Técnicas inteligentes hídridas para o controle de sistemas não lineares

A neuro-fuzzy system consists of two or more control techniques in only one structure. The main characteristic of this structure is joining one or more good aspects from each technique to make a hybrid controller. This controller can be based in Fuzzy systems, artificial Neural Networks, Genetics Algorithms or rein forced learning techniques. Neuro-fuzzy systems have been shown as a promising technique in industrial applications. Two models of neuro-fuzzy systems were developed, an ANFIS model and a NEFCON model. Both models were applied to control a ball and beam system and they had their results and needed changes commented. Choose of inputs to controllers and the algorithms used to learning, among other information about the hybrid systems, were commented. The results show the changes in structure after learning and the conditions to use each one controller based on theirs characteristics

Influência da chuva após aplicação de imazamox sobre o controle de plantas daninhas aquáticas

This study aimed to evaluate the imazamox control efficiency on aquatic plants under different intervals of simulated rain after its spraying. The experiment was carried out in completely random design with four replications. The imazamox at 290.4 g ha(-1) was tested on three aquatic weed species, Eichhornia crassipes (Mart.) Solms, Pistia stratiotes L. and Salvinia adnata Desv and, under eight different rain-free periods (0, 2, 4, 6, 8, 12, 24 hours). Rainfall was simulated using a sprinkler irrigation system (20mm). There was a good control of Eichhornia crassipes, regardless of periods without rain after herbicide spraying. However, Pistia stratiotes took a rain-free period of at least eight hours to obtain an effective control. In Salvinia adnata, whole rain-free periods affected the control provided by the herbicide.

Lógica Fuzzy para Controle de pH em um Processo Petrolífero

This work proposes the design, the performance evaluation and a methodology for tuning the initial MFs parameters of output of a function based Takagi-Sugeno-Kang Fuzzy-PI controller to neutralize the pH in a stirred-tank reactor. The controller is designed to perform pH neutralization of industrial plants, mainly in units found in oil refineries where it is strongly required to mitigate uncertainties and nonlinearities. In addition, it adjusts the changes in pH regulating process, avoiding or reducing the need for retuning to maintain the desired performance. Based on the Hammerstein model, the system emulates a real plant that fits the changes in pH neutralization process of avoiding or reducing the need to retune. The controller performance is evaluated by overshoots, stabilization times, indices Integral of the Absolute Error (IAE) and Integral of the Absolute Value of the Error-weighted Time (ITAE), and using a metric developed by that takes into account both the error information and the control signal. The Fuzzy-PI controller is compared with PI and gain schedule PI controllers previously used in the testing plant, whose results can be found in the literature.

Ambiente de simulação híbrido integrando hysys e rede industrial Foundation Fieldbus aplicado ao controle de uma coluna de destilação

The main purpose of this work is to develop an environment that allows HYSYS R chemical process simulator communication with sensors and actuators from a Foundation Fieldbus industrial network. The environment is considered a hybrid resource since it has a real portion (industrial network) and a simulated one (process) with all measurement and control signals also real. It is possible to reproduce different industrial process dynamics without being required any physical network modification, enabling simulation of some situations that exist in a real industrial environment. This feature testifies the environment flexibility. In this work, a distillation column is simulated through HYSYS R with all its variables measured and controlled by Foundation Fieldbus devices

Sistema automatizado para o aproveitamento de água cinza e azul, com controle de PH utilizando lógica fuzzy

Every day, water scarcity becomes a more serious problem and, directly affects global society. Studies are directed in order to raise awareness of the rational use of this natural asset that is essential to our survival. Only 0.007% of the water available in the world have easy access and can be consumed by humans, it can be found in rivers, lakes, etc... To better take advantage of the water used in homes and small businesses, reuse projects are often implemented, resulting in savings for customers of water utilities. The reuse projects involve several areas of engineering, like Environmental, Chemical, Electrical and Computer Engineering. The last two are responsible for the control of the process, which aims to make gray water (soapy water), and clear blue water (rain water), ideal for consumption, or for use in watering gardens, flushing, among others applications. Water has several features that should be taken into consideration when it comes to working its reuse. Some of the features are, turbidity, temperature, electrical conductivity and, pH. In this document there is a proposal to control the pH (potential Hydrogen) through a microcontroller, using the fuzzy logic as strategy of control. The controller was developed in the fuzzy toolbox of Matlab®

Desacoplamento de um gerador síncrono através de um controle adaptativo por modelo de referência baseado em funções de Base radial

