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 14 of 14 for “"Ball Screw"”.
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Design of an Underactuated Lower Body Exoskeleton Using a Pantograph
… is in stance, effectively pushing between the ball of the foot and the hips, and is disengaged during leg swing. This support force is provided by a linear actuator on each leg that consists of a compression spring, ball screw, and motor. It works by having the motor turn the ball screw, which …
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Design and fabrication of the MesoMill : a five-axis milling machine for meso-scaled parts
… machining centers including wire capstan drives, ball-screw splines, and an air bearing spindle with an integral Z-axis.
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Design of a low-cost high-performance flexural six degree-of-freedom positioning stage
… by six flexural legs that each ride on a ball screw assembly. The required degrees of freedom and range of motion for the flexural and rolling elements are analyzed. The stiffness and stress analysis of each element is presented along with a model for system level stiffness, inertia, and …
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Design and fabrication of a high precision wafer polishing machine
… a pneumatic piston, in parallel with a "rotary" ball screw. The x-axis moves the upper machine structure, which weighs over 2000 lbs. The x-axis has a travel of 82", a maximum velocity of 12 in/sec, a maximum acceleration of 0.2g's, a resolution of 10 microns, and a repeatability of 0.002". The …
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Design of Linear Series Elastic Actuators for a Humanoid Robot
… Operations Robot (THOR). The THOR SEA pairs a ball screw driven linear actuator with a configurable titanium leaf spring. A removable pivot changes the effective cantilever length, setting the compliance to either 372 or 655 kN/m. Unlike typical SEAs which measure actuator load through spring …
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Position and strain feedback control for shaping an active truss
… aluminum T-sections attached by one to three-ball screw actuators. The actuators have been pinned at each beam location to allow rotation during extension, while also allowing the effect of a variable number of actuators to be examined. The three-actuator arrangement enables independent …
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Design, Modeling and Control of Vibration Systems with Electromagnetic Energy Harvesters and their Application to Vehicle Suspensions
… electromagnetic energy harvester using a ball-screw mechanism and two one-way clutches for the application of replacing the viscous damper in vehicle suspensions. Compared to commercial linear harvesters, the proposed design is able to provide large damping forces and increase …
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Electromechanical systems to enhance the usability and diagnostic capabilities of ultrasound imaging
… The first system, a hand-held servo-driven ball screw stage, improves image repeatability by applying a constant, programmable contact force between the probe and the patient, and attenuates hand tremors by a factor of 10. The second system, a force/torque-measuring ultrasound probe, was …
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Design and evaluation of a reaction-force series elastic actuator configurable as biomimetic powered ankle and knee prostheses
… pole-count drone motor that directly drives a ball screw with a tunable, low-gear ratio lead. The design enables high dynamic range providing a closed-loop, torque-controlled joint that can demonstrate arbitrary levels of impedance. This control fidelity is important to support smooth control …
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Design of an Ankle Exoskeleton Employing Dual Action Plantarflexion Assistance and Gait Progression Detection
… an underlying Bowden cable system. The metric ball screw and BLDC motor implemented in the linear actuator were selectively chosen to minimize the motor torque and current required to assist wearers impacted by a degree of muscle weakness under an assistance-as-needed design paradigm. The …
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Development of a Variational Part Model Using In-Process Dimensional Measurement Error
… scheme assumes the machine tool's static error (ball screw error, joint misalignment, perpendicularity error, etc.) has been addressed by some other compensating method and this scheme only addresses the dynamic machining error. To create the Variational Part Model, the machined part is measured …
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Elements for the design of precision machine tools and their application to a prototype 450mm Si-wafer grinder
… compact precision machines. In particular, a ball screw preloaded height adjustable kinematic coupling and a magnetically preloaded hydrostatic thrust bearing were designed and built. The adjustable kinematic coupling allows for up to 8mm of vertical height adjust and 7N/nm stiffness at 26 kN …
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Design, Modeling and Tests of Electromagnetic Energy Harvesting Systems for Railway Track and Car Applications
… a unidirectional rotation of the generator. The ball screw mechanism is configured such that it has reduced backlash and thus can more efficiently harvest energy from low-amplitude vibrations. Two prototype harvesters are fabricated and tested extensively in the laboratory using a suspension …
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Model, Design, and Control for Power Conversion in Wave Energy Converter System
… components such as one-way clutches, gears, a ball screw, mechanical couplings, and generator are derived respectively to describe the dry frictions, viscous damping, and mechanical compliances in these components. The non-ideal efficiency and force of the PTO are predicted in electrical …