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Desenvolvimento de um atuador de posição baseado em liga de memória de forma com resfriamento forçado.; Development of a position actuator based on a shape memory alloy with forced cooling.

Romano, Roberto
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 27/11/2006 PT
Relevância na Pesquisa
45.91%
As ligas com memória de forma (Shape Memory Alloy - SMA) consistem em um grupo de materiais metálicos que possuem a habilidade de retornar a um formato ou tamanho previamente definido quando submetidas a um ciclo térmico adequado, devido a alterações em sua estrutura cristalina. Esta mudança não é um processo termodinamicamente reversível, apresentando, conseqüentemente, histerese. Portanto, a característica principal destes materiais é a habilidade de sofrer grandes deformações e, em seguida, recuperar sua forma original quando a carga é removida ou o material é aquecido. Assim, pode-se utilizar esse fenômeno para construir atuadores leves e silenciosos, como verdadeiros músculos metálicos. O desenvolvimento de atuadores com as SMAs apresenta grande atrativo para diversos campos da engenharia, principalmente na área de robótica, substituindo os atuadores convencionais de grande peso e ruidosos, como motores, válvulas solenóides, etc. Entretanto, para o bom desempenho de atuadores SMA requer-se um complexo sistema de controle e resfriamento, reduzindo-se o tempo de resposta do atuador e minimizando-se os efeitos da histerese. Neste trabalho, propõe-se um inovador sistema de resfriamento, baseado em pastilha termo-elétrica (efeito Seebeck-Peltier). Este método possui a vantagem de ser mais compacto e simples que outros métodos de resfriamento forçado. Um modelo matemático completo foi também desenvolvido...

Controlador de posição linear hidro-pneumático.; Hydro pneumatic linear position controller.

Jesus, Sidney Nogueira Pereira de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/03/2008 PT
Relevância na Pesquisa
55.86%
Nessa pesquisa é apresentada uma inovação tecnológica em aplicações de controle de posição em máquinas e/ou dispositivos: o Controlador de Posição Linear Hidro- Pneumático. Para os casos nos quais têm-se grandes esforços combinados com pequenos deslocamentos, normalmente esse trabalho é feito com o uso de Sistemas Servo-Hidráulcos nos quais, devido às características mencionadas do nicho de mercado visado pela presente proposta, representam um custo elevado quando comparado com a solução Hidro-Pneumática aqui descrita. Salienta-se a simplicidade da infra-estrutura requerida para a instalação dessa alternativa, e também a redução do desperdício energético com relação à tecnologia tradicional com a Servo-Hidráulica. Observou-se nos testes com o protótipo, um excelente desempenho do sistema em termos de rapidez de resposta, como ainda no quesito resolução de posicionamento cujos valores encontrados apresentam-se na casa de 0,05 segundos e 0,01 mm, respectivamente. O pequeno tamanho físico obtido com essa nova tecnologia é outro item relevante, permitindo-se o seu emprego em locais de reduzido espaço disponível. . Resultados de simulações numéricas e de testes experimentais são apresentadas, bem como perspectivas de desenvolvimentos futuros.; This research presents a technological innovation for applications in machine / device position control: the Hydro-Pneumatic Linear Position controller. In cases where great efforts are combined with small dislocations...

Técnicas de controle para posicionamento de múltiplos navios em operações de lançamento de estruturas submarinas.; Control techniques for multiple positioning vessels in launching operations of subsea structures.

