• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 11
  • 7
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 50
  • 50
  • 40
  • 12
  • 12
  • 11
  • 10
  • 10
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Desenvolvimento da base e controle do grau de liberdade rotacional de um robô cilíndrico com acionamento pneumático

Rijo, Marcos Giovane de Quevedo January 2013 (has links)
Este trabalho aborda o desenvolvimento da estrutura da base e do sistema de acionamento, transmissão e controle do 1º grau de liberdade de um robô cilíndrico de 5 graus de liberdade acionado pneumaticamente. A base é construída com alumínio estruturado de elevada rigidez, o que confere a sua estrutura mecânica baixas deformações em situações de operação do robô. Além de constituir a estrutura de apoio do manipulador, a base serve de repositório para diversos componentes de sensoriamento e comando dos diversos graus de liberdade do robô e ainda apresenta elementos estruturais que são utilizados como acumuladores de ar comprimido que servem para atenuar as flutuações de pressão nos atuadores pneumáticos. O 1º grau de liberdade do robô, de acordo com a concepção de um robô cilíndrico, é relativo ao giro do conjunto de elos do manipulador em torno do eixo vertical. O seu movimento é comandado por um atuador pneumático linear acoplado a um eixo rotativo por uma correia sincronizadora. O controlador proposto é baseado na técnica de realimentação de estados com alocação de polos e compensa a variação do momento de inércia do manipulador devida ao movimento do robô. Este esquema é baseado em um modelo matemático parametrizado que provê continuamente o valor de massa equivalente acoplada ao primeiro grau de atuador de liberdade. Assim, a cada ciclo de controle, os ganhos do controlador são recalculados a partir do valor atual da massa equivalente, visando a compensar sua variação. São apresentados resultados experimentais e discussões sobre o cálculo da massa equivalente e desempenho do controlador no seguimento de trajetória. / This work deals with the design of the base frame, drive, transmission and control systems used in the first degree of freedom of a pneumatically actuated cylindrical robot with five degrees of freedom. The base is constructed with high stiffness aluminum parts, which achieve low mechanical deformation in operational working conditions. Furthermore, the base structure in used as sensor and pneumatic components compartment and comprises aluminum structural elements that are used as accumulators compressed air used for reducing the pressure fluctuations on the pneumatic actuators operation. The first degree of freedom, according to the usual design of a cylindrical robot, is relative to the rotation of the manipulator arm around its vertical axis. This degree of freedom is controlled by a linear pneumatic actuator coupled to a rotary axis mechanism by an industrial synchronous belt. The proposed controller is based on the state feedback technique with pole location and compensates the variation of the moment of inertia of the manipulator due to the motion of the robot. This scheme is based on a parameterized mathematical model that continuously provides the equivalent mass value coupled to the first degree of freedom actuator. So, in each control cycle, the controller gains are recalculated on the basis of the equivalent mass, compensating its variation. Results of experiments and discussions about the equivalent mass calculation and controller performance are presented.
12

Desenvolvimento da base e controle do grau de liberdade rotacional de um robô cilíndrico com acionamento pneumático

