While an infant is learning to grasp, there are two key processes that she uses for leading a successful development. In the first process, infants use an intuitional approach where the hand is moved towards the object to create an initial contact regardless of the object properties. The contact is followed by a tactile grasping phase where the object is enclosed by the hand. This intuitive grasping behavior leads an grasping mechanism, which utilizes visual input and incorporates this into the grasp plan. The second process is called scaffolding, a guidance by stating how to accomplish the task or modifying its behaviors by interference. Infants pay attention to such guidance and understand the indication of important features of an object from 9 months of age. This supervision mechanism plays an important role for learning how to grasp certain objects in a proper way. To simulate these behavioral findings, a reaching and a tactile grasping controller was implemented on iCub humanoid robot which allowed it to reach an object from different directions, and enclose its fingers to cover the object. With these, a human-like grasp learning for iCub is proposed. Namely, the first step is an unsupervised learning where the robot is experimenting how to grasp objects. The second step is supervised learning phase where a caregiver modifies the end-effectors position when the robot is mistaken. By doing several experiments for two different grasping styles, we observe that the proposed methodology shows a better learning rate comparing to the scaffolding-only learning mechanism.

This thesis focuses on the definition of a task for the determination, tracking and execution of a grasp on an unknown object. In particular, it is considered the case in which the object is ideally planar and the grasp has to be executed with a two-fingered, parallel-jaw gripper using vision as the source of sensor data. For the specification of this task, an architecture is defined that is based on three basic components -virtual sensors, filters, and actuators-, which can be connected to define a control loop. Each step in this task is analyzed separately, considering several options in some cases.Some of the main contributions of this thesis include: (1) the use of a modular approach to the specification of a control task that provides a basic framework for supporting the concept of behavior; (2) the analysis of several strategies for obtaining a compact representation of the contour of an object; (3) the development of a method for the evaluation and search of a grasp on a planar object for a two-fingered gripper; (4) the specification of different representations of a grasp and the analysis of their use for tracking the grasp between different views of an object; (5) the specification of algorithms for the tracking of a grasp along the views of an object obtained from a sequence of single images and a sequence of stereo images; (6) the definition of parametrized models of the target position of the grasp points and of the feasibility of this target grasp, and of an off-line procedure for the computation of some of the reference values required by this model; and (7) the definition and analysis of a visual servoing control scheme to guide the gripper of a robot arm towards an unknown object using the grasp points computed for that object as control features.

Pickup and delivery problems (PDPs) have been studied extensively in past decades. A wide variety of research exits on both exact algorithms and heuristics for generic variations of the problem as well as real-life applications, which continue to spark new challenges and open up new opportunities for researchers. In this dissertation, we study two variations of pickup and delivery problem that arise in industry and develop new computational methods that are shown to be effective with respect to existing algorithms and scheduling procedures found in practice. The first problem is the pickup and delivery problem with transshipment (PDPT). The work presented here was inspired by a daily route planning problem at a regional air carrier. In structuring the analysis, we describe a unique way to model the transshipment option on a directed graph. With the graph as the foundation, we implemented a branch and price algorithm. Preliminary results showed that it has difficulty in solving large instances. As an alternative, we developed a greedy randomized adaptive search procedure (GRASP) with several novel features. In the construction phase, shipment requests are inserted into routes until all demand is satisfied or no feasible insertion exists. In the improvement phase, an adaptive large neighborhood search algorithm is used to reconstruct portions of the feasible routes. Specialized removal and insertion heuristics were designed for this purpose. We also developed a procedure for generating problem instances in the absence of any in the