Oshiro, Anderson Takehiro
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 28/08/2012 PT
Relevância na Pesquisa
45.92%
Este trabalho apresenta o desenvolvimento de uma técnica de controle cooperativo aplicado para embarcações dotadas de sistema de posicionamento dinâmico (sistema DP). Um caso ilustrativo é estudado: o lançamento de um equipamento submarino utilizando duas embarcações DP. Neste exemplo, o sistema cooperativo controla a distância relativa das duas embarcações DP. As vantagens deste método se da no aumento da janela operacional, na tensão no cabo de lançamento que pode ser reduzida pela metade, entre outras. Um mapeamento dinâmico foi obtido utilizando um simulador 2D simplificado previamente validado por comparação com testes experimentais e o simulador no domínio do tempo TPN Tanque de Provas Numérico. Nestes mapas, duas regiões foram definidas, de ocorrência e não ocorrência de afrouxamento nos cabos em função da distancia entre as embarcações, profundidade do equipamento submarino e período da onda. Este mapa definiu as posições desejadas das embarcações para cada profundidade do equipamento. Foi proposto um controle da posição relativa das embarcações tentando manter os movimentos do ponto de conexão em oposição de fase. Isto evita a ocorrência de afrouxamentos no cabo de lançamento. Para isso...

Modelagem e controle de atuador antagônico de liga de memória de forma.; Modelling and control of an antagonistic shape memory alloy actuator.

Ianagui, André Seiji Sandes
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 05/10/2012 PT
Relevância na Pesquisa
45.95%
Este trabalho apresenta a modelagem, identificação de parâmetros e projeto do sistema de controle de um atuador rotacional antagônico com refrigeração forçada baseado em fios de liga de memória de forma, tendo em vista a aplicação em manipuladores robóticos. O modelo é baseado na abordagem de transformação de fases por subcamadas, que leva em conta a alta não linearidade que ocorre devido à dinâmica de transformação de fases do fio de memória de forma (especialmente a alta histerese envolvida). Um algoritmo de otimização por meio de Programação Quadrática Sequencial é então usado para se estimar os parâmetros do modelo de difícil obtenção exata, como as temperaturas de transição de fase dos fios de liga de memória de forma e o coeficiente de convecção. A função objetivo adotada é o erro entre a posição medida experimentalmente e a posição obtida por meio de modelagem e simulação. Parte-se de valores de parâmetros iniciais de tabela para a aplicação do algoritmo. Os resultados são em seguida comparados e avaliados com experimentos independentes em malha aberta, com o modelo apresentando boa correlação com a planta para uma excitação de até 2,0 Hz. Por fim, um sistema de controle não linear por modos deslizantes baseado no modelo é desenvolvido e simulado utilizando o modelo estimado...

Planejamento e rastreamento de trajetorias e controle de posição atraves de algoritmos geneticos e redes neurais artificiais; Planning and tracking of trajectories and position control by genetic algorithms and artificial neural networks

Dionne Cavalcante Monteiro
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/10/2003 PT
Relevância na Pesquisa
55.84%
Neste trabalho os algoritmos genéticos e as redes neurais artificiais, técnicas de inteligência artificial, são empregadas para algumas das tarefas que podem ser realizadas por um braço de robô. Inicialmente os algoritmos genéticos são empregados para o controle de trajetória de um robô em um espaço de trabalho que possui a presença de um obstáculo. Operações como crossover e mutação são apresentadas, principalmente por estar-se tratando de trajetórias que são formadas por segmentos de retas. As redes neurais artificiais são testadas no controle direto de dois processos reais usados como paradigma: uma mesa XY e um pêndulo invertido acionado. Para tais processos, é utilizada uma estrutura bastante simplificada, onde a rede neural artificial fornece um ganho para o controlador proporcional que calcula o sinal de controle a ser aplicado. O erro do processo serve para treinar a rede neural sem ser considerado nenhum tipo de treinamento anterior, ou seja, todo o controle neural é executado em tempo real, além disso, uma função determina a taxa de aprendizagem do algoritmo back-propagation em função dos erro existentes nas malhas de controle dos processos. Como existem diversas variáveis para tais controladores neurais...

Variable structure position control of an industrial robotic manipulator

Mendes,M. F.; Kraus Jr.,W.; Pieri,E. R. de
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2002 EN
Relevância na Pesquisa
55.89%
The use of a robust position controller for a robotic manipulator moving in free space is presented. The aim is to implement in practice a controller that is robust to uncertainties in the model of the system, as well as being inexpensive from a computational point of view. Variable structure theory provides the technique for the design of such controller. The design steps are presented, first from a theoretical perspective and then applied to the control of a two degree-of-freedom manipulator. Simulation results that backed the implementation are presented, followed by the experiments conducted and the results that were obtained. The conclusion is that variable structure control is readily applicable to industrial robots for the robust control of positions.