Rijo, Marcos Giovane de Quevedo January 2013 (has links)
Este trabalho aborda o desenvolvimento da estrutura da base e do sistema de acionamento, transmissão e controle do 1º grau de liberdade de um robô cilíndrico de 5 graus de liberdade acionado pneumaticamente. A base é construída com alumínio estruturado de elevada rigidez, o que confere a sua estrutura mecânica baixas deformações em situações de operação do robô. Além de constituir a estrutura de apoio do manipulador, a base serve de repositório para diversos componentes de sensoriamento e comando dos diversos graus de liberdade do robô e ainda apresenta elementos estruturais que são utilizados como acumuladores de ar comprimido que servem para atenuar as flutuações de pressão nos atuadores pneumáticos. O 1º grau de liberdade do robô, de acordo com a concepção de um robô cilíndrico, é relativo ao giro do conjunto de elos do manipulador em torno do eixo vertical. O seu movimento é comandado por um atuador pneumático linear acoplado a um eixo rotativo por uma correia sincronizadora. O controlador proposto é baseado na técnica de realimentação de estados com alocação de polos e compensa a variação do momento de inércia do manipulador devida ao movimento do robô. Este esquema é baseado em um modelo matemático parametrizado que provê continuamente o valor de massa equivalente acoplada ao primeiro grau de atuador de liberdade. Assim, a cada ciclo de controle, os ganhos do controlador são recalculados a partir do valor atual da massa equivalente, visando a compensar sua variação. São apresentados resultados experimentais e discussões sobre o cálculo da massa equivalente e desempenho do controlador no seguimento de trajetória. / This work deals with the design of the base frame, drive, transmission and control systems used in the first degree of freedom of a pneumatically actuated cylindrical robot with five degrees of freedom. The base is constructed with high stiffness aluminum parts, which achieve low mechanical deformation in operational working conditions. Furthermore, the base structure in used as sensor and pneumatic components compartment and comprises aluminum structural elements that are used as accumulators compressed air used for reducing the pressure fluctuations on the pneumatic actuators operation. The first degree of freedom, according to the usual design of a cylindrical robot, is relative to the rotation of the manipulator arm around its vertical axis. This degree of freedom is controlled by a linear pneumatic actuator coupled to a rotary axis mechanism by an industrial synchronous belt. The proposed controller is based on the state feedback technique with pole location and compensates the variation of the moment of inertia of the manipulator due to the motion of the robot. This scheme is based on a parameterized mathematical model that continuously provides the equivalent mass value coupled to the first degree of freedom actuator. So, in each control cycle, the controller gains are recalculated on the basis of the equivalent mass, compensating its variation. Results of experiments and discussions about the equivalent mass calculation and controller performance are presented.
13

Desenvolvimento da base e controle do grau de liberdade rotacional de um robô cilíndrico com acionamento pneumático

Rijo, Marcos Giovane de Quevedo January 2013 (has links)
Este trabalho aborda o desenvolvimento da estrutura da base e do sistema de acionamento, transmissão e controle do 1º grau de liberdade de um robô cilíndrico de 5 graus de liberdade acionado pneumaticamente. A base é construída com alumínio estruturado de elevada rigidez, o que confere a sua estrutura mecânica baixas deformações em situações de operação do robô. Além de constituir a estrutura de apoio do manipulador, a base serve de repositório para diversos componentes de sensoriamento e comando dos diversos graus de liberdade do robô e ainda apresenta elementos estruturais que são utilizados como acumuladores de ar comprimido que servem para atenuar as flutuações de pressão nos atuadores pneumáticos. O 1º grau de liberdade do robô, de acordo com a concepção de um robô cilíndrico, é relativo ao giro do conjunto de elos do manipulador em torno do eixo vertical. O seu movimento é comandado por um atuador pneumático linear acoplado a um eixo rotativo por uma correia sincronizadora. O controlador proposto é baseado na técnica de realimentação de estados com alocação de polos e compensa a variação do momento de inércia do manipulador devida ao movimento do robô. Este esquema é baseado em um modelo matemático parametrizado que provê continuamente o valor de massa equivalente acoplada ao primeiro grau de atuador de liberdade. Assim, a cada ciclo de controle, os ganhos do controlador são recalculados a partir do valor atual da massa equivalente, visando a compensar sua variação. São apresentados resultados experimentais e discussões sobre o cálculo da massa equivalente e desempenho do controlador no seguimento de trajetória. / This work deals with the design of the base frame, drive, transmission and control systems used in the first degree of freedom of a pneumatically actuated cylindrical robot with five degrees of freedom. The base is constructed with high stiffness aluminum parts, which achieve low mechanical deformation in operational working conditions. Furthermore, the base structure in used as sensor and pneumatic components compartment and comprises aluminum structural elements that are used as accumulators compressed air used for reducing the pressure fluctuations on the pneumatic actuators operation. The first degree of freedom, according to the usual design of a cylindrical robot, is relative to the rotation of the manipulator arm around its vertical axis. This degree of freedom is controlled by a linear pneumatic actuator coupled to a rotary axis mechanism by an industrial synchronous belt. The proposed controller is based on the state feedback technique with pole location and compensates the variation of the moment of inertia of the manipulator due to the motion of the robot. This scheme is based on a parameterized mathematical model that continuously provides the equivalent mass value coupled to the first degree of freedom actuator. So, in each control cycle, the controller gains are recalculated on the basis of the equivalent mass, compensating its variation. Results of experiments and discussions about the equivalent mass calculation and controller performance are presented.
14