literature. Testing was done on existing PDP data sets and generated PDPT data set. For the former, the performance and solution quality of the GRASP were comparable to the best known heuristics. For the latter, GRASP found the near optimal solution in most test cases. In the second part of the dissertation, we focus on a new version of the heterogeneous PDP in which the capacity of each vehicle can be modified by reconfiguring its interior to satisfy different types of customer demands. The work was motivated by a daily route planning problem arising at a senior activity center. A fleet of configurable vans is available each day to transport participants to and from the center as well as to secondary facilities for rehabilitative and medical treatment. To find solutions, we developed a two-phase heuristic that makes use of ideas from greedy randomized adaptive search procedures with multiple starts. In phase I, a set of good feasible solutions is constructed using a series of randomized procedures. A representative subset of those solutions is selected as candidates for improvement by solving a max diversity problem. In phase II, an adaptive large neighborhood search (ALNS) heuristic is used to find local optima by reconstructing portions of the feasible routes. Also, a specialized route feasibility check with vehicle type reassignment is introduced to take full advantage of the heterogeneous nature of vehicles. The effectiveness of the proposed methodology is demonstrated by comparing the solutions it provided for the equivalent of several weeks with those that were used in practice and derived manually. The analysis indicates that anywhere from 30% to 40% savings can be achieved with the multi-start ALNS heuristic. An exact method is introduced based on branch and price and cut for settings with more restricted time windows. In the procedure, the master problem at each node in the search tree is solved by column generation to find a lower bound. To improve the bound, subset-row inequalities are applied to the variables of the master problem. Columns are generated by solving the pricing subproblems with a labeling algorithm enhanced by new dominance conditions. Local search on the columns is used to quickly find promising alternatives. Implementation details and ways to improve the performance of the overall procedure are discussed. Testing was done on a set of real instances as well as a set of randomly generated instances with up to 50 customer requests. The results show that optimal solutions are obtained in majority of cases. / text

The reactive control of fingertip forces maintaining grasp stability was examined in man during a prehensile task. Blindfolded subjects used the precision grip between the tips of index finger and thumb to restrain an object that was subjected to unpredictable load forces. These were delivered tangential to the parallel grip surfaces of the object. Load forces, grip forces (perpendicular to the grip surfaces) and position of the object were recorded.Subjects automatically adjusted the grip forces to loads of various amplitudes and rates. Thereby they maintained a reliable safety margin against frictional slips without using excessive grip forces. A rapid rise in grip force lasting about 0.2 s was triggered after a short delay following the onset of a sustained ramp load increase. This 'catch-up' response caused a quick restoration of an adequate grip:load force ratio that prevented frictional slips. If the ramp load continued to increase after the catchup response, the grip force also increased in parallel with the load change in a 'tracking' manner. Consequently, during the hold phases of 'ramp-and-hold' loads, the employed grip forces were approximately proportional to the load amplitude. Sensory information about the rate of change of the load force parametrically scaled the 'catchup' and 'tracking' responses.Following anesthetic block of sensory input from the digits, the grip responses were both delayed and attenuated or even abolished. To compensate for these impairments, subjects had to voluntarily maintain exceedingly high grip forces to prevent the object from slipping. The grip control improved slightly during hand and forearm support conditions that allowed marked wrist movements to occur in response to the loading. This indicates that signals from receptors in muscles, joints or skin areas proximal to the digits can to some extent be used to adjust grip forces during impaired digital sensibility. In contrast, these signals had only minor influence on the control during normal digital sensibility.Grip responses to loads delivered in various directions revealed that the load direction, in relation to gravity and to the hand's geometry, represents intrinsic task variables in the automatic processes that maintain a stable grasp. The load direction influenced both the response latencies and the magnitudes of the grip responses. The