Página 1 dos resultados de 226 itens digitais encontrados em 0.046 segundos

Estudo de estratégias de rastreamento da corrente e da tensão de saída CA de um conversor do tipo fonte de tensão.; Output voltage and current tracking strategies of a voltage source converter.

Martinz, Fernando Ortiz
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/09/2007 PT
Relevância na Pesquisa
45.89%
Este trabalho apresenta algumas estratégias de controle das malhas de rastreamento de tensão e corrente no lado CA de conversores do tipo fonte de tensão com filtro L ou LC. A topologia escolhida para o controle de tensão CA do inversor é a de duas malhas de controle em cascata: malha de tensão e malha de corrente, sendo esta última mais interna no sistema de controle. A metodologia de trabalho utilizada consiste na modelagem do sistema (sistema controlado e controladores), ajuste dos parâmetros do controlador, simulação computacional do sistema "inversor + controlador", implementação de alguns controladores propostos utilizando um DSP e testes em um sistema real com inversor. O estudo das técnicas de controle concentra-se inicialmente na estratégia de realimentação de dois estados no domínio de tempo contínuo, evoluindo para estratégias em tempo discreto que consideram o atraso na atuação do inversor devido ao tempo de cálculo do algoritmo de controle. Em tempo discreto, são analisados controladores preditivos para as malhas de tensão e corrente, bem como o emprego de controladores Proporcional-Integral (PI) na malha de tensão. Os dois últimos controladores são testados em um inversor PWM de baixa potência para diversos tipos de carga...

MPC adaptativo - multimodelos para controle de sistemas não-lineares.; MPC adaptive - multimodels for control of nonlinear systems.

Paula, Neander Alessandro da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/04/2009 PT
Relevância na Pesquisa
45.8%
Durante a operação de um controlador MPC, a planta pode ir para outro ponto de operação principalmente pela decisão operacional ou pela presença de perturbações medidas/não-medidas. Assim, o modelo do controlador deve ser adaptado para a nova condição de operação favorecendo o controle sob as novas condições. Desta forma, as condições ótimas de controle podem ser alcançadas com a maior quantidade de modelos identificados e com um controlador adaptativo que seja capaz de selecionar o melhor modelo. Neste trabalho é apresentada uma metodologia de controle adaptativo com identificação on-line do melhor modelo o qual pertence a um conjunto previamente levantado. A metodologia proposta considera um controlador em duas camadas e a excitação do processo através de um sinal GBN na camada de otimização com o controlador em malha fechada. Está sendo considerada a validação deste controlador adaptativo através da comparação dos resultados com duas diferentes técnicas Controlador MMPC e Identificação ARX, para a comprovação dos bons resultados desta metodologia.; During the operation of a MPC, the plant can change the operation point mainly due to management decision or due to the presence of measured or unmeasured disturbances. Thus...

Sistema de controle para o filtro óptico sintonizável Fabry-Perot do instrumento BTFI.; Control system for the Fabry-Perot optical tunable filter of the BTFI instrument.

Cavalcanti, Luiz Eduardo Mendonça
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/02/2011 PT
Relevância na Pesquisa
55.86%
Este trabalho trata do desenvolvimento de um sistema de controle para um módulo do instrumento astronômico BTFI (Brazilian Tunable Filter Imager), um filtro óptico sintonizável altamente versátil que está instalado no telescópio SOAR, localizado no Chile. Será empregado neste instrumento um novo interferômetro Fabry-Perot, capaz de realizar observações em uma ampla faixa de resoluções espectrais. Para operar com resolução espectral variável, o Fabry-Perot proposto neste projeto terá uma faixa mais ampla de ajuste do vão entre suas placas refletivas, utilizando atuadores piezelétricos amplificados com grande capacidade de deslocamento e sensores capacitivos de alta precisão. O novo controlador apresenta uma malha de controle totalmente digital, implementada com um DSP (Digital Signal Processor) sintetizado num dispositivo FPGA (Field-programmable Gate Array). Na primeira etapa do desenvolvimento, trabalhou-se com um sistema de posicionamento nanométrico utilizando um protótipo simplificado com um canal composto por um sensor capacitivo de distância e um atuador piezelétrico. A partir dos bons resultados obtidos no sistema de um canal, realizou-se a expansão para um sistema de controle multi-malha de três canais com protótipo do Fabry-Perot...

