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  • 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.
101

Planejamento ótimo de trajetórias para um robô escalador. / Optimal trajectory planning for a climbing robot.

Lucas Franco da Silva 20 February 2018 (has links)
Este trabalho trata do planejamento de trajetórias que minimizam as perdas elétricas no KA\'I yxo, um robô escalador de árvores que tem por finalidade realizar monitoramento ambiental em florestas através da coleta de diferentes tipos de dados. Como essa aplicação requer que o robô permaneça em ambientes remotos, o estudo de técnicas que reduzam as perdas de energia a fim de que se aumente o tempo em operação do robô se mostra relevante, sendo a minimização das perdas elétricas uma contribuição importante nesse sentido. Estruturalmente, o KA\'I yxo consiste em um robô bípede com duas garras e quatro ligamentos interconectados por três juntas rotacionais. Além disso, seu mecanismo de andadura foi biologicamente inspirado na forma de locomoção observada em lagartas mede-palmos, o que permitiu tratar o robô como um manipulador industrial, cuja base é o ligamento associado à garra engastada e cujo efetuador é o ligamento associado à garra livre. Com isso, quando conveniente, o robô foi tratado em dois casos, conforme a garra que se encontra engastada. Inicialmente, realizou-se a modelagem matemática do robô, obtendo-se as equações cinemáticas direta e inversa, e dinâmicas, bem como o modelo das juntas segundo a abordagem do controle independente por junta. Posteriormente, formulou-se um problema de controle ótimo, solucionado através de um método numérico que o transformou em um problema de programação quadrática, que por sua vez foi resolvido iterativamente. Por fim, as trajetórias ótimas planejadas foram implementadas no robô real e, como forma de validação, as novas perdas elétricas foram comparadas com as das trajetórias anteriormente executadas pelo robô, determinando-se a correspondente economia de energia. / This work deals with the minimum-energy trajectory planning, related to the electrical losses, in KA\'I yxo, a tree-climbing robot that aims to perform environmental monitoring in forests through the collection of different types of data. As this application requires that the robot remains in remote environments, the study of techniques that reduce energy losses in order to increase the operation time of the robot is shown to be relevant, and the minimization of the electrical losses is an important contribution in this sense. Structurally, KA\'I yxo consists of a biped robot with two claws and four links interconnected by three revolute joints. In addition, its gait mechanism was biologically inspired in the form of locomotion observed in caterpillars, allowing to treat the robot as an industrial manipulator, which base is the link associated with the fixed claw and which end-effector is the link associated with the free claw. In consequence, when convenient, the robot was treated in two cases, according to the claw that is fixed. Initially, the mathematical model of the robot was developed, being obtained the forward and inverse kinematic and dynamic equations, as well as the model of the joints according to the independent joint control approach. Subsequently, an optimal control problem was formulated, which was solved through a numerical method that turned it into a quadratic programming problem, which in turn was solved iteratively. Finally, the planned optimal trajectories were implemented in the real robot and, as a form of validation, the new electrical losses were compared with those of the trajectories previously executed by the robot, being determined the corresponding energy saving.
102

Construção de separadores globalmente suaves para conjuntos de pontos no R2 e geração de base mínima / Construction of globally smooth separators for sets of points in R2 and generation of minimum basis

