L’analyse de tolérances par des ensembles de contraintes repose sur la détermination de l’accumulation de variations géométriques par des sommes et intersections d’ensembles opérandes 6d. Les degrés de liberté des liaisons et les degrés d’invariance des surfaces génèrent des opérandes non-bornés (polyèdres), posant des problèmes de simulation. En 2014, L. Homria proposé une méthode pour résoudre ce problème, consistant à ajouter des limites artificielles(contraintes bouchon) sur les déplacements non-bornés. Même si cette méthode permet la manipulation d’objets bornés (polytopes), les contraintes bouchon augmentent la complexité des simulations. En réponse à cette difficulté, une méthode dérivée est proposée dans cette thèse.Cette méthode consiste à tracer et simplifier les contraintes bouchon au travers des opérations.Puis une seconde stratégie basée sur la décomposition d’un polyèdre en une somme d’un polytope et de lignes droites (associées aux déplacements non-bornés). Cette stratégie consiste à simuler d’une part les sommes de droites, et d’autre part, à déterminer la somme de polytopes dans un sous-espace de dimension inférieur à 6. Ces trois stratégies sont comparées au travers d’une application industrielle. Cela montre que la traçabilité des contraintes bouchons est un aspect fondamental pour contrôler leur propagation et pour réduire le temps de calcul des simulations. Toutefois, cette méthode exige encore de déterminer les limites des déplacements non-bornés. La deuxième méthode, adaptant systématiquement la dimension de l’espace de calcul, elle permet de diminuer davantage le temps de calcul. Ce travail permet d’envisager la mise en oeuvre de cette méthode selon des formulations statistiques avec la prise en compte des défauts de forme des surfaces. / The cumulative stack-up of geometric variations in mechanical systems can be modelled summing and intersecting sets of constraints. These constraints derive from tolerance zones or from contact restrictions between parts. The degrees of freedom (DOF) of jointsgenerate unbounded sets (i.e. polyhedra) which are difficult to deal with. L. Homri presented in 2014 a solution based on the setting of fictitious limits (called cap constraints) to each DOFto obtain bounded 6D sets (i.e. polytopes). These additional constraints, however, increase the complexity of the models, and therefore, of the computations. In response to this situation,we defined a derived strategy to control the effects of the propagation of the fictitious limits by tracing and simplifying the generated, new cap constraints. We proposed a second strategy based on the decomposition of polyhedra into the sum of a polytope and a set of straight lines.The strategy consists in isolating the straight lines (associated to the DOF) and summing the polytopes in the smallest sub-space. After solving an industrial case, we concluded that tracing caps constraints during the operations allows reducing the models complexity and,consequently, the computational time; however, it still involves working in 6d even in caseswhere this is not necessary. In contrast, the strategy based on the operands decompositionis more efficient due to the dimension reduction. This study allowed us to conclude that the management of mechanisms’ mobility is a crucial aspect in tolerance simulations. The gain on efficiency resulting from the developed strategies opens up the possibility for doing statistical treatment of tolerances and tolerance synthesis.

Este trabalho aborda o projeto de um manipulador robótico cilíndrico acionado pneumaticamente de baixo custo e com 5 graus de liberdade. Este robô está sendo desenvolvido para realizar operações de movimentação de peças que venham a substituir postos de trabalho com ambiente insalubre e/ou de ações repetitivas nas quais as exigências de precisão, velocidade e capacidade de carga sejam limitadas. Os requisitos de projeto foram obtidos por meio de uma pesquisa em uma fábrica de ferramentas manuais. É apresentada a proposta de uma estrutura mecânica para suprir parte significativa das necessidades usuais de movimentação de peças em indústrias manufatureiras e o seu correspondente modelo teórico dinâmico não-linear, considerando o equacionamento dos atuadores pneumáticos acoplados ao sistema mecânico. Finalmente, é apresentado o projeto de um controlador linear por meio da técnica de realimentação de estados, com os ganhos definidos pela alocação de pólos a partir de um modelo linearizado de 3ª ordem. Para validação do modelo teórico e do algorítmo de controle propostos são apresentadas simulações de movimentação ponto a ponto e seguimento de trajetória. Os resultados mostram que a precisão de posicionamento do efetuador final é adequada para as tarefas de manipulação. / This work proposes the design of a low cost cylindrical robotic manipulator actuated pneumatically with 5 degrees of freedom. This robot is being developed to perform manipulation of parts, aiming to replace tasks usually performed in unhealthy environment and/or repetitive actions in which the requirements of accuracy, speed and load capacity are limited. The project requirements were obtained through a research in a manual tools factory. It is proposed a geometry that is intended to meet a significant amount of the usual moving parts demands in manufacturing industries and its corresponding nonlinear dynamic theoretic model, considering the pneumatic actuators model coupled to the mechanical system. Finally, the application of a linear control-law based on the technique of state feedback with design made by pole assignment using a linearized model of 3rd order is described. For validation of the theoretic model and proposed control algorithm are presented simulations of point to point regulation problem and trajectory tracking. The results show that the positioning accuracy of the end effector is suitable for achieving the planned tasks.