Inversor CS Boost monofásico em aplicações com fontes renováveis

De Brito, Moacyr A.G.; Sampaio, Leonardo P.; Luigi, G.; Canesin, Carlos A.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência
POR
Relevância na Pesquisa
65.97%
This paper presents a new methodology for the operation and control of a single-phase current-source (CS) Boost Inverter, considering that the conventional current-source inverter (CSI) has a right-half-plane (RHP) zero in its control-to-output transfer function, and this RHP zero causes the known non-minimum-phase effects. In this context, a special design with low boost inductance and a multi-loop control is developed in order to assure stable and very fast dynamics. Furthermore, the Inverter presents output voltage with very low total harmonic distortion (THD), reduced components and high power density. Therefore, this paper presents the inverter operation, the proposed control technique, and main simulation and experimental results in order to demonstrate the feasibility of the proposal. © 2010 IEEE.

Single-phase current-source-boost inverter for renewable energy sources

Sampaio, Leonardo P.; De Brito, Moacyr A.G.; Junior, Luigi G.; De A. E Melo, Guilherme; Canesin, Carlos A.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 1118-1123
ENG
Relevância na Pesquisa
65.88%
This paper presents a new methodology for the operation and control of a single-phase current-source (CS) Boost Inverter, considering that the conventional CS boost inverter has a right-half-plane (RHP) zero in its control-to-output transfer function, and this RHP zero causes the known non-minimum-phase effects. In this context, a special design with low boost inductance and a multi-loop control is developed in order to assure stable and very fast dynamics. Furthermore, the proposed inverter presents output voltage with very low total harmonic distortion (THD), reduced components and high power density. Therefore, this paper presents the inverter operation, the proposed control technique, the main simulation results and a prototype in order to demonstrate the feasibility of the proposal. © 2011 IEEE.

Uma nova metodologia de projeto e controle para o inversor Boost (CSI) monofásico, para o aproveitamento de fontes alternativas e renováveis de energia elétrica

Sampaio, Leonardo Poltronieri
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 110 f. : il.
POR
Relevância na Pesquisa
65.9%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Engenharia Elétrica - FEIS; Este trabalho propõe uma nova abordagem na metodologia de operação para o inversor Boost monofásico, como estrutura base para o aproveitamento de fontes alternativas e renováveis de energia elétrica. Considerando-se que equipamentos eletro/eletrônicos convencionais em CA (corrente alternada) necessitam, normalmente, de níveis e formato de tensão diferentes daqueles fornecidos por essas fontes de energia, o inversor proposto é uma estrutura integrada que tem a capacidade de operar como conversor elevador de tensão e inversor, apresentando um número reduzido de componentes e rendimento maior, quando comparado às formas tradicionais de se associar em cascata o conversor elevador com o inversor. O projeto convencional do inversor fonte de corrente (CSI) exige uma indutância elevada de entrada, além disso, o modelo a pequeno sinais do CSI é semelhante ao do conversor Boost no modo de condução contínua, apresentando um zero no semi-plano direito na função de transferência para o controle da tensão de saída, sendo que este zero causa o conhecido efeito de fase não-mínima. Desta forma, uma metodologia especial de projeto é apresentada resultando numa indutância Boost reduzida e numa técnica de controle utilizando um sistema multi-malhas...

Recursive neuro fuzzy techniques for online identification and control

Oliveira, Tiago Miguel Brites
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
45.8%
Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores; The main goal of this thesis will be focused on developing an adaptative closed loop control solution, using fuzzy methodologies. A positive theoretical and experimental contribution, regarding modelling and control of fuzzy and neuro fuzzy systems, is expected to be achieved. Proposed non-linear identification solution will use for modelling and control, a recurrent neuro fuzzy architecture. Regarding model solution, a state space approach will be considered during fuzzy consequent local models design. Developed controller will be based on model parameters, being expected not only a stable closed loop solution, but also a static error with convergence towards zero. Model and controller fuzzy subspaces, will be partitioned throughout process dynamical universe, allowing fuzzy local models and controllers commutation and aggregation. With the aim of capturing process under control dynamics using a real time approach, the use of recursive optimization techniques are to be adopted. Such methods will be applied during parameter and state estimation, using a dual decoupled Kalman filter extended with unscented transformation. Two distinct processes one single-input (SISO) other multi-input (MIMO)...