Malheiro, Ana Paula Resende 18 August 2018 (has links)
Orientador: Jorge Stolfi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-18T02:35:56Z (GMT). No. of bitstreams: 1 Malheiro_AnaPaulaResende_D.pdf: 11382454 bytes, checksum: 9ea58ac7af766674dc90224444666560 (MD5) Previous issue date: 2011 / Resumo: Esta tese tem duas partes relativamente independentes. A primeira estuda o problema de construir uma curva suave (C1) que separa dois conjuntos de pontos do plano. Especificamente, a curva é definida por uma equação implícita F(x, y) = 0 onde F é uma spline polinomial de grau 2 com continuidade adequada. O objetivo é determinar uma única cônica se possível, senão uma curva que minimiza uma função quadrática de "energia". O problema é reduzido a um problema de minimização quadrática com restrições, que é resolvido por uma biblioteca existente (CGAL). A segunda parte descreve um algoritmo geral para determinar uma base de elementos finitos em um espaço de splines arbitrário, definido por exemplo por restrições lineares homogêneas de continuidade ou contorno. Neste caso o problema é caracterizado como o problema de encontrar uma base de peso máximo em um matróide e, portanto, pode ser resolvido pelo algoritmo guloso de Edmonds. Esse algoritmo tem custo exponencial no número n de células da malha. Entretanto, esta tese mostra que para casos de interesse - onde existe uma base de elementos finitos com suporte de k células, no máximo - o algoritmo pode ser melhorado de modo a terminar em tempo O(n km3), onde m é a dimensão do espaço (que é geralmente O(n)) / Abstract: This thesis has two relatively independent parts. The first part considers the problem of constructing a smooth (C1) curve separating two sets of points of the plane. Specifically, the curve is defined by an implicit equation F(x, y) = 0, where F is a polynomial spline of degree 2 with appropriate continuity. The goal is to determine a unique conic wherever possible, or a piecewise-defined curve that minimizes a quadratic "energy" function. The problem is reduced to a quadratic minimization problem with constraints, which is solved by an existing library (CGAL). The second part describes a general algorithm to determine a finite-element basis on an arbitrary space of splines; for example, a space defined by homogeneous linear boundary or continuity constraints. In this case the problem is defined as the problem of finding a maximum weight basis in a matroid, and therefore can be solved by the greedy algorithm of Edmonds. This algorithm has exponential cost in the number n of mesh cells. However, we show that for cases of interest - wherever there is a finite-element basis with maximum support of ? cells - the algorithm can be improved so as to finish in time O(n km3), where m is the dimension of the space (which is usually O(n)) / Doutorado / Ciência da Computação / Doutor em Ciência da Computação
103

Metodos de pontos interiores aplicados ao problema de pre-despacho de um sistema hidrotermico / Interior points methods for the hydrothermal scheduling problem

Probst, Roy Wilhelm 24 March 2006 (has links)
Orientador: Aurelio Ribeiro Leite de Oliveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-06T01:00:20Z (GMT). No. of bitstreams: 1 Probst_RoyWilhelm_M.pdf: 553863 bytes, checksum: a1307892a77da1b88d7536dd9027a4c3 (MD5) Previous issue date: 2006 / Resumo: Os métodos de pontos interiores primais-duais de trajetória central e preditor-corretor são desenvolvidos para o problema de minimização das perdas na geração e transmissão do pré-despacho DC de um sistema de potência hidrotêrmico e a estrutura matricial resultante explorada obtendo uma implementação eficiente. No pré-despacho de sistemas hidrotêrmicos, as usinas hidroelétricas têm uma meta a cumprir em um determinado dia, estabelecida pelo planejamento de longo prazo. As usinas termoelétricas, por sua vez, apresentam restrições de rampa, pois necessitam de um determinado tempo tanto para aumentar quanto para reduzir sua produção de energia. A implementação dos métodos de pontos interiores é testada em estudos de casos com sistemas IEEE / Abstract: The central path and the predictor-corrector primal-dual interior points methods are developed for the generation and transmission losses optimization problem for a DC power flow model in a hydrothermal power system and the resulting matrix structure is exploited leading to an efficient implementation. In short term hydrothermal scheduling, the hydro generating units need to satisfy daily targets, established by long-term scheduling models. The thermal generating units have ramp constraints because they need a certain amount of time to change de level of power delivery. Case studies with the developed interior point implementation for IEEE power systems are presented. / Mestrado / Pesquisa Operacional / Mestre em Matemática Aplicada
104

Modelagem e otimização de fermentadores para obtenção de etanol / Modelling and optimization of fermentors for ethanol production

