The goal of this thesis is to develop a soft multiple-degree-of-freedom (multi-DOF) load cell that is robust and light weight for use in robotics applications to sense three axes of force and a single axis of torque. The displacement of the magnet within the elastomer changes the magnetic flux density which is sensed by two 3-axis Hall effect sensors. Experimental measurements of magnetic flux density within the area of interest were used to formulate analytic expressions that relate magnet field strength to the position of the magnet. The displacement and orientation measurement and the material properties of the elastomer are used to calibrate and calculate the applied load. The ability to measure 3-DOF force and axial torque was evaluated with combined loading applied by a robotic arm (KUKA, LBR r820 iiwa). The decoupled results show the 4-DOF load cell was able to distinguish 3-axis force and 1-axis torque with 6.9% averaged error for normal force, 4.3% and 2.6% for shear force in the X and Y axis and 8.6% for the torque. The results show good accuracy for a soft multi-axis sensor that would be applicable in many robotic applications where high accuracy is not required.

Industrial works in the sea, such as renewable energy or oil industries are dependent on underwater repairs which on great depths needs to be unmanned. Since the ability to sense and control applied forces is imperative to minimize damage on company property, the goal for this master thesis was toinvestigate and develop different force feedback control algorithms compatible with the Saab Seaeye eM1-7 electric manipulator, utilizing a 6-DOF load cell. This thesis addressed the conditions for the force feedback control and the behaviour of the control strategies in MATLAB and Gazebo. Tests with the manipulator concluded that force feedback control is possible with the suggested strategies but that the kinematic control needs further development in order to conduct simulations of assembly tasks which requires collaboration between the force feedback and kinematic control objectives.

I en kantviksmaskin som används för plåtbockning sker oönskade deformationer i mekanismen som klämmer fast arbetsmaterialet. Risken finns att deformationerna gör så arbetsmaterialet flyttas och det kan påverka positionen för bockningen.Målet med studien var att mäta laster och deformationer i kantviksmaskinen och sammanställa mätdata för att jämföra med FEM-analyser av konstruktionen och till grund för framtida arbete med maskinen. Problemet undersöktes genom att utföra mätningar med LVDT-givare och en lastcell. Mätresultatet visade att det blev en förskjutning och vid fastklämningen av arbetsmaterialet varierade klämkraften. FEM-analyserna kom upp i en lägre förskjutning än den uppmätta. Det finns då misstanke om att en del av förskjutningen kan bero på en mekanism för verktygsbyte. För att bekräfta detta behöver mätningar genomföras som kan visa bidraget av deformation från denna mekanism. FEM-analyserna gjordes med olika lastfördelning för att motsvara klämkraften. Analysen med en uppdelad last var baserad på klämkraftens fördelning som var uppmätt och det gav en fördelning av förskjutningen som var lik den uppmätta. För framtida analyser rekommenderas att använda denna eller en liknande lastfördelning. Utifrån mätningar och analyser konstateras det att överprismat böjs och vrids under klämningen. Detta i sin tur ändrar öververktygens position samt bidrar till att klämning inte sker i mittenpositionerna. / In an edge folding machine, used for sheet metal bending, which have undesired deformations in the mechanism that clamps the work material there is a risk that the deformations will cause the work material to be moved and this can affect the position of the bending. The aim of the study was to measure loads and deformations in the edge folding machine and compile measurement data to compare with FEM-analyzes of the design to get a basis for future work with the machine. The problem was investigated by carrying out measurements with LVDT-sensors and a load cell. The results showed that there was a displacement in the clamping of the work material and that the clamping force varied. The FEM-analyzes came up in a lower displacement than the measured one. A possible conjecture could be that a part of the displacement may be due to the tool change mechanism. To confirm this, measurements need to be performed which can show the contribution of deformation from this mechanism. The FEM-analyzes were made with different load distribution to correspond to the clamping force. The analysis with a divided load where the sectioning was based on the distribution of the clamping force that was measured gave a distribution of the displacement that was similar to the measured. For future analyzes it is recommended to use this or a similar load distribution. Based on measurements and analyzes it is found that the upper prism is bent and twisted during the clamping. This changes the position of the top tools and contribute to no clamping in the middle positions.

