Recently, permanent magnet assisted (PMa)-synchronous reluctance motors (SynRM) have been considered as a possible alternative motor drive for high performance applications. In order to have an efficient motor drive, performing of three steps in design of the overall drive is not avoidable. These steps are design optimization of the motor, identification of the motor parameter and implementation of an advanced control system to ensure optimum operation. Therefore, this dissertation first deals with the design optimization of the Permanent Magnet Assisted Synchronous Reluctance Motor (PMa-SynRM). Various key points in the rotor design of a low cost PMa-SynRM are introduced and their effects are studied. Finite element approach has been utilized to show the effects of these parameters on the developed average electromagnetic torque and the total d-q inductances. As it can be inferred from the name of the motor, there are some permanent magnets mounted in the rotor core. One of the features considered in the design of this motor is the magnetization of the permanent magnets mounted in the rotor core using the stator windings to reduce the manufacturing cost. At the next step, identification of the motor parameters is discussed. Variation of motor parameters due to temperature and airgap flux has been reported in the literatures. Use of off-line models for estimating the motor parameters is known as a computationally intensive method, especially when the models include the effect of cross saturation. Therefore in practical applications, on-line parameter estimation is favored to achieve a high performance control system. In this dissertation, a simple practical method for parameter estimation of the PMa-SynRM is introduced. Last part of the dissertation presents one advanced control strategy which utilized the introduced parameter estimator. A practical Maximum Torque Per Ampere (MTPA) control scheme along with a simple parameter estimator for PMa-SynRM is introduced. This method is capable of maintaining the MTPA condition and stays robust against the variations of motor parameters. Effectiveness of the motor design procedure and the control strategy is validated by presenting simulation and experimental results of a 1.5 kW prototype PMa-SynRM, designed and manufactured through the introduced design method.

Model Reference Adaptive Control (MRAC) is a widely studied adaptive control methodology that aims to ensure that a nonlinear plant with significant modeling uncertainty behaves like a chosen reference model. MRAC methods attempt to achieve this by representing the modeling uncertainty as a weighted combination of known nonlinear functions, and using a weight update law that ensures weights take on values such that the effect of the uncertainty is mitigated. If the adaptive weights do arrive at an ideal value that best represent the uncertainty, significant performance and robustness gains can be realized. However, most MRAC adaptive laws use only instantaneous data for adaptation and can only guarantee that the weights arrive at these ideal values if and only if the plant states are Persistently Exciting (PE). The condition on PE reference input is restrictive and often infeasible to implement or monitor online. Consequently, parameter convergence cannot be guaranteed in practice for many adaptive control applications. Hence it is often observed that traditional adaptive controllers do not exhibit long-term-learning and global uncertainty parametrization. That is, they exhibit little performance gain even when the system tracks a repeated command. This thesis presents a novel approach to adaptive control that relies on using current and recorded data concurrently for adaptation. The thesis shows that for a concurrent learning adaptive controller, a verifiable condition on the linear independence of the recorded data is sufficient to guarantee that weights arrive at their ideal values even when the system states are not PE. The thesis also shows that the same condition can guarantee exponential tracking error and weight error convergence to zero, thereby allowing the adaptive controller to recover the desired transient response and robustness properties of the chosen reference models and to exhibit long-term-learning. This condition is found to be less restrictive and easier to verify online than the condition on persistently exciting exogenous input required by traditional adaptive laws that use only instantaneous data for adaptation. The concept is explored for several adaptive control architectures, including neuro-adaptive flight control, where a neural network is used as the adaptive element. The performance gains are justified theoretically using Lyapunov based arguments, and demonstrated experimentally through flight-testing on Unmanned Aerial Systems.

No description available.

Using the dual Black-Scholes partial differential equation, Dupire derived an explicit formula, involving the ratio of partial derivatives of the evolving fair value of a European call option (ECO), for recovering information about its variable volatility. Because the prices, as a function of maturity and strike, are only available as discrete noisy observations, the evaluation of Dupire’s formula reduces to being an ill-posed numerical differentiation problem, complicated by the need to take the ratio of derivatives. In order to illustrate the nature of ill-posedness, a simple finite difference scheme is first used to approximate the partial derivatives. A new method is then proposed which reformulates the determination of the volatility, from the partial differential equation defining the fair value of the ECO, as a parameter identification activity. By using the weak formulation of this equation, the problem is localized to a subregion on which the volatility surface can be approximated by a constant or a constant multiplied by some known shape function which models the local shape of the volatility function. The essential regularization is achieved through the localization, the choice of the analytic weight function, and the application of integration-by-parts to the weak formulation to transfer the differentiation of the discrete data to the differentiation of the analytic weight function.

