los resultados obtenidos de la técnica de Síntesis de Controlador Mínima. Los resultados en el ámbito matemático como en la planta real, son comparados con otras técnicas desarrolladas para la planta Roto-Imán y el Inversor basado en LCL; y en base a ello, se observan sus ventajas y desventajas, para luego presentar los avances logrados en la técnica. Decir además que se ha buscado que las explicaciones sean detalladas y de fácil comprensión a lo largo de todos los capítulos de la tesis, enriqueciendo esta descripción con referencias a múltiples artículos científicos y textos, que permitan orientar de mejor forma y profundizar en los temas de acuerdo a los intereses y requerimientos de cada lector.Postprint (published version

Development, modelling and control of a multi-degree-of-freedom dynamic wind tunnel rig

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

On-line monitoring and control of the injection moulding process

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Producció científica de l'ETSEIB a Futur. Articles de revista i publicacions a congressos dels investigadors de l'ETSEIB durant l'any 2019

Postprint (author's final draft