Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"Contact dynamics"”.
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Aspects of computational contact dynamics
… for dealing with dynamic multi-body frictional contact problems. It is in fact a detailed account of an instance of the Contact Dynamics method by Moreau and Jean. Hence the title. Multi-body systems with contact constraints are common. Some of them, such as machines or arrangements of …
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A Statistical Approach to Modeling Wheel-Rail Contact Dynamics
The wheel-rail contact mechanics and dynamics that are of great importance to the railroad industry are evaluated by applying statistical methods to the large volume of data that is collected on the VT-FRA state-of-the-art roller rig. The intent is to use the statistical principles to highlight the …
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Effect of Wheel and Rail Conditions on Contact Dynamics and Mechanics
… conditions affect the wheel-rail interface (WRI) dynamics and mechanics under repeatable and precise test settings. The advanced roller rig is used to emulate wheel loads, lateral positions, angles of attack, cant angles, and creepages that commonly occur in a train. It features a quarter-scale …
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The influence of vapor pressure on droplet contact dynamics on smooth surfaces.
… was significant variance in the magnitude of the contact times at the same Weber numbers for different fluids. It is hypothesized that the vapor output from the droplets themselves, in the immediate area surrounding the droplet, impacts the air film dynamics, as this vapor is constituted by the …
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Planning, Sensing, and Control for Contact-rich Robotic Manipulation with Quasi-static Contact Models
… our palms, arms, body and legs to make and break contact with the manipuland whenever and wherever necessary. In contrast, the vast majority of robotic manipulators are artificially divided into a small end effector that makes all the interactions, and a hefty arm that needs to always remain …
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Model Predictive Control Approaches for Dynamic Table Tennis Swinging
… planning the return ball trajectory through the contact dynamics, and generating a swing to achieve it. This controller improves the hit rate of the system from 88.3% to 97.6% and significantly enhances strike condition accuracy and smoothness enabling control over the landing location and spin …
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Geometric Approaches for 3-Dimensional Shape Approximation
… models which represent the visual geometry and contact dynamics of arbitrary objects is important for achieving robust planning and control for robotic manipulation tasks and sim2real transfer. Currently, the most common solution for obtaining such models is generating them by hand. However, …
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Ultrasonic Welding of Glassy Thermoplastic Polymers
… and residual stress, the measurement of contact dynamics at the initiation of welding and the influence of polymer chain interdiffusion by reference to simple thermal welds. A description of defects present in an ultrasonic weld is given and this is extended to a proposed scheme for …
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Experimental characterization of the dynamic response of a mock-up CANDU fuel bundle
… cameras and laser displacement sensors. The contact dynamics between the fuel bundle and the pressure tube are replicated using a high precision custom-made setup. Also, the contact between the fuel bundle and the neighboring fuel bundles are replicated using dummy endplates. The results show …
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Augmenting physics simulators with neural networks for model learning and control
… many real-world control problems involve complex contact dynamics that cannot be characterized analytically. Therefore, most physics simulators employ approximations that lead to a loss in precision. We propose a hybrid dynamics model, combining a deterministic physical simulator with a stochastic …
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Application of Koopman Operator Theory to Legged Locomotion
… from complicated robot systems and harsh contact dynamics have long impeded the effectiveness of optimal control strategies for legged robots. In this work, we present a linearized simple walking model using Koopman Operator Theory, and its usage in Linear Model Predictive Control (L-MPC). …
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Modeling and control of undesirable dynamics in atomic force microscopes
… In this thesis, a detailed model of AFM dynamics has been developed. It includes a new model for the piezoelectric scanner coupled longitudinal and lateral dynamics, creep, and hysteresis. Models for probe-sample interactions and cantilever dynamics were also included. The models were …
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Policy regularized model predictive control framework for robust legged locomotion
… the key nonlinearities characteristic to legged contact dynamics while reducing the complexity of the continuous dynamics. Nominal footstep locations and feedforward forces for controlling the robot's center of mass are designed from simple physics-based heuristics for steady state legged …
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Roots adhesion processes in the Mediterranean seagrass Posidonia oceanica
… plasticity, forming adhesive pads that maximize contact. Peel tests identified optimal adhesion at substrate roughness between 3 and 26 µm. Electron microscopy revealed branching hairs and a glue-like substance at the interface, indicating a dual mechanism of mechanical interlocking and …
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Contact-aware and multi-modal robotic manipulation
… ability to effectively recognize and understand contact dynamics, which are critical for performing manipulation tasks beyond basic pick-and-place operations. This thesis argues and proves that contact awareness is essential for the successful deployment of robotic systems, not only in structured …
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Leveraging Structure for Efficient and Dexterous Contact-Rich Manipulation
Contact-rich manipulation has proved challenging due to the need to consider multiple combinatoric possibilities of making or breaking contact with the surrounding environment. As a result, existing methods have often resorted to combinatorial optimization that utilizes dynamics structure but …
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Autonomous rendezvous and docking with tumbling, uncooperative, and fragile targets under uncertain knowledge
… approach trajectory to soft docking, the contact dynamics of docking between two spacecraft, the optimization of the detumble procedure to bring the Target to stabilization, and adaptive control techniques to handle uncertainties in spacecraft knowledge. The software developed in support …
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The two-way street between discrete and continuum models of particle systems
… In such a suspension, the microstructure of the contact network between particles gives rise to macroscopic electrical conductivity. Developing this model consists of two phases: 1) developing a discrete model for the conductivity of a simplified network, and 2) embedding the discrete model into …
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Contact geometric theory of Anosov flows in dimension three and related topics
This thesis consists of the author's work on the contact and symplectic geometric theory of Anosov flows in low dimensions, as well as the related topics from Riemannian geometry. This includes the study of the interplay between various geometric, topological and dynamical features of such flows. …
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Non-smooth dynamics and sensitivity analysis of multibody systems with clearances and friction in differential variational inequality framework
… bodies to undergo a certain misalignment and the dynamics is governed by the contacts thus formed. The conventional formulations of joints as smooth algebraic constraints ignore the effect of clearances. To deal with contacts, and hence clearances, while the popular continuous dynamics approaches …
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