In this work, we propose an approach that allows to explore the potential pathophysiological mechanisms (at neuronal population level) of ictogenesis by combining clinical intracranial electroencephalographic (iEEG) recordings with a neural mass model. IEEG recordings from temporal lobe epilepsy (TLE) patients around seizure onset were investigated. Physiologically meaningful parameters (average synaptic gains of the excitatory, slow and fast inhibitory population, Ae, B and G) were identified during interictal to ictal transition. We analyzed the temporal evolution of four ratios, i.e. Ae/G, Ae/B, Ae/(B + G), and B/G. The excitation/inhibition ratio increased around seizure onset and decreased before seizure offset, suggesting the disturbance and restoration of balance between excitation and inhibition around seizure onset and before seizure offset, respectively. Moreover, the slow inhibition may have an earlier effect on the breakdown of excitation/inhibition balance. Results confirm the decrease in excitation/inhibition ratio upon seizure termination in human temporal lobe epilepsy, as revealed by optogenetic approaches both in vivo in animal models and in vitro. We further explored the distribution of the average synaptic gains in parameter space and their temporal evolution, i.e. the path through the model parameter space, in TLE patients. Results showed that the synaptic gain values located roughly on a plane before seizure onset, dispersed during ictal and returned when the seizure terminated. Cluster analysis was performed on seizure paths and demonstrated consistency in synaptic gain evolution across different seizures from individual patients. Furthermore, two patient groups were identified, each one corresponding to a specific synaptic gain evolution in the parameter space during a seizure. Results were validated by a bootstrapping approach based on comparison with random paths. The differences in the path revealed variations in EEG dynamics for patients despite showing an identical seizure onset pattern. Our approach may have the potential to classify the epileptic patients into subgroups based on different mechanisms revealed by subtle changes in synaptic gains and further enable more robust decisions regarding treatment strategy. The increase of excitation/inhibition ratios, i.e. Ae/G, Ae/B and Ae/(B+G), around seizure onset makes them potential cues for seizure detection. We explored the feasibility of a model based seizure detection algorithm. A simple thresholding method was employed. We evaluated the algorithm against the manual scoring of a human expert on iEEG samples from patients suffering from different types of epilepsy. Results suggest that Ae/(B+G), i.e. excitation/(slow + fast inhibition) ratio, allowed the best performance and that the algorithm best suited TLE patients. Leave-one-out cross-validation showed that the algorithm achieved 94.74% sensitivity for TLE patients. The median false positive rate was 0.16 per hour, and median detection delay was -1.0 s. Of interest, the values of the threshold determined by leave-one-out cross-validation for TLE patients were quite constant, suggesting a general excitation/inhibition balance baseline in background iEEG among TLE patients. Such a model-based seizure detection approach is of clinical interest and could also achieve good performance for other types of epilepsy provided that more appropriate model, i.e. better describe epileptic EEG waveforms for other types of epilepsy, is implemented. Altogether, this thesis contributes to the field of epilepsy research from two perspectives. Scientifically, it gives new insights into the mechanisms underlying interictal to ictal transition, and facilitates better understanding of epileptic seizures. Clinically, it provides a tool for reviewing EEG data in a more efficient and objective manner and offers an opportunity for on-demand therapeutic devices. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Le travail principal de cette thèse consiste à proposer une nouvelle procédure d'identification inverse appliquée aux situations de mise en forme et d'usinage des métaux, qui peut fournir un ensemble de paramètres appropriés pour toute loi constitutive elastoplastique suivant le modèle de plasticité de type J_{2} avec écrouissage isotrope, en évaluant la corrélation entre les réponses expérimentales et numériques. En premier lieu, un programme d'identification a été développé, en combinant l'algorithme de Levenberg-Marquardt et des méthodes de traitement de données pour identifier les paramètres constitutifs. En termes d'expérimentation, des essais de compression et de traction dynamiques ont été effectués. La forme finale déformée des spécimens, qui repose sur une analyse post-mortem, a été choisie comme quantité d'observation. Comme pour la simulation numérique, des modèles numériques de ces mêmes procédures expérimentales ont été construits en utilisant le code éléments finis Abaqus/Explicit afin de fournir des réponses numériques. Un algorithme numérique a été proposé pour l'implémentation de lois constitutives elastoplastiques définies par l'utilisateur dans Abaqus/Explicit. / The main concern of this thesis is to propose a new inverse identification procedure applied to metal forming and machining situations, which can provide an appropriate parameters set for any elastoplastic constitutive law following J_{2} plasticity and isotropic hardening, by evaluating the correlation between the experimental and numerical responses. Firstly the identification program has been developed, which combines the Levenberg-Marquardt algorithm and the Data processing methods to optimize the constitutive parameters. In terms of experimentation, dynamic compression and tensile tests have been conducted. The final deformed shape of specimens, which relies on a post-mortem analysis, has been selected as the observation quantity. As for the numerical simulation, the numerical models of the same experimental procedure have been built with the finite element software Abaqus/Explicit in order to provide numerical responses. A numerical algorithm has been proposed for the implementation of user defined elastoplastic constitutive laws in Abaqus/Explicit.