Oliveira, Patricia Candioto Migliari 31 July 2007 (has links)
Orientador: Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-08T18:46:56Z (GMT). No. of bitstreams: 1 Oliveira_PatriciaCandiotoMigliari_D.pdf: 1584587 bytes, checksum: 8622cb86aacfe987908422e98c40d2c8 (MD5) Previous issue date: 2007 / Resumo: O trabalho envolveu modelo estruturado adaptado de um modelo estruturado de crescimento para processo de fermentação contínua realizado em um bioreator do tipo torre com células imobilizadas para produção de etanol. O modelo estruturado utilizado inclui equações de balanço para as rotas metabólicas fermentativa e respiratória, assim como termos cinéticos para o efeito de inibição pelo etanol, substrato e saturação celular no pellet. Os parâmetros cinético do modelo estruturado foram otimizados através da metodologia desenvolvida por Rivera (2005) onde envolve a aplicação de Algoritmo Genético, Planejamento Fatorial Fracionário proposto por Plackett Burman (1946) e Algoritmo Quasy Newton. Os resultados obtidos na simulação do modelo utilizando os parâmetros otimizados por esta metodologia representou de forma efetiva o modelo. A otimização do processo teve inicio com a Análise de Superfície de Resposta, que consistiu em um planejamento fatorial em estrela de dois níveis (-1 e +1) com um ponto central. A metodologia por Superfície de Resposta mostrou-se uma ferramenta poderosa para otimização preliminar das variáveis operacionais no sentido de que seus resultados foram usados como estimativas iniciais para o procedimento formal de otimização, SQP (Programação Quadrática Sucessiva). Esta metodologia de Superfície de resposta possibilita visualização do comportamento das variáveis que se quer otimizar, identificando a região do ponto ótimo, o que não é possível pelo método SQP. A metodologia SQP foi implementada com sucesso no modelo determinístico, obtendo as melhores condições de operação para as variáveis manipuláveis / Abstract: The work involved adapted of a structured model of growth structured model for process of continuous fermentation accomplished in a bioreator of the type tower with immobilized cells for etanol production. The used structured model includes reaction rate equations for the respiratory and glicolitic metabolic pathways, as well as kinetic terms for the inhibition effect for the etanol, substrate and cellular saturation in the pellet. The kinetic of the structured model parameters went optimized through to methodology developed by Rivera (2005) where it involves the application of Genetic Algorithm, methodology of Plackett¿Burman (1946) and Algorithm Quasi Newton. The results obtained in the simulation of the model using the parameters optimized for this methodology represented in an effective way the model. The optimization of the process had I begin with the Analysis of Surface of Answer, that consisted of a planning fatorial in star of two levels (-1 and +1) with a central point. The methodology for Surface of Answer a powerful tool was shown for preliminary optimization of the operational variables in the sense that its results were used as initial estimates for the formal procedure of optimization, SQP. This methodology of answer Surface facilitates visualization of the behavior of the variables that if that otimizar, identifying the area of the great point, what is not possible for the method SQP. The methodology SQP was implemented with success in the model deterministic, obtaining the best operation conditions for the variables manipulated. / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química
105

Métodos de programação quadrática convexa esparsa e suas aplicações em projeções em poliedros / Sparse convex quadratic programming methods and their applications in projections onto poliedra

Jeinny Maria Peralta Polo 07 March 2013 (has links)
O problema de minimização com restrições lineares e importante, não apenas pelo problema em si, que surge em várias áreas, mas também por ser utilizado como subproblema para resolver problemas mais gerais de programação não-linear. GENLIN e um método eficiente para minimização com restrições lineares para problemas de pequeno e médio porte. Para que seja possível a implementação de um método similar para grande porte, é necessário ter um método eficiente, também para grande porte, para projeção de pontos no conjunto de restrições lineares. O problema de projeção em um conjunto de restrições lineares pode ser escrito como um problema de programação quadrática convexa. Neste trabalho, estudamos e implementamos métodos esparsos para resolução de problemas de programação quadrática convexa apenas com restrições de caixa, em particular o clássico método Moré-Toraldo e o \"método\" NQC. O método Moré-Toraldo usa o método dos Gradientes Conjugados para explorar a face da região factível definida pela iteração atual, e o método do Gradiente Projetado para mudar de face. O \"método\" NQC usa o método do Gradiente Espectral Projetado para definir em que face trabalhar, e o método de Newton para calcular o minimizador da quadrática reduzida a esta face. Utilizamos os métodos esparsos Moré-Toraldo e NQC para resolver o problema de projeção de GENLIN e comparamos seus desempenhos / The linearly constrained minimization problem is important, not only for the problem itself, that arises in several areas, but because it is used as a subproblem in order to solve more general nonlinear programming problems. GENLIN is an efficient method for solving small and medium scaled linearly constrained minimization problems. To implement a similar method to solve large scale problems, it is necessary to have an efficient method to solve sparse projection problems onto linear constraints. The problem of projecting a point onto a set of linear constraints can be written as a convex quadratic programming problem. In this work, we study and implement sparse methods to solve box constrained convex quadratic programming problems, in particular the classical Moré-Toraldo method and the NQC \"method\". The Moré-Toraldo method uses the Conjugate Gradient method to explore the face of the feasible region defined by the current iterate, and the Projected Gradient method to move to a different face. The NQC \"method\" uses the Spectral Projected Gradient method to define the face in which it is going to work, and the Newton method to calculate the minimizer of the quadratic function reduced to this face. We used the sparse methods Moré-Toraldo and NQC to solve the projection problem of GENLIN and we compared their performances
106