Continental glaciers covered as much as thirty percent of the present-day inhabited earth during the Quaternary period. Traditionally, one-dimensional consolidation has been considered as the main process of formation for the soils deposited during glaciation. One of the outcomes of accepting one-dimensional consolidation as the main process of formation is that the geomechanical properties of soil in a horizontal plane are isotropic (known as cross-anisotropy). Recent measurements of subglacial pore pressure and preconsolidation pressure profile have indicated that this might not be the case. The role of subglacial shear action has probably been long neglected. The main objective of this research is to investigate the effects of subglacial shearing on the geomechanical properties of glaciated soils. <p> Recent research has found evidence of horizontal property anisotropy associated with the direction of the ice-sheet movement. A testing program was thus proposed to explore the relationship between the anisotropy of property and the direction of past glacier movement. The program involves several fundamental engineering parameters of soils. These parameters together with the corresponding test methods are as follows: (i) Conventional oedometer test yield stress anisotropy; (ii) Oedometer test with lateral stress measurement stiffness anisotropy; (iii) Load cell pressuremeter (LCPM) test in situ stress anisotropy. <p> The physical meaning of yield stress determined by conventional oedometer tests was interpreted as the critical state of structural collapse. The literature review and an experimental study on kaolin samples with a known stress history suggested that yield stress possesses certain dependency on the sampling direction. The anisotropy of yield stress for Battleford till from Birsay, Saskatchewan was also explored by testing directional oedometer samples. In addition, the anisotropy of stiffness was also investigated using a newly developed lateral stress oedometer that is capable of independent measurement of horizontal stresses at three different points with angles of 120 degrees. Preliminary evidence of a correlation between the direction of maximum stiffness in a horizontal plane and the known direction of glacial shear was observed. The correlation between the direction of maximum yield stress and known direction of glaciation was rather poor. Anisotropy of in situ stresses was investigated by conducting LCPM tests in Pot clay in the Netherlands. Based on the LCPM test results, it was concluded that the evidence of a correlation between the anisotropy of in situ stress and known direction of glacial advance is still rather obscure. <p> Although both the laboratory studies and field studies cannot sufficiently confirm the existence of lateral anisotropy of geomechanical properties and its relationship to the direction of the Quaternary ice-sheet movement, the effects of subglacial shearing should not be neglected in assessing the geotechnical properties of glaciated soils. In practice, it is usually found that the preconsolidation pressure profile does not follow the gravitational line as predicted by the one-dimensional consolidation theory and its magnitude is not compatible with the measured effective pressure values at the base of the glacier. It has been suggested that changes in seepage gradient (upward or downward) are responsible for the deviation of preconsolidation pressure profile away from the gravitational line. In this thesis, a new glacial process model consolidation coupled shearing was proposed. This model is based on the framework of traditional soil mechanics (critical state theory, Modified Cam-clay model and one-dimensional consolidation theory) and is consistent with the general geological and glaciological evidences. This model may provide an alternative explanation for the preconsolidation pressure patterns generally observed in practice. It can also be combined with groundwater flow characteristics to explain the diversity of the preconsolidation consolidation patterns. The proposed model was used successfully to obtain the preconsolidation pressure profile observed in Battleford till at Birsay and the subglacial shear-softening phenomenon.

Continental glaciers covered as much as thirty percent of the present-day inhabited earth during the Quaternary period. Traditionally, one-dimensional consolidation has been considered as the main process of formation for the soils deposited during glaciation. One of the outcomes of accepting one-dimensional consolidation as the main process of formation is that the geomechanical properties of soil in a horizontal plane are isotropic (known as cross-anisotropy). Recent measurements of subglacial pore pressure and preconsolidation pressure profile have indicated that this might not be the case. The role of subglacial shear action has probably been long neglected. The main objective of this research is to investigate the effects of subglacial shearing on the geomechanical properties of glaciated soils. <p> Recent research has found evidence of horizontal property anisotropy associated with the direction of the ice-sheet movement. A testing program was thus proposed to explore the relationship between the anisotropy of property and the direction of past glacier movement. The program involves several fundamental engineering parameters of soils. These parameters together with the corresponding test methods are as follows: (i) Conventional oedometer test yield stress anisotropy; (ii) Oedometer test with lateral stress measurement stiffness anisotropy; (iii) Load cell pressuremeter (LCPM) test in situ stress anisotropy. <p> The physical meaning of yield stress determined by conventional oedometer tests was interpreted as the critical state of structural collapse. The literature review and an experimental study on kaolin samples with a known stress history suggested that yield stress possesses certain dependency on the sampling direction. The anisotropy of yield stress for Battleford till from Birsay, Saskatchewan was also explored by testing directional oedometer samples. In addition, the anisotropy of stiffness was also investigated using a newly developed lateral stress oedometer that is capable of independent measurement of horizontal stresses at three different points with angles of 120 degrees. Preliminary evidence of a correlation between the direction of maximum stiffness in a horizontal plane and the known direction of glacial shear was observed. The correlation between the direction of maximum yield stress and known direction of glaciation was rather poor. Anisotropy of in situ stresses was investigated by conducting LCPM tests in Pot clay in the Netherlands. Based on the LCPM test results, it was concluded that the evidence of a correlation between the anisotropy of in situ stress and known direction of glacial advance is still rather obscure. <p> Although both the laboratory studies and field studies cannot sufficiently confirm the existence of lateral anisotropy of geomechanical properties and its relationship to the direction of the Quaternary ice-sheet movement, the effects of subglacial shearing should not be neglected in assessing the geotechnical properties of glaciated soils. In practice, it is usually found that the preconsolidation pressure profile does not follow the gravitational line as predicted by the one-dimensional consolidation theory and its magnitude is not compatible with the measured effective pressure values at the base of the glacier. It has been suggested that changes in seepage gradient (upward or downward) are responsible for the deviation of preconsolidation pressure profile away from the gravitational line. In this thesis, a new glacial process model consolidation coupled shearing was proposed. This model is based on the framework of traditional soil mechanics (critical state theory, Modified Cam-clay model and one-dimensional consolidation theory) and is consistent with the general geological and glaciological evidences. This model may provide an alternative explanation for the preconsolidation pressure patterns generally observed in practice. It can also be combined with groundwater flow characteristics to explain the diversity of the preconsolidation consolidation patterns. The proposed model was used successfully to obtain the preconsolidation pressure profile observed in Battleford till at Birsay and the subglacial shear-softening phenomenon.

