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 17 of 17 for “"Flexible beam"”.
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Parameter identification of a flexible beam using a modal domain optical fiber sensor
… is used for identification of a cantilevered beam under conditions of various concentrated mass loadings. A model of the sensor as well as the dynamic system is developed and used to test the reliability of the identification. Input/output data from an experiment is gathered and used in the …
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Experiments and simulations of large-angle flexible beam control using an adaptive truss
… adaptive truss with an appended flexible beam. Three cases are studied. The first case is an experimental and analytical investigation of flexible beam control using an adaptive truss positioned in an equilibrium configuration such that the beam is parallel to the gravity field. A …
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On falling spheres : the dynamics of water entry and descent along a flexible beam
… of the motion of a sphere on an inclined flexible beam. A theoretical model based on Euler-Bernoulli beam theory is developed to describe the dynamics, and in the limit where the beam reacts instantaneously to the loading, we obtain exact solutions for the sphere trajectory and descent …
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Investigations on Vortex-induced Vibration (VIV) Phenomena of Single-and-double-cylinder Flexible Beam Arrangements of Energy Harvesters
… a finite length cylinder fixed to one end of a flexible thin beam, is the research object in an incoming flow in the CCNY wind tunnel. We report on the efforts to improve the state-of-the-art harvester, called reconfigurable harvester, which has functions of changing its length (aspect ratio, …
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Theoretical and experimental study into the dynamics and control of a flexible beam with a DC-servo motor actuator
Position and vibration control of a flexible beam is studied analytically and in the laboratory. Two different motor types are compared as actuators throughout the thesis: a standard voltage controlled motor and a torque controlled motor. The experimental beam is controlled with a dc-servo motor at …
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Position control and vibration suppression of a flexible beam-like structure cantilevered from a rotary actuator within a gravitational field
… into the position and vibration control of beam-like structures within a gravity field using only root actuation was performed. Two methods were used to linearize the system's equations of motion. This, in turn, allowed for the use of powerful Modern Control Theory pole-location techniques …
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Design and fabrication of a test apparatus for lightweight flexible space modules for assembly
… made of lightweight materials, and will be very flexible. In MIT's Field and Space Robotics Lab (FSRL), algorithms are being developed to optimize the transportation and assembly of large, flexible structures. To test these algorithms, it is necessary to have laboratory flexible beam modules with …
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Estimation and control of flexible space structures for autonomous on-orbit assembly
… of the structure. Since these elements are often flexible and lack embedded actuators and sensors, the assembly robot must use its own actuators and onboard measurements to suppress vibrations during transportation maneuvers. This thesis will examine the dynamic modeling of a free-flying robot …
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Design of robust feedback control laws for high-dimensioned systems
… of feedback control laws for discrete models of flexible structures is addressed. Two strategies are proposed. First, a parameter optimization method is used, in which the behavior of the controller is described by a performance measure and numerically optimized. A second method, based on …
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Output feedback rotational maneuvers and vibration damping of Nasa Scole system by inversion theory
… vibration of the rigid space shuttle, the flexible beam and the reflector with an offset mass. The contribution of this thesis lies in the development of two control systems based on (i) Euler angles or (ii) angular velocity components as output variables for large rotational maneuvers and …
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Dynamics and control of a planar truss actuator
… of the truss are derived. A model for a generic flexible beam is then appended to the planar truss model. A linear time-invariant optimal control law is found, followed by a presentation of an experimental planar truss built to test the concept. Physical parameters are then substituted into the …
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Adaptive Augmentation of Non-Minimum Phase Flexible Aerospace Systems
… of direct adaptive augmentation on a robotic flexible system as an analogue of a large flexible aerospace structure such as a launch vehicle or aircraft. To that end, a robot was constructed as a control system testbed. This robot, named “Penny,” contains the command and data acquisition …
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Nonlinear attitude control of spacecraft with strain-actuated solar arrays
… of freedom cylinder (rigid body rotation) with flexible appendages (infinite-dimensional system). The equations of motion that describe system evolution are derived using the extend generalizations of the Lagrangian for infinite dimension systems. Precision attitude control is achieved by …
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The Effect of Adhesion on the Contact of an Elastica with a Rigid Surface
… of a elastica. The elastica acts as an extremely flexible beam and provides a structure that will permit measurable deformation of the solid by relatively small surface attractions. The ends of the elastica are lifted, bent, and clamped vertically at an equal height and specified distance apart. …
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Time-optimal and saturating controls with application to flexible structures
… slewing and vibration suppression of a flexible beam, possibly with a tip mass. This application arises in the design of large space structures and flexible lightweight and accurate robotic arms. The solution of the soft-constrained time-optimal control problem is expressed in terms of …
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A CFD study of fluid-structure interaction problems for floating offshore wind turbines
… fully coupled system where the wind turbine with flexible blades and the floating platform with its mooring system interact with each other in wind and waves, which makes old design tools inadequate.;This work aims to develop a fully coupled high-fidelity aero-hydro-mooring-elastic analysis tool, …
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An analytic model to predict detection threshold and performance data for misconvergence on a shadow-mask CRT
… phosphor-dot arrangement as well as the electron beam phase relationships. The model also includes a flexible beam profile which allows the user to specify the desired shape of the beam profile, that is, whether the profile is described with a Gaussian, leptokurtic, or platykurtic distribution. …