Closed-Loop Control in Fused MR-TRUS Image-Guided Prostate Biopsy

Xu, Sheng; Kruecker, Jochen; Guion, Peter; Glossop, Neil; Neeman, Ziv; Choyke, Peter; Singh, Anurag K.; Wood, Bradford J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
45.8%
Multi-modality fusion imaging for targeted prostate biopsy is difficult because of prostate motion during the biopsy procedure. A closed-loop control mechanism is proposed to improve the efficacy and safety of the biopsy procedure, which uses real-time ultrasound and spatial tracking as feedback to adjust the registration between a preoperative 3D image (e.g. MRI) and real-time ultrasound images. The spatial tracking data is used to initialize the image-based registration between intraoperative ultrasound images and a preoperative ultrasound volume. The preoperative ultrasound volume is obtained using a 2D sweep and manually registered to the MRI dataset before the biopsy procedure. The accuracy of the system is 2.3±0.9 mm in phantom studies. The results of twelve patient studies show that prostate motion can be effectively compensated using closed-loop control.

The Benefits of Soft Sensor and Multi-Rate Control for the Implementation of Wireless Networked Control Systems

Mansano, Raul K.; Godoy, Eduardo P.; Porto, Arthur J. V.
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 18/12/2014 EN
Relevância na Pesquisa
45.79%
Recent advances in wireless networking technology and the proliferation of industrial wireless sensors have led to an increasing interest in using wireless networks for closed loop control. The main advantages of Wireless Networked Control Systems (WNCSs) are the reconfigurability, easy commissioning and the possibility of installation in places where cabling is impossible. Despite these advantages, there are two main problems which must be considered for practical implementations of WNCSs. One problem is the sampling period constraint of industrial wireless sensors. This problem is related to the energy cost of the wireless transmission, since the power supply is limited, which precludes the use of these sensors in several closed-loop controls. The other technological concern in WNCS is the energy efficiency of the devices. As the sensors are powered by batteries, the lowest possible consumption is required to extend battery lifetime. As a result, there is a compromise between the sensor sampling period, the sensor battery lifetime and the required control performance for the WNCS. This paper develops a model-based soft sensor to overcome these problems and enable practical implementations of WNCSs. The goal of the soft sensor is generating virtual data allowing an actuation on the process faster than the maximum sampling period available for the wireless sensor. Experimental results have shown the soft sensor is a solution to the sampling period constraint problem of wireless sensors in control applications...

Closed-loop control of spacecraft formations with applications on SPHERES

Jeffrey, Matthew M
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 157 p.
ENG
Relevância na Pesquisa
45.8%
Formation flying satellites offer potentially greater science returns and operational capabilities than attainable with a monolithic spacecraft. Successful control of a formation of spacecraft can be divided into two separate stages. The first stage creates a plan that meets a set of mission objectives, and the second stage implements the plan. Plans are specified as a sequence of [delta]V commands executed at specific times during an orbit. This thesis presents an online method for generating fleet-wide plans, using convex optimization techniques, that satisfy multiple objectives. The approach allows for minimum and balanced fuel usage, can position spacecraft in arbitrary configurations, and favors low-maintenance orbits that do not drift apart. Additionally, the architecture is applicable not only to formation-keeping maneuvers, but also to formation reconfigurations. Various simulations demonstrate the importance of accurately implementing plans for formation flying as well as autonomous rendezvous and docking missions. Specifically, the relationships between process error, overall fuel use, and position error are studied. Theory is put into practice with the development of a new low-level, closed-loop thrust controller for the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES). The controller processes measurements from accelerometers and gyroscopes to monitor thruster performance in real-time. Experiments conducted on the International Space Station (ISS) validate the controller and establish a foundation for future enhancements to the underlying algorithm. Finally...

A novel model-free adaptive control design for multivariable industrial processes

Xu, D.; Jiang, B.; Shi, P.
Fonte: IEEE Publicador: IEEE
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
45.79%
In this paper, a multiple adaptive observer-based strategy is proposed for the control of multi-input multi-output nonlinear processes using input/output (I/O) data. In the strategy, the pseudopartial-derivative parameter matrix of compact form dynamic linearization is estimated by a multiple adaptive observer, which is used to dynamically linearize a nonlinear system. Then, the proposed data-driven model-free-adaptive-control algorithm is only based on the online identified multiobserver models derived from the I/O data of the controlled plants, and Lyapunov-based stability analysis is used to ensure that all signals of the close-loop control system are bounded. A numerical example and a Wood/Berry distillation column example are provided to show that the proposed control algorithm has a very reliable tracking ability and a satisfactory robustness to disturbances and process dynamics variations.; Dezhi Xu, Bin Jiang and Peng Shi

The benefits of soft sensor and multi-rate control for the implementation of wireless networked control systems