Made available in DSpace on 2014-06-11T19:22:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-05-30Bitstream added on 2014-06-13T20:47:51Z : No. of bitstreams: 1 freitas_rlb_me_ilha.pdf: 2701208 bytes, checksum: 5ab311e644d8a3837fea549fd3136b7e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho, descreve-se um sistema eletrônico informatizado implementado com o objetivo de medir a distribuição do peso corporal na região plantar de pacientes, visando relacioná-la diretamente à tipologia e deformidades dos pés e associando-a, indiretamente, a eventuais deformidades dos membros inferiores, coluna vertebral, algias músculoesqueléticas e instabilidades da postura humana. O sistema é constituído por células de carga com extensômetros, montadas em uma base metálica, circuito de condicionamento de sinais, circuito de interfaceamento e um display de cristal líquido. Foi construída uma plataforma piloto com 4 células de carga, mas o projeto do sistema prevê a construção de duas plataformas com 45 células de cargas, cada uma. As células de carga apresentaram resposta linear, precisão superior a 2%, resolução inferior a 0,5 N e histerese desprezível. São apresentados os resultados de medições, efetuadas com o sistema, para medir a distribuição de forças nas quatro células de carga, quando se aplicou sobre elas um peso conhecido. As informações foram apresentadas em um display de cristal líquido e posteriormente serão apresentadas na tela de um computador, por meio de um programa desenvolvido em Delphi, facilitando a visualização para especialistas da área, principalmente médicos, fisioterapeutas e terapeutas ocupacionais. Com o equipamento proposto será possível investigar, clinicamente, patologias estudadas pela Podologia, Posturologia e Podoposturologia, viabilizando, com as informações captadas pelo sistema, metodologias mais adequadas de tratamentos. / In this work we describe an electrical system implemented with the purpose of measuring the distribution of body weight in plantar region of patients, aiming to relate it directly to the typology and deformities of the feet and involving it, indirectly, to any deformities of the lower limbs, skeletal spine, muscle-skeletal pains and human posture instability. The system consists of load cells with strain gages within a metal base, signal conditioning circuit, interfacing circuit, and a liquid crystal display. A prototype platform with 4 load cells was built, but the system will have two platforms with 45 loads of cells, each one. The load cells presented linear response, precision better than 2%, resolution less than 0.5 N, and low hysteresis. We show the results of the force distribution when a know weight is applied over the four load cells. The informations have been presented in a liquid crystal display, but later they will be presented in the screen of a computer, facilitating the visualization for specialists, mainly doctors, physiotherapists and occupational therapists. With the proposed equipment it will be possible to investigate, clinically, pathologies studied by Podology, Posturology and Podoposturology making feasible, with the information obtained with the system, more appropriate methodologies of treatment.