Les travaux décrits dans ce document abordent le problème du couplage dynamique homme-système haptique. Nous proposons une étude de ce couplage basée sur l'hypothèse d'un système hybride temporaire. Selon cette hypothèse, le système formé lors du couplage peut être considéré comme un système dynamique dont les deux parties ne peuvent pas être séparées. Ce sujet est pluridisciplinaire, se situant à l'intersection des sciences cognitives, de l'automatique et de l'haptique. La première partie du document comporte un état de l'art sur l'analyse du couplage dans ces trois domaines, une description de la problématique et de la méthode à utiliser pour notre étude ainsi qu'une proposition des typologies du geste. Lors de cette étude du couplage, nous nous intéressons à un groupe de gestes particuliers, notamment le geste périodique et le geste passif dans une situation de simulation haptique ainsi qu'aux modèles d'interaction capables de les générer. La méthode générale, consiste à définir des approches pour la modélisation du couplage main-système haptique pour ensuite réaliser une analyse du système couplé à partir d'une acquisition des données du système lors du couplage et en utilisant des méthodes d'identification de paramètres issus de l'automatique pour caractériser les modèles. La dernière partie, décrit la mise en place du dispositif pour l'analyse expérimentale du couplage en situation de simulation avec une interaction haptique. Ce dispositif permet l'acquisition des données du geste pour l'analyse. Nous présentons également, l'étude réalisée sur le simulateur haptique afin d'établir l'équivalence entre les paramètres virtuels introduits et issus du simulateur et des paramètres physiques réels. Ensuite, nous décrivons l'analyse expérimentale des différentes situations de couplage proposées. Les expériences effectuées lors de cette étude ont été réalisées sur la plateforme temps réel ERGON_X, conçue par l'ACROE/ICA. Les résultats de ces expériences ont permis de quantifier les modèles du geste et d'observer ses composantes, selon les modèles établis. Mots clés : haptique, interface haptique, interfaces homme-machine, simulation temps réel, couplage homme-objet, geste, modélisation physique, identification de paramètres. / The work described in this document deals with the problem of human-haptic system dynamic coupling. We propose a study of this kind of coupling based on the hypothesis of a temporary hybrid system. Under this hypothesis, the system formed during the coupling can be considered as a dynamic system in which the two parties that compose it cannot be separated. This is multidisciplinary topic, situated at the intersection of cognitive science, automation and haptics. The first part of the document includes a state of the art on the analysis of coupling in these three areas, the description of the problem and the methodology for the study as well as a proposal of gesture typology. In this study of coupling, we are interested in a particular group of actions, such as periodic movement and passive gesture in a situation of haptic simulation and also, in the interaction models able to generate them. The general method is to define the approaches for modeling the hand-haptic device coupling and then perform an analysis of the coupled system by acquiring system data during the coupling and using parameter identification methods to characterize the models. The final section describes the implementation of the device for the experimental analysis of coupling during simulation with a haptic interaction. This device allows data acquisition for gesture analysis. We also present the study of the haptic simulator to establish the equivalence between virtual parameters introduced to and returned by the simulator and real physical parameters. Then, we describe the experimental analysis of different proposed coupling situations. The experiments performed for this study were performed using the real-time platform ERGON_X, designed by ACROE / ICA. The results of these experiments were used to quantify gesture models and to observe its components, according to established models. Keywords: haptic, haptic interface, human-machine interfaces, real-time simulation, human-object coupling, gesture, physical modeling, parameter identification.