Mise en oeuvre d'une régulation thermique sur une machine de mesure dimensionnelle de très haute exactitude. Utilisation d'un modèle d'ordre faible en boucle fermée / Implementation of a Thermal Regulation on a High Accuracy Dimensional Measuring Machine : Use of a Reduced Model for Feedback Control

Bouderbala, Kamélia 16 December 2015 (has links)
Ce manuscrit décrit la modélisation et la régulation de la température au sein d’un dispositif expérimental développé initialement pour valider les principes de conception adoptés pour une nouvelle machine de mesure de cylindricité au Laboratoire Commun de Métrologie du Laboratoire national de métrologie et d’essais – Conservatoire national des arts et métiers.L’appareil a été équipé de 19 sondes à résistance de platine raccordées à une référence nationale afin d’étudier l’influence sur son comportement des perturbations thermiques générées par des sources de chaleur internes et externes. L’investigation de l’influence de ces perturbations sur les mesures réalisées avec des capteurs de déplacement capacitifs a également été menée. Les perturbations thermiques internes simulant les puissances dissipées par les éléments de guidage mécaniques ont été générées par l’intermédiaire de trois films chauffants. Une modélisation par éléments finis du dispositif expérimental a été réalisée et les résultats numériques comparés à des résultats expérimentaux réalisés dans les mêmes conditions. Les écarts obtenus, de l’ordre de 0,1 °C, sont trop élevés pour que ce modèle soit adopté pour l’élaboration d’une régulation thermique en temps réel. Dans la suite, un modèle réduit a été développé à partir des données expérimentales à l’aide de la méthode d’identification modale (MIM). Le résidu obtenu lors de la comparaison des résultats issus de ce modèle et expérimentalement est inférieur à 0,003 °C. Finalement, une régulation thermique à mieux que le centième de degré a été mise en oeuvre en utilisant une commande prédictive associée à un filtre de Kalman. / This thesis describes the modelling and real-time regulation of the temperature inside an apparatus developed to validate the design principles of a cylindricity measurement machine at the Laboratoire Commun de Métrologie du Laboratoire national de métrologie et d’essais – Conservatoire national des arts et métiers. To study the effect of internal and external perturbations on the behaviour of the system, the apparatus is equipped with 19 platinum resistance thermometers calibrated with respect to the national standard. The effect of perturbations on the behaviour of capacitive displacement sensors has also been studied. The effect of internal perturbations generated by the mechanical guide rails was simulated using three film resistive heaters. Finite element modeling of the system temperature was carried out and the numerical results compared with experiment. The offsets about 0.1°C are too large for the model to be used for real-time temperature control. Subsequently, a reduced model wasdeveloped based on experimental data using the modal identification method (MIM). The residual obtained when its results are compared with experiment is 0.003°C. Finally, a temperature servo implemented using predictive control combined with a Kalman filter.
15

Consensus control of a class of nonlinear systems

Mohd Isira, Ahmad Sadhiqin Bin January 2016 (has links)
This dissertation aims at solving the consensus control problem of multi-agent systems with Lipschitz nonlinearity. This depends on the design of the controller that enables each agent or subsystem in multi-agent systems with Lipschitz nonlinearity to reach consensus; using the understanding of the agents' connection network from the knowledge of graph theory as well as the control system design strategy. The objective is achieved by designing a type of distributed control, namely the consensus control, which manipulates the relative information of each agent in a multi-agent systems in order to arrive at a single solution. In addition, containment control is also developed to solve containment problem. It is an extension of consensus control via leader-follower configuration, aimed at having each agent contained by multiple leaders in a multi-agent systems with Lipschitz nonlinearity. Four types of controllers are proposed - state-feedback consensus controller, observer-based consensus controller, state-feedback containment controller and observer-based containment controller; each provides the stability conditions based on Lyapunov stability analysis in time domain which enabled each agent or subsystem to reach consensus. The observer-based controllers are designed based on the consensus observer that is related to Luenberger observer. Linear Matrix Inequality (LMI) and Algebraic Riccati Equation (ARE) are utilized to obtain the solutions for the stability conditions. The simulation results of the proposed controllers and observers have been carried out to prove their theoretical validity. Several practical examples of flexible robot arm simulations are included to further validate the theoretical aspects of the thesis.
16