An alternative nonlinear technique for decoupling and control is presented. This technique is based on a RBF (Radial Basis Functions) neural network and it is applied to the synchronous generator model. The synchronous generator is a coupled system, in other words, a change at one input variable of the system, changes more than one output. The RBF network will perform the decoupling, separating the control of the following outputs variables: the load angle and flux linkage in the field winding. This technique does not require knowledge of the system parameters and, due the nature of radial basis functions, it shows itself stable to parametric uncertainties, disturbances and simpler when it is applied in control. The RBF decoupler is designed in this work for decouple a nonlinear MIMO system with two inputs and two outputs. The weights between hidden and output layer are modified online, using an adaptive law in real time. The adaptive law is developed by Lyapunov s Method. A decoupling adaptive controller uses the errors between system outputs and model outputs, and filtered outputs of the system to produce control signals. The RBF network forces each outputs of generator to behave like reference model. When the RBF approaches adequately control signals, the system decoupling is achieved. A mathematical proof and analysis are showed. Simulations are presented to show the performance and robustness of the RBF network

Identificação em tempo real de modelo dinâmico de robô móvel com acionamento diferencial e zona morta

Several mobile robots show non-linear behavior, mainly due friction phenomena between the mechanical parts of the robot or between the robot and the ground. Linear models are efficient in some cases, but it is necessary take the robot non-linearity in consideration when precise displacement and positioning are desired. In this work a parametric model identification procedure for a mobile robot with differential drive that considers the dead-zone in the robot actuators is proposed. The method consists in dividing the system into Hammerstein systems and then uses the key-term separation principle to present the input-output relations which shows the parameters from both linear and non-linear blocks. The parameters are then simultaneously estimated through a recursive least squares algorithm. The results shows that is possible to identify the dead-zone thresholds together with the linear parameters

Seletividade e eficiência agronômica de herbicidas no controle de capim-colchão na cultura da melancia

Foi avaliada a seletividade e a eficiência agronômica dos herbicidas clethodim e sethoxydim, no controle de Digitaria horizontalis (capim-colchão) na cultura da melancia (cv. Crimson Sweet). O experimento foi conduzido em campo, no município de Floresta, PR, em 1995/96, em delineamento de blocos ao acaso, com quatro repetições. Os tratamentos avaliados foram clethodim nas doses de 84; 96 e 108 g i.a./ha adicionado de 1,0 L/ha de óleo mineral (Dytrol), sethoxydim na dose de 230 g i.a./ha adicionado de 1,0 L/ha de óleo mineral (Assist) e testemunhas com e sem capina. Os herbicidas foram aplicados em pós-emergência, quando a melancia apresentava ramas com 1,4 m e a D. horizontalis em estádio de três folhas a três perfilhos e densidade de 240 plantas/m². Para a aplicação dos herbicidas utilizou-se pulverizador costal de pressão mantida por injeção de CO2, equipado com pontas de jato plano XR110.02 e volume de calda de 200 L/ha. As avaliações de seletividade (Escala E.W.R.C.) e controle das plantas daninhas (0 - 100%) foram efetuadas aos 7; 15 e 30 dias após aplicação dos tratamentos. Os resultados indicaram que o herbicida clethodim, a partir de 96 g i.a./ha, controlou eficientemente a D. horizontalis, sendo estatisticamente superior ao herbicida sethoxydim e à testemunha sem capina. Nenhum dos tratamentos químicos causou fitotoxicidade que afetasse o desenvolvimento e a produção da melancia. A D. horizontalis interferiu no desenvolvimento da cultura, causando redução média de 36,0% da produção da melancia.

Implementação de um sistema embarcado aplicado ao controle de pressão arterial

Hypertension is a dangerous disease that can cause serious harm to a patient health. In some situations the necessity to control this pressure is even greater, as in surgical procedures and post-surgical patients. To decrease the chances of a complication, it is necessary to reduce blood pressure as soon as possible. Continuous infusion of vasodilators drugs, such as sodium nitroprusside (SNP), rapidly decreased blood pressure in most patients, avoiding major problems. Maintaining the desired blood pressure requires constant monitoring of arterial blood pressure and frequently adjusting the drug infusion rate. Manual control of arterial blood pressure by clinical personnel is very demanding, time consuming and, as a result, sometimes of poor quality. Thus, the aim of this work is the design and implementation of a database of tuned controllers based on patients models, in order to find a suitable PID to be embedded in a Programmable Integrated Circuit (PIC), which has a smaller cost, smaller size and lower power consumption. For best results in controlling the blood pressure and choosing the adequate controller, tuning algorithms, system identification techniques and Smith predictor are used. This work also introduces a monitoring system to assist in detecting anomalies and optimize the process of patient care.

Enxertia em plantas de pimentão no controle da murcha de fitóftora em ambiente protegido