Design of a large-scale constrained optimization algorithm and its application to digital human simulation

Nicholson, John Corbett 01 May 2017 (has links)
A new optimization algorithm, which can efficiently solve large-scale constrained non-linear optimization problems and leverage parallel computing, is designed and studied. The new algorithm, referred to herein as LASO or LArge Scale Optimizer, combines the best features of various algorithms to create a computationally efficient algorithm with strong convergence properties. Numerous algorithms were implemented and tested in its creation. Bound-constrained, step-size, and constrained algorithms have been designed that push the state-of-the-art. Along the way, five novel discoveries have been made: (1) a more efficient and robust method for obtaining second order Lagrange multiplier updates in Augmented Lagrangian algorithms, (2) a method for directly identifying the active constraint set at each iteration, (3) a simplified formulation of the penalty parameter sub-problem, (4) an efficient backtracking line-search procedure, (5) a novel hybrid line-search trust-region step-size calculation method. The broader impact of these contributions is that, for the first time, an Augmented Lagrangian algorithm is made to be competitive with state-of-the-art Sequential Quadratic Programming and Interior Point algorithms. The present work concludes by showing the applicability of the LASO algorithm to simulate one step of digital human walking and to accelerate the optimization process using parallel computing.
107

Convex relaxations in nonconvex and applied optimization

Chen, Jieqiu 01 July 2010 (has links)
Traditionally, linear programming (LP) has been used to construct convex relaxations in the context of branch and bound for determining global optimal solutions to nonconvex optimization problems. As second-order cone programming (SOCP) and semidefinite programming (SDP) become better understood by optimization researchers, they become alternative choices for obtaining convex relaxations and producing bounds on the optimal values. In this thesis, we study the use of these convex optimization tools in constructing strong relaxations for several nonconvex problems, including 0-1 integer programming, nonconvex box-constrained quadratic programming (BoxQP), and general quadratic programming (QP). We first study a SOCP relaxation for 0-1 integer programs and a sequential relaxation technique based on this SOCP relaxation. We present desirable properties of this SOCP relaxation, for example, this relaxation cuts off all fractional extreme points of the regular LP relaxation. We further prove that the sequential relaxation technique generates the convex hull of 0-1 solutions asymptotically. We next explore nonconvex quadratic programming. We propose a SDP relaxation for BoxQP based on relaxing the first- and second-order KKT conditions, where the difficulty and contribution lie in relaxing the second-order KKT condition. We show that, although the relaxation we obtain this way is equivalent to an existing SDP relaxation at the root node, it is significantly stronger on the children nodes in a branch-and-bound setting. New advance in optimization theory allows one to express QP as optimizing a linear function over the convex cone of completely positive matrices subject to linear constraints, referred to as completely positive programming (CPP). CPP naturally admits strong semidefinite relaxations. We incorporate the first-order KKT conditions of QP into the constraints of QP, and then pose it in the form of CPP to obtain a strong relaxation. We employ the resulting SDP relaxation inside a finite branch-and-bound algorithm to solve the QP. Comparison of our algorithm with commercial global solvers shows potential as well as room for improvement. The remainder is devoted to new techniques for solving a class of large-scale linear programming problems. First order methods, although not as fast as second-order methods, are extremely memory efficient. We develop a first-order method based on Nesterov's smoothing technique and demonstrate the effectiveness of our method on two machine learning problems.
108

Control system design using artificial intelligence

Tebbutt, Colin Dean January 1991 (has links)
Includes bibliography. / Successful multivariable control system design demands knowledge, skill and creativity of the designer. The goal of the research described in this dissertation was to investigate, implement, and evaluate methods by which artificial intelligence techniques, in a broad sense, may be used in a design system to assist the user. An intelligent, interactive, control system design tool has been developed to fulfil this aim. The design tool comprises two main components; an expert system on the upper level, and a powerful CACSD package on the lower level. The expert system has been constructed to assist and guide the designer in using the facilities provided by the underlying CACSD package. Unlike other expert systems, the user is also aided in formulating and refining a comprehensive and achievable design specification, and in dealing with conflicts which may arise within this specification. The assistance is aimed at both novice and experienced designers. The CACSD package includes a synthesis program which attempts to find a controller that satisfies the design specification. The synthesis program is based upon a recent factorization theory approach, where the linear multivariable control system design problem is translated into, and techniques efficiency solved as, a quadratic programming problem, which significantly improve the time and space of this method have been developed, making it practical to solve substantial multivariable design problems using only a microcomputer. The design system has been used by students at the University of Cape Town. Designs produced using the expert system tool are compared against those produced using classical design methods.
109