Control of Water Content and Retention in Hydropower Plant Cascades

Gullhamn, Esbjörn January 2004 (has links)
The discharge through a river hydropower plant must be controlled such that the water level at a pre-specified point close to the facility is kept within given bounds. The controllers used today have a somewhat demanding tuning and often create too much amplified, unnatural discharge variations resulting in unsatisfactory control performance.This will affect both surrounding nature and imposing problems for river navigation. This thesis will present a new type of controller called Override Selector feedback Control that adds an estimator for the water levels and water flows in the up- and downriver for each hydropower plant on top of the old controller. The objective of the state feedback control is to keep the total variation of the water levels and the waterflows as small as possible. After the linear, discrete time model of the power plant cascade in a river derived from the Saint Venant equations have been developed, the new concept is evaluated. Both the water level sloshing and the amplification of the discharges compared to the structure used today is damped with the new control structure. Other advantages of the proposed controller is that it will be cost efficient to implement because of the add-on approach. This is seen as a very important factor while the actual benefit that can be made by improving the water level control is very limited and thereby also the will to make extensive control investments. The control structure will be easily implemented as the estimators only need the same input data as used today.
17

Contribución al control geométrico de sistemas de eventos discretos en el álgebra max-plus / Contribution à la commande géométrique des systèmes à événements discrets dans l’algèbre max-plus

Cardenas Lucena, Carolina 23 November 2016 (has links)
Le travail présenté s'inscrit dans le contexte de la théorie des systèmes linéaires dans les dioïdes. La motivation initiale de cette étude a été de contribuer à l'analyse et la commande de systèmes linéaires dans max-plus en utilisant spécifiquement une approche géométrique. La contribution de cette thèse est centrée sur deux problèmes. La première partie est dédiée à l'étude de la relation entre les notions d'invariance contrôlée et d'invariance contrôlée par retour d'état dynamique dans un semi-anneau. Cette relation permet de montrer l'équivalence de ces deux notions. La deuxième partie concerne un problème original dans la théorie des systèmes linéaires dans max-plus, il s'agit de la synthèse d'une loi de commande par retour d'état, qui permette de satisfaire un ensemble de spécifications exprimées sous la forme de restrictions sur l'état du système, avec une approche géométrique. Il s'agit plus précisément de commander des systèmes à événements discrets décrits par un modèle linéaire dans max-plus. Nous définissons et caractérisons l'ensemble des conditions initiales admissibles, lesquelles sont à l'origine de solutions non décroissantes. Les restrictions temporelles imposées à l'espace d'état du système sont décrites par le semi-module défini par l'image de l'étoile de Kleene de la matrice associée aux restrictions temporelles. Les propriétés géométriques de ce semi-module permettant de garantir que l'évolution du système en boucle fermée satisfasse les restrictions sont étudiées. Des conditions suffisantes concernant l'existence d'une loi de commande causale par retour d'état statique sont présentées. Le calcul des lois de commande causales est également présenté. Pour illustrer l'application de cette approche, deux problèmes de commande sont présentés. / This work is in the context of the theory of linear Systems in the dioids. The initial motivation of this study was to contribute to the analysis and control of max-plus linear systems, specifically using a geometric approach. The contribution of this thesis focuses on two issues. The first part is dedicated to study of the relationship between the concepts of controlled invariance and dynamic state feedback controlled invariance in a semi-ring. This relationship allows us to show the equivalence of these two concepts. The second part relates to a new problem in the theory of max-plus linear systems, it is the synthesis, with a geometric approach, of a static state feedback control law, in order to satisfy a set of specifications that apply to the state space of the system. This is specifically to control of discrete event systems described by a linear model in max-plus. We define and characterize the set of admissible initial conditions, which are the cause of non-decreasing solutions. Temporal restrictions on the system state space are described by the semi-module defined by the image of the Kleene star of the matrix associated with time restrictions. The geometric properties of this semi-module are studied. Sufficient conditions for the existence of a causal control law by static feedback are presented. Calculating causal control laws is also presented. To illustrate the application of this approach, two control problems are presented.
18

Projeto de um manipulador robótico cilíndrico de cinco eixos atuado por motores de passo