Mansano, Raul K.; Godoy, Eduardo P.; Porto, Arthur J. V.
Fonte: Mdpi Ag Publicador: Mdpi Ag
Tipo: Artigo de Revista Científica Formato: 24441-24461
ENG
Relevância na Pesquisa
45.79%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 2011/23217-0; Recent advances in wireless networking technology and the proliferation of industrial wireless sensors have led to an increasing interest in using wireless networks for closed loop control. The main advantages of Wireless Networked Control Systems (WNCSs) are the reconfigurability, easy commissioning and the possibility of installation in places where cabling is impossible. Despite these advantages, there are two main problems which must be considered for practical implementations of WNCSs. One problem is the sampling period constraint of industrial wireless sensors. This problem is related to the energy cost of the wireless transmission, since the power supply is limited, which precludes the use of these sensors in several closed-loop controls. The other technological concern in WNCS is the energy efficiency of the devices. As the sensors are powered by batteries, the lowest possible consumption is required to extend battery lifetime. As a result, there is a compromise between the sensor sampling period, the sensor battery lifetime and the required control performance for the WNCS. This paper develops a model-based soft sensor to overcome these problems and enable practical implementations of WNCSs. The goal of the soft sensor is generating virtual data allowing an actuation on the process faster than the maximum sampling period available for the wireless sensor. Experimental results have shown the soft sensor is a solution to the sampling period constraint problem of wireless sensors in control applications...

A transient response analysis of a multi-loop computation servomechanism in the SUBROC MK 75, Attack Analyzer.

Rorie, Conrad J.
Fonte: Monterey, California: U.S. Naval Postgraduate School Publicador: Monterey, California: U.S. Naval Postgraduate School
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
45.83%
Distinguished Alumni Award Program author. RADM Conrad J. Rorie, USN (Ret) (Presented 31 Oct 07); The multi-loop Lead Angle servo loop is utilized as a analog computing loop that mechanizes the range-bearing torpedo fire control equation. This thesis applies several new servo analysis techniques, develops system component transfer functions, analyzes individual loops, and examines qualitative stability and response of the overall system. No response or error criteria was specified. Based on the author' experience and advice from submariners a minimum error criteria is derived. This thesis preposes several modifications of the origional system in order to improve performance, points out several deficiencies, and recommends areas of further study.; http://www.archive.org/details/transientrespons00rori; U.S. Navy (U.S.N.) author.

Collision-Free Multi-UAV Optimal Path Planning and Cooperative Control for Tactical Applications

Bollino, Kevin P.; Lewis, L. Ryan
Fonte: The American Institute of Aeronautics and Astronautics (AIAA) Publicador: The American Institute of Aeronautics and Astronautics (AIAA)
Tipo: Conference Paper
Relevância na Pesquisa
45.79%
The article of record as published may be located at http://arc.aiaa.org; Approved for public display, distribution unlimited; AIAA Guidance, Navigation and Control Conference and Exhibit 18 - 21 August 2008, Honolulu, Hawaii; Stemming from previous work that addressed the optimal path planning of an unmanned aerial vehicle (UAV) in obstacle-rich environments, this paper demonstrates the approach's scalability to that of a multi-UAV application. The proposed concept, based on optimal control techniques and Pseudospectral methods, offers the improved system flexibility and autonomy demanded by UAV tactical missions in urban areas. As demonstrated, employing optimal control methods for path planning problems provides a simplistic yet powerful capability of flight trajectory optimization that includes simultaneous collision avoidance between vehicles and terrain obstacles. Departing from traditional techniques that harbor non-optimal architectures, the employed method facilitates real-time, onboard computations that may potentially improve overall system performance. Recent developments in the field of optimal control theory point at an emerging paradigm shift that may involve less dependency on the typical inner-loop control. Extending these developments...

The Influence of the feedback control of the hexapod platform of the SAAM dynamic driving simulator on neuromuscular dynamics of the drivers

AYKENT, Baris; PAILLOT, Damien; MERIENNE, Frédéric; KEMENY, Andras
Fonte: INRETS Publicador: INRETS
EN
Relevância na Pesquisa
45.91%
Multi sensorial cues (visual, auditory, haptic, inertial, vestibular, neuromuscular) [Ang2] play important roles to represent a proper sensation (objectively) and so a perception (subjectively as cognition) in driving simulators. Driving simulator aims at giving the sensation of driving as in a real case. For a similar situation, the driver has to react in the same way as in reality in terms of ‘self motion’. To enable this behavior, the driving simulator must enhance the virtual immersion of the subject in the driving situation. The subject has to perceive the motion of his own body in the virtual scene of the virtual car as he will have in a real car. For that reason, restituting the inertial cues on driving simulators is essential to acquire a more proper functioning [Kol20]. Simulation sickness has been one of the main research topics for the driving simulators. It was assessed between dynamic and static simulators [Cur7], [Wat32]). For a braking maneuver, [Sie29] stated that if the motion platform is activated the bias in reaching increased levels of decelerations was reduced strongly comparing to inactivated platform case. However, there has been lack in publications of vehicle-vestibular cue conflict based illness rating approach and its correlation with the neuromuscular dynamics for that kind of research. In order to reduce the simulator sickness...