Avaliou-se a viabilidade de utilização da enxertia em plantas de pimentão (Capsicum annuum, L.), visando o controle da murcha de fitóftora. A pesquisa foi conduzida de setembro de 2000 a julho de 2001, na UNESP, Botucatu, em ambiente protegido. Adotou-se o delineamento experimental de blocos ao acaso, com 4 repetições e 5 plantas por parcela. Foram utilizados dois porta-enxertos resistentes a Phytophthora capsici, híbridos F1 de Capsicum annuum, e três híbridos comerciais suscetíveis (Elisa, Margarita e Magali-R). A enxertia foi realizada quando porta-enxertos e enxertos apresentavam respectivamente sete e três folhas verdadeiras, pelo método de garfagem fenda simples. Aos 14 dias após o transplante das mudas foi feita a inoculação do fungo, utilizando sementes de trigo infestadas pelo patógeno, depositadas ao redor do colo da planta. Quatro dias após a inoculação, e a partir daí a cada 15 dias, foram feitas avaliações que confirmaram a resistência dos porta-enxertos e a suscetibilidade das plantas não enxertadas. Observou-se bom nível de compatibilidade de enxertia em todas as combinações, precocidade de florescimento das plantas não enxertadas, manutenção de resistência à doença pelas plantas enxertadas durante todo o período e variações na altura das plantas em algumas combinações. Com relação à produção, verificou-se que os frutos mantiveram as características fenotípicas de cada híbrido, revelando que não houve interferência dos porta-enxertos neste aspecto. Concluiu-se haver viabilidade técnica de utilização da enxertia no controle da murcha de fitóftora em ambiente protegido.

Controle inteligente de pressão para uma rede sem reservatório de abastecimento urbano de água

The sanitation companies from Brazil has a great challenge for the XXI century: seek to mitigate the rate of physical waste (water, chemicals and electricity) and financial waste caused by inefficient operating systems drinking water supply, considering that currently we already face, in some cases, the scarcity of water resources. The supply systems are increasingly complex as they seek to minimize waste and at the same time better serve the growing number of users. However, this technological change is to reduce the complexity of the challenges posed by the need to include users with higher quality and efficiency in services. A major challenge for companies of water supplies is to provide a good quality service contemplating reducing expenditure on electricity. In this situation we developed a research by a method that seeks to control the pressure of the distribution systems that do not have the tank in your setup and the water comes out of the well directly to the distribution system. The method of pressure control (intelligent control) uses fuzzy logic to eliminate the waste of electricity and the leaks from the production of pumps that inject directly into the distribution system, which causes waste of energy when the consumption of households is reduced causing the saturation of the distribution system. This study was conducted at Green Club II condominium, located in the city of Parnamirim, state of Rio Grande do Norte, in order to study the pressure behavior of the output of the pump that injects water directly into the distribution system. The study was only possible because of the need we had to find a solution to some leaks in the existing distribution system and the extensions of the respective condominium residences, which sparked interest in developing a job in order to carry out the experiments contained in this research

Desenvolvimento de esquema de controle com realimentação visual para um robô manipulador

This work proposes a kinematic control scheme, using visual feedback for a robot arm with five degrees of freedom. Using computational vision techniques, a method was developed to determine the cartesian 3d position and orientation of the robot arm (pose) using a robot image obtained through a camera. A colored triangular label is disposed on the robot manipulator tool and efficient heuristic rules are used to obtain the vertexes of that label in the image. The tool pose is obtained from those vertexes through numerical methods. A color calibration scheme based in the K-means algorithm was implemented to guarantee the robustness of the vision system in the presence of light variations. The extrinsic camera parameters are computed from the image of four coplanar points whose cartesian 3d coordinates, related to a fixed frame, are known. Two distinct poses of the tool, initial and final, obtained from image, are interpolated to generate a desired trajectory in cartesian space. The error signal in the proposed control scheme consists in the difference between the desired tool pose and the actual tool pose. Gains are applied at the error signal and the signal resulting is mapped in joint incrementals using the pseudoinverse of the manipulator jacobian matrix. These incrementals are applied to the manipulator joints moving the tool to the desired pose

Algoritmos genéricos para otimização de uma arquitetura de controle inteligente híerárquico

A hierarchical fuzzy control scheme is applied to improve vibration suppression by using an electro-mechanical system based on the lever principle. The hierarchical intelligent controller consists of a hierarchical fuzzy supervisor, one fuzzy controller and one robust controller. The supervisor combines controllers output signal to generate the control signal that will be applied on the plant. The objective is to improve the performance of the electromechanical system, considering that the supervisor could take advantage of the different techniques based controllers. The robust controller design is based on a linear mathematical model. Genetic algorithms are used on the fuzzy controller and the supervisor tuning, which are based on non-linear mathematical model. In order to attest the efficiency of the hierarchical fuzzy control scheme, digital simulations were employed. Some comparisons involving the optimized hierarchical controller and the non-optimized hierarchical controller will be made to prove the efficiency of the genetic algorithms and the advantages of its use

Construção e controle inteligente de um manipulador robótico com dois graus de liberdade

The present work shows the development and construction of a robot manipulator with two rotary joints and two degrees of freedom, driven by three-phase induction motors. The positions of the arm and base are made, for comparison, by a fuzzy controller and a PID controller implemented in LabVIEW® programming environment. The robot manipulator moves in an area equivalent to a quarter of a sphere. Experimental results have shown that the fuzzy controller has superior performance to PID controller when tracking single and multiple step trajectories, for the cases of load and no load

Modelagem linear e identificação do modelo dinâmico de um robô móvel com acionamento diferencial

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