Presynaptic Modulation of Ia Afferents in Young and Old Adults When Performing Force and Position Control

Baudry, Stéphane; Maerz, Adam H.; Enoka, Roger M.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.9%
The present work investigated presynaptic modulation of Ia afferents in the extensor carpi radialis (ECR) when young and old adults exerted a wrist extension force either to support an inertial load (position control) or to achieve an equivalent constant torque against a rigid restraint (force control) at 5, 10, and 15% of the maximal force. H reflexes were evoked in the ECR by stimulating the radial nerve above the elbow. A conditioning stimulus was applied to the median nerve above the elbow to assess presynaptic inhibition of homonymous Ia afferents (D1 inhibition) or at the wrist (palmar branch) to assess the ongoing presynaptic inhibition of heteronymous Ia afferents that converge onto the ECR motor neuron pool (heteronymous Ia facilitation). The young adults had less D1 inhibition and greater heteronymous Ia facilitation during the position task (79 and 132.1%, respectively) compared with the force task (69.1 and 115.1%, respectively, P < 0.05). In contrast, the old adults exhibited no difference between the two tasks for either D1 inhibition (∼72%) or heteronymous Ia facilitation (∼114%). Contraction intensity did not influence the amount of D1 inhibition or heteronymous Ia facilitation for either group of subjects. The amount of antagonist coactivation was similar between tasks for young adults...

Development of X-Y Servo Pneumatic-Piezoelectric Hybrid Actuators for Position Control with High Response, Large Stroke and Nanometer Accuracy

Chiang, Mao-Hsiung
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 25/03/2010 EN
Relevância na Pesquisa
45.88%
This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

Towards a Naturalistic Brain-Machine Interface: Hybrid Torque and Position Control Allows Generalization to Novel Dynamics

Chhatbar, Pratik Y.; Francis, Joseph T.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 24/01/2013 EN
Relevância na Pesquisa
46.01%
Realization of reaching and grasping movements by a paralytic person or an amputee would greatly facilitate her/his activities of daily living. Towards this goal, control of a computer cursor or robotic arm using neural signals has been demonstrated in rodents, non-human primates and humans. This technology is commonly referred to as a Brain-Machine Interface (BMI) and is achieved by predictions of kinematic parameters, e.g. position or velocity. However, execution of natural movements, such as swinging baseball bats of different weights at the same speed, requires advanced planning for necessary context-specific forces in addition to kinematic control. Here we show, for the first time, the control of a virtual arm with representative inertial parameters using real-time neural control of torques in non-human primates (M. radiata). We found that neural control of torques leads to ballistic, possibly more naturalistic movements than position control alone, and that adding the influence of position in a hybrid torque-position control changes the feedforward behavior of these BMI movements. In addition, this level of control was achievable utilizing the neural recordings from either contralateral or ipsilateral M1. We also observed changed behavior of hybrid torque-position control under novel external dynamic environments that was comparable to natural movements. Our results demonstrate that inclusion of torque control to drive a neuroprosthetic device gives the user a more direct handle on the movement execution...

Modelagem e controle de atuadores rob??ticos e ve??culos subaqu??ticos n??o tripulados