Robust Multi-loop Airborne SLAM in Unknown Wind Environments

Kim, Jonghyuk; Sukkarieh, Salah
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
Relevância na Pesquisa
55.75%
This paper presents a robust multi-loop airborne SLAM structure which also augments wind information. The air velocity observation from an air data system can be used to estimate the error of the on-board Inertial Navigation System (INS). However, due to

Multi-loop feedback control for atom laser coherence

Yanagisawa, Masahiro; James, Matthew
Fonte: Elsevier Publicador: Elsevier
Tipo: Conference paper
Relevância na Pesquisa
45.85%
In this paper we present a multi-loop measurement feedback control scheme to improve atom laser coherence. The first loop (proposed by Thomsen and Wiseman, 2002) aims to cancel the decohering effects of the nonlinear atom-atom interactions via direct meas

Cooperative Target Realization in Multi-Agent Systems Allowing Choice-Based Actions

Guo, Ge; Wong, Wing Shing; Liu, Zhongchang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/06/2012
Relevância na Pesquisa
45.8%
In this paper, we study cooperative multi-agent systems in which the target objective and the controls exercised by the agents are dependent on the choices they made at initial system time. Such systems have been investigated in several recently published papers, mainly from the perspective of system analysis on issues such as control communication complexity, control energy cost and the feasibility of realization of target functions. This paper continues this line of research by developing optimal control design methodology for linear systems that are collaboratively manipulated by multiple agents based on their distributed choices. For target matrices that satisfy particular structural constraints, we derive control algorithms that can achieve the specified targets with minimum control cost. We compare state-feedback as well as open-loop control strategies for target realization and extend the optimality result to an arbitrary target matrix. The optimal control solutions are obtained by minimizing the average control cost subject to the set of specified target-state constraints by means of modern variation theory and the Lagrange multiplier method.; Comment: 31 pages, 5 figures

Approximate Consensus Multi-Agent Control Under Stochastic Environment with Application to Load Balancing

Amelina, Natalia; Fradkov, Alexander; Jiang, Yuming; Vergados, Dimitrios J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/06/2013
Relevância na Pesquisa
45.85%
The paper is devoted to the approximate consensus problem for networks of nonlinear agents with switching topology, noisy and delayed measurements. In contrast to the existing stochastic approximation-based control algorithms (protocols), a local voting protocol with nonvanishing step size is proposed. Nonvanishing (e.g., constant) step size protocols give the opportunity to achieve better convergence rate (by choosing proper step sizes) in coping with time-varying loads and agent states. The price to pay is replacement of the mean square convergence with an approximate one. To analyze dynamics of the closed loop system, the so-called method of averaged models is used. It allows to reduce analysis complexity of the closed loop system. In this paper the upper bounds for mean square distance between the initial system and its approximate averaged model are proposed. The proposed upper bounds are used to obtain conditions for approximate consensus achievement. The method is applied to the load balancing problem in stochastic dynamic networks with incomplete information about the current states of agents and with changing set of communication links. The load balancing problem is formulated as consensus problem in noisy model with switched topology. The conditions to achieve the optimal level of load balancing (in the sense that if no new task arrives...

Numerical approach to multi-loop integrals

Kato, K.; de Doncker, E.; Hamaguchi, N.; Ishikawa, T.; Koike, T.; Kurihara, Y.; Shimizu, Y.; Yuasa, F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/01/2012
Relevância na Pesquisa
45.8%
For the calculation of multi-loop Feynman integrals, a novel numerical method, the Direct Computation Method (DCM) is developed. It is a combination of a numerical integration and a series extrapolation. In principle, DCM can handle diagrams of arbitrary internal masses and external momenta, and can calculate integrals with general numerator function. As an example of the performance of DCM, a numerical computation of two-loop box diagrams is presented. Further discussion is given on the choice of control parameters in DCM. This method will be an indispensable tool for the higher order radiative correction when it is tested for a wider class of physical parameters and the separation of divergence is done automatically.; Comment: 7 pages; The XXth International Workshop High Energy Physics and Quantum Field Theory, September 24-October 1, 2011, Sochi Russia