response latencies were shortest for loads in directions that were the most critical with regard to the consequences of frictional slippage, i.e., loads directed away from the palm or in the direction of gravity. Recordings of signals in cutaneous afferents innervating the finger tips demonstrated that these effects on the response latencies depended on differences in the time needed by the central nervous system to implement the motor responses. The short latencies in the most ‘criticar load directions may reflect the preparation of a default response, while additional central processing would be needed to execute the response to loads in other directions. Adjustments to local frictional anisotropies at the digit-object interface largely explained the magnitude effects.In conclusion, grip responses are automatically adjusted to the current loading condition during unpredictable loading of a hand held object. Subjects call up a previously acquired sensorimotor transform that supports grasp stability by preventing both object slippage and excessive grip forces. Cutaneous sensory information about tangential forces and frictional conditions at the digit-object interface is used to initiate and scale the grip responses to the current loading conditions, largely in a predictive manner. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1995, Härtill 5 uppsatser</p> / digitalisering@umu

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-30Bitstream added on 2014-06-13T21:01:25Z : No. of bitstreams: 1 rahmani_m_dr_ilha.pdf: 1611068 bytes, checksum: 2b5fe6298f168bf850731b36fc9d3069 (MD5) / O estado da arte em modelagem matemática do problema de planejamento da expansão de sistemas de transmissão (TEP) é analisado nesta tese de doutorado. É proposto um novo modelo linear disjuntivo para o problema TEP baseado no conceito de sistemas de numeração binária para transformar o modelo linear disjuntivo convencional em um problema com um número de variáveis binárias e contínuas muito menores, assim como do número de restrições relacionadas com essas variáveis. Também é usada a fase construtiva da metaheurística GRASP e restrições adicionais, encontradas da generalização do equilibrio de fluxo de potência em uma barra ou conjunto de barras para reduzir o espaço de busca. Os resultados mostram a importância da estratégia de redução do espaço de busca do problema TEP para resolver os modelos de transporte e linear disjuntivo. O problema TEP multiestágio é modelado como um problema de programação linear binária mista e resolvido usando um solver do tipo branch and bound comercial com tempos de processamento relativamente baixos. Outro tópico pesquisado foi a alocação de dispositivos FACTS tais como os capacitores fixos em série (FSCs) para aproveitar melhor a capacidade de transmissão das linhas e adiar ou reduzir o investimento em novas linhas de transmissão em um ambiente de planejamento multiestágio. Assim, pode ser esperado uma excelente relação custo/benefício da integração de dispositivos FSCs no planejamento multiestágio da expansão de sistemas de transmissão. Os resultados encontrados usando alguns sistemas testes mostram que a inclusão de FSCs no problema TEP é uma estratégia válida e efetiva em investimento para as empresas transmissoras e para os responsáveis da expansão nacional do sistema elétrico. / State-of-the-art models for transmission expansion planning problem are provided in this thesis. A new disjunctive model for the TEP problem based on the concept of binary numerical systems is proposed in order to transform the conventional disjunctive model to a problem with many fewer binary and continuous variables as well as connected constraints. The construction phase of a greedy randomized adaptive search procedure (GRASP-CP) together with fence constraints, obtained from power flow equilibrium, are employed in order to reduce search space. The studies demonstrate that the proposed search space reduction strategy, has an excellent performance in reducing the search space of the transportation model and reduced disjunctive model of TEP problem. The multistage TEP problem is modeled as a mixed binary linear programming problem and solved using a commercial branch and bound solver with relatively low computational time. Another topic studied in this thesis, is the allocation of FACTS devices in TEP problem. FACTS devices such as fixed series capacitors (FSCs) are considered in the multistage TEP problem to beter utilize the whole transfer capacity of the network and, consequently, to postpone or reduce the investment in new transmission lines. An excellent benefit-cost ratio can be expected from integration of FSC in multistage transmission expansion planning. The results obtained by using some real test systems indicate that the inclusion of FSCs in the TEP problem is a viable and cost-effective strategy for transmission utilities and national planning bureaus.