Made available in DSpace on 2014-12-17T14:56:05Z (GMT). No. of bitstreams: 1 PatriciaNG.pdf: 767778 bytes, checksum: 287c497d20e307221386eeee17df3f9d (MD5) Previous issue date: 2005-02-03 / This work presents a modelling and identification method for a wheeled mobile robot, including the actuator dynamics. Instead of the classic modelling approach, where the robot position coordinates (x,y) are utilized as state variables (resulting in a non linear model), the proposed discrete model is based on the travelled distance increment Delta_l. Thus, the resulting model is linear and time invariant and it can be identified through classical methods such as Recursive Least Mean Squares. This approach has a problem: Delta_l can not be directly measured. In this paper, this problem is solved using an estimate of Delta_l based on a second order polynomial approximation. Experimental data were colected and the proposed method was used to identify the model of a real robot / Esta disserta??o apresenta uma metodologia de modelagem e identifica??o para um rob? m?vel dotado de rodas. O modelo din?mico discreto proposto leva em considera??o a din?mica dos atuadores. Ao contr?rio da abordagem cl?ssica, onde as coordenadas de posi??o do rob? (x, y) s?o usadas como vari?veis de estado (o que resulta em um modelo n?o linear), o modelo discreto proposto utiliza o incremento na dist?ncia percorrida pelo rob? Delta_l. Com isto, o modelo resultante ? linear e invariante no tempo, podendo ser identificado utilizando qualquer m?todo cl?ssico, como por exemplo os m?nimos quadrados recursivos. Um problema desta abordagem ? que a vari?vel Delta_l n?o ? diretamente mensur?vel. Nesta proposta, este problema ? contornado usando uma estimativa de Delta_l calculada assumindo que o caminho percorrido durante um per?odo de amostragem pode ser aproximado por uma curva de segundo grau. O m?todo proposto ? validado atrav?s de resultados de simula??o computacional e experi?ncias pr?ticas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the present work the effect of a dry friction damper device on the dynamic behavior of vibratory systems is analyzed. Two friction devices are designed consisting of a sphere in contact with a flat steel bar. In the first prototype the normal force on the contact is kept constant. In the second device a piezoelectric actuator is used to vary the intensity of the normal force. An experimental methodology is developed to analyze the dynamic behavior of a vibratory system and to identify the physical properties of the friction damper devices. The mathematical-computational models of the two friction dampers are used to perform simulations with a vibratory system, in order to analyze the influence of the variation of the normal contact force on the behavior of the vibratory system and to evaluate the dissipation of vibrational energy. In the first damper, an experimental methodology is used to identify the behavior of friction force induced on the vibratory system, and also to identify nonlinearities due to friction Frequency response is used to identify the structural frequencies generated by the device, as well the operational band of the damper device with constant normal force. The time domain vibratory system response is used to identify the Coulomb friction model. The second damper is designed by finite element method. Experimental analysis of the device is applied to identify the parameters that define the static and dynamic behavior of the damper with variable normal load, The frequency response is used to identify the structural frequencies generated by the device, as well it s effective operational band.. Another experiment evaluates the effect of the normal contact force variation on the dynamic response of a vibratory structure. The vibratory system response is identified using Coulomb friction models. Finally, numerical simulations are used to evaluate the effect of the normal contact variation, generated by a semi active control, on the vibratory system dynamic behavior. The vibration attenuation and the power demand of the piezoelectric actuator .are evaluated. / Neste trabalho é analisado o efeito de amortecedores de atrito seco sobre o comportamento dinâmico de um sistema vibratório de um grau de liberdade São projetados dois dispositivos de atrito constituídos por uma esfera em contato com um barra plana de aço. No primeiro protótipo a força normal no contato é mantida constante. No segundo dispositivo é utilizado um atuador piezelétrico para variar a intensidade da força normal. É desenvolvida uma metodologia experimental para analisar o comportamento dinâmico do sistema vibratório e identificar as propriedades físicas dos amortecedores de atrito. Os modelos matemáticos-computacionais dos dois amortecedores de atrito são usados para realizar simulações com um sistema vibratório, com a finalidade de analisar a influência da variação da força normal de contato sobre o comportamento do sistema vibratório e avaliar a capacidade de dissipação da energia vibratória. No primeiro