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Browsing by Author "Skidmore, Gary R."

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    Experimental-theoretical study of velocity feedback damping of structural vibrations
    Skidmore, Gary R. (Virginia Polytechnic Institute and State University, 1985)
    This study concerns the active damping of structural vibrations through the application of various forms of velocity feedback control. Active damping will be required for large space structures which are performance-sensitive to motion or inaccurate pointing. Several control forms, including modal-space active damping and direct rate feedback, are analyzed theoretically, and three laboratory models are described. A previous, unsuccessful attempt at control is reviewed and explained. The remaining control forms developed in the theoretical section were implemented successfully and the results compare favorably with theoretical predictions. Each control form is analyzed relative to its own merits and in comparison with other methods. An important point is the stability assured by a dual (colocated) configuration. of velocity sensors and control force actuators. Modal-space active damping is shown to be an effective control method with predictable performance in controlled modes and beneficial spillover into residual (non-controlled) modes.
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    A study of modal-space control of a beam-cable structure: experiment and theory
    Skidmore, Gary R. (Virginia Polytechnic Institute and State University, 1983)
    The objectives of this experimentally and to simulate study were to implement theoretically a method of active vibration control, known as modal-space control, on a relatively simple beam-cable structure. The control was implemented in analog form and provided modal viscous damping in each of the three modes of the structure. Transient response to initial conditions was analyzed experimentally and theoretically. Control hardware included permanent magnet-coil systems for the three control force actuators and the single velocity sensor, and an analog controller built around integrated circuit operational amplifiers. This thesis compares open-loop experimental response and closed-loop experimental and theoretical response on the basis of Fast Fourier Transforms of transient time data.