Real-time MRI scanning is used to visualize tissue and organs in motion. The real-time approach requires new interaction techniques to facilitate interaction with the scanning plane. The aim of this thesis is to investigate the use of input with six degrees of freedom – 6DOF. An overview over existing 6DOF input devices is given. Three devices are chosen for implementation and evaluation, Flock of Birds, SpaceBall and SpaceMouse. A simulator application is developed to test the different input devices. The simulator purpose is to imitate the real-time scanning situation. To be able to evaluate speed andaccuracy of the different interaction techniques, methods for measuring time and error are developed. A statistical survey is done on two different tasks to gather data of the interaction. The data is analyzed and the result is that the test subjects find the SpaceMouse superior to the other devices thanks to its kinesthetic feed-back properties and ergonomic benefits. However, the statistical data shows that Flock of Birds is the fastest device and no great difference is showed in accuracy between Flock of Birds and SpaceMouse. SpaceBall was the device that generated the least satisfying data.

Walking comes naturally to us and appears to be simple. However, this is not so and it is known that walking requires high level neural control and muscle coordination. There is no single, unifying theory of bipedal walking. Models of walking are useful in various ways such as developing computational theories of neural control, understanding muscle coordination and to design and analyze lower extremity prostheses. This thesis deals with modeling and simulation of walking from a kinematics and dynamics view point. Three sagittal planar models with increasing levels of complexity are presented in this thesis. The first model is a simple two degrees of freedom (DoF) model representing the motion at the hip and the knee joint. The second model is a three DoF model where the ankle joint motion is also taken into account. Finally, the third model considers both the legs and has seven DoF. The kinematic and dynamic equations of the models are derived, and the inverse dynamic analysis and forward dynamic simulation of the models are performed. The simulation results are compared with experimental data available in literature.

The successful prediction of spacecraft motion is often heavily based upon assumptions used to simplify the problem without compromising solution accuracy. For many analyses, a primary assumption used is the decoupling of trajectory and attitude dynamics when calculating trajectories. In cases where spacecraft or objects have high area to mass ratios, non-conservative effects such as atmospheric drag and solar radiation pressure can greatly perturb spacecraft translational motion based on rotational state. A modular, six degree of freedom (6DOF) simulation with coupled orbit and attitude dynamics has been developed to model spacecraft and orbits of arbitrary geometries. First, the basis for the modular rotational and translational equations of motion are introduced. Next, formulations are provided for the gravity gradient torque, solar radiation pressure, aerodynamic, and non-spherical gravity potential sources of perturbations, and the Marshall Engineering Thermosphere atmospheric model used is described. A first test case is performed using the 6DOF simulation to simulate the deorbit of the spacecraft Lightsail 1, which flew in 2015. Next, predictive cases are demonstrated using the simulation for a theoretical sail-boom-rocket combination representative of a debris removal scenario, and for the Aerodynamic Deorbit Experiement, which will demonstrate a passively stable drag sail technology and characterize its effectiveness on orbit. All simulation cases have had aerodynamic perturbation formulations compared against high fidelity Direct Simulation Monte Carlo runs, and suggestions have been made for the future development of the simulation tool.