Gomes, Samuel da Silva
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
45.88%
Disserta????o(mestrado) - Universidade Federal do Rio Grande, Programa de P??s-Gradua????o em Engenharia Oce??nica, Escola de Engenharia, 2011.; Esta disserta????o trata da modelagem e do controle de um atuador rob??tico e de ve??culos subaqu??ticos n??o tripulados. Primeiramente o trabalho compara e valida experimentalmente dois modelos de atrito existentes na literatura (LuGre e Gomes). Desenvolve-se um controle de posi????o baseado em estrutura vari??vel para o atuador rob??tico do tipo harmonic-drive. Simula????es s??o realizadas a fim de verificar a robustez do controlador perante a varia????o param??trica em compara????o com o controle proporcional, integral e derivativo (PID). Resultados experimentais das aplica????es dos controles s??o obtidos mostrando desempenhos muito pr??ximos aos de simula????o. Posteriormente ?? feito um estudo sobre ve??culos subaqu??ticos n??o tripulados (Tatu?? e Nerov). A modelagem cinem??tica ?? descrita por ??ngulos de Euler e a modelagem din??mica inclui a intera????o da estrutura mec??nica do ve??culo com o meio aqu??tico e a a????o dos propulsores. Desenvolve-se um sistema de controle de posi????o e orienta????o utilizando estrutura vari??vel. Resultados de simula????o ilustram as caracter??sticas do controlador com incertezas param??tricas e correntes oce??nicas em compara????o com o PID usando a estrat??gia de lineariza????o por realimenta????o.; The subject of this dissertation is the modeling and control of a robotic actuator and also of unmanned underwater vehicles. Firstly...

Active Position Control of a Shape Memory Alloy Wire Actuated Composite Beam

Song, G.; Kelly, B.; Agrawal, B.N.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Relevância na Pesquisa
46.07%
The article of record as published may be found at http://dx.doi.org/10.1088/0964-1726/9/5/316; This paper presents the design and the experimental result of the active position control of a shape memory alloy (SMA) wire actuated composite beam. The composite beam has a honeycomb structure with SMA wires embedded in one of its face sheets for the active actuation. The potential applications of this experiment include thermo-distortion compensation for precision space structure, stern shape control for submarines, and flap shape control for aeronautical applications. SMA wires are chosen as the actuating elements due to their high recovery stress (>500 MPa) and tolerance to high strain (up to 6%). However, SMA wires are inherently nonlinear and pose a challenge for control design. A robust controller is designed and implemented to actively control the tip position of the composite beam. The experiment set-up consists of the composite beam with embedded SMA wires, a programmable current/voltage amplifier to actuate the SMA wires, an infrared laser range sensor to detect the beam tip displacement, and a real-time data acquisition and control system. The experimental result demonstrates the effectiveness of the robust control.This paper presents the design and the experimental result of the active position control of a shape memory alloy (SMA) wire actuated composite beam. The composite beam has a honeycomb structure with SMA wires embedded in one of its face sheets for the active actuation. The potential applications of this experiment include thermo-distortion compensation for precision space structure...

Position control of a 3 DOF compliant micro-motion stage

Lu, T.F.; Handley, D.; Yong, Y.
Fonte: IEEE; CD-ROM Publicador: IEEE; CD-ROM
Tipo: Conference paper
Publicado em //2004 EN
Relevância na Pesquisa
45.88%
This paper focuses on the open-loop and closed-loop position control of a three degree-of-freedom (DOF) compliant micro-motion stage with flexure hinges. This micro-motion stage has a parallel structure for better stiffness and accuracy than serial structures and is driven by three PZT stack actuators. It was discussed in the authors' previous paper that due to the limitation of current modeling methods for compliant mechanisms the derived kinematic model is not able to accurately describe the behavior of the investigated micro-motion stage. Therefore, an experimentally determined constant Jacobian matrix is used to relate the extensions of PZTs and the end-effector movement for position control. With the use of the experimentally determined Jacobian in open-loop control, the micro-motion stage is proved able to achieve good positioning accuracy. Nevertheless, the positioning accuracy is significantly improved by incorporating end-effector closed-loop control.