amortecedor mediante uma metodologia experimental, é possível identificar o comportamento da força de atrito induzida ao sistema dinâmico, são identificadas também as não linearidades devidas ao atrito. Na resposta em frequência é possível identificar as frequências estruturais geradas pelo dispositivo, assim como a banda de atuação do amortecedor de força normal constante. Por ultimo é identificada a resposta do sistema dinâmico no domínio do tempo, mediante os modelos Coulomb do atrito. Para o segundo amortecedor é apresentado a analise estática dos elementos constituintes via um estudo em elementos finitos. Métodos de analise experimental aplicados para identificar os parâmetros que determinam o comportamento estático e dinâmico do amortecedor de carga normal variável. Na resposta em frequência é possível identificar as frequências estruturais geradas pelo dispositivo, assim como também, a banda de atuação do amortecedor de força normal variável. Em uma segunda fase experimental, avaliam-se os efeitos da variação da força normal no contato, na resposta dinâmica da estrutura vibratória e determina-se o comportamento da força do amortecedor, assim como também se identifica a resposta do sistema, com os modelos de atrito de Coulomb. Finalmente, é avaliada numericamente o efeito do ajuste da força normal do contato, mediante um controle semiativo., Verifica-se a eficiência do controle sobre a vibração da estrutura .e sobre o consumo de potência do atuador piezelétrico. / Mestre em Engenharia Mecânica

Sistemas de levitação eletromagnética são de interesse quando se necessita de tecnologia envolvendo redução de atrito, atuação sem contato físico, máquinas rotativas e trens de alta velocidade. Devido à presença de não linearidades em sua dinâmica, pesquisadores têm dado atenção ao desenvolvimento de controladores mais sofisticados, com o objetivo de melhorar o desempenho desses sistemas. Controladores lineares apresentam limitações na faixa de operação da variável controlada e, geralmente apresentam baixa robustez quando aplicados em sistemas não lineares. O objetivo deste trabalho é desenvolver controladores não lineares com diferentes estruturas e analisá-los quando aplicados em um protótipo do sistema físico. Inicialmente, o sistema é modelado matematicamente através da abordagem fenomenológica. Em seguida, os parâmetros do modelo são identificados através de dados obtidos experimentalmente. Conhecendo bem a dinâmica do sistema através do modelo, são projetados três controladores de diferentes estruturas utilizando simulações computacionais. O primeiro é o PID clássico, controle linear amplamente utilizado em processos industriais. O segundo controlador é um PID com topologia não linear, denominado NPID. Este visa reduzir as limitações encontradas no PID linear, através de funções não lineares em seus termos. O último e mais complexo se trata do controle por modos deslizantes (SMC). Também com estrutura não linear, o SMC possui como característica intrínseca a robustez a variações da planta. Ao final, são realizadas simulações e os controladores avaliados são implementados de maneira digital em um hardware de controle e aplicados em uma planta piloto de levitação eletromagnética. Os resultados de desempenho obtidos permitem avaliar qual topologia de controlador melhor se enquadra diante dessa aplicação. / Electromagnetic levitation systems are of interest when it is necessary the use of technology involving reduction of friction, acting without physical contact, rotating machinery and high speed trains. Due to the nonlinear dynamics, researchers have paid attention to the development of more sophisticated controllers, in order to improve the performance of these systems. Linear controllers have limitations in the operating range of the controlled variable and generally have low robustness when applied to linear systems. The objective of this work is to develop nonlinear controllers with different structures and analyze them, when applied to a prototype of the physical system. Initially the system is modeled mathematically through the phenomenological approach. Then the model parameters are identified by experimentally obtained data. Knowing the dynamic of the system through the model, three different controllers are designed using computer simulations. The first is the classic PID, a linear control widely used in industrial processes. The second controller is a PID with nonlinear topology, called NPID. This controller is intended to reduce the limitations found in the linear PID through non linear functions on its terms. The last and most complex is the sliding mode control (SMC). Also a nonlinear structure, the SMC has the intrinsic characteristic of robustness to variations of the plant. In the end, the simulations are performed and the evaluated controllers are implemented in digital form in a hardware control and applied in a pilot plant of an electromagnetic levitation system. With the performance results it is possible to verify which controller topology best fits this application.