This report presents a thesis done at the programme Master of Science in Engineering and Education at KTH and SU. This project aims to create a laboratory work trying to inspire students for the technical subjects (mathematics, physics, technology and computer science) and is conducted at the department IfU at RWTH University in Aachen, Germany. It is a part of the project RoboScope, developed in Germany to inspire young people to study more engineering. This laboratory work uses Lego Mindstorms and the students should work with robotics. The laboratory work is based on a theme; the students will build a robot that can complete a specific task, a rescue task in a nuclear power plant. The new parts in the laboratory work “Rescue Work” involve more interactivity, higher degree of freedom, older students and the programming is made in Java. The laboratory work uses the model of Brall. Evaluation of the laboratory work has been done together with colleagues at IfU and a group of school students. / Denna rapport redovisar ett examensarbete gjort på programmet Civilingenjör och Lärare på KTH och SU. Examensarbetets syfte är att skapa en laboration för att försöka inspirera studenter till de tekniska ämnena (matematik, fysik, teknik och datavetenskap) och är genomfört vid institutionen IfU på universitetet RWTH i Aachen, Tyskland. Den är en del av ett projekt RoboScope, drivet i Tyskland för att inspirera fler elever till att studera till ingenjörer. Denna laboration använder sig av Lego Mindstorms och studenterna arbetar med robotik. Laborationen utgår från ett tema och studenterna ska bygga en robot som kan genomföra den specifika uppgiften de blir tilldelade. Uppgiften är en räddningsaktion i ett kärnkraftverk. De nya delarna i denna laboration involverar mer interaktivitet, högre frihetsgrader, äldre elever och programmeringen genomförs i Java. Laboration använder sig av modellen av Brall. En utvärdering är gjord tillsammans med kollegor på IfU och en grupp av studenter.

This study seeks to understand upper limb tremor in subjects with essential tremor (ET). A thorough understanding of tremor distribution will allow for the more effective development of tremor suppression devices, which offer an alternative to current treatments. Previous studies primarily focused on tremor in the hand only. This study seeks to characterize the distribution of tremor throughout the upper limb.We measured tremor in 25 subjects diagnosed with ET using motion capture, which provided displacement information of the limb during multiple postural and kinetic tasks. Inverse kinematics allowed us to analyze the motion capture data in the 7 major degrees of freedom (DOF) of the upper limb. The power spectral density estimate was used to determine: relative tremor magnitude throughout the DOFs, tremor variation between tasks, variation between subjects, and frequency variations between DOFs. Data analysis revealed that tremor increase is roughly proximal to distal. We also show that tremor magnitude in kinetic tasks is significantly higher than in postural tasks. Although we found some variation in tremor distribution between subjects, the roughly proximal to distal increase in tremor severity holds for several subsets of the study population. Finally, we found that tremor frequency doesnt vary significantly (< 1 Hz) between DOFs, in subjects with severe tremor. Our study shows that tremor distribution is quite stereotyped between subjects with ET. Furthermore, we have shown that tremor is greatest in the distal DOFs. This provides a compelling starting point for the development of future tremor suppression devices.

No description available.

Optimizing launcher trajectories is essential for effective mission planning, and specialized software like ASTOS provide an initial, precise overview. However, as launcher development progresses, there is a growing need for the creation of an autonomous flight trajectory software that offers greaterflexibility in adjusting simulation parameters and better represents actual, real-life trajectories. Thisreport introduces an initial version of a comprehensive six-degree-of-freedom launcher trajectory calculation software developed using MATLAB and Simulink. The emphasis is on the development strategy, encompassing discussions on dynamics equations, essential features, and crucial models necessary for accurate simulations. Real-world scenarios often deviate from optimized trajectories, and the software addresses these deviations using sensitivity analysis through Monte Carlosimulations, enabling a thorough examination of uncertainties in input parameters and their impact on trajectories. The article delves into the establishment of the dispersion analysis tool and offers suggestions for further enhancements for both the Simulink model and this dispersion analysis tool. / Optimering av flygbanor är avgörande för effektiv uppdragsplanering, och specialiserad programvara som ASTOS ger en initial, exakt översikt. Men när flygbanans utveckling fortskrider finns det ett växande behov av att skapa en autonom flygbana som erbjuder större flexibilitet när det gäller attjustera simuleringsparametrar och bättre representerar faktiska, verkliga banor. Den här rapporten introducerar en initial version av en omfattande beräkningsprogramvara utvecklad med MATLAB och Simulink för sex frihetsgraders lanseringsbana. Tyngdpunkten ligger på utvecklingsstrategin, som omfattar diskussioner om dynamikekvationer, väsentliga funktioner och avgörande modeller som är nödvändiga för exakta simuleringar. Scenarier i verkligheten avviker ofta från optimerade banor, och programvaran adresserar dessa avvikelser med känslighetsanalys genom Monte Carlo-simuleringar,vilket möjliggör en grundlig undersökning av osäkerheter i inmatningsparametrar och deras påverkan på banor. Rapporten går in i skapandet av spridningsanalysverktyget och erbjuder förslag till ytterligare förbättringar för både Simulink-modellen och detta dispersionsanalysverktyg.