POSITION CONTROL OF A PNEUMATIC SYSTEM USING ADAPTIVE INTELLIGENT METHODS

Dehghan, Behrad
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
65.91%
Behrad Dehghan: Position Control of a Pneumatic System using Adaptive Intelligent Methods. M.A.Sc. Thesis, Queen’s University, June, 2012. A large body of research is devoted to the development of advanced control techniques to improve the positioning performance of pneumatic systems, which are known to be highly nonlinear systems. Although model based controllers show good results, the requirement for a system model makes these methods difficult to implement. So-called intelligent algorithms, such as neural networks and fuzzy rule based controllers, are attractive since they do not require a model. The performance of these controllers can be enhanced by adding an adaptive mechanism to adjust controller parameters in a continuous on-line fashion. The objective of this thesis was to explore different adaptive intelligent controllers for position control of a pneumatic system. The application was the x-axis and z-axis of a pneumatic gantry robot. They were tested independently for their ability to track step and sine wave trajectories. The rodded x-axis cylinder was an example of a short stroke low friction application. The rodless z-axis cylinder was an example of a long stroke high friction application. Five different controllers were tested: 1) PID...

CONTROL OF A PNEUMATIC SYSTEM WITH ADAPTIVE NEURAL NETWORK COMPENSATION

TAGHIZADEH, SASAN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
46.01%
Considerable research has been conducted on the control of pneumatic systems due to their potential as a low-cost, clean, high power-to-weight ratio actuators. However, nonlinearities such as those due to compressibility of air continue to limit their accuracy. Among the nonlinearities in a pneumatic system, friction can have a significant effect on tracking performance, especially in applications that use rodless cylinders which have higher Coulomb friction than rodded cylinders. Compensation for nonlinearities in pneumatic systems has been a popular area of research in pneumatic system control. Most advanced nonlinear control strategies are based on a detailed mathematical model of the system. If a simplified mathematical model is used, then performance is sensitive to uncertainties and parameter variations in the robot. Although they show relatively good results, the requirement for model parameter identification has made these methods difficult to implement. This highlights the need for an adaptive controller that is not based on a mathematical model. The objective of this thesis was to design and evaluate a position and velocity controller for application to a pneumatic gantry robot. An Adaptive Neural Network (ANN) structure was implemented as both a controller and as a compensator. The implemented ANN had online training as this was considered to be the algorithm that had the greatest potential to enhance the performance of the pneumatic system. One axis of the robot was used to obtain results for the cases of velocity and position control. Seven different velocity controllers were tested and their performance compared. For position control...

Model-based decoupling control method for dual-drive gantry stages : A case study with experimental validations

GARCÍA-HERREROS, Iván; KESTELYN, Xavier; GOMAND, Julien; COLEMAN, Ralph; BARRE, Pierre-Jean
Fonte: Control Engineering Practice - ELSEVIER Publicador: Control Engineering Practice - ELSEVIER
EN
Relevância na Pesquisa
55.85%
La version éditeur de cet article est disponible à l'adresse suivante : http://dx.doi.org/10.1016/j.conengprac.2012.10.010; Industrial motion control of dual–drive gantry stages is usually performed by position controllers acting independently on each actuator. This approach neglects the unbalance and the mechanical coupling between actuators, leading to poor positioning performances. To overcome this drawback, a model–based decoupling control is proposed. Initially, a dynamic model of the gantry stage is proposed. Once identified and validated,such model is written in terms of a decoupling basis. Then, by model inversion, a feedback feedforward decoupling control is presented. Experimental results show that, in comparison to the independent axis control approach, the proposed solution leads to improved motion control.; This research project is funded and supported by ETEL SA. http://www.etel.ch and the CIFRE research grant No. 448/2008 of the French National Association of Research and Technology.

Real-time Position Control of Concentric Tube Robots

Dupont, Pierre E.; Lock, Jesse; Itkowitz, Brandon
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 03/05/2010 EN
Relevância na Pesquisa
45.9%
A novel approach to constructing robots is based on concentrically combining pre-curved elastic tubes. By rotating and extending the tubes with respect to each other, their curvatures interact elastically to position and orient the robot's tip, as well as to control the robot's shape along its length. Since these robots form slender curves, they are well suited for minimally invasive medical procedures. A substantial challenge to their practical use is the real-time solution of their kinematics that are described by differential equations with split boundary equations. This paper proposes a numerically efficient approach to real-time position control. It is shown that the forward kinematics are smooth functions that can be pre-computed and accurately approximated using Fourier series. The inverse kinematics can be solved in real time using root finding applied to the functional approximation. Experimental demonstration of real-time position control using this approach is also described.

