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 34 for “"air-bearing"”.
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Dynamic and Control of Air-Bearing Spacecraft Simulator
<p>An air bearing is being designed as a spacecraft rotational motion simulator, featuring the Sawyer Robot and its control box. The objective is to maneuver the robot as desired, performing operations specific to on-orbit servicing operations while maintaining stability of the system. Before the …
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Development of a microfabricated turbine-driven air bearing rig
… of integrating the radial-inflow turbine rotor, bearings, and gas interconnects into a small package. The rotor is a 300 µm thick, 4 millimeter diameter disk supported by a nominally 10 µm wide air journal bearing. This structure, called the microbearing rig, is not only a vehicle for the …
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The development of a novel air bearing device for aerodynamic flow control
… introduces a new novel method, a so called "air bearing device" (ABD) which provides both drag reduction and enhancement of lift.<br/><br/>The basic principle of this technique is to introduce a groove in the solid upper surface and an air stream is injected into one side of the groove and …
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Fast star tracker centroid algorithm for high performance CubeSat with air bearing validation
… computation time by a factor of 10 with a novel air bearing hardware testbed. This thesis also develops a high fidelity optical imager model in MATLAB Simulink. This model can be used to test centroiding algorithms and to simulate optical systems in a spacecraft pointing simulator. The model is …
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Experiments and numerical analysis on air bearing slumping of segmented thin-shell mirrors for X-ray telescopes
… preceding contact slumping, which utilizes a pair of porous air bearing mandrels through which compressed nitrogen is forced, with a thin piece of glass sheet floating between two thin layers of nitrogen during the thermal cycle. However, the underlying mechanism behind air bearing slumping …
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Study of Autonomous Capture and Detumble of Non-Cooperative Target by a Free-Flying Space Manipulator Using an Air-Bearing Platform
This thesis developed a 3-DOF satellite simulator with an attached 3-DOF manipulator to capture and detumble a target satellite simulator. Existing systems are heavily dependent on external systems to compute the position and orientation of the chaser and target satellite simulators. Using external …
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A fluid loop actuator for active spacecraft attitude control - A Parametric Sizing Model and the Design, Verification, Validation and Test with a Prototype on an Air Bearing
… to verify the model, as well as a spherical air bearing to verify the rotational aspects of the various fluid loop configurations. The model was applied to various hypothetical missions. In conclusion, the fluid loop has the fundamental potential to replace reaction wheels in a wide variety …
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The Distributed Spacecraft Attitude Control System Simulator: From Design Concept to Decentralized Control
… of the influences of gravity and friction. An air bearing provides a very low-torque environment for experimentation, thereby recapturing the freedom of the space environment as effectively as possible. Depending upon con- figuration, air-bearing systems provide some combination of …
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Advancements in the Design and Development of CubeSat Attitude Determination and Control Testing at the Virginia Tech Space Systems Simulation Laboratory
… The final test setup will consist of an air bearing platform placed inside a square Helmholtz cage. The Helmholtz cage will provide an adjustable magnetic field to simulate that of a low earth orbit (LEO), and the spherical air bearing will simulate the frictionless environment of space. …
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COMPLIANT END-EFFECTOR COUPLING FOR ROBOTIC ASSEMBLY
… during constrained motion. It features an air bearing, a variable stiffness air spring and a centre-locking mechanism. The end-effector assembly being centrally unlocked floats within the designed compliance limits assisted by the air bearing. These frictionless and free conditions …
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A laser speckle based position sensing technique
… laser beam is directed at the surface of an air-bearing spindle. An imaging system is set up to capture speckle patterns scattered from the spindle surface. These patterns are highly correlated over small angular displacements of the spindle. We use correlation-based image-processing …
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Design and fabrication of the MesoMill : a five-axis milling machine for meso-scaled parts
… wire capstan drives, ball-screw splines, and an air bearing spindle with an integral Z-axis.
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Adaptive Control Applied to the Cal Poly Spacecraft Attitude Dynamics Simulator
… Attitude Dynamics Simulator is a student-built air bearing spacecraft simulator controlled by four reaction wheels in a pyramidal arrangement. Tests were performed to determine the effectiveness of the two adaptive control theories under nominal operating conditions, a “plug-and-play” spacecraft …
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Applied System Identification for a Four Wheel Reaction Wheel Platform
… pyramidal simulator platform supported by an air-bearing. This simulator has the current capability to measure the wheel speeds and angular velocity of the platform, and with these measurements, the system identification process was used to obtain the mass properties of this simulator. A …
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Quantifying and modelling adaptive astronaut movement : motion strategies for long-duration spaceflight missions
… Experiments were conducted on a 1-G air-bearing floor microgravity simulator and underwater to provide contrasting dynamic and gravitational environments. Subjects performed leg push-offs and hand landings to demonstrate their control strategies as they adapted.
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Adaptive Control and Estimation of the Center of Mass of a 5-degree-of-freedom Spacecraft Testbed
… common way to simulate these conditions is with air-bearing-based testbeds. These testbeds reduce friction significantly to almost space-like conditions. Air-bearing technology can provide virtually frictionless translational and rotational motion. However, when frictionless rotational motion is …
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Direct simulation Monte Carlo (DSMC) in micro flows
… flows. Furthermore, 3-D micro flows in a slider air bearing and micro flows in a??slip flowa?? and a??transition flowa?? regime in micro ducts with different cross-sections are studied using present DSMC method.
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Design and qualification of an absolute thickness measuring machine
… machine was developed that uses a precision air-bearing XY stage to scan a target between two confocal displacement lasers that measure the profile of each side of the target. A NIST traceable gage block of known thickness is used to calculate the thickness of the target. This paper describes …
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Theoretical and Experimental Investigation of Attitude Control for Underactuated Spacecraft
… nonlinear control (QBNC) and NMPC. Finally, an air-bearing testbed with a floating satellite simulator that closely mimics the dynamics of a spacecraft is used to validate the use of NMPC for attitude control through experimentation. Air thrusters and a reaction wheel is used to perform two …
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Development and analysis of a small satellite attitude determination and control system testbed
… style, three degree of freedom, rotational air bearing, which uses four reaction wheels for attitude control and a series of sensors for attitude determination. The testbed includes all the equipment necessary to allow for closed loop testing of individual ADCS components and integrated ADCS …
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