Silveira, Iago Camargo January 2018 (has links)
Este trabalho contempla o projeto de um manipulador robótico cilindro atuado por motores de passo com cinco juntas de atuação. As etapas do projeto do robô, que tratam este estudo, foram divididas em: projeto mecânico; modelagem matemática; projeto do controlador; e simulações. O projeto mecânico apresenta uma proposta de configuração e dimensionamento mecânicos que supre a demanda exigida para a operação analisada. O modelo matemático apresenta as características elétricas e mecânicas do atuador e as características mecânicas do robô. O projeto de um controlador linear é realizado por meio da alocação dos polos do sistema em malha fechada através da realimentação dos estados de posição e de velocidade angulares do rotor unidos a um integrador do erro de posição angular. Para o primeiro grau de liberdade, por conta da variação do momento de inércia de massa associado a essa junta, um controlador com ganhos parametrizados foi projetado, no qual os ganhos são calculados baseado no modelo matemático relativo ao momento de inércia de massa associado a essa junta. Por meio de simulações computacionais, avaliou-se o projeto dos controladores no movimento ponto a ponto dos cinco eixos de atuação e a variação do momento de inércia de massa sobre a primeira junta. Os resultados dessas simulações mostraram que os controladores propostos cumprem com a dinâmica desejada nos cinco graus de liberdade do robô. / This work contemplates the design of a robotic manipulator, which is operated by a stepper motor with five actuation joints. The robot design steps were divided into: mechanical design; mathematical modeling; controller design; and simulations. The mechanical design presents a proposal of mechanical configuration and sizing that supplies the required demand for the analyzed operation. The mathematical model presents the electrical and mechanical characteristics of the actuator and the mechanical characteristics of the robot. The design of a linear controller is accomplished by allocating the poles of the closed loop system by states feedback of the position and angular speed of the rotor attached to an angular position error integrator. For the first degree of freedom, due to the variation of mass moment of inertia associated with this joint, a controller with parameterized gains was projected, in which the gains are calculated based on the mathematical model related to the mass moment of inertia associated to this joint. By means of computational simulations, we evaluated the design of the controllers in the point-to-point movement of the five actuation joints and the variation of the mass moment of inertia on the first joint. The results of these simulations showed that the proposed controllers comply with the desired dynamics in the robot’s five degrees of freedom.
19

Theoretical Framework for Modeling Ingressive Phonation

Brougham, Michael V Unknown Date
No description available.
20

CSI Feedback and Power Control in Wireless Networks

Karamad, Ehsan 10 January 2014 (has links)
We investigate the effects of quantized channel state information (CSI) on the performance of resource allocation algorithms in wireless networks. The thesis starts with a brief overview of a specific type of quantizer, referred to as a conservative quantizer where we propose the optimality and sufficiency conditions as well as practical methods to find such quantizers. We apply this theory to the quantization of transmitter CSI in point-to-point Gaussian channels and transmission under short-term power constraints. Next, we show that in a multiple-node decode-and-forward (DF) cooperative network, the same structure for quantizer is close to op- timal for the sum-rate objective function. Based on a proposed upper bound on the rate loss in such scenarios, we also argue that the quantizer should assign uneven numbers of quantization bits to different links in the network. The simulation results show that given a target rate loss level, through quantization and bit allocation, there is, on average, 0.5−1 bits per link savings in CSI feedback requirements compared to the uniform and equal bit allocation approaches. Given the many benefits in non-uniform allocation of CSI rate in the network, we formulate a generalized bit allocation scheme which is extensible to arbitrary classes of network resource allocation problems. In the last part of this thesis, we focus on power control in an interference network and then, investigate the effects of CSI imperfections on the performance of power control algorithms. First, we propose an iterative power control algorithm based on a fixed-point iteration and prove its local convergence. Then, we show that for a centralized implementation of the power control algorithm, a uniform in dB (geometric) quantizer of channel power is efficient. Based on this choice of channel quantizer, we propose a bound on rate loss in terms of the resolution of the ii deployed quantizer, where a 3 dB in quantization error is shown to contribute to a maximum of 1 bit rate loss at each user. Similarly to the previous scenario, the upper bound suggests that an uneven assignment of numbers of quantization levels leads to smaller distortion. Based on this bound, we develop the corresponding bit allocation laws. We also investigate the effects of CSI errors on the performance of distributed power control algorithms and show that, compared to the centralized case, the distributed algorithm could lead to a further SINR loss of up to 3 dB for one or more transmitters. This error is due to the fact that because of CSI errors, the estimated interference level at each receiver is different from the induced interference wireless transmitters expect.

Page generated in 0.0527 seconds