A New Position Control Strategy for VTOL UAVs using IMU and GPS measurements

Roberts, Andrew; Tayebi, Abdelhamid
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.89%
We propose a new position control strategy for VTOL-UAVs using IMU and GPS measurements. Since there is no sensor that measures the attitude, our approach does not rely on the knowledge (or reconstruction) of the system orientation as usually done in the existing literature. Instead, IMU and GPS measurements are directly incorporated in the control law. An important feature of the proposed strategy, is that the accelerometer is used to measure the apparent acceleration of the vehicle, as opposed to only measuring the gravity vector, which would otherwise lead to unexpected performance when the vehicle is accelerating (i.e. not in a hover configuration). Simulation results are provided to demonstrate the performance of the proposed position control strategy in the presence of noise and disturbances.; Comment: Submitted to Automatica

Stability of position control of traveling waves in reaction-diffusion systems

Löber, Jakob
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/12/2013
Relevância na Pesquisa
45.87%
We consider the stability of position control of traveling waves in reaction-diffusion system as proposed in {[}J. L\"ober, H. Engel, arXiv:1304.2327{]}. Instead of analyzing the controlled reaction-diffusion system, stability is studied on the reduced level of the equation of motion for the position over time of perturbed traveling waves. We find an interval of perturbations of initial conditions for which position control is stable. This interval can be interpreted as a localized region where traveling waves are susceptible to perturbations. For stationary solutions of reaction-diffusion systems with reflection symmetry, this region does not exist. Analytical results are in qualitative agreement with numerical simulations of the controlled Schl\"ogl model.

On Replacing PID Controller with ANN Controller for DC Motor Position Control

Aamir, Muhammad
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/11/2013
Relevância na Pesquisa
45.9%
The process industry implements many techniques with certain parameters in its operations to control the working of several actuators on field. Amongst these actuators, DC motor is a very common machine. The angular position of DC motor can be controlled to drive many processes such as the arm of a robot. The most famous and well known controller for such applications is PID controller. It uses proportional, integral and derivative functions to control the input signal before sending it to the plant unit. In this paper, another controller based on Artificial Neural Network (ANN) control is examined to replace the PID controller for controlling the angular position of a DC motor to drive a robot arm. Simulation is performed in MATLAB after training the neural network (supervised learning) and it is shown that results are acceptable and applicable in process industry for reference control applications. The paper also indicates that the ANN controller can be less complicated and less costly to implement in industrial control applications as compared to some other proposed schemes.; Comment: 9 pages, 9 figures, 2 tables

Optimising position control of a solar parabolic trough

Naidoo,Puramanathan; van Niekerk,Theo I
Fonte: South African Journal of Science Publicador: South African Journal of Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 EN
Relevância na Pesquisa
46%
In today's climate of growing energy needs and increasing environmental concerns, alternatives to the use of non-renewable and polluting fossil fuels have to be investigated. One such alternative is solar energy. This study is based on the implementation of a mathematical computation - the PSA (Plataforma Solar de Almeria) computation developed at PSA (the European Test Centre for solar energy applications) - embedded in a control algorithm to locate the position of the sun. Tests were conducted on a solar parabolic trough (SPT) constructed at the Solar Thermal Applications Research Laboratory of the Mangosuthu University of Technology (Durban, South Africa) for optimal position control using the PSA value. The designed control algorithm embedded in an industrial Siemens S7-314 C-2PtP programmable logic controller compared the PSA computation to a measured position of the SPT to optimally rotate the SPT to a desired position with the constant movement of the sun. The two main angles of the sun relative to the position of the SPT on earth, the zenith angle and the azimuth angle, both calculated in the PSA from the vertical and horizontal planes, respectively, were applied to the control algorithm to generate an appropriate final tracking angle within a 0.007 radian (0º 24' 3.6") tolerance...