O fenômeno de vibrações induzidas pelo escoamento em pipelines e dutos próximos ao leito oceânico é de grande importância para a Engenharia Naval e Oceânica. O caso prático do vão livre de duto pode ser considerado um assunto ainda pouco discutido. A presente dissertação encontra motivação na compreensão do fenômeno fluidodinâmico através da abordagem experimental. O sistema físico estudado inclui um longo cilindro, de baixa razão de massa (m*) e de natureza flexível (L/D = 131; 45), disposto próximo à uma placa plana. O comportamento assimétrico do escoamento ao redor de um corpo que se encontra próximo à uma placa plana não é governado apenas pelo número de Reynolds, sendo a distância adimensional, e/D, entre o cilindro e a placa de grande impacto no fenômeno. O objetivo principal desta dissertação é caracterizar o comportamento dinâmico de cilindros flexíveis horizontais na presença de uma placa plana sob os efeitos do fenômeno da vibração induzida por vórtices, bem como a interferência na distância entre as duas estruturas na resposta dinâmica do cilindro. A revisão bibliográfica foi pautada na compreensão do problema e no fornecimento de subsídios teóricos para realização do experimento e posterior análise dos dados. O efeito da proximidade da placa foi analisado para quatro diferentes arranjos, e/D = 0, 0.5, 1.0 e 2.0 e variadas condições de escoamento foram testadas, todas contidas no regime sub-crítico (103 < Re < 104). Adicionalmente, a condição do cilindro isolado, ou seja sem a presença da placa, foi investigada. Obteve-se o deslocamento do cilindro, no tempo e espaço, possibilitando grande diversidade na demonstração dos resultados, destaca-se a análise no domínio da frequência e do tempo e a recuperação da trajetória em todos os instantes ao longo do comprimento do cilindro. Os resultados apresentados evidenciam uma magnitude de oscilação maior para as condições em que o cilindro está distante ou isolado da placa. Para todas as condições a natureza flexível do modelo pode ser identificada e discutida pela análise no domínio da frequência e da trajetória descrita pelo cilindro. Na maior parte dos casos, a amplitude transversal cresceu de maneira pronunciada a partir de VR > 3:50 e alcançou amplitudes nominais da ordem de 0.8D. A resposta na direção horizontal apresentou uma dependência linear com a velocidade do escoamento, atingindo valores próximos a 0.65D. Tal magnitude releva a importância do movimento na direção in-line, diferente dos clássicos casos de VIV, onde a amplitude em X é de pouca significância. / The present work aims at improving the understanding of flow induced vibrations on pipelines near the seabed triggered by the current. The present work aims at improving the understanding of flow induced vibrations on pipelines near the seabed triggered by the current, it is of great importance for Naval and Oceanic Engineering. The physical system includes a long cylinder, with low mass ratio (m*) and flexible (L=D = 131; 45), near a at plate. When a cylindrical body is laying close to a at plate, the asymmetric ow behavior around it is no longer solely dominated by the Reynolds number, but the adimensional distance e/D, between the cylinder and the at plate, play an important role in the phenomenon. The main objective of the research conducted is to characterize the behavior of exible horizontal cylinders under the efect of vortex induced vibrations, highlighting the in fluence of the distance between the two structures in the cylinder dynamic response. The experimental data was collected in a towing tank with a model scaled for e/D= 0, 0.5, 1.0, 2.0 and >> 2:0 and Reynolds number ranging from 103 to 104. The cylinder\'s response is presented in terms of its amplitude and frequency. The results shown a high magnitude of oscillation for the conditions in which the cylinder is distant or isolated from the plate. For all conditions the exible behavior was identified and discussed through the analysis in the frequency domain and the trajectory described by the cylinder. In most cases, the transverse amplitude grew steeply from VR > 3:50 and reached nominal amplitudes of the order of 0.8D. The response in horizontal direction showed a linear dependence with the flow velocity, reaching values close to 0.65D. Such magnitude highlights the importance of movement in the in-line direction, different from the classical cases of VIV.