Orientador: Aparecido Augusto de Carvalho / Banca: Nobuo Oki / Banca: Josivaldo Godoy da Silva / Resumo: Neste trabalho, descreve-se um sistema eletrônico informatizado implementado com o objetivo de medir a distribuição do peso corporal na região plantar de pacientes, visando relacioná-la diretamente à tipologia e deformidades dos pés e associando-a, indiretamente, a eventuais deformidades dos membros inferiores, coluna vertebral, algias músculoesqueléticas e instabilidades da postura humana. O sistema é constituído por células de carga com extensômetros, montadas em uma base metálica, circuito de condicionamento de sinais, circuito de interfaceamento e um display de cristal líquido. Foi construída uma plataforma piloto com 4 células de carga, mas o projeto do sistema prevê a construção de duas plataformas com 45 células de cargas, cada uma. As células de carga apresentaram resposta linear, precisão superior a 2%, resolução inferior a 0,5 N e histerese desprezível. São apresentados os resultados de medições, efetuadas com o sistema, para medir a distribuição de forças nas quatro células de carga, quando se aplicou sobre elas um peso conhecido. As informações foram apresentadas em um display de cristal líquido e posteriormente serão apresentadas na tela de um computador, por meio de um programa desenvolvido em Delphi, facilitando a visualização para especialistas da área, principalmente médicos, fisioterapeutas e terapeutas ocupacionais. Com o equipamento proposto será possível investigar, clinicamente, patologias estudadas pela Podologia, Posturologia e Podoposturologia, viabilizando, com as informações captadas pelo sistema, metodologias mais adequadas de tratamentos. / Abstract: In this work we describe an electrical system implemented with the purpose of measuring the distribution of body weight in plantar region of patients, aiming to relate it directly to the typology and deformities of the feet and involving it, indirectly, to any deformities of the lower limbs, skeletal spine, muscle-skeletal pains and human posture instability. The system consists of load cells with strain gages within a metal base, signal conditioning circuit, interfacing circuit, and a liquid crystal display. A prototype platform with 4 load cells was built, but the system will have two platforms with 45 loads of cells, each one. The load cells presented linear response, precision better than 2%, resolution less than 0.5 N, and low hysteresis. We show the results of the force distribution when a know weight is applied over the four load cells. The informations have been presented in a liquid crystal display, but later they will be presented in the screen of a computer, facilitating the visualization for specialists, mainly doctors, physiotherapists and occupational therapists. With the proposed equipment it will be possible to investigate, clinically, pathologies studied by Podology, Posturology and Podoposturology making feasible, with the information obtained with the system, more appropriate methodologies of treatment. / Mestre

<p>  </p> <p>Knot tying boards are low fidelity surgical simulators used to practice tying suture, but devices on the market currently provide no feedback and no way of changing out bands. A simple-to-use knot tying board with interchangeable bands capable of measuring force was designed. This board is comparable in cost to products currently available on the market. The knot tying board was then prototyped and tested. Four MD students completed trials of one-handed and two-handed knot tying with three throws per trail. In testing, the knot tying board was capable of measuring force data, such as peak force during knot tying and the final force the knot exerts on the bands. The device used in conjunction with experienced surgical skills coaches could prove a powerful tool for providing feedback to trainees, and a similar approach could be used with other low fidelity surgical simulators to improve feedback.</p>

No description available.

An investigation into the load-settlement behavior of two drilled shafts, founded in shale, is presented. The motivation for this research is to advance the understanding on how drilled shafts react under loading in stiff clays and shales. The objectives of the study are to measure the strengths within the subsurface material at the test site, estimate the unit side shear and unit end bearing of the shale-shaft interaction by running two axial load tests, and compare the results to the current design methods that are used to predict the axial capacity of drilled shafts. A comprehensive field investigation, performed by Fugro Consultants, provided strength profiles of the subsurface material at the test site. Through the cooperation of the Texas Department of Transportation (TxDOT), the Association of Drilled Shaft Contractors, and McKinney Drilling Company, two drilled shafts were installed at a highway construction site in Austin, Texas. The load tests were performed by Loadtest, Inc.; using the patented Osterberg-Cell™ loading technique to axially displace the shafts. Ensoft, Inc. installed strain gauges at multiple levels within the shafts, making it possible to analyze the shaft mobilization during loading. Ultimate end bearing values of about 100- and 120-ksf were measured for Test Shafts #1 and #2, respectively. The current methods for estimating unit end bearing, developed by TxDOT and the Federal Highway Administration, provide fairly accurate predictions when compared to the measured information. The ultimate side resistance obtained near the O-Cell™ in each test was about 20-ksf, however, the measured ultimate side resistance steadily decreased nearing the tip of the shaft. For the zones where the side resistance was believed to be fully mobilized, the TxDOT design method accurately predicts the side resistance. A limited amount of information is currently available for load tests performed in soils with TCP values harder than 2-in per 100 blows. Additional load test information should allow for a stronger correlation between TCP tests and unit resistances for very hard clay-shales, as well as, allowing for further evaluation of the shale-shaft interaction near the shaft tip. The results presented herein demonstrate the effectiveness of the current design methods for drilled shafts and the non-uniformity of side resistance within one- to two-diameters of the shaft tip. / text