177 research outputs found

    Advance Servo Control for Hard Disk Drive in Mobile Application

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    Ph.DDOCTOR OF PHILOSOPH

    Robust periodic disturbance compensation via multirate control

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    Master'sMASTER OF ENGINEERIN

    A novel actuator controller: delivering a practical solution to realization of active-truss-based morphing wings

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    A novel actuator controller is proposed in this paper for active-truss-based morphing wings (ATBMWs). An ATBMW is a new type of smart structure capable of smooth and continuous profile change, and has the potential to provide better stealth and aerodynamic performance over airfoils with discrete control surfaces. However, the sophisticated ATBMW framework and large amount of highly interacted actuators make it difficult to obtain the overall rigid-body dynamics of the wing for controller design and inconvenient to tune controllers on board. The focus of this study is, thus, to solve the aforementioned problems by developing an actuator-level control scheme that does not rely on the wing rigid-body dynamics and on-board tuning. The linear-quadratic-Gaussian (LQG) controller is adopted for actuator trajectory tracking, and a novel unknown-input estimator (UIE) is devised to handle unmodeled dynamics. By integrating the UIE with the LQG algorithm, a new tracking controller with enhanced tolerance to uncertainties is constructed. It is shown in simulations and experiments on an ATBMW prototype that the proposed UIE-integrated LQG controller can be designed simply using the known actuator dynamics without on-board tuning, and superior trajectory tracking of actuators was observed despite the presence of unmodeled dynamics and exogenous disturbances.Difan Tang, Lei Chen, Eric Hu, and Zhao F. Tia

    ADVANCED SENSOR FUSION AND VIBRATION CONTROL TECHNOLOGIES FOR ULTRA-HIGH DENSITY HARD DISK DRIVES

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    Ph.DDOCTOR OF PHILOSOPH

    Parametric analysis for robust force/torque tracking control of a virtual stiffness-damping system in airfoil aeroelasticity testing

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    The force/torque tracking control of a virtual stiffness-damping system (VSDS) for airfoil aeroelasticity testing is studied in this paper. Existing test-beds rely on elastic elements or structures to set airfoil elasticity in tests, which can be costly and inconvenient in cases of frequent stiffness adjustment across a wide range. A possible alternative is the VSDS that utilizes electric drives to simulate the effects of structural elasticity and damping, as seen in marine and biomechanics engineering. However, the potential VSDS for airfoil aeroelasticity testing is more prone to transmission powerloss caused by generally unknown inputs including frictions as well as other un-modeled dynamics and disturbances, due to different operation principle and conditions compared with other existing VSDSs. This is a critical problem that can result in inaccurate virtual stiffness and damping. In this paper we tackle this problem by treating power loss as an unknown input and employing the linear-quadratic-Gaussian (LQG) tracking control enhanced by unknown-input estimation (UIE). A systematic procedure based on numerical study is proposed to investigate the effects of UIE-related parameters on system sensitivity and stability robustness. To confront uncertainties in parametric analysis, a stability robustness index is proposed. Findings from the proposed parametric analysis not only assist effective controller design but also correct and supplement the existing knowledge in literature. Wind-tunnel experiments were conducted with comparisons drawn between standard LQG tracking control and the UIE-LQG scheme, and satisfactory performance of the VSDS under the systematically synthesized UIE-LQG control was confirmed.Difan Tang, Lei Chen, Zhao Feng Tian and Eric H

    DISCRETE-TIME ADAPTIVE CONTROL ALGORITHMS FOR REJECTION OF SINUSOIDAL DISTURBANCES

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    We present new adaptive control algorithms that address the problem of rejecting sinusoids with known frequencies that act on an unknown asymptotically stable linear time-invariant system. To achieve asymptotic disturbance rejection, adaptive control algorithms of this dissertation rely on limited or no system model information. These algorithms are developed in discrete time, meaning that the control computations use sampled-data measurements. We demonstrate the effectiveness of algorithms via analysis, numerical simulations, and experimental testings. We also present extensions to these algorithms that address systems with decentralized control architecture and systems subject to disturbances with unknown frequencies

    Proceedings of the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications

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    The proceedings of the National Space Science Data Center Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications held July 23 through 25, 1991 at the NASA/Goddard Space Flight Center are presented. The program includes a keynote address, invited technical papers, and selected technical presentations to provide a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include magnetic disk and tape technologies, optical disk and tape, software storage and file management systems, and experiences with the use of a large, distributed storage system. The technical presentations describe integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's

    Design of an adaptive 3-dimensional display enabled by a swarm of autonomous micro air vehicles

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 149-151).This thesis is motivated by the concept of a system consisting of a swarm of small, automatically controlled air vehicles, each carrying a colour-controlled light source (payload), capable of executing coordinated maneouvres for the purpose of entertainment or data visualization. It focuses on a number of issues associated with the implementation of such a system, and specifically on the development of a non-linear, robust controller with feed-forward compensation, designed for control of a quad-rotor helicopter in the presence of aerodynamic interference generated by other vehicles in swarm-like operational conditions. System requirements and driving factors are identified, and various types of overall system architectures as well as vehicle designs are considered. The vehicle prototyping process is described, with specific emphasis on electronic design and hardware integration. Several problems associated with the flight of numerous vehicles in close proximity are addressed. Simulation and laboratory testing is described and results are presented and interpreted. Finally, consideration is given to the future development of such a system, as well as possible large-scale implementations and commercial opportunities.by Erich Mueller.S.M

    Robot manipulation in human environments

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 211-228).Human environments present special challenges for robot manipulation. They are often dynamic, difficult to predict, and beyond the control of a robot engineer. Fortunately, many characteristics of these settings can be used to a robot's advantage. Human environments are typically populated by people, and a robot can rely on the guidance and assistance of a human collaborator. Everyday objects exhibit common, task-relevant features that reduce the cognitive load required for the object's use. Many tasks can be achieved through the detection and control of these sparse perceptual features. And finally, a robot is more than a passive observer of the world. It can use its body to reduce its perceptual uncertainty about the world. In this thesis we present advances in robot manipulation that address the unique challenges of human environments. We describe the design of a humanoid robot named Domo, develop methods that allow Domo to assist a person in everyday tasks, and discuss general strategies for building robots that work alongside people in their homes and workplaces.by Aaron Ladd Edsinger.Ph.D
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