Constrained Control for Helicopter Shipboard Operations and Moored Ocean Current Turbine Flight Control

Ngo, Tri Dinh 30 June 2016 (has links)
This dissertation focuses on constrained control of two applications: helicopter and ocean current turbines (OCT). A major contribution in the helicopter application is a novel model predictive control (MPC) framework for helicopter shipboard operations in high demanding sea-based conditions. A complex helicopter-ship dynamics interface has been developed as a system of implicit nonlinear ordinary differential equations to capture essential characteristics of the nonlinear helicopter dynamics, the ship dynamics, and the ship airwake interactions. Various airwake models such as Control Equivalent Turbulence Inputs (CETI) model and Computation Fluid Dynamics (CFD) data of the airwake are incorporated in the interface to describe a realistic model of the shipborne helicopter. The feasibility of the MPC design is investigated using two case studies: automatic deck landing during the ship quiescent period in sea state 5, and lateral reposition toward the ship in different wind-over-deck conditions. To improve the overall MPC performance, an updating scheme for the internal model of the MPC is proposed using linearization around operating points. A mixed-integer MPC algorithm is also developed for helicopter precision landing on moving decks. The performance of this control structure is evaluated via numerical simulations of the automatic deck landing in adverse conditions such as landing on up-stroke, and down-stroke moving decks with high energy indices. Kino-dynamic motion planning for coordinated maneuvers to satisfy the helicopter-ship rendezvous conditions is implemented via mixed integer quadratic programming. In the OCT application, the major contribution is that a new idea is leveraged from helicopter blade control by introducing cyclic blade pitch control in OCT. A minimum energy, constrained control method, namely Output Variance Constrained (OVC) control is studied for OCT flight control in the presence of external disturbances. The minimum achievable output variance bounds are also computed and a parametric study of design parameters is conducted to evaluate their influence on the OVC performance. The performance of the OVC control method is evaluated both on the linear and nonlinear OCT models. Furthermore, control design for the OCT with sensor failures is also examined. Lastly, the MPC strategy is also investigated to improve the OCT flight control performance in simultaneous satisfaction of multiple constraints and to avoid blade stall. / Ph. D.
110

Controlling Autonomous Baker Robot Using Signal Temporal Logic and Control Barrier Functions

Bernpaintner, Gustav, Allen, Marcus January 2022 (has links)
Autonomous systems are slowly moving into the mainstream with things like self driving cars and autonomous robots in storage facilities already in use today. The aim of this project is to simulate a virtual bakery with a baker-robot (agent)that is able to complete recipes within strict deadlines.Signal temporal logic (STL) is used to define instructions that can be understood by the agent. In order to carry out these instructions, a control barrier function (CBF) is used.CBFs are time and state dependent, are used to describe the desired behavior of the agent, and are designer made. If the CBF corresponding to the task is non-negative from beginning to end during the task, the task has been completed successfully.A virtual robot was used in this project and was tasked with moving to and staying in different areas, which represents picking up and dropping off ingredients, all whilst staying within the boundaries of the bakery. The focus of this work is on completing the large amount (10+) of sequential tasks required to completea recipe. The CBF remained positive during the task, and the task was completed successfully. / Autonoma system börjar ta mer och mer plats i vardagen med saker som självkörande bilar och autonoma robotar i lagerlokaler som redan används idag. Syftet med det här projektet är att simulera ett virtuellt bageri med en bagarrobot (agent) som kan laga recept under strikta tidskrav. Signal temporal logic (STL) används för att definiera instruktioner som kan förstås av agenten. För att genomföra dessa instruktioner korrekt används en control barrier function (CBF). CBF:er är tidsoch tillståndsberoende, används för att beskriva agentens önskade beteende, och är skapade av en designer. Om CBF:en är positiv från början till slut under uppgiftens gång så har uppgiften genomförts som önskat. En virtuell robot användes i det här projektet och fick i uppdrag att flytta till och stanna inom olika områden, vilket representerar att plocka upp och lämna ingredienser, allt medan den vistas inom bageriets gränser. Fokus för detta arbete ligger på att slutföra den stora mängd (10+) av sekventiella uppgifter sim krävs för att laga ett recept. CBF:en var positiv under hela uppgiften, och uppgiften genomfördes framgångsrikt. / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm

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