Orientador: Rubén Augusto Romero Lázaro / Coorientador: Marcos Julio Rider Flores / Banca: José Roberto Sanches Mantovani / Banca: Antonio Cesar Baleeiro Alves / Banca: Sergio Luis Haffner / Banca: Gerson Couto de Oliveira / Resumo: O estado da arte em modelagem matemática do problema de planejamento da expansão de sistemas de transmissão (TEP) é analisado nesta tese de doutorado. É proposto um novo modelo linear disjuntivo para o problema TEP baseado no conceito de sistemas de numeração binária para transformar o modelo linear disjuntivo convencional em um problema com um número de variáveis binárias e contínuas muito menores, assim como do número de restrições relacionadas com essas variáveis. Também é usada a fase construtiva da metaheurística GRASP e restrições adicionais, encontradas da generalização do equilibrio de fluxo de potência em uma barra ou conjunto de barras para reduzir o espaço de busca. Os resultados mostram a importância da estratégia de redução do espaço de busca do problema TEP para resolver os modelos de transporte e linear disjuntivo. O problema TEP multiestágio é modelado como um problema de programação linear binária mista e resolvido usando um solver do tipo branch and bound comercial com tempos de processamento relativamente baixos. Outro tópico pesquisado foi a alocação de dispositivos FACTS tais como os capacitores fixos em série (FSCs) para aproveitar melhor a capacidade de transmissão das linhas e adiar ou reduzir o investimento em novas linhas de transmissão em um ambiente de planejamento multiestágio. Assim, pode ser esperado uma excelente relação custo/benefício da integração de dispositivos FSCs no planejamento multiestágio da expansão de sistemas de transmissão. Os resultados encontrados usando alguns sistemas testes mostram que a inclusão de FSCs no problema TEP é uma estratégia válida e efetiva em investimento para as empresas transmissoras e para os responsáveis da expansão nacional do sistema elétrico. / Abstract: State-of-the-art models for transmission expansion planning problem are provided in this thesis. A new disjunctive model for the TEP problem based on the concept of binary numerical systems is proposed in order to transform the conventional disjunctive model to a problem with many fewer binary and continuous variables as well as connected constraints. The construction phase of a greedy randomized adaptive search procedure (GRASP-CP) together with fence constraints, obtained from power flow equilibrium, are employed in order to reduce search space. The studies demonstrate that the proposed search space reduction strategy, has an excellent performance in reducing the search space of the transportation model and reduced disjunctive model of TEP problem. The multistage TEP problem is modeled as a mixed binary linear programming problem and solved using a commercial branch and bound solver with relatively low computational time. Another topic studied in this thesis, is the allocation of FACTS devices in TEP problem. FACTS devices such as fixed series capacitors (FSCs) are considered in the multistage TEP problem to beter utilize the whole transfer capacity of the network and, consequently, to postpone or reduce the investment in new transmission lines. An excellent benefit-cost ratio can be expected from integration of FSC in multistage transmission expansion planning. The results obtained by using some real test systems indicate that the inclusion of FSCs in the TEP problem is a viable and cost-effective strategy for transmission utilities and national planning bureaus. / Doutor

Improving robotic manipulation is critical for robots to be actively useful in realworld factories and homes. While some success has been shown in simulation and controlled environments, robots are slow, clumsy, and not general or robust enough when interacting with their environment. By contrast, humans effortlessly manipulate objects. One possible reason for this discrepancy is that, starting from birth, humans have years of experience to collect data and develop good internal models of what happens when they manipulate objects. If robots could also learn models from a large amount of real data, perhaps they, too, could become more capable manipulators. In this thesis, we propose to improve robotic manipulation by solving two problems. First, we look at how robots can collect a large amount of manipulation data without human intervention. Second, we study how to build statistical models of robotic manipulation from the collected data. These data-driven models can then be used for planning more robust manipulation actions. To solve the first problem of enabling large data collection, we perform several different robotic manipulation experiments and use these as case studies. We study bin-picking, post-grasp manipulation, pushing, tray tilting, planar grasping, and regrasping. These case studies allow us to gain insights on how robots can collect a large amount of accurate data with minimal human intervention. To solve the second problem of statistically modeling manipulation actions, we propose models for different parts of various manipulation actions. First, we look at how to model post-grasp manipulation actions by modeling the probability distribution of where an object ends up in a robot’s hand, and how this affects its success rate at various tasks such as placing or insertion. Second, we model how robots can change the pose of an object in their hand with regrasp actions. Third, we improve on the place and pick regrasp action by modeling each separately with more data. These learned data-driven models can then be used for planning more robust and accurate manipulation actions.

abstract: Anticipatory planning of digit positions and forces is critical for successful dexterous object manipulation. Anticipatory (feedforward) planning bypasses the inherent delays in reflex responses and sensorimotor integration associated with reactive (feedback) control. It has been suggested that feedforward and feedback strategies can be distinguished based on the profile of grip and load force rates during the period between initial contact with the object and object lift. However, this has not been validated in tasks that do not constrain digit placement. The purposes of this thesis were (1) to validate the hypothesis that force rate profiles are indicative of the control strategy used for object manipulation and (2) to test this hypothesis by comparing manipulation tasks performed with and without digit placement constraints. The first objective comprised two studies. In the first study an additional light or heavy mass was added to the base of the object. In the second study a mass was added, altering the object's center of mass (CM) location. In each experiment digit force rates were calculated between the times of initial digit contact and object lift. Digit force rates were fit to a Gaussian bell curve and the goodness of fit was compared across predictable and unpredictable mass and CM conditions. For both experiments, a predictable object mass and CM elicited bell shaped force rate profiles, indicative of feedforward control. For the second objective, a comparison of performance between subjects who performed the grasp task with either constrained or unconstrained digit contact locations was conducted. When digit location was unconstrained and CM was predictable, force rates were well fit to a bell shaped curve. However, the goodness of fit of the force rate profiles to the bell shaped curve was weaker for the constrained than the unconstrained digit placement condition. These findings seem to indicate that brain can generate an appropriate feedforward control strategy even when digit placement is unconstrained and an infinite combination of digit placement and force solutions exists to lift the object successfully. Future work is needed that investigates the role digit positioning and tactile feedback has on anticipatory control of object manipulation. / Dissertation/Thesis / M.S. Bioengineering 2011

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2016-05-20T08:41:16Z No. of bitstreams: 1 texto completo.pdf: 1841361 bytes, checksum: 460f1d8d605da4af4e1d8d606edfaa05 (MD5) / Made available in DSpace on 2016-05-20T08:41:16Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1841361 bytes, checksum: 460f1d8d605da4af4e1d8d606edfaa05 (MD5) Previous issue date: 2007-10-26 / O pivô central é um sistema de irrigação de grande porte, que utiliza grandes quantidades de água durante seu funcionamento. A criação de uma escala de funcio- namento para os pivôs centrais que atuam compartilhando um mesmo recurso hídrico é uma solução para reduzir custos com energia elétrica e controlar o consumo de água visando evitar possíveis danos ambientais sem comprometer a eficácia na irrigação. Para encontrar tal solução, um modelo matemático que representa o problema foi criado e validado. Este modelo serviu de base para a construção de algoritmos que geram a escala de funcionamento dos pivôs centrais. Devido ao grau de complexidade do problema, o uso das metaheurísticas Simulated Annealing e GRASP foi adotado na busca de boas soluções em curto espaço de tempo. A aplicação das metaheurís- ticas foi feita de maneira simples, oferecendo a opção de modificar os parâmetros do problema, de acordo com as necessidades encontradas, sendo possível adaptar a forma de execução dos algoritmos à diferentes realidades. Uma interface que utiliza os al- goritmos desenvolvidos foi construída com o objetivo de facilitar a manipulação das informações de entrada e saída do sistema. Os resultados dos testes obtidos com o sistema utilizando ambos os algoritmos geraram soluções que atenderam plenamente a expectativa inicial sendo, inclusive, avaliados por profissionais da área. Além disto, um estudo de caso, utilizando os algoritmos desenvolvidos, foi realizado com base em informações reais do Projeto Colonização Paracatu Entre-Ribeiros, localizado na Bacia do Rio São Francisco, um dos maiores perímetros de irrigação com pivô central da América Latina. / The central pivot is an system of great importance, which uses much water resource during its working. The development of a working scale to the central pivots that act using one same water resource is a solution to reduce costs with electric energy and to control the water consumption being aimed at to avoid possible nature damages, without compromising its eficiency. To find such solution, a mathematical model that represents the problem was created and validated. This model was the base for the construction of algorithms which solving the scale of the central pivots. Due to the complexity of the problem, the use of metaheuristic Simulated Annealing and GRASP was adopted in the searches of good solutions in very small period of time. The application of the metaheuristics made very simply, offering the options to modify the parameters of the execution, in accordance with the found necessities, being possible to adapt the form of execution of the algorithms to the different realities. An interface that uses the algorithms was constructed with the objective to facilitate to the manipulation of the input and output of the system. The obtained results of tests with the system using both the algorithms had generated solutions that had taken care of the initial expectation fully being, also, evaluated for professionals of the area. Moreover, a case study, using the developed algorithms, were carried through with basis of information of the Project Colonização Paracatu Entre-Ribeiros, located in the Basin of the Rio São Francisco, one of the biggest perimeters of irrigation with central pivot of Latin America. / Dissertação antiga

Made available in DSpace on 2015-06-17T19:34:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-20. Added 1 bitstream(s) on 2015-06-18T12:47:16Z : No. of bitstreams: 1 000829891.pdf: 830355 bytes, checksum: fcd5ae47130818a153876fd967c1679d (MD5) / Neste trabalho propõe-se uma heurística especializada para a alocação ótima de bancos de capacitores para os sistemas de distribuição radiais, cujo objetivo é minimizar os custos devido às perdas de energia, sujeitas a certas restrições operativas do sistema elétrico de distribuição. Para realizar este objetivo foram desenvolvidos os seguintes tópicos: Um algoritmo heurístico construtivo, que tem como atividade principal a alocação de bancos de capacitores nas barras com demanda de potências reativas maiores e também procura uma solução inicial de minimização de custos das perdas de energia e uma metaheurística de busca em vizinhança variável descendente. Nessa metaheurística são implementadas estruturas de vizinhança adequadas para o problema de alocação de bancos de capacitores nas barras do sistema elétrico. A heurística especializada tem um novo conceito para a alocação ótima de bancos de capacitores ao desenvolver uma ferramenta amigável e poderosa de otimização no desenvolvimento de modelos matemáticos para os problemas de programação não linear inteiro misto. A heurística especializada foi implementada em linguagem de programação Fortran 90 e foram realizadas simulações com sistemas de distribuição radial de 33, 70 e 202 barras. Os resultados foram comparados com pesquisas que realizaram testes com esses sistemas elétricos. Assim, foi verificado um bom desempenho do algoritmo, pois gera soluções de boa qualidade atendendo a todas as restrições físicas e operacionais do problema / In this work we proposes a specialized heuristic algorithm for optimal allocation of capacitor banks in radial distribution systems, whose goal is to minimize costs due to energy losses, subject to some operational restrictions of the electric distribution system. To accomplish this goal the following subjects were developed: A constructive heuristic algorithm, which has as primary task the allocation of capacitor banks in buses with the most high-demand for reactive power and also search for an initial solution to minimize energy losses costs and a meta-heuristic which uses variable neighborhood descend search, in which we implemented appropriate neighborhood structures for the allocation problem of capacitor banks in electric system buses. The specialized heuristic uses a new concept for the optimal allocation of capacitor banks to develop a powerful and user-friendly optimization tool for the development of mathematical models for mixed integer nonlinear programming problems. The specialized heuristic was implemented in the programming language Fortran 90 and simulations were performed with radial distribution systems of 33, 70 and 202 buses. The results were compared with other research works that also tested with these electrical systems. Thus, it was verified that the algorithm has a good performance because it generates good quality solutions meeting all